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Papers for Wednesday, Feb 14 2024

Papers with local authors

The relaxation of a weakly collisional plasma is described by the Boltzmann-Poisson equations with the Lenard-Bernstein collision operator. We perform a perturbative analysis of these equations, and obtain, for the first time, exact analytic solutions, enabling definitive resolutions to long-standing controversies regarding the impact of weak collisions on continuous spectra and Landau eigenmodes. Unlike some previous studies, we retain both damping and diffusion terms in the collision operator. We find that the linear response is a temporal convolution of a continuum that depends on the continuous velocities of particles, and discrete normal modes that encapsulate coherent oscillations. The normal modes are exponentially damped over time due to collective effects (Landau damping) as well as collisional dissipation. The continuum is also damped by collisions but somewhat differently. Up to a collision time, which is the inverse of the collision frequency νc, the continuum decay is driven by velocity diffusion and occurs super-exponentially over a timescale ν1/3c. After a collision time, however, the continuum decay is driven by the collisional damping of particle velocities and diffusion of their positions, and occurs exponentially over a timescale νc. This hitherto unknown, slow exponential decay causes perturbations to damp the most on scales comparable to the mean free path, but very slowly on larger scales, which establishes the local thermal equilibrium, the essence of the fluid limit. The long-term decay of the response is driven by the normal modes on scales smaller than the mean free path, but, on larger scales, is governed by the slowly decaying continuum and the least damped normal mode. Our analysis firmly establishes a long-sought connection between the collisionless and fluid limits of weakly collisional plasmas.

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Paper 4 — arXiv:2402.07978
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Paper 4 — arXiv:2402.07978

A new type of self-similarity is found in the problem of a plane-parallel, ultra-relativistic blast wave, propagating in a powerlaw density profile of the form ρzk. Self-similar solutions of the first kind can be found for k<7/4 using dimensional considerations. For steeper density gradients with k>2, second type solutions are obtained by eliminating a singularity from the equations. However, for intermediate powerlaw indices 7/4<k<2 the flow does not obey any of the known types of self-similarity. Instead, the solutions belong to a new class in which the self-similar dynamics are dictated by the non self-similar part of the flow. We obtain an exact solution to the ultra-relativistic fluid equations and find that the non self-similar flow is described by relativistic expansion into vacuum, composed of (1) an accelerating piston that contains most of the energy and (2) a leading edge of fast material that coincides with the interiors of the blastwave and terminates at the shock. The dynamics of the piston itself are self-similar and universal, and do not depend on the external medium. The exact solution of the non self-similar flow is used to solve for the shock in the new class of solutions.

Nick Loudas, Nikolaos D. Kylafis, Joachim E. Trümper

13 pages, 9 figures. Accepted for publication in A&A

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Paper 7 — arXiv:2402.07983
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Paper 7 — arXiv:2402.07983

Magnetic neutron stars (NSs) often exhibit a cyclotron resonant scattering feature (CRSF) in their X-ray spectra, but the site of the CRSF formation is still an open puzzle. A promising candidate for high-luminosity sources has always been the radiative shock (RS) in the accretion column. Yet, no quantitative calculations of spectral formation at the RS have been performed so far. Here we explore the scenario where the shock is the site of the CRSF formation. We study spectral formation at the RS and the emergent spectral shape across a wide range of the parameter space. We developed a Monte Carlo code to conduct radiation transfer simulations at the RS, adopting a fully relativistic scheme for the interaction between radiation and electrons. We properly treated bulk-motion Comptonization in the pre-shock region, thermal Comptonization in the post-shock region, and resonant Compton scattering in both regions. We calculated the angle- and energy-dependent emergent X-ray spectrum from the RS, focusing on both the CRSF and the X-ray continuum, under diverse conditions. We find that a power law, hard X-ray continuum and a CRSF are naturally produced by the first-order Fermi energization as the photons criss-cross the shock. The CRSF shape depends mainly on the transverse optical depth and the post-shock temperature. We show that the CRSF energy centroid is shifted by ~(20-30)% to lower energies compared to the classical cyclotron energy, due to the Doppler boosting between the shock frame and the bulk-motion frame. We demonstrate that a "bump" feature arises in the right wing of the CRSF due to upscattering of photons by the accreting plasma and extends to higher energies for larger optical depths and post-shock temperatures. The implications of the Doppler effect on the centroid of the emergent CRSF must be considered if an accurate determination of the magnetic field strength is desired.

Li-Jen Chen, Daniel Gershman, Brandon Burkholder, Yuxi Chen, Menelaos Sarantos, Lan Jian, James Drake, Chuanfei Dong, Harsha Gurram, Jason Shuster, Daniel Graham, Olivier Le Contel, Steven Schwartz, Hadi Madanian, Craig Pollock, Haoming Liang, Matthew Argall, Richard Denton, Rachel Rice, Jason Beedle, Kevin Genestreti, Akhtar Ardakani, Adam Stanier, Ari Le, Jonathan Ng, Naoki Bessho, Megha Pandya, Frederick Wilder, Christine Gabrieles, Ian Cohen, Hanying Wei, Christopher T. Russell, Robert Ergun, Roy Torbert, James Burch

15 pages, including 5 figures

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Paper 7 — arXiv:2402.08091
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Paper 7 — arXiv:2402.08091

In this paper, we report Magnetospheric Multiscale (MMS) observations of the dayside magnetosphere when the upstream Alfv\'en speed rises above the solar wind speed (sub-Alfv\'enic), causing the windsock-like magnetosphere to transform into Alfv\'en wings. The event occurred in the magnetic cloud of a Coronal Mass Ejection (CME) on April 24, 2023. We highlight the following outstanding features: (1) a layer of accelerated cold CME flow directly adjacent to the wing and to the magnetopause, which represents a rare regime of the terrestrial magnetosphere interaction with unshocked CME plasma; (2) moving filaments of the Alfv\'en wing created by magnetic reconnection, which represent new channels of connection between Earth's magnetosphere and the foot points of the Sun's erupted flux rope; (3) cold CME ion deceleration with little heating across the magnetopause. The reported MMS measurements advance our knowledge of CME interaction with planetary magnetospheres, and open new opportunities to further understand how sub-Alfv\'enic plasma flows impact astrophysical bodies such as Mercury, moons of Jupiter, and exoplanets that are close to their host stars.

John F. Wu, Christian Kragh Jespersen, Risa H. Wechsler

20 pages, 9 Figures, submitted to ApJ. Comments welcome!

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Paper 12 — arXiv:2402.07995
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Paper 12 — arXiv:2402.07995

We investigate the connection between galaxies, dark matter halos, and their large-scale environments with Illustris TNG300 hydrodynamic simulation data. We predict stellar masses from subhalo properties to test two types of machine learning (ML) models: Explainable Boosting Machines (EBMs) with simple galaxy environment features and E(3)-invariant graph neural networks (GNNs). The best-performing EBM models leverage spherically averaged overdensity features on 3 Mpc scales. Interpretations via SHapley Additive exPlanations (SHAP) also suggest that, in the context of the TNG300 galaxy--halo connection, simple spherical overdensity on 3 Mpc scales is more important than cosmic web distance features measured using the DisPerSE algorithm. Meanwhile, a GNN with connectivity defined by a fixed linking length, L, outperforms the EBM models by a significant margin. As we increase the linking length scale, GNNs learn important environmental contributions up to the largest scales we probe (L=10 Mpc). We conclude that 3 Mpc distance scales are most critical for describing the TNG galaxy--halo connection using the spherical overdensity parameterization but that information on larger scales, which is not captured by simple environmental parameters or cosmic web features, can further augment these models. Our study highlights the benefits of using interpretable ML algorithms to explain models of astrophysical phenomena, and the power of using GNNs to flexibly learn complex relationships directly from data while imposing constraints from physical symmetries.

G. P. Donnelly, J. D. T. Smith, B. T. Draine, A. Togi, T. S.-Y. Lai, L. Armus, D. A. Dale, V. Charmandaris

19 pages, 13 figures, accepted by The Astrophysical Journal

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Paper 24 — arXiv:2402.08123
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Paper 24 — arXiv:2402.08123

We present a focused study of radially-resolved varying PAH emission in the low-luminosity AGN-host NGC 4138 using deep Spitzer/IRS spectral maps. Using new model PAH spectra, we investigate whether these variations could be associated with changes to the PAH grain size distribution due to photodestruction by the AGN. Separately, we model the effects of the varying radiation field within NGC 4138, and we use this model to predict the corresponding changes in the PAH emission spectrum. We find that PAH band ratios are strongly variable with radius in this galaxy with short-to-long wavelength band ratios peaking in the starburst ring. The changing mix of starlight appears to have a considerable effect on the trends in these band ratios, and our radiation model predicts the shapes of these trends. However, the amplitude of observed variation is ~2.5 times larger than predicted for some ratios. A cutoff of small grains in the PAH size distribution, as has been suggested for AGN, together with changes in PAH ionization fraction could explain the behavior of the shorter bands, but this model fails to reproduce longer band behaviors. Additionally, we find that short-to-long wavelength PAH band ratios increase slightly within ~270pc of the center, suggesting that the AGN may directly influence PAH emission there.

S. Grandis, V. Ghirardini, S. Bocquet, C. Garrel, J. J. Mohr, A. Liu, M. Kluge, L. Kimmig, T. H. Reiprich, A. Alarcon, A. Amon, E. Artis, Y. E. Bahar, F. Balzer, K. Bechtol, M. R. Becker, G. Bernstein, E. Bulbul, A. Campos, A. Carnero Rosell, M. Carrasco Kind, R. Cawthon, C. Chang, R. Chen, I. Chiu, A. Choi, N. Clerc, J. Comparat, J. Cordero, C. Davis, J. Derose, H. T. Diehl, S. Dodelson, C. Doux, A. Drlica-Wagner, K. Eckert, J. Elvin-Poole, S. Everett, A. Ferte, M. Gatt, G. Giannini, P. Giles, D. Gruen, R. A. Gruendl, I. Harrison, W. G. Hartley, K. Herner, E. M. Huf, F. Kleinebreil, N. Kuropatkin, P. F. Leget, N. Maccrann, J. Mccullough, A. Merloni, J. Myles, K. Nandra, A. Navarro-Alsina, N. Okabe, F. Pacaud, S. Pandey, J. Prat, P. Predehl, M. Ramos, M. Raveri, R. P. Rollins, A. Roodman, et al.

27 pages, 18 figures, 2 appendices, submitted to A\&A

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Paper 47 — arXiv:2402.08455
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Paper 47 — arXiv:2402.08455

Number counts of galaxy clusters across redshift are a powerful cosmological probe, if a precise and accurate reconstruction of the underlying mass distribution is performed -- a challenge called mass calibration. With the advent of wide and deep photometric surveys, weak gravitational lensing by clusters has become the method of choice to perform this measurement. We measure and validate the weak gravitational lensing (WL) signature in the shape of galaxies observed in the first 3 years of the DES Y3 caused by galaxy clusters selected in the first all-sky survey performed by SRG/eROSITA. These data are then used to determine the scaling between X-ray photon count rate of the clusters and their halo mass and redshift. We empirically determine the degree of cluster member contamination in our background source sample. The individual cluster shear profiles are then analysed with a Bayesian population model that self-consistently accounts for the lens sample selection and contamination, and includes marginalization over a host of instrumental and astrophysical systematics. To quantify the accuracy of the mass extraction of that model, we perform mass measurements on mock cluster catalogs with realistic synthetic shear profiles. This allows us to establish that hydro-dynamical modelling uncertainties at low lens redshifts (z<0.6) are the dominant systematic limitation. At high lens redshift the uncertainties of the sources' photometric redshift calibration dominate. With regard to the X-ray count rate to halo mass relation, we constrain all its parameters. This work sets the stage for a joint analysis with the number counts of eRASS1 clusters to constrain a host of cosmological parameters. We demonstrate that WL mass calibration of galaxy clusters can be performed successfully with source galaxies whose calibration was performed primarily for cosmic shear experiments.

All other papers

Z. Eker, F. Soydugan, S. Bilir

26 pages, 7 figures and 2 tables, accepted for publication in Physics and Astronomy Reports

Developments on various relations among stellar variables such as the main sequence empirical mass-luminosity (MLR), mass-radius (MRR) and mass-effective temperature (MTR) relations were reviewed. Conceptual changes in their understanding and usages were discussed. After its discovery, MLR was treated as one of the fundamental secrets of the cosmos. Differences between fundamental laws and statistical relations were used to understand long-term developments of MLR, MRR and MTR. Developments show a break point, initiated by Andersen et al. (1991), in the line of progress. Before the break when reliable data were limited, MLR and MRR were calibrated using M, L, and R of binary components of all kinds visual, spectroscopic, and eclipsing for two purposes: i) obtaining mean mass, mean luminosity, and mean radius, ii) to estimate M and R of single stars. By the time of the break, the number of solutions from detached double-lined eclipsing binaries (DDEB) giving accurate M and R within a few percent levels are increased. Parameters from very close, semi-detached, and contact binaries were excluded for refinement, however, MLR and MRR diagrams were found insufficient to derive MLR and MRR functions because the dispersions are not only due to random observational errors but also due to chemical composition and age differences. Then, a new trend was adopted by replacing classical MLR and MRR with empirical M and R predicting relations. Thus, the purpose one was suppressed also because the new trend found a fruitful application in determining M and R of exoplanet hosting single stars. Corrections on misnames and devising new classical MLR, MRR, and MTR, giving mean values are encouraged since they are still useful and needed by astrophysical models requiring such mean values, not only beneficial to astrophysics, but also beneficial to Galactic, extragalactic search, even cosmological models.

Harshita Gandhi, Ritesh Patel, Vaibhav Pant, Satabdwa Majumdar, Sanchita Pal, Dipankar Banerjee, Huw Morgan

Accepted for publication in Space Weather Journal

This study addresses the limitations of single-viewpoint observations of Coronal Mass Ejections (CMEs) by presenting results from a 3D catalog of 360 CMEs during solar cycle 24, fitted using the GCS model. The dataset combines 326 previously analyzed CMEs and 34 newly examined events, categorized by their source regions into active region (AR) eruptions, active prominence (AP) eruptions, and prominence eruptions (PE). Estimates of errors are made using a bootstrapping approach. The findings highlight that the average 3D speed of CMEs is 1.3 times greater than the 2D speed. PE CMEs tend to be slow, with an average speed of 432 km s1. AR and AP speeds are higher, at 723 km s1 and 813 km s1, respectively, with the latter having fewer slow CMEs. The distinctive behavior of AP CMEs is attributed to factors like overlying magnetic field distribution or geometric complexities leading to less accurate GCS fits. A linear fit of projected speed to width gives a gradient of 2 km s1deg1, which increases to 5 km s1deg1 when the GCS-fitted `true' parameters are used. Notably, AR CMEs exhibit a high gradient of 7 km s1deg1, while AP CMEs show a gradient of 4 km s1deg1. PE CMEs, however, lack a significant speed-width relationship. We show that fitting multi-viewpoint CME images to a geometrical model such as GCS is important to study the statistical properties of CMEs, and can lead to a deeper insight into CME behavior that is essential for improving future space weather forecasting.

Wen Yin, Taiki Bessho, Yuji Ikeda, Hitomi Kobayashi, Daisuke Taniguchi, Hiroaki Sameshima, Noriyuki Matsunaga, Shogo Otsubo, Yuki Sarugaku, Tomomi Takeuchi, Haruki Kato, Satoshi Hamano, Hideyo Kawakita

15 pages, 4 figures, 1 table, 6 data files attached

The identity of dark matter has been a mystery in astronomy, cosmology, and particle theory for about a century. Bessho, Ikeda, and Yin (2022), three of the current authors, proposed using the state-of-the-art infrared spectrographs, including WINERED at 6.5m Magellan Clay telescope and NIRSpec at James Webb Space Telescope, as efficient detectors for the indirect detection of dark matter with the mass around eV by measuring the line photons from the dark matter two body decays. Applying this concept, we have performed spectrographic observations of dwarf spheroidal galaxies (dSphs) Leo V and Tucana II using WINERED by utilizing an object-sky-object nodding observation technique for background subtraction. We present the first result from this dark matter search. Employing zero consistent flux data after the sky subtraction, we have established one of the most stringent limits to date on dark matter decaying into line photons in the mass range of 1.82.7eV. Our data can also be applied to constrain other spectra of photons from the dSphs.

Geneviève Parmentier

accepted for publication in the Astrophysical Journal, 29 pages, 12 figures

The phenomenon of multiple stellar populations is exacerbated in massive globular clusters, with the fraction of first-population (1P) stars a decreasing function of the cluster present-day mass. We decipher this relation in far greater detail than has been done so far. We assume (i) a fixed stellar mass threshold for the formation of second-population (2P) stars, (ii) a power-law scaling F1Pm1ecl between the mass mecl of newly-formed clusters and their 1P-star fraction F1P, and (iii) a constant F1P over time. The F1P(mecl) relation is then evolved up to an age of 12Gyr for tidal field strengths representative of the entire Galactic halo. The 12Gyr-old model tracks cover extremely well the present-day distribution of Galactic globular clusters in (mass,F1P) space. The distribution is curtailed on its top-right side by the scarcity of clusters at large Galactocentric distances, and on its bottom-left side by the initial scarcity of very high-mass clusters, and dynamical friction. Given their distinct dissolution rates, "inner" and "outer" model clusters are offset from each other, as observed. The locus of Magellanic Clouds clusters in (mass,F1P) space is as expected for intermediate-age clusters evolving in a gentle tidal field. Given the assumed constancy of F1P, we conclude that 2P-stars do not necessarily form centrally-concentrated. We infer a minimum mass of 4105 M for multiple-populations clusters at secular evolution onset. This high-mass threshold severely limits the amount of 2P-stars lost from evolving clusters, thereby fitting the low 2P-star fraction of the Galactic halo field.

Meghana Killi, Michele Ginolfi, Gergö Popping, Darach Watson, Giovanni Zamorani, Brian C. Lemaux, Seiji Fujimoto, Andreas Faisst, Matthieu Bethermin, Michael Romano, Yoshinobu Fudamoto, Sandro Bardelli, Médéric Boquien, Stefano Carniani, Miroslava Dessauges-Zavadsky, Carlotta Gruppioni, Nimish Hathi, Eduardo Ibar, Gareth C. Jones, Anton M. Koekemoer, Ivanna Langan, Hugo Méndez-Hernández, Yuma Sugahara, Livia Vallini, Daniela Vergani

20 pages, 8 figures. Submitted to MNRAS; second revision

Galaxy morphology is shaped by stellar activity, feedback, gas and dust properties, and interactions with surroundings, and can therefore provide insight into these processes. In this paper, we study the spatial offsets between stellar and interstellar medium emission in a sample of 54 main-sequence star-forming galaxies at z46 observed with the Atacama Large Millimeter/submillimeter Array (ALMA) and drawn from the ALMA Large Program to INvestigate C+ at Early times (ALPINE). We find no significant spatial offset for the majority ( 70 percent) of galaxies in the sample among any combination of [C II], far-infrared continuum, optical, and ultraviolet emission. However, a fraction of the sample ( 30 percent) shows offsets larger than the median by more than 3σ significance (compared to the uncertainty on the offsets), especially between [C II] and ultraviolet emission. We find that these significant offsets are of the order of 0.5-0.7 arcsec, corresponding to 3.5-4.5 kiloparsecs. The offsets could be caused by a complex dust geometry, strong feedback from stars and active galactic nuclei, large-scale gas inflow and outflow, or a combination of these phenomena. However, our current analysis does not definitively constrain the origin. Future, higher resolution ALMA and JWST observations may help resolve the ambiguity. Regardless, since there exist at least some galaxies that display such large offsets, galaxy models and spectral energy distribution fitting codes cannot assume co-spatial emission in all main-sequence galaxies, and must take into account that the observed emission across wavelengths may be spatially segregated.

Danny Horta, Michael S. Petersen, Jorge Peñarrubia

Under review in MNRAS. 15 pages, 10 figures, and 2 tables

The inner 5 kiloparsec (kpc) region of the Milky Way is complex. Unravelling the evolution of the Galaxy requires precise understanding of the formation of this region. We report a study focused on disentangling the inner Galaxy (r<5 kpc) using the measured positions, velocities, and element abundance ratios of red giant stars from the APOGEEGaia surveys. After removing the stellar halo, inner Galaxy populations can be grouped into three main components based on their angular momentum: bar, disc, and a previously unreported ``knot'' component. The knot has a spheroidal shape, is concentrated in the inner 1.5 kpc, is comprised of stars on nearly-radial orbits, and contains stars with super-solar [Fe/H] element abundances. The chemical compositions of the knot are qualitatively similar to the Galactic bar and inner disc, suggestive that these three populations share a common genesis; the chemical/dynamic properties of the knot suggest it could constitute a classical bulge formed via secular evolution. Moreover, our results show that the bar is more slowly rotating than previously thought, with a pattern speed of Ωbar=24±3 km s1 kpc1. This new estimate suggests that the influence of the bar extends beyond the solar radius, with RCR9.49.8 kpc, depending on the adopted Milky Way rotation curve; it also suggests a ratio of corotation to bar length of R1.82. Our findings help place constraints on the formation and evolution of inner Galaxy populations, and directly constrain dynamical studies of the Milky Way bar and stars in the solar neighbourhood.

Brandon Buncher, Gilbert Holder, Selim Hotinli

11 pages, 4 figures

We investigate lensing reconstruction using the clustered galaxy distribution as a source field, using both the traditional cosmic microwave background quadratic estimator and a shear-only estimator. We calculate the expected signal-to-noise ratio of the cross power spectrum of such reconstructions with cosmic shear measurements for an LSST-like galaxy survey. Modeling the galaxy field as a Gaussian random field, we find that there is substantial clustering signal in the source field at angular scales substantially smaller than those typically used by CMB reconstructions. The expected signal-to-noise for cross-correlations in LSST from cosmic shear is 60 in the presence of shape noise, while cross correlating with a sample-variance limited mass map would have signal-to-noise in the hundreds. This type of cross-correlation could be used as a way to identify systematic errors in lensing studies and is just one example of many possible higher order correlations in galaxy surveys that may contain substantial cosmological information.

Irene Shivaei, Stacey Alberts, Michael Florian, George Rieke, Stijn Wuyts, Sarah Bodansky, Andrew J. Bunker, Alex J. Cameron, Mirko Curti, Francesco D'Eugenio, Ugne Dudzeviciute, Ivan Kramarenko, Zhiyuan Ji, Benjamin D. Johnson, Jianwei Lyu, Jorryt Matthee, Jane Morrison, Rohan Naidu, Naveen Reddy, Brant Robertson, Pablo G. Pérez-González, Yang Sun, Sandro Tacchella, Katherine Whitaker, Christina C. Williams, Christopher N. A. Willmer, Joris Witstok, Mengyuan Xiao, Yongda Zhu

Submitted to A&A

This paper utilizes the JWST MIRI multi-band imaging data from the SMILES survey (5-25micron), complemented with HST and NIRCam photometric and spectroscopic data from the JADES and FRESCO surveys for 443 star-forming (non-AGN) galaxies at z=0.7-2.0 to extend the study of dust and PAH emission to a new mass and SFR parameter space beyond our local universe. We find a strong correlation between the fraction of dust in PAHs (PAH fraction, q_PAH) with stellar mass. Moreover, the PAH fraction behavior as a function of gas-phase metallicity is similar to that at z~0 from previous studies, suggesting a universal relation: q_PAH is constant (~3.4%) above a metallicity of ~ 0.5Z and decreases to <1% at metallicities <0.3Z. This indicates that metallicity is a good indicator of the ISM properties that affect the balance between the formation and destruction of PAHs. The lack of a redshift evolution from z~0-2 also implies that above 0.5Z, the PAH emission effectively traces obscured luminosity and the previous locally-calibrated PAH-SFR calibrations remain applicable in this metallicity regime. We observe a strong correlation between obscured UV luminosity fraction (ratio of obscured to total luminosity) and stellar mass. Above the stellar mass of >5×109M, on average, more than half of the emitted luminosity is obscured, while there exists a non-negligible population of lower mass galaxies with >50% obscured fractions. At a fixed mass, the obscured fraction correlates with SFR surface density. This is a result of higher dust covering fractions in galaxies with more compact star forming regions. Similarly, galaxies with high IRX (IR to UV luminosity) at a given mass or UV continuum slope tend to have higher SFR surface density and shallower attenuation curves, owing to their higher effective dust optical depths and more compact star forming regions.

Scott D. Joffre, Núria Torres-Albà, Marco Ajello, Daniel Kocevski, Rolf Buehler

To be submitted to ApJ in Feb. 2024. 26 pages, 6 figures, 5 Tables

The Fermi All-sky Variability Analysis (FAVA) provides a photometric alternative for identifying week-long gamma-ray flares across the entire sky while being independent of any diffuse Galactic or isotropic emission model. Thorough analysis was conducted on 779 weeks of Fermi-LAT data analyzed by FAVA to estimate the rate and origin of Galactic gamma-ray flares, and to search for new variable Galactic gamma-ray transients. We report an estimated yearly rate of ~8.5 Galactic gamma-ray flares/year with ~1 being from an unknown source. Out of the known gamma-ray sources that are spatially coincident with these detected flares, six lack any previously reported gamma-ray flare. All six are classified as pulsars, or a special case (a supernova remnant or pulsar wind nebula). This potentially means these sites are tentative candidates to be the second known site of a variable gamma-ray pulsar wind nebula (PWN), behind the famous Crab Nebula's PWN. Additionally, we identify 9 unassociated flares that are unlikely to have originated from nearby gamma-ray sources, 3 of which lack previous X-ray observations at their locations.

Aswin Suresh, Viraj Karambelkar, Mansi M. Kasliwal, Michael C. B. Ashley, Kishalay De, Matthew J. Hankins, Anna M. Moore, Jamie Soon, Roberto Soria, Tony Travouillon, Kayton K. Truong

15 pages, 15 figures

Stars in the Asymptotic Giant Branch (AGB) phase, dominated by low to intermediate-mass stars in the late stage of evolution, undergo periodic pulsations, with periods of several hundred days, earning them the name Long Period Variables (LPVs). These stars gradually shed their mass through stellar winds and mass ejections, enveloping themselves in dust. Infrared (IR) surveys can probe these dust-enshrouded phases and uncover populations of LPV stars in the Milky Way. In this paper, we present a catalog of 159,696 Long Period Variables using near-IR lightcurves from the Palomar Gattini - IR (PGIR) survey. PGIR has been surveying the entire accessible northern sky (δ>28) in the J-band at a cadence of 2-3 days since September 2018, and has produced J-band lightcurves for more than 60 million sources. We used a gradient-boosted decision tree classifier trained on a comprehensive feature set extracted from PGIR lightcurves to search for LPVs in this dataset. We developed a parallelized and optimized code to extract features at a rate of ~0.1 seconds per lightcurve. Our model can successfully distinguish LPVs from other stars with a true positive rate and weighted g-mean of 0.95. 73,346 (~46%) of the sources in our catalog are new, previously unknown LPVs.

Zhijie Qu, Hsiao-Wen Chen, Sean D. Johnson, Gwen C. Rudie, Fakhri S. Zahedy, David DePalma, Joop Schaye, Erin T. Boettcher, Sebastiano Cantalupo, Mandy C. Chen, Claude-André Faucher-Giguère, Jennifer I-Hsiu Li, John S. Mulchaey, Patrick Petitjean, Marc Rafelski

Resubmitted to ApJ; 28 pages, 16 figures

This paper presents a newly established sample of 103 unique galaxies or galaxy groups at 0.4z0.7 from the Cosmic Ultraviolet Baryon Survey (CUBS) for studying the warm-hot circumgalactic medium (CGM) probed by both O VI and Ne VIII absorption. The galaxies and associated neighbors are identified at <1 physical Mpc from the sightlines toward 15 CUBS QSOs at zQSO0.8. A total of 30 galaxies or galaxy groups exhibit associated O VI λλ 1031, 1037 doublet absorption within a line-of-sight velocity interval of ±250 km/s, while the rest show no trace of O VI to a detection limit of logNOVI/cm213.7. Meanwhile, only five galaxies or galaxy groups exhibit the Ne VIII λλ 770,780 doublet absorption, down to a limiting column density of logNNeVIII/cm214.0. These O VI- and Ne VIII-bearing halos reside in different galaxy environments with stellar masses ranging from logMstar/M8 to 11.5. The warm-hot CGM around galaxies of different stellar masses and star formation rates exhibits different spatial profiles and kinematics. In particular, star-forming galaxies with logMstar/M911 show a significant concentration of metal-enriched warm-hot CGM within the virial radius, while massive quiescent galaxies exhibit flatter radial profiles of both column densities and covering fractions. In addition, the velocity dispersion of O VI absorption is broad with σv>40 km/s for galaxies of logMstar/M>9 within the virial radius, suggesting a more dynamic warm-hot halo around these galaxies. Finally, the warm-hot CGM probed by O VI and Ne VIII is suggested to be the dominant phase in sub-L galaxies with logMstar/M910 based on their high ionization fractions in the CGM.

C. Boettner, P. Dayal, M. Trebitsch, N. Libeskind, K. Rice, C. Cockell, B. I. Tieleman

19 pages, 13 figures, submitted to A&A. Code available at this https URL

Stellar populations and their distribution differ widely across the Galaxy, which is likely to affect planet demographics. Our local neighbourhood is dominated by young, metal-rich stars in the galactic thin disc, while the stellar halo and galactic bulge host a large fraction of older, metal-poor stars. We study the impact of these variations on planet populations in different regions of the Galaxy by combining a high-resolution galaxy formation simulation with state-of-the-art planet population synthesis models. We construct a population model to estimate occurrence rates of different planet types, based on the New Generation Planet Population Synthesis by Emsenhuber et al., 2021. We apply this to a simulated Milky Way--Analogue in the HESTIA galaxy formation simulation. We study the planet occurrence rate in the metal-rich regions of the inner Galaxy, i.e. in the galactic bulge and thin disc, and contrast them to the frequencies in the more distant, metal-poor region like the thick disc and stellar halo. We find that the planet demographics in the metal-poor regions of the Milky Way-Analogue, differ strongly from the planet populations in the more distant, metal-poor regions. The occurrence rate of giant planets (>300M) is 10 to 20 times larger in the thin disc compared to the thick disc, driven by the low amounts of solid material available for planet formation around metal-poor stars. Similarly, low-mass Earth-like planets around Sun-like stars are most abundant in the thick disc, being 1.5 times more frequent than in the thin disc. Moreover, low-mass planets are expected to be abundant throughout the galaxy, from the central regions to the outer halo, due to their formation processes being less dependent on stellar metallicity. The planet populations differ more strongly around Sun-like stars compared to dwarfs with masses 0.3 - 0.5 M.

Noah Tuchow, Chris Stark, Eric Mamajek

Accepted for publication in the Astronomical Journal. The HPIC is hosted on the NASA Exoplanet Archive at this https URL

The Habitable Worlds Observatory Preliminary Input Catalog (HPIC) is a list of ~13,000 nearby bright stars that will be potential targets for the Habitable Worlds Observatory (HWO) in its search for Earth-sized planets around Sun-like stars. We construct this target list using the TESS and Gaia DR3 catalogs, and develop an automated pipeline to compile stellar measurements and derived astrophysical properties for all stars. We benchmark the stellar properties in the HPIC relative to those of the manually curated ExEP HWO Precursor Science Stars list and find that, for the 164 best targets for exo-Earth direct imaging, our stellar properties are consistent. We demonstrate the utility of the HPIC by using it as an input for yield calculations to predict the science output of various mission designs including those with larger telescope diameters and those focused on other planet types besides Earth analogs, such as Jupiter-mass planets. The breadth and completeness of the HPIC is essential for accurate HWO mission trade studies, and it will be useful for other exoplanet studies and general astrophysics studying the population of bright nearby stars.

Izabela Kowalska-Leszczynska, Marzena A. Kubiak, Maciej Bzowski, Marek Strumik

Submitted to ApJ

Direct observations of solar wind are mostly limited to the vicinity of the ecliptic plane. Retrieving the latitudinal structure of solar wind indirectly based on observations of the backscatter glow of interstellar neutral hydrogen is complex and requires support from theoretical models. The GLOWS instrument, to operate on the planned IMAP mission, will scan the helioglow along circumsolar rings with an angular distance of ~75 degrees. Its objective is to retrieve the latitudinal structure of the ionization rate of interstellar hydrogen and with this, the structure of the solar wind. In preparation for future analysis, we studied the sensitivity of the light curves to temporal and latitudinal variation of the ionization rate of interstellar hydrogen and the solar Lyman-alpha illumination. Based on carefully planned numerical experiments, we analyze the time delay and relaxation time of the system for variations of the ionization rate and solar illumination in heliolatitude and with time. We found that variations in the solar illumination are reflected in the helioglow without delay, but relaxation takes longer than the variation rise time. By contrast, variations in the ionization rate are anti-correlated with the helioglow brightness with a delay of several months. We also found that the helioglow is not sensitive to variations in the ionization rate at the solar poles, so retrieving the ionization rate and solar wind at the poles requires an approximation of the ionization rate profiles with appropriate parametric functions.

By using recent observations of the Dydimos-Dimorphos system from the Hubble Space Telescope, 37 boulders with a size of 4 to 7 meters ejected from the system during the impact with the DART spacecraft were identified. In this work, we studied the orbital evolution of a swarm of boulders with a similar size to that of the detected ones. By using recent estimates for the ejection velocity of the boulders, we numerically propagated the dynamics of the swarm for 20 kyr in the future. We found that the ejection velocities and the non-gravitational effects are not strong enough to change the secular evolution significantly. The minimum orbit intersection distance (MOID) with the Earth will be reached in about 2.5 kyr, but it will not fall below 0.02 au. On the contrary, the Mars MOID will be very small in four instances, two near 6 kyr and the other two near 15 kyr. Therefore, there may be a chance for them to impact Mars in the future. Given the rarefaction of the Martian atmosphere, we expect the boulders to arrive intact on the ground and excavate a small impact crater. The results presented here provide a further indication that some meteorites found on Earth originated in collisions of 100 m near-Earth asteroids with projectiles of 1 m in size.

L. Colomban, O. V. Agapitov, V. Krasnoselskikh, M. Kretzschmar, T. Dudok de Wit, S. Karbashewski, F. S. Mozer, J. W. Bonnell, S. Bale, D. Malaspina, N. E. Raouafi

The search-coil magnetometer (SCM) aboard Parker Solar Probe (PSP) measures the 3 Hz to 1 MHz magnetic field fluctuations. During Encounter 1, the SCM operated as expected; however, in March 2019, technical issues limited subsequent encounters to two components for frequencies below 1 kHz. Detrimentally, most whistler waves are observed in the affected frequency band where established techniques cannot extract the wave polarization properties under these conditions. Fortunately, the Electric Field Instrument aboard PSP measures two electric field components and covers the affected bandwidth. We propose a technique using the available electromagnetic fields to reconstruct the missing components by neglecting the electric field parallel to the background magnetic field. This technique is applicable with the assumptions of (a) low-frequency whistlers in the plasma frame relative to the electron cyclotron frequency; (b) a small propagation angle with respect to the background magnetic field; and (c) a large wave phase speed relative to the cross-field solar wind velocity. Critically, the method cannot be applied if the background magnetic field is aligned with the affected SCM coil. We have validated our method using burst mode measurements made before March 2019. The reconstruction conditions are satisfied for 80% of the burst mode whistlers detected during Encounter 1. We apply the method to determine the polarization of a whistler event observed after March 2019 during Encounter 2. Our novel method is an encouraging step toward analyzing whistler properties in affected encounters and improving our understanding of wave-particle interactions in the young solar wind.

Context. Acoustic waves in the Sun are affected by the atmospheric layers, but this region is often ignored in forward models due to the increase in computational cost. Aims. The purpose of this work is to take into account the solar atmosphere without increasing significantly the computational cost. Methods. We solve a scalar wave equation that describes the propagation of acoustic modes inside the Sun using a finite element method. The boundary conditions used to truncate the computational domain are learned from the Dirichlet-to-Neumann operator, that is the relation between the solution and its normal derivative at the computational boundary. These boundary conditions may be applied at any height above which the background medium is assumed to be radially symmetric. Results. Taking into account the atmosphere is important even for wave frequencies below the acoustic cut-off. In particular, the mode frequencies computed for an isothermal atmosphere differ by up 10 {\mu}Hz from those computed for the VAL-C atmospheric model. We show that learned infinite elements lead to a numerical accuracy similar to that obtained for a traditional radiation boundary condition. Its main advantage is to reproduce the solution for any radially symmetric atmosphere to a very good accuracy at a low computational cost. Conclusions. This work emphasizes the importance of including atmospheric layers in helioseismology and proposes a computationally efficient method to do so.

Stephan G. Heinemann, Chaitanya Sishtla, Simon Good, Maxime Grandin, Jens Pomoell

accepted version February 09, 2024

High-speed solar wind streams (HSSs) interact with the preceding ambient solar wind to form Stream Interaction Regions (SIRs), which are a primary source of recurrent geomagnetic storms. However, HSSs may also encounter and subsequently interact with Interplanetary Coronal Mass Ejections (ICMEs). In particular, the impact of the interaction between slower ICMEs and faster HSSs, represents an unexplored area that requires further in-depth investigation. This specific interaction can give rise to unexpected geomagnetic storm signatures, diverging from the conventional expectations of individual SIR events sharing similar HSS properties. Our study presents a comprehensive analysis of solar wind data spanning from 1996 to 2020, capturing 23 instances where such encounters led to geomagnetic storms (SymH <30 nT). We determined that interaction events between preceding slower ICMEs and faster HSSs possess the potential to induce substantial storm activity, statistically nearly doubling the geoeffective impact in comparison to SIR storm events. The increase in the amplitude of the SymH index appears to result from heightened dynamic pressure, often coupled with the concurrent amplification of the CMEs rearward |B| and/or Bz components.

John Franklin Crenshaw, Andrew J. Connolly, Joshua E. Meyers, J. Bryce Kalmbach, Guillem Megias Homar, Tiago Ribeiro, Krzysztof Suberlak, Sandrine Thomas, Te-wei Tsai

24 pages, 21 figures

The Vera C. Rubin Observatory will, over a period of 10 years, repeatedly survey the southern sky. To ensure that images generated by Rubin meet the quality requirements for precision science, the observatory will use an Active Optics System (AOS) to correct for alignment and mirror surface perturbations introduced by gravity and temperature gradients in the optical system. To accomplish this Rubin will use out-of-focus images from sensors located at the edge of the focal plane to learn and correct for perturbations to the wavefront. We have designed and integrated a deep learning model for wavefront estimation into the AOS pipeline. In this paper, we compare the performance of this deep learning approach to Rubin's baseline algorithm when applied to images from two different simulations of the Rubin optical system. We show the deep learning approach is faster and more accurate, achieving the atmospheric error floor both for high-quality images, and low-quality images with heavy blending and vignetting. Compared to the baseline algorithm, the deep learning model is 40x faster, the median error 2x better under ideal conditions, 5x better in the presence of vignetting by the Rubin camera, and 14x better in the presence of blending in crowded fields. In addition, the deep learning model surpasses the required optical quality in simulations of the AOS closed loop. This system promises to increase the survey area useful for precision science by up to 8%. We discuss how this system might be deployed when commissioning and operating Rubin.

Cheongho Han, Andrzej Udalski, Youn Kil Jung, Andrew Gould, Doeon Kim, Michael D. Albrow, Sun-Ju Chung, Kyu-Ha Hwang, Chung-Uk Lee, Yoon-Hyun Ryu, Yossi Shvartzvald, In-Gu Shin, Jennifer C. Yee, Hongjing Yang, Weicheng Zang, Sang-Mok Cha, Dong-Jin Kim, Seung-Lee Kim, Dong-Joo Lee, Yongseok Lee, Byeong-Gon Park, Richard W. Pogge, Przemek Mróz, Mateus Mróz, Michał K. Szymański, Jan Skowron, Radosław Poleski, Igor Soszyński, Paweł Pietrukowicz, Szymon Kozłowski, Krzysztof A. Rybicki, Patryk Iwanek, Krzysztof Ulaczyk, Marcin Wrona, Mariusz Gromadzki

11 pages, 12 figures

Light curves of microlensing events occasionally deviate from the smooth and symmetric form of a single-lens single-source event. While most of these anomalous events can be accounted for by employing a binary-lens single-source (2L1S) or a single-lens binary-source (1L2S) framework, it is established that a small fraction of events remain unexplained by either of these interpretations. We carry out a project in which data collected by high-cadence microlensing surveys were reinvestigated with the aim of uncovering the nature of anomalous lensing events with no proposed 2L1S or 1L2S models. From the project, we find that the anomaly appearing in the lensing event OGLE-2023-BLG-0836 cannot be explained by the usual interpretations and conduct a comprehensive analysis of the event. From thorough modeling of the light curve under sophisticated lens-system configurations, we have arrived at the conclusion that a triple-mass lens system is imperative to account for the anomaly features observed in the lensing light curve. From the Bayesian analysis using the measured observables of the event time scale and angular Einstein radius, we determine that the least massive component of the lens has a planetary mass of 4.36+2.352.18 MJ. This planet orbits within a stellar binary system composed of two stars with masses 0.71+0.380.36 M and 0.56+0.300.28 M. This lensing event signifies the sixth occurrence of a planetary microlensing system in which a planet belongs to a stellar binary system.

Isaac Cheng, Tyrone E. Woods, Patrick Côté, Jennifer Glover, Dhananjhay Bansal, Melissa Amenouche, Madeline A. Marshall, Laurie Amen, John Hutchings, Laura Ferrarese, Kim A. Venn, Michael Balogh, Simon Blouin, Ryan Cloutier, Nolan Dickson, Sarah Gallagher, Martin Hellmich, Vincent Hénault-Brunet, Viraja Khatu, Cameron Lawlor-Forsyth, Cameron Morgan, Harvey Richer, Marcin Sawicki, Robert Sorba

24 pages, 16 figures, 3 tables, accepted for publication in AJ

The Cosmological Advanced Survey Telescope for Optical and ultraviolet Research (CASTOR) is a proposed Canadian-led 1m-class space telescope that will carry out ultraviolet and blue-optical wide-field imaging, spectroscopy, and photometry. CASTOR will provide an essential bridge in the post-Hubble era, preventing a protracted UV-optical gap in space astronomy and enabling an enormous range of discovery opportunities from the solar system to the nature of the Cosmos, in conjunction with the other great wide-field observatories of the next decade (e.g., Euclid, Roman, Vera Rubin). FORECASTOR (Finding Optics Requirements and Exposure times for CASTOR) will supply a coordinated suite of mission-planning tools that will serve as the one-stop shop for proposal preparation, data reduction, and analysis for the CASTOR mission. We present the first of these tools: a pixel-based, user-friendly, extensible, multi-mission exposure time calculator (ETC) built in Python, including a modern browser-based graphical user interface that updates in real time. We then provide several illustrative examples of FORECASTOR's use that advance the design of planned legacy surveys for the CASTOR mission: a search for the most massive white dwarfs in the Magellanic Clouds; a study of the frequency of flaring activity in M stars, their distribution and impacts on habitability of exoplanets; mapping the proper motions of faint stars in the Milky Way; wide and deep galaxy surveys; and time-domain studies of active galactic nuclei.

Maria Jose Colmenares, Michiel Lambrechts, Elishevah van Kooten, Anders Johansen

15 pages, 10 figures, 2 tables, 5 appendices (4 additional pages, 6 additional figures). Accepted for publication in A&A

During protoplanetary disk formation, dust grains located in the outer disk retain their pristine icy composition, while solids in the inner stellar-heated disk undergo volatile loss. This process may have left a fossil record in Solar System material showing different nucelosynthetic imprints that have been attributed to different degrees of thermal processing. However, it remains unclear how a large mass fraction of thermally-processed inner-disk pebbles is produced and how these grains are subsequently transported throughout the disk. In this work we numerically investigate the evolution in time of a two-component pebble disk, consisting of pristine pebbles and those that underwent ice sublimation. We find that stellar outbursts exceeding 1000 times the solar luminosity are efficient in thermally altering, through ice sublimation, a large mass fraction of pebbles (around 80%). After the establishment of this initial radial dust composition gradient throughout the disk, the subsequent mixing and inward drift of pristine outer-disk pebbles alter the inner disk bulk composition from processed to more unprocessed in time. Therefore, if processed pebbles without ice mantles have an isotopic composition similar to ureilite meteorites from the inner Solar System, inner-disk minor bodies forming from the early pebble flux (<1Myr) will be isotopically ureilite-like, while later-formed bodies will be increasingly admixed with the signature of the late incoming CI chondrite-like unprocessed pebbles. This appears to be largely consistent with the trend seen between the accretion age of different meteoric classes and their different stable isotope composition anomalies (in μ54Cr, μ48Ca, μ30Si, μ58Ni), but further work may be needed to explain the role of isotopically anomalous refractory inclusions and anomaly trends in other elements.

Alex Laguë, Fiona McCarthy, Mathew Madhavacheril, J. Colin Hill, Frank J. Qu

Comments welcome

The predicted present-day amplitude of matter fluctuations based on cosmic microwave background (CMB) anisotropy data has sometimes been found discrepant with more direct measurements of late-time structure. This has motivated many extensions to the standard cosmological model, including kinetic interactions between dark matter and dark energy that introduce a drag force slowing the growth of structure at late times. Exploring this scenario, we develop a model for quasi-linear scales in the matter power spectrum by calculating the critical overdensity in the presence of this interaction and a varying dark energy equation of state. We explicitly avoid modeling or interpretation of data on non-linear scales in this model (such as use of ΛCDM-calibrated priors), which would require numerical simulations. We find that the presence of the drag force hinders halo formation, thus increasing the deviation from ΛCDM in the mildly non-linear regime. We use CMB lensing observations from the sixth data release of the Atacama Cosmology Telescope up to L=1250 (in combination with Planck, Sloan Digital Sky Survey, and 6dFGS data) to derive the strongest constraints to date on the amplitude of the drag term, finding the dimensionless interaction strength ΓDMDE/(H0ρc)<0.831(2.81) at the 68\% (95\%) confidence level. The inclusion of non-linear corrections improves our constraints by about 35\% compared to linear theory. Our results do not exclude the best-fit values of ΓDMDE found in previous studies using information from galaxy weak lensing, though we find no statistical preference for the dark matter-dark energy kinetic interactions over ΛCDM. We implement our model in a publicly available fork of the Boltzmann code CLASS at https://github.com/fmccarthy/Class_DMDE.

Yoo Jung Kim, Michael P. Fitzgerald, Jonathan Lin, Steph Sallum, Yinzi Xin, Nemanja Jovanovic, Sergio Leon-Saval

Accepted for publication in ApJ

Photonic Lanterns (PLs) are tapered waveguides that gradually transition from a multi-mode fiber geometry to a bundle of single-mode fibers (SMFs). They can efficiently couple multi-mode telescope light into a multi-mode fiber entrance at the focal plane and convert it into multiple single-mode beams. Thus, each SMF samples its unique mode (lantern principal mode) of the telescope light in the pupil, analogous to subapertures in aperture masking interferometry (AMI). Coherent imaging with PLs can be enabled by interfering SMF outputs and applying phase modulation, which can be achieved using a photonic chip beam combiner at the backend (e.g., the ABCD beam combiner). In this study, we investigate the potential of coherent imaging by interfering SMF outputs of a PL with a single telescope. We demonstrate that the visibilities that can be measured from a PL are mutual intensities incident on the pupil weighted by the cross-correlation of a pair of lantern modes. From numerically simulated lantern principal modes of a 6-port PL, we find that interferometric observables using a PL behave similarly to separated-aperture visibilities for simple models on small angular scales (<λ/D) but with greater sensitivity to symmetries and capability to break phase angle degeneracies. Furthermore, we present simulated observations with wavefront errors and compare them to AMI. Despite the redundancy caused by extended lantern principal modes, spatial filtering offers stability to wavefront errors. Our simulated observations suggest that PLs may offer significant benefits in the photon noise-limited regime and in resolving small angular scales at low contrast regime.

J. Pace VanDevender, T. Sloan, Michael Glissman

30 pages, 11 figures, 5 tables

A search has been carried out for Magnetized Quark Nuggets (MQNs) accumulating in iron ore over geologic time. MQNs, which are theoretically consistent with the Standard Models of Physics and of Cosmology, have been suggested as dark-matter candidates. Indirect evidence of MQNs has been previously inferred from observations of magnetars and of non-meteorite impact craters. It is shown in this paper that MQNs can accumulate in taconite (iron ore) and be transferred into ferromagnetic rod-mill liners during processing of the ore. When the liners are recycled to make fresh steel, they are heated to higher than the Curie temperature so that their ferromagnetic properties are destroyed. The MQNs would then be released and fall into the ferromagnetic furnace bottom where they would be trapped. Three such furnace bottoms have been magnetically scanned to search for the magnetic anomalies consistent with trapped MQNs. The observed magnetic anomalies are equivalent to an accumulation rate of ~1 kg of MQNs per 1.2 x 108 kg of taconite ore processed. The results are consistent with MQNs but there could be other, unknown explanations. We propose an experiment and calculations to definitively test the MQN hypothesis for dark matter.

Chia Min Tan, Emmanuel Fonseca, Kathryn Crowter, Fengqiu Adam Dong, Victoria M. Kaspi, Kiyoshi W. Masui, James W. McKee, Bradley W. Meyers, Scott M. Ransom, Ingrid H. Stairs

14 pages, 4 figures, accepted for publication in ApJ

We performed near-daily observations on the binary pulsars PSR J0218+4232, PSR J1518+4904 and PSR J2023+2853 with the Canadian Hydrogen Intensity Mapping Experiment (CHIME). For the first time, we detected the Shapiro time delay in all three pulsar-binary systems, using only 2--4 years of CHIME/Pulsar timing data. We measured the pulsar masses to be 1.49+0.230.20 M, 1.470+0.0300.034 M and 1.50+0.490.38 M respectively. The companion mass to PSR J0218+4232 was found to be 0.179+0.0180.016 M. We constrained the mass of the neutron-star companion of PSR J1518+4904 to be 1.248+0.0350.029 M, using the observed apsidal motion as a constraint on mass estimation. The binary companion to PSR J2023+2853 was found to have a mass of 0.93+0.170.14 M; in the context of the near-circular orbit, this mass estimate suggests that the companion to PSR J2023+2853 is likely a high-mass white dwarf. By comparing the timing model obtained for PSR J0218+4232 with previous observations, we found a significant change in the observed orbital period of the system of ˙Pb=0.14(2)×1012; we determined that this variation arises from ``Shklovskii acceleration" due to relative motion of the binary system, and used this measurement to estimate a distance of d=(6.7±1.0) kpc to PSR J0218+4232. This work demonstrates the capability of high-cadence observations, enabled by the CHIME/Pulsar system, to detect and refine general-relativistic effects of binary pulsars over short observing timescales.

Meng-Hua Chen, Li-Xin Li, Qiu-Hong Chen, Rui-Chong Hu, En-Wei Liang

7 pages, 4 figures, Accepted for publication in MNRAS

The discovery of the radioactively powered kilonova AT2017gfo, associated with the short-duration gamma-ray burst GRB 170817A and the gravitational wave source GW170817, has provided the first direct evidence supporting binary neutron star mergers as crucial astrophysical sites for the synthesis of heavy elements beyond iron through r-process nucleosysthesis in the universe. However, recent identifications of kilonovae following long-duration gamma-ray bursts, such as GRB 211211A and GRB 230307A, has sparked discussions about the potential of neutron star-white dwarf mergers to also produce neutron-rich ejecta and contribute to the production of heavy r-process elements. In this work, we estimate the contribution of binary neutron star mergers to the total mass of r-process elements in the Milky Way and investigate the possibility of neutron star-white dwarf mergers as alternative astrophysical sites for r-process nucleosynthesis through an analysis of the total mass of the r-process elements in the Milky Way. Our results reveal that binary neutron star mergers can sufficiently account for the Galactic heavy r-process elements, suggesting that these events are the dominant contributor to the production of heavy r-process elements in the Milky Way. Considering the total mass of r-process elements in the Milky Way and the higher occurrence rate of neutron star-white dwarf mergers, it is unlikely that such mergers can produce a significant amount of neutron-rich ejecta, with the generated mass of r-process elements being lower than 0.005M.

Srimanta Banerjee, Gulab C. Dewangan, Christian Knigge, Maria Georganti, Poshak Gandhi, N. P. S. Mithun, Payaswini Saikia, Dipankar Bhattacharya, David M. Russell, Fraser Lewis, Andrzej A. Zdziarski

29 pages, 19 figures, 8 Tables, Accepted for publication in The Astrophysical Journal

We present a comprehensive multi-wavelength spectral analysis of the black hole X-ray binary MAXI J1820+070 during its 2018 outburst, utilizing AstroSat far UV, soft and hard X-ray data, along with (quasi-)simultaneous optical and X-ray data from Las Cumbres Observatory and NICER, respectively. In the soft state, we detect soft X-ray and UV/optical excess components over and above the intrinsic accretion disk emission (kTin0.58 keV) and a steep X-ray power-law component. The soft X-ray excess is consistent with a high-temperature blackbody (kT0.79 keV), while the UV/optical excess is described by UV emission lines and two low-temperature blackbody components (kT3.87 eV and 0.75 eV). Employing continuum spectral fitting, we determine the black hole spin parameter (a=0.77±0.21), using the jet inclination angle of 64±5 and a mass spanning 510M. In the hard state, we observe a significantly enhanced optical/UV excess component, indicating a stronger reprocessed emission in the outer disk. Broad-band X-ray spectroscopy in the hard state reveals a two-component corona, each associated with its reflection component, in addition to the disk emission (kTin0.19 keV). The softer coronal component dominates the bolometric X-ray luminosity and produces broader relativistic reflection features, while the harder component gets reflected far from the inner disk, yielding narrow reflection features. Furthermore, our analysis in the hard state suggests a substantial truncation of the inner disk (51 gravitational radii) and a high disk density (1020 cm3).

Izumi Hachisu, Mariko Kato, Katsura Matsumoto

26 pages, 11 figures. accepted for publication in ApJ

The classical nova V339 Del 2013 is characterized by a 1.5 mag dip of the V light curve owing to a dust shell formation, during which soft X-ray emissions coexist. We present Str\"omgren y band light curve, which represents continuum emission, not influenced by strong [O III] emission lines. The y light curve monotonically decreases in marked contrast to the V light curve that shows a 1.5 mag dip. We propose a multiwavelength light curve model that reproduces the y and V light curves as well as the gamma-ray and X-ray light curves. In our model, a strong shock arises far outside the photosphere after optical maximum, because later ejected matter collides with earlier ejected gas. Our shocked shell model explains optical emission lines, Hα, hard X-ray, and gamma-ray fluxes. A dust shell forms behind the shock that suppresses [O III]. This low flux of [O III] shapes a 1.5 mag drop in the V light curve. Then, the V flux recovers by increasing contribution from [O III] lines, while the y flux does not. However, the optical depth of the dust shell is too small to absorb the photospheric (X-ray) emission of the white dwarf. This is the reason that a dust shell and a soft X-ray radiation coexist. We determined the white dwarf mass to be MWD=1.25±0.05 M and the distance modulus in the V band to be (mM)V=12.2±0.2; the distance is d=2.1±0.2 kpc for the reddening of E(BV)=0.18.

Qinghui Sun, Sharon Xuesong Wang, Luis Welbanks, Johanna Teske, Johannes Buchner

4 figures, 5 tables, accepted for publication in AJ

The two prevailing planet formation scenarios, core-accretion and disk instability, predict distinct planetary mass-metallicity relations. Yet, the detection of this trend remains challenging due to inadequate data on planet atmosphere abundance and inhomogeneities in both planet and host stellar abundance measurements. Here we analyze high-resolution spectra for the host stars of 19 transiting exoplanets to derive the C, O, Na, S, and K abundances, including planetary types from cool mini-Neptunes to hot Jupiters (Teq  300 - 2700 K; planet radius 0.1 - 2 RJ). Our Monte Carlo simulations suggest that the current dataset, updated based on Welbanks et al. 2019, is unable to distinguish between a linear relation and an independent distribution model for the abundance-mass correlation for water, Na, or K. To detect a trend with strong evidence (Bayes factor > 10) at the 2σ confidence interval, we recommend a minimum sample of 58 planets with HST measurements of water abundances coupled with [O/H] of the host stars, or 45 planets at the JWST precision. Coupled with future JWST or ground-based high resolution data, this well-characterized sample of planets with precise host star abundances constitute an important ensemble of planets to further probe the abundance-mass correlation.

F. Kiefer, M. Bonnefoy, B. Charnay, A. Boccaletti, A.-M. Lagrange, G. Chauvin, B. Bézard, M. Mâlin

20 pages, 25 figures, 5 tables, accepted for publication in A&A

Molecular mapping is a supervised method exploiting the spectral diversity of integral field spectrographs to detect and characterize resolved exoplanets blurred into the stellar halo. We present an evolution of the method to remove the stellar halo and the nuisance of telluric features in the datacubes and access a continuum-subtracted spectra of the planets at R4000. We derive planet atmosphere properties from a direct analysis of the planet telluric-corrected absorption spectrum. We applied our methods to the SINFONI observation of the planet β Pictoris b. We recover the CO and H2O detections in the atmosphere of β Pic b using molecular mapping. We further determine some basic properties of its atmosphere, with Teq=1748+34 K, a sub-solar [Fe/H]=0.235+0.0150.013 dex, and a solar C/O=0.551±0.002 in contrast with values measured for the same exoplanet with other infrared instruments. We confirm a low projected equatorial velocity of 25+56 km s1. We are also able to measure, for the first time with a medium-resolution spectrograph, the radial velocity of β Pic b relative to the central star at MJD=56910.38 with a km/s precision of 11.3±1.1 km s1, compatible with ephemerides based on the current knowledge of the β Pic system.

Victor P. Debattista, Tigran Khachaturyants, Joao A. S. Amarante, Christopher Carr, Leandro Beraldo e Silva, Chervin F. P. Laporte

21 pages. Submitted to MNRAS. Comments welcomed

We study azimuthal variations in the mean stellar metallicity, <[Fe/H]>, in a self-consistent, isolated simulation in which all stars form out of gas. We find <[Fe/H]> variations comparable to those observed in the Milky Way and which are coincident with the spiral density waves. The azimuthal variations are present in young and old stars and therefore are not a result of recently formed stars. Similar variations are present in the mean age and alpha-abundance. We measure the pattern speeds of the <[Fe/H]>-variations and find that they match those of the spirals, indicating that they are at the origin of the metallicity patterns. Because younger stellar populations are not just more [Fe/H]-rich and alpha-poor but also dynamically cooler, we expect them to more strongly support spirals, which is indeed the case in the simulation. However, if we measure the radial action, J_R, using the Stackel axisymmetric approximation, we find that the spiral ridges are traced by regions of high J_R, contrary to expectations. Assuming that the passage of stars through the spirals leads to unphysical variations in the measured J_R, we obtain an improved estimate of J_R by averaging over a 1 Gyr time interval. This time-averaged J_R is a much better tracer of the spiral structure, with minima at the spiral ridges. We conclude that the errors incurred by the axisymmetric approximation introduce correlated deviations large enough to render the instantaneous radial action inadequate for tracing spirals.

T. van Eeden (for the KM3NeT Collaboration)

20 pages, 30 figures

The KM3NeT/ARCA neutrino detector is currently under construction at 3500 m depth offshore Capo Passero, Sicily, in the Mediterranean Sea. The main science objectives are the detection of high-energy cosmic neutrinos and the discovery of their sources. Simulations were conducted for the full KM3NeT/ARCA detector, instrumenting a volume of 1 km3, to estimate the sensitivity and discovery potential to point-like neutrino sources and an all-sky diffuse neutrino flux. This paper covers the reconstruction of track- and shower-like signatures, as well as the criteria employed for neutrino event selection. By leveraging both the track and shower observation channels, the KM3NeT/ARCA detector demonstrates the capability to detect the diffuse astrophysical neutrino flux within half a year of operation, achieving a 5σ statistical significance. With an angular resolution below 0.1 for tracks and under 2 for showers, the sensitivity to point-like neutrino sources surpasses existing observed limits across the entire sky.

Davide Abriola, Daniele Della Pergola, Marco Lombardi, Pietro Bergamini, Mario Nonino, Claudio Grillo, Piero Rosati

We present a new weak lensing analysis of the Hubble Frontier Fields galaxy cluster Abell 2744 (z = 0.308) using new Magellan/MegaCam multi-band gri imaging data. We carry out our study by applying brand-new PSF and shape measurement softwares that allow for the use of multi-band data simultaneously, which we first test on Subaru/Suprime-Cam BRcz imaging data of the same cluster. The projected total mass of this system within 2.35Mpc from the south-west BCG is (2.56±0.26)×1015M, which makes Abell 2744 one of the most massive clusters known. This value is consistent, within the errors, with previous weak lensing and dynamical studies. Our analysis reveals the presence of three high-density substructures, thus supporting the picture of a complex merging scenario. This result is also confirmed by a comparison with a recent strong lensing study based on high-resolution JWST imaging. Moreover, our reconstructed total mass profile nicely agrees with an extrapolation of the strong lensing best-fit model up to several Mpc from the BCG centre.

Kishore Gopalakrishnan, Nishant K Singh

17 pages, 1 figure, 1 table. Submitted to ApJ. Scripts for calculation are available on Zenodo (see link in introduction)

The small-scale dynamo is typically studied by assuming that the correlation time of the velocity field is zero. Some authors have used a smooth renovating flow model to study how the properties of the dynamo are affected by the correlation time being nonzero. Here, we assume the velocity is an incompressible Gaussian random field (which need not be smooth), and derive the lowest-order corrections to the evolution equation for the two-point correlation of the magnetic field in Fourier space. Using this, we obtain the evolution equation for the longitudinal correlation function of the magnetic field in nonhelical turbulence, valid for arbitrary Prandtl number. Even at high Prandtl number, the derived evolution equation is qualitatively different from that obtained from the renovating flow model. Further, the growth rate of the magnetic energy is much smaller. Nevertheless, the magnetic power spectrum still retains the Kazantsev form at high Prandtl number.

Melissa Pesce-Rollins, Karl-Ludwig Klein, Säm Krucker, Alexander Warmuth, M. Astrid Veronig, Nicola Omodei, Christian Monstein

12 pages, 7 figures, accepted for publication in Astronomy and Astrophysics

We report on the detection of the gamma-ray emission above 100 MeV from the solar flare of September 29, 2022, by Fermi LAT with simultaneous coverage in HXR by Solar Orbiter STIX. The Solar Orbiter-Earth separation was 178 at the time of the flare as seen from Earth, with Solar Orbiter observing the east limb. Based on STIX imaging, the flare was located 16 behind the eastern limb as seen from Earth. The STIX and GBM non-thermal emission and the LAT emission above 100 MeV all show similarly shaped time profiles, and the Fermi profiles peaked only 20 seconds after the STIX signal from the main flare site, setting this flare apart from all the other occulted flares observed by Fermi LAT. The radio spectral imaging based on the Nan\c{c}ay Radioheliograph and ORFEES spectrograph reveal geometries consistent with a magnetic structure that connects the parent active region behind the limb to the visible disk. We studied the basic characteristics of the gamma-ray time profile, in particular, the rise and decay times and the time delay between the gamma-ray and HXR peak fluxes. We compared the characteristics of this event with those of four Fermi LAT behind-the-limb flares and with an on-disk event and found that this event is strikingly similar to the impulsive on-disk flare. Based on multiwavelength observations, we find that the gamma-ray emission above 100 MeV originated from ions accelerated in the parent active region behind the limb and was transported to the visible disk via a large magnetic structure connected to the parent active region behind the limb. Our results strongly suggest that the source of the emission above 100 MeV from the September 29, 2022 flare cannot be the CME-driven shock.

Clément Staelen, Jean-Marc Huré

Accepted for publication in A&A. 14 pages, 11 figures, 8 tables. A minimum driver program is available at this https URL

We show that the two-dimensional structure of a rigidly rotating self-gravitating body is accessible with relatively good precision by assuming a purely spheroidal stratification. With this hypothesis, the two-dimensional problem becomes one-dimensional, and consists in solving two coupled fixed-point equations in terms of equatorial mass density and eccentricity of isopycnics. We propose a simple algorithm of resolution based on the self-consistent field method. Compared to the full unconstrained-surface two-dimensional problem, the precision in the normalized enthalpy field is better than 103 in absolute, and the computing time is drastically reduced. In addition, this one-dimensional approach is fully appropriate to fast rotators, works for any density profile (including any barotropic equation of state), and can account for mass density jumps in the system, including the existence of an ambient pressure. Several tests are given.

Hong-Xuan Jiang, Indu K. Dihingia, Liu Cheng, Yosuke Mizuno, Tao Zhu

14 pages, 5 figures. Submitted to JCAP. Welcome comments!

The Blandford-Znajek (BZ) process powers energetic jets by extracting the rotating energy of a Kerr black hole. It is important to understand this process in non-Kerr black hole spacetimes. In this study, we conduct two-dimensional and three-dimensional two-temperature General Relativistic Magnetohydrodynamic (GRMHD) simulations of magnetized accretion flows onto a rotating Loop-Quantum black hole (LQBH). Our investigation focuses on the accretion flow structure and jet launching dynamics from our simulations. We observe that the loop quantum effects increase the black hole angular frequency for spinning black holes.This phenomenon intensifies the frame-dragging effect, leading to an amplification of the toroidal magnetic field within the funnel region and enhancement of the launching jet power. It is possible to fit the jet power following a similar fitting formula of the black hole angular frequency as seen in the Kerr black hole. Based on the General Relativistic Radiation Transfer (GRRT) calculation, we find that the jet image from LQBH has a wider opening angle and an extended structure than the Kerr BH.

Ruby J. Wright, Rachel S. Somerville, Claudia del P. Lagos, Matthieu Schaller, Romeel Davé, Daniel Anglés-Alcázar, Shy Genel

20 pages, 8 figures. Submitted to MNRAS 13/02/24

In recent years, cosmological hydrodynamical simulations have proven their utility as key interpretative tools in the study of galaxy formation and evolution. In this work, we present a like-for-like comparison between the baryon cycle in three publicly available, leading cosmological simulation suites: EAGLE, IllustrisTNG, and SIMBA. While these simulations broadly agree in terms of their predictions for the stellar mass content and star formation rates of galaxies at z0, they achieve this result for markedly different reasons. In EAGLE and SIMBA, we demonstrate that at low halo masses (M200c1011.5M), stellar feedback (SF)-driven outflows can reach far beyond the scale of the halo, extending up to 23×R200c. In contrast, in TNG, SF-driven outflows, while stronger at the scale of the ISM, recycle within the CGM (within R200c). We find that AGN-driven outflows in SIMBA are notably potent, reaching several times R200c even at halo masses up to M200c1013.5M. In both TNG and EAGLE, AGN feedback can eject gas beyond R200c at this mass scale, but seldom beyond 23×R200c. We find that the scale of feedback-driven outflows can be directly linked with the prevention of cosmological inflow, as well as the total baryon fraction of haloes within R200c. This work lays the foundation to develop targeted observational tests that can discriminate between feedback scenarios, and inform sub-grid feedback models in the next generation of simulations.

E. Bulbul, A. Liu, M. Kluge, X. Zhang, J. S. Sanders, Y. E. Bahar, V. Ghirardini, E. Artis, R. Seppi, C. Garrel, M. E. Ramos-Ceja, J. Comparat, F. Balzer, K. Böckmann, M. Brüggen, N. Clerc, K. Dennerl, K. Dolag, M. Freyberg, S. Grandis, D. Gruen, F. Kleinebreil, S. Krippendorf, G. Lamer, A. Merloni, K. Migkas, K. Nandra, F. Pacaud, P. Predehl, T. H. Reiprich, T. Schrabback, A. Veronica, J. Weller, S. Zelmer

in press in A&A. 27 pages, 21 figures, 3 tables

Clusters of galaxies can be used as powerful probes to study astrophysical processes on large scales, test theories of the growth of structure, and constrain cosmological models. The driving science goal of the SRG/eROSITA All-Sky Survey (eRASS) is to assemble a large sample of X-ray-selected clusters with a well-defined selection function to determine the evolution of the mass function and, hence, the cosmological parameters. We present here a catalog of 12247 optically confirmed galaxy groups and clusters detected in the 0.2-2.3 keV as extended X-ray sources in a 13,116deg2 region in the western Galactic hemisphere of the sky, which eROSITA surveyed in its first six months of operation. The clusters in the sample span the redshift range 0.003<z<1.32. The majority (68%) of these clusters, 8361 sources, represent new discoveries without known counterparts in the literature. The mass range of the sample covers three orders of magnitude from 5×1012Msun to 2×1015Msun. We construct a sample for cosmology with a higher purity level (~95%) than the primary sample, comprising 5259 securely detected and confirmed clusters in the 12791deg2 common footprint with the DESI Legacy Survey DR10. We characterize the X-ray properties of each cluster, including their flux, luminosity and temperature, the total mass, gas mass, gas mass fraction, and mass proxy YX. These are determined within two apertures, 300 kpc, and the overdensity radius R500, and are calculated by applying a forward modeling approach with a rigorous X-ray background treatment, K-factor, and the Galactic absorption corrections. Population studies utilizing LogN-LogS, the number of clusters detected above a given flux limit, and the luminosity function show overall agreement with the previous X-ray surveys after accounting for the survey completeness and purity (ABRIDGED)

M. Kluge, J. Comparat, A. Liu, F. Balzer, E. Bulbul, J. Ider Chitham, V. Ghirardini, C. Garrel, Y. E. Bahar, E. Artis, R. Bender, N. Clerc, T. Dwelly, M. H. Fabricius, S. Grandis, D. Hernández-Lang, G. J. Hill, J. Joshi, G. Lamer, A. Merloni, K. Nandra, F. Pacaud, P. Predehl, M. E. Ramos-Ceja, T. H. Reiprich, M. Salvato, J. S. Sanders, T. Schrabback, R. Seppi, S. Zelmer, A. Zenteno, X. Zhang

36 pages, 23 figures, 6 tables. Submitted to A&A

The first SRG/eROSITA All-Sky Survey (eRASS1) provides the largest intracluster medium-selected galaxy cluster and group catalog covering the western galactic hemisphere. Compared to samples selected purely on X-ray extent, the sample purity can be enhanced by identifying cluster candidates using optical and near-infrared data from the DESI Legacy Imaging Surveys. Using the red-sequence-based cluster finder eROMaPPer, we measure individual photometric properties (redshift zλ, richness λ, optical center, and BCG position) for 12,000 eRASS1 clusters over a sky area of 13,116 deg2, augmented by 247 cases identified by matching the candidates with known clusters from the literature. The median redshift of the identified eRASS1 sample is z=0.31, with 10% of the clusters at z>0.72. The photometric redshifts have an accuracy of δz/(1+z)<0.005 for 0.05<z<0.9. Spectroscopic cluster properties (redshift zspec and velocity dispersion σ) are measured a posteriori for a subsample of 3,210 and 1,499 eRASS1 clusters, respectively, using an extensive compilation of spectroscopic redshifts of galaxies from the literature. We infer that the primary eRASS1 sample has a purity of 86% and optical completeness >95% for z>0.05. For these and further quality assessments of the eRASS1 identified catalog, we apply our identification method to a collection of galaxy cluster catalogs in the literature, as well as blindly on the full Legacy Surveys covering 24,069 deg2. Using a combination of these cluster samples, we investigate the velocity dispersion-richness relation, finding log(λ)=2.401×log(σ)5.074 with an intrinsic scatter of 0.10±0.01 dex. Our main result is the identified eRASS1 cluster catalog with a high purity and a well-defined X-ray selection process, enabling precise cosmological analyses presented in companion papers.

A. Liu, E. Bulbul, M. Kluge, V. Ghirardini, X. Zhang, J.S. Sanders, E. Artis, Y.E. Bahar, F. Balzer, M. Brueggen, N. Clerc, J. Comparat, C. Garrel, E. Gatuzz, S. Grandis, G. Lamer, A. Merloni, K. Migkas, K. Nandra, P. Predehl, M.E. Ramos-Ceja, T.H. Reiprich, R. Seppi, S. Zelmer

A&A in press

Superclusters of galaxies mark the large-scale overdense regions in the Universe. Superclusters provide an ideal environment to study structure formation and to search for the emission of the intergalactic medium such as cosmic filaments and WHIM. In this work, we present the largest-to-date catalog of X-ray-selected superclusters identified in the first SRG/eROSITA All-Sky Survey (eRASS1). By applying the Friends-of-Friends method on the galaxy clusters detected in eRASS1, we identified 1338 supercluster systems in the western Galactic hemisphere up to redshift 0.8, including 818 cluster pairs and 520 rich superclusters with 3 members. The most massive and richest supercluster system is the Shapley supercluster at redshift 0.05 with 45 members and a total mass of 2.58±0.51×1016M. The most extensive system has a projected length of 127~Mpc. The sizes of the superclusters we identified in this work are comparable to the structures found with galaxy survey data. We also found a good association between the eRASS1 superclusters and the large-scale structures formed by optical galaxies. 3948 clusters, corresponding to 45% of the cluster sample, were identified as supercluster members. The reliability of each supercluster was estimated by considering the uncertainties in cluster redshifts and peculiar velocities. 63\% of the systems have a reliability larger than 0.7. The eRASS1 supercluster catalog provided in this work represents the most extensive sample of superclusters selected in the X-ray band in terms of the unprecedented sample volume, sky coverage, redshift range, the availability of X-ray properties, and the well-understood selection function of the parent cluster sample, which enables direct comparisons with numerical simulations. This legacy catalog will greatly advance our understanding of superclusters and the cosmic large-scale structure.

Florian Kleinebreil, Sebastian Grandis, Tim Schrabback, Vittorio Ghirardini, I-Non Chiu, Ang Liu, Matthias Kluge, Thomas H. Reiprich, Emmanuel Artis, Emre Bahar, Fabian Balzer, Esra Bulbul, Nicolas Clerc, Johan Comparat, Christian Garrel, Daniel Gruen, Xiangchong Li, Hironao Miyatake, Satoshi Miyazaki, Miriam E. Ramos-Ceja, Jeremy Sanders, Riccardo Seppi, Nobuhiro Okabe, Xiaoyuan Zhang

22 pages, 23 figures

We aim to participate in the calibration of the X-ray photon count rate to halo mass scaling relation of galaxy clusters selected in the first eROSITA All-Sky Survey on the Western Galactic Hemisphere (eRASS1) using KiDS-1000 weak-lensing (WL) data. We measure the radial shear profiles around eRASS1 galaxy clusters using background galaxies in KiDS-1000, as well as the cluster member contamination. Furthermore we provide consistency checks with the other stage-III WL surveys who take part in the eRASS1 mass calibration, DES Y3 and HSC-Y3. We determine the cluster member contamination of eRASS1 clusters present in KiDS-1000 based on source number density profiles, where we account for the obscuration caused by cluster galaxies. The extracted shear profiles, together with the contamination model and the lens sample selection, are then analysed through a Bayesian population model. We calibrate the WL mass bias parameter by analysing realistic synthetic shear profiles from mock cluster catalogues. Our consistency checks between KiDS-1000 and DES Y3 & HSC-Y3 include the comparison of contamination-corrected density contrast profiles employing the union of background sources around common clusters, as well as the individual scaling relation results. We present a global contamination model for eRASS1 clusters in KiDS-1000 and the calibration results of the X-ray photon count rate to halo mass relation. The results of the WL mass bias parameter show that the uncertainty of the multiplicative shear bias dominates the systematic error budget at low clusters redshifts while the uncertainty of our contamination model does at high ones. The cross-checks between the three WL surveys show that they are statistically consistent with each other. This enables for the first time cosmological constraints from clusters calibrated by three state-of-the-art WL surveys. (abridged)

N. Clerc, J. Comparat, R. Seppi, E. Artis, Y. E. Bahar, F. Balzer, E. Bulbul, T. Dauser, C. Garrel, V. Ghirardini, S. Grandis, C. Kirsch, M. Kluge, A. Liu, F. Pacaud, M. E. Ramos-Ceja, T. H. Reiprich, J. S. Sanders, J. Wilms, X. Zhang

24 pages, 31 figures, 2 tables. Submitted to A&A

Characterising galaxy cluster populations from catalog of sources selected in astronomical surveys requires knowledge of sample incompleteness, known as selection function. The first All-Sky Survey (eRASS1) by eROSITA onboard Spectrum Roentgen Gamma (SRG) has enabled the collection of large samples of galaxy clusters detected in the soft X-ray band over the Western Galactic hemisphere. The driving goal consists in constraining cosmological parameters, which puts stringent requirements on accuracy, flexibility and explainability of the selection function models. We use a large set of mock observations of the eRASS1 survey and we process simulated data identically to the real eRASS1 events. We match detected sources to simulated clusters and we associate detections to intrinsic cluster properties. We train a series of models to build selection functions depending only on observable surface brightness data. We develop a second series of models relying on global cluster characteristics such as X-ray luminosity, flux, and expected instrumental count-rate as well as on morphological properties. We validate our models using our simulations and we rank them according to selected performance metrics. We validate the models with datasets of clusters detected in X-rays and via the Sunyaev-Zeldovich effect. We present the complete Bayesian population modelling framework developed for this purpose. Our results reveal the surface brightness characteristics most relevant to cluster selection in the eRASS1 sample, in particular the ambiguous role of central surface brightness at the scale of the instrument resolution. We have produced a series of user-friendly selection function models and demonstrated their validity and their limitations. Our selection function for bright sources reproduces well the catalog matches with external datasets. (abridged)

V. Ghirardini, E. Bulbul, E. Artis, N. Clerc, C. Garrel, S. Grandis, M. Kluge, A. Liu, Y. E. Bahar, F. Balzer, I. Chiu, J. Comparat, D. Gruen, F. Kleinebreil, S. Krippendorf, A. Merloni, K. Nandra, N. Okabe, F. Pacaud, P. Predehl, M. E. Ramos-Ceja, T. H. Reiprich, J. S. Sanders, T. Schrabback, R. Seppi, S. Zelmer, X. Zhang, W. Bornemann, H. Brunner, V. Burwitz, D. Coutinho, K. Dennerl, M. Freyberg, S. Friedrich, R. Gaida, A. Gueguen, F. Haberl, W. Kink, G. Lamer, X. Li, T. Liu, C. Maitra, N. Meidinger, S. Mueller, H. Miyatake, S. Miyazaki, J. Robrade, A. Schwope, I. Stewart

43 pages, 22 figures, submitted to A&A

The cluster mass function traces the growth of linear density perturbations and provides valuable insights into the growth of structures, the nature of dark matter, and the cosmological parameters governing the Universe. The primary science goal of eROSITA, on board the {\it Spectrum Roentgen Gamma (SRG)} mission, launched in 2019, is to constrain cosmology through the evolution of cluster mass function. In this paper, we present the cosmological constraints obtained from 5259 clusters of galaxies detected over an area of 12791~deg2 in the Western Galactic Hemisphere of the eROSITA's first All-Sky Survey (eRASS1). The common footprint region between the eROSITA Survey and DES, KiDS, and HSC surveys is used for calibration of the scaling between X-ray count rate and their total mass through measurements of their weak gravitational lensing signal. eRASS1 cluster abundances constrain the ΛCDM parameters, which are the energy density of the total matter to Ωm=0.29+0.010.02, and the normalization of the density fluctuations to σ8=0.88±0.02 and their combination yields S8=σ8(Ωm/0.3)0.5=0.86±0.01, consistent and at a similar precision with the state-of-the-art CMB measurements. eRASS1 cosmological experiment places a most stringent upper limit on the summed masses of left-handed light neutrinos to mν<0.22 eV (95\% confidence interval). Combining eRASS1 cluster abundance measurements with CMB and ground-based neutrino oscillation experiments, we measure the summed neutrino masses to be mν=0.08+0.030.02 eV or mν=0.12+0.030.01 eV depending on the mass hierarchy scenario for neutrino eigenstates. eRASS1 cluster abundances significantly improve the constraints on the dark energy equation of state parameter to w=1.12±0.12. (ABRIDGED)

E. Artis, V. Ghirardini, E. Bulbul, S. Grandis, C. Garrel, N. Clerc, R. Seppi, J. Comparat, M. Cataneo, Y.E. Bahar, F. Balzer, I. Chiu, D. Gruen, F. Kleinebreil, M. Kluge, S. Krippendorf, X. Li, A. Liu, A. Merloni, H. Miyatake, S. Miyazaki, K. Nandra, N. Okabe, F. Pacaud, P. Predehl, M.E. Ramos-Ceja, T.H. Reiprich, J.S. Sanders, T. Schrabback, S. Zelmer, X. Zhang

13 pages, 6 figures, submitted to A&A

The evolution of the cluster mass function traces the growth of the linear density perturbations and can be utilized for constraining the parameters of cosmological and alternative gravity models. In this context, we present new constraints on potential deviations from general relativity by investigating the Hu-Sawicki parametrization of the f(R) gravity with the first SRG-eROSITA All-Sky Survey (eRASS1) cluster catalog in the Western Galactic Hemisphere in combination with the overlapping Dark Energy Survey Year 3, KiloDegree Survey and Hyper Supreme Camera data for weak lensing mass calibration. For the first time, we present constraints obtained from cluster abundances only. When we consider massless neutrinos, we find a strict upper limit of log |fR0| < -4.31 at 95% confidence level. Massive neutrinos suppress structure growth at small scales, and thus have the opposite effect of f(R) gravity. We consequently investigate the joint fit of the mass of the neutrinos with the modified gravity parameter. We obtain log |fR0| < -4.12 jointly with \sum m_\nu < 0.44 e.V. at 95% confidence level, tighter than the limits in the literature utilizing cluster counts only. At log |fR0|= - 6, the number of clusters is not significantly changed by the theory. Consequently, we do not find any statistical deviation from general relativity from the study of eRASS1 cluster abundance. Deeper surveys with eROSITA, increasing the number of detected clusters, will further improve constraints on log |fR0| and investigate alternative gravity theories.

R. Seppi, J. Comparat, V. Ghirardini, C. Garrel, E. Artis, A. G. Sanchez, A. Liu, N. Clerc, E. Bulbul, S. Grandis, M. Kluge, T. H. Reiprich, A. Merloni, X. Zhang, Y. E. Bahar, S. Shreeram, J. Sanders, M. Ramos-Ceja, M. Krumpe

Submitted to A&A, 17 pages, 15 figures

The spatial distribution of galaxy clusters provides a reliable tracer of the large-scale distribution of matter in the Universe. The clustering signal depends on intrinsic cluster properties and cosmological parameters. The ability of eROSITA onboard Spectrum-Roentgen-Gamma (SRG) to discover galaxy clusters allows probing the association of extended X-ray emission to dark matter haloes. We aim to measure the projected two-point correlation function to study the occupation of dark matter halos by clusters and groups detected by the first eROSITA all-sky survey (eRASS1). We create five volume-limited samples probing clusters with different redshift and X-ray luminosity. We interpret the correlation function with halo occupation distribution (HOD) and halo abundance matching (HAM) models. We simultaneously fit cosmological parameters and halo bias of a flux-limited sample of 6493 clusters with purity > 96%. Results. We obtain a detailed view of the halo occupation for eRASS1 clusters. The fainter population at low redshift (S0: LX = 4.63E43 erg/s, 0.1 < z < 0.2) is the least biased compared to dark matter, with b = 2.95 ± 0.21. The brightest clusters up to higher redshift (S4: LX = 1.77E44 erg/s , 0.1 < z < 0.6) exhibit a higher bias b = 4.34 ± 0.62. Satellite groups are rare, with a satellite fraction < 14.9% (8.1) for the S0 (S4) sample. We combine the HOD prediction with a HAM procedure to constrain the scaling relation between LX and mass in a new way and find a scatter of 0.36. We obtain cosmological constraints for the physical cold dark matter density 0.12+0.03-0.02 and an average halo bias b = 3.63+1.02-0.85. We model the clustering of galaxy clusters with a HOD approach for the first time, paving the way for future studies combining eROSITA with 4MOST, SDSS, Euclid, Rubin, and DESI to unravel the cluster distribution in the Universe.

Jiasheng Wang, Jeongwoo Lee, Jongchul Chae, Yan Xu, Wenda Cao, Haimin Wang

Minifilament (MF) eruption producing small jets and micro-flares is regarded as an important source for coronal heating and the solar wind transients through studies mostly based on coronal observations in the extreme ultraviolet (EUV) and X-ray wavelengths. In this study, we focus on the chromospheric plasma diagnostics of a tiny minifilament in quiet Sun located at [71'', 450''] on 2021--08--07 at 19:11 UT observed as part of the ninth encounter of the PSP campaign. Main data obtained are the high cadence, high resolution spectroscopy from the Fast Imaging Solar Spectrograph (FISS) and high-resolution magnetograms from the Near InfraRed Imaging Spectropolarimeter (NIRIS) on the 1.6~m Goode Solar Telescope (GST) at Big Bear Solar Observatory (BBSO). The mini-filament with size 1''×5'' and a micro-flare are detected in both the Hα line center and SDO/AIA 193, 304~\AA\ images. On the NIRIS magnetogram, we found that the cancellation of a magnetic bipole in the footpoints of the minifilament triggered its eruption in a sigmoidal shape. By inversion of the \ha\ and Ca {\sc ii} spectra under the embedded cloud model, we found a temperature increase of 3,800 K in the brightening region, associated with rising speed average of MF increased by 18~km s1. This cool plasma is also found in the EUV images. We estimate the kinetic energy change of the rising filament as 1.5×1025~ergs, and thermal energy accumulation in the MF, 1.4×1025~ergs. From the photospheric magnetograms, we find the magnetic energy change is 1.6×1026~ergs across the PIL of converging opposite magnetic elements, which amounts to the energy release in the chromosphere in this smallest two-ribbon flare ever observed.

P. North, M. Hayes, M. Millon, A. Verhamme, M. Trebitsch, J. Blaizot, F. Courbin, D. Chelouche

15 pages, 8 figures; accepted for publication in A&A

The radio-quiet quasar SDSS J1240+1455 lies at a redshift of z=3.11, is surrounded by a Ly-alpha blob (LAB), and is absorbed by a proximate damped Ly-alpha system. In order to better define the morphology of the blob and determine its emission mechanism, we gathered deep narrow-band images isolating the Ly-alpha line of this object in linearly polarized light. We provide a deep intensity image of the blob, showing a filamentary structure extending up to 16'' (or ~122 physical kpc) in diameter. No significant polarization signal could be extracted from the data, but 95% probability upper limits were defined through simulations. They vary between ~3% in the central 0.75'' disk (after subtraction of the unpolarized quasar continuum) and ~10% in the 3.8-5.5'' annulus. The low polarization suggests that the Ly-alpha photons are emitted mostly in situ, by recombination and de-excitation in a gas largely ionized by the quasar ultraviolet light, rather than by a central source and scattered subsequently by neutral hydrogen gas. This blob shows no detectable polarization signal, contrary to LAB1, a brighter and more extended blob that is not related to the nearby active galactic nucleus (AGN) in any obvious way, and where a significant polarization signal of about 18% was detected.

Alexander A. Marchuk, Ilia V. Chugunov, George A. Gontcharov, Aleksandr V. Mosenkov, Vladimir B. Ilin, Sergey S. Savchenko, Anton A. Smirnov, Denis M. Poliakov, Jonah Seguine, Maxim I. Chazov

Accepted for publication in MNRAS

Spiral structure can contribute significantly to a galaxy's luminosity. However, only rarely are proper photometric models of spiral arms used in decompositions. As we show in the previous work, including the spirals as a separate component in a photometric model of a galaxy would both allow to obtain their structural parameters, and reduce the systematic errors in estimating the parameters of other components. Doing so in different wavebands, one can explore how their properties vary with the wavelength. In this paper, second in this series, we perform decomposition of M 51 in 17 bands, from the far UV to far IR, using imaging from the DustPedia project. We use the same 2D photometric model of spiral structure where each arm is modelled independently. The complex and asymmetric spiral structure in M 51 is reproduced relatively well with our model. We analyze the differences between models with and without spiral arms, and investigate how the fit parameters change with wavelength. In particular, we find that the spiral arms demonstrate the largest width in the optical, whereas their contribution to the galaxy luminosity is most significant in the UV. The disk central intensity drops by a factor of 1.25--3 and its exponential scale changes by 5--10\% when spiral arms are included, depending on wavelength. Taking into account the full light distribution across the arms, we do not observe the signs of a long-lived density wave in the spiral pattern of M 51 as a whole.

Bendik Nyheim, Signe Riemer-Sørensen, Rodrigo Parra, Claudia Cicone

Submitted to the Nordic Machine Intelligence journal. The code is available at this https URL Comments welcome

Radio, sub-millimiter and millimeter ground-based telescopes are powerful instruments for studying the gas and dust-rich regions of the Universe that are invisible at optical wavelengths, but the pointing accuracy is crucial for obtaining high-quality data. Pointing errors are small deviations of the telescope's orientation from its desired direction. The telescopes use linear regression pointing models to correct for these errors, taking into account various factors such as weather conditions, telescope mechanical structure, and the target's position in the sky. However, residual pointing errors can still occur due to factors that are hard to model accurately, such as thermal and gravitational deformation and environmental conditions like humidity and wind. Here we present a proof-of-concept for reducing pointing error for the Atacama Pathfinder EXperiment (APEX) telescope in the high-altitude Atacama Desert in Chile based on machine learning. Using historic pointing data from 2022, we trained eXtreme Gradient Boosting (XGBoost) models that reduced the root-mean-square errors (RMSE) for azimuth and elevation (horizontal and vertical angle) pointing corrections by 4.3% and 9.5%, respectively, on hold-out test data. Our results will inform operations of current and future facilities such as the next-generation Atacama Large Aperture Submillimeter Telescope (AtLAST).

L.A. Cañizares, S.T. Badman, S.A. Maloney, M.J. Owens, D.M. Weigt, E.P. Carley, P.T. Gallagher

13 pages, 12 figures, in press, accepted by Astronomy and Astrophysics for publication

Solar radio bursts (SRBs), are emitted by electrons propagating through the corona and interplanetary space. Tracking such bursts is key to understanding the properties of accelerated electrons and radio wave propagation as well as the local plasma environment that they propagate through. Here, we present a novel multilateration algorithm called BayEsian LocaLisation Algorithm (BELLA). In addition, apparent SRB positions from BELLA are compared with comparable localisation methods and the predictions of solar wind models. BELLA uses Bayesian inference to create probabilistic distributions of source positions and their uncertainties. This facilitates the estimation of algorithmic, instrumental, and physical uncertainties in a quantitative manner. We validated BELLA using simulations and a Type III SRB observed by STEREO A/B and Wind. BELLA tracked the Type III source from 10--150 Rsun (2-0.15 MHz) along a spiral trajectory. This allowed for an estimate of an apparent solar wind speed of vsw 400 km s1 and a source longitude of ϕ0 30deg. We compared these results with well-established methods of positioning: Goniopolarimetric (GP), analytical time-difference-of-arrival (TDOA), and Solar radio burst Electron Motion Tracker (SEMP). We found them to be in agreement with the results obtained by BELLA. Additionally, the results aligned with solar wind properties assimilated by the Heliospheric Upwind Extrapolation with time dependence (HUXt) model. We have validated BELLA and used it to identify apparent source positions as well as velocities and densities of the solar wind. Furthermore, we identified higher than expected electron densities, suggesting that the true emission sources were at lower altitudes than those identified by BELLA, an effect that may be due to appreciable scattering of electromagnetic waves by electrons in interplanetary space.

A. Y. Ibrahim, A. Borghese, F. Coti Zelati, E. Parent, A. Marino, O. S. Ould-Boukattine, N. Rea, S. Ascenzi, D. P. Pacholski, S. Mereghetti, G. L. Israel, A. Tiengo, A. Possenti, M. Burgay, R. Turolla, S. Zane, P. Esposito, D. Gotz, S. Campana, F. Kirsten, M. P. Gawronski, J. W. T. Hessels

16 pages, 6 figures, accepted for publication on ApJ

Recently, the Galactic magnetar SGR J1935+2154 has garnered attention due to its emission of an extremely luminous radio burst, reminiscent of Fast Radio Bursts (FRBs). SGR J1935+2154 is one of the most active magnetars, displaying flaring events nearly every year, including outbursts as well as short and intermediate bursts. Here, we present our results on the properties of the persistent and bursting X-ray emission from SGR J1935+2154, during the initial weeks following its outburst on October 10, 2022. The source was observed with XMM-Newton and NuSTAR (quasi-)simultaneously during two epochs, separated by 5 days. The persistent emission spectrum is well described by an absorbed blackbody plus power-law model up to an energy of 25 keV. No significant changes were observed in the blackbody temperature (kTBB 0.4 keV) and emitting radius (RBB 1.9 km) between the two epochs. However, we observed a slight variation in the power-law parameters. Moreover, we detected X-ray pulsations in all the datasets and derived a spin period derivative of ˙P=5.52(5)×1011 ss. This is 3.8 times larger than the value measured after the first recorded outburst in 2014. Additionally, we performed quasi-simultaneous radio observations using three 25--32-m class radio telescopes for a total of 92.5 hr to search for FRB-like radio bursts and pulsed emission. However, our analysis did not reveal any radio bursts or periodic emission.

P. Yu. Minaev, A. S. Pozanenko, S. A. Grebenev, I. V. Chelovekov, N. S. Pankov, A. A. Khabibullin, R. Ya. Inasaridze, A. O. Novichonok

21 pages, 14 figures, accepted to Astronomy Letters at 2023 November 21

The results of a study of the short gamma-ray burst GRB 231115A in the X-ray and gamma-ray ranges are presented, based on data from the INTEGRAL and Fermi space observatories. The source of the burst is localized by the IBIS/ISGRI telescope of INTEGRAL observatory with an accuracy of 1.5 arcmin, it is located in the Cigar Galaxy (M 82). Early follow-up observations of the burst localization region were carried out in the optical range with the 36-cm telescope of the ISON-Kitab observatory and the 70-cm telescope AS-32 of the Abastumani Astrophysical Observatory, the optical emission has not been detected. The proximity of the host galaxy (DL3.5 Mpc) significantly limits energetics of the event (Eiso  1045 erg) and allows us to interpret the burst as a giant flare of a previously unknown soft gamma repeater (SGR) which is an extreme manifestation of the activity of a highly magnetized neutron star (magnetar). This conclusion is confirmed by the energy spectrum atypically hard for cosmological gamma-ray bursts, as well as the absence of optical afterglow and gravitational wave signal, which should have been detected in the LIGO/Virgo/KAGRA experiments if the burst was caused by a merger of binary neutron stars. The location of the burst in the Ep,i -- Eiso and T90,i -- EH diagrams also suggests that GRB 231115A was a magnetar giant flare. This is the first well-localized giant flare of an extragalactic SGR.

Ziyuan Yin, Austin Hinkel

12 pages, 10 sub figures and one animation across 5 figures. Animation may not work in all pdf-viewing softwares. Accepted in ApJ

As the number of known Galactic structures mounts thanks to the Gaia Space Telescope, it is now pertinent to study methods for disentangling structures occupying the same regions of the Milky Way. Indeed, understanding the precise form of each individual structure and the interactions between structures may aid in understanding their origins and chronology. Moreover, accounting for known structures allows one to probe still finer Galactic structure. In order to demonstrate, we have developed an odd low-pass filter (OLPF) which removes smaller, odd-parity structures like the vertical waves, and use the filtered data to examine the location of the Galaxy's mid-plane. We find that the radial wave identified by Xu et al. (2015) continues inward to at least the Sun's location, with an amplitude that decreases towards the inner, denser parts of the disk, consistent with a simple, qualitative simulation. Additionally, we employ the OLPF results to determine the solar offset, z, with smaller structures filtered out. We find that z=34.2±0.3 pc.

Zefeng Li, Robert J. J. Grand, Emily Wisnioski, J. Trevor Mendel, Mark R. Krumholz, Yuan-Sen Ting, Ruediger Pakmor, Facundo A. Gómez, Federico Marinacci, Ioana Ciucă

12 pages, 10 figures, 1 table, accepted for publication in MNRAS

We study the cosmological evolution of the two-point correlation functions of galactic gas-phase metal distributions using the 28 simulated galaxies from the Auriga Project. Using mock observations of the z=0 snapshots to mimic our past work, we show that the correlation functions of the simulated mock observations are well matched to the correlation functions measured from local galaxy surveys. This comparison suggests that the simulations capture the processes important for determining metal correlation lengths, the key parameter in metallicity correlation functions. We investigate the evolution of metallicity correlations over cosmic time using the true simulation data, showing that individual galaxies undergo no significant systematic evolution in their metal correlation functions from z3 to today. In addition, the fluctuations in metal correlation length are correlated with but lag ahead fluctuations in star formation rate. This suggests that re-arrangement of metals within galaxies occurs at a higher cadence than star formation activity, and is more sensitive to the changes of environment, such as galaxy mergers, gas inflows / outflows, and fly-bys.

We study how large fluctuations are spatially correlated in the presence of quantum diffusion during inflation. This is done by computing real-space correlation functions in the stochastic-δN formalism. We first derive an exact description of physical distances as measured by a local observer at the end of inflation, improving on previous works. Our approach is based on recursive algorithmic methods that consistently include volume-weighting effects. We then propose a "large-volume'' approximation under which calculations can be done using first-passage time analysis only, and from which a new formula for the power spectrum in stochastic inflation is derived. We then study the full two-point statistics of the curvature perturbation. Due to the presence of exponential tails, we find that the joint distribution of large fluctuations is of the form P(ζR1,ζR2)=F(R1,R2,r)P(ζR1)P(ζR2), where ζR1 and ζR2 denote the curvature perturbation coarse-grained at radii R1 and R2, around two spatial points distant by r. This implies that, on the tail, the reduced correlation function, defined as P(ζR1>ζc,ζR2>ζc)/[P(ζR1>ζc)P(ζR2>ζc)]1, is independent of the threshold value ζc. This contrasts with Gaussian statistics where the same quantity strongly decays with ζc, and shows the existence of a universal clustering profile for all structures forming in the exponential tails. Structures forming in the intermediate (i.e. not yet exponential) tails may feature different, model-dependent behaviours.

Diogo Belloni, Joanna Mikołajewska, Matthias R. Schreiber

Submitted to A&A

To shed light on the origin of magnetic symbiotic stars, we investigated the system FN Sgr in detail. We searched for a reasonable formation pathway to explain its stellar and binary parameters including the magnetic field of the accreting white dwarf. We used the MESA code to carry out pre-CE and post-CE binary evolution and determined the outcome of CE evolution assuming the energy formalism. For the origin and evolution of the white dwarf magnetic field, we adopted the crystallization scenario. We found that FN Sgr can be explained as follows. First, a non-magnetic white dwarf is formed through CE evolution. Later, during post-CE evolution, the white dwarf starts to crystallize and a weak magnetic field is generated. After a few hundred Myr, the magnetic field penetrates the white dwarf surface and becomes detectable. Meanwhile, its companion evolves and becomes an evolved red giant. Subsequently, the white dwarf accretes part of the angular momentum from the red giant stellar winds. As a result, the white dwarf spin period decreases and its magnetic field reaches super-equipartition, getting amplified due to a rotation- and crystallization-driven dynamo. The binary then evolves into a symbiotic star, with a magnetic white dwarf accreting from an evolved red giant through atmospheric Roche-lobe overflow. We conclude that the rotation- and crystallization-driven dynamo scenario, or any age-dependent scenario, can explain the origin of magnetic symbiotic stars reasonably well. This adds another piece to the pile of evidence supporting this scenario. If our formation channel is correct, our findings suggest that white dwarfs in most symbiotic stars formed through CE evolution might be magnetic, provided that the red giant has spent >3 Gyr as a main-sequence star.

Hugh Garsden, Philip Bull, Mike Wilensky, Zuhra Abdurashidova, Tyrone Adams, James E. Aguirre, Paul Alexander, Zaki S. Ali, Rushelle Baartman, Yanga Balfour, Adam P. Beardsley, Lindsay M. Berkhout, Gianni Bernardi, Tashalee S. Billings, Judd D. Bowman, Richard F. Bradley, Jacob Burba, Steven Carey, Chris L. Carilli, Kai-Feng Chen, Carina Cheng, Samir Choudhuri, David R. DeBoer, Eloy de Lera Acedo, Matt Dexter, Joshua S. Dillon, Scott Dynes, Nico Eksteen, John Ely, Aaron Ewall-Wice, Nicolas Fagnoni, Randall Fritz, Steven R. Furlanetto, Kingsley Gale-Sides, Bharat Kumar Gehlot, Abhik Ghosh, Brian Glendenning, Adelie Gorce, Deepthi Gorthi, Bradley Greig, Jasper Grobbelaar, Ziyaad Halday, Bryna J. Hazelton, Jacqueline N. Hewitt, Jack Hickish, Tian Huang, Daniel C. Jacobs, Alec Josaitis, Austin Julius, et al. (48 additional authors not shown)

21 pages, 18 figures, submitted to Monthly Notices of the Royal Astronomical Society

Radio interferometers targeting the 21cm brightness temperature fluctuations at high redshift are subject to systematic effects that operate over a range of different timescales. These can be isolated by designing appropriate Fourier filters that operate in fringe-rate (FR) space, the Fourier pair of local sidereal time (LST). Applications of FR filtering include separating effects that are correlated with the rotating sky vs. those relative to the ground, down-weighting emission in the primary beam sidelobes, and suppressing noise. FR filtering causes the noise contributions to the visibility data to become correlated in time however, making interpretation of subsequent averaging and error estimation steps more subtle. In this paper, we describe fringe rate filters that are implemented using discrete prolate spheroidal sequences, and designed for two different purposes -- beam sidelobe/horizon suppression (the `mainlobe' filter), and ground-locked systematics removal (the `notch' filter). We apply these to simulated data, and study how their properties affect visibilities and power spectra generated from the simulations. Included is an introduction to fringe-rate filtering and a demonstration of fringe-rate filters applied to simple situations to aid understanding.

Zipeng Wang, Thomas Helfer, Dina Traykova, Katy Clough, Emanuele Berti

10 pages, 6 figures

In fluid dynamics, the Magnus effect is the force perpendicular to the motion of a spinning object as it moves through a medium. In general relativity, an analogous effect exists for a spinning compact object moving through matter, purely as a result of gravitational interactions. In this work we consider a Kerr black hole moving at relativistic velocities through scalar dark matter that is at rest. We simulate the system numerically and extract the total spin-curvature force on the black hole perpendicular to its motion. We confirm that the force scales linearly with the dimensionless spin parameter a/M of the black hole up to a/M=0.99, and measure its dependence on the speed v of the black hole in the range 0.1v0.55 for a fixed spin. Compared to previous analytic work applicable at small v, higher-order corrections in the velocity are found to be important: the total force is nonzero, and the dependence is not linear in v. We find that in all cases the total force is in the opposite direction to the hydrodynamical analogue, although at low speeds it appears to approach the expectation that the Weyl and Magnus components cancel. Spin-curvature effects may leave an imprint on gravitational wave signals from extreme mass-ratio inspirals, where the secondary black hole has a nonnegligible spin and moves in the presence of a dark matter cloud. We hope that our simulations can be used to support and extend the limits of analytic results, which are necessary to better quantify such effects in the relativistic regime.

Conor Dyson, Jaime Redondo-Yuste, Maarten van de Meent, Vitor Cardoso

15 pages, 8 figures

Astrophysical black holes do not exist in vacuum, and their motion is affected by the galactic environment. As a black hole moves it attracts stars and matter, creating a wake that, in turn, exerts an effective friction slowing down the black hole. This force is known as dynamical friction, and has significant consequences, ranging from the formation of supermassive black hole binaries to modifications in the phase of binary mergers. In this work we explore the motion of spinning black holes on a medium. We find that the classical drag along the velocity direction is modified and two novel forces appear: a rotational force, which in the context of fluid dynamics is dubbed the Magnus force, and a lift, orthogonal to the direction of motion. We develop a first-principles fully-relativistic treatment of these spin-induced aerodynamic forces in two types of environment: i) collisionless corpuscular matter and ii) a light scalar field, exploring the differences between both cases. In both cases we find that the total rotational force acts precisely in the opposite direction as compared to the classical set-up of a spinning ball moving through a fluid. Finally, we comment on the consequences of these new effects for astrophysics and gravitational wave observations.

Emmanuel Chávez Nambo, Alberto Diez-Tejedor, Armando A. Roque, Olivier Sarbach

15+1 pages and 10 figures

In this paper we study the linear stability of selfinteracting boson stars in the nonrelativistic limit of the Einstein-Klein-Gordon theory. For this purpose, based on a combination of analytic and numerical methods, we determine the behavior of general linear perturbations around the stationary and spherically symmetric solutions of the Gross-Pitaevskii-Poisson system. In particular, we conclude that ground state configurations are linearly stable if the selfinteraction is repulsive, whereas there exist a state of maximum mass that divides the stable and the unstable branches in case the selfinteraction is attractive. Regarding the excited states, they are in general unstable under generic perturbations, although we identify a stability band in the first excited states of the repulsive theory. This result is independent of the mass of the scalar field and the details of the selfinteraction potential, and it is in contrast to the situation of vanishing selfinteraction, in which excited states are always unstable.

Recent studies have shown that orbital eccentricity may indicate dynamical assembly as a formation mechanism for binary black holes. Eccentricity leaves a distinct signature in gravitational wave signals and it may be measured if the binary remains eccentric when it enters the LIGO band. Although eccentricity has not yet been confidently detected, the possibility of detecting eccentric binaries is becoming more likely with the improved sensitivity of gravitational wave detectors such as LIGO, Virgo, and KAGRA. It is crucial to assess the accuracy of current search pipelines in recovering eccentricity from gravitational wave signals if it is present. In this study, we investigate the ability of parameter estimation pipeline RIFT to recover eccentricity in the non-spinning and aligned-spin cases for low mass binary black holes. We use TaylorF2Ecc and TEOBResumS to inject sets of synthetic signals and test how well RIFT accurately recovers key binary black hole parameters. Our findings provide valuable insights into the capability of current parameter estimation methods to detect and measure eccentricity in gravitational wave signals.

Massimo Giovannini

36 pages, 7 figures

We observe that the energy and the enthalpy densities can be smeared by two fudge factors that are constrained by the contracted Bianchi identities. Depending on the smearing functions the underlying cosmological solutions belong to two complementary (but physically different) classes, namely the bounces of the scale factor and the curvature bounces. Gradient instabilities and singularities may appear in the evolution of curvature inhomogeneities and this general conclusion is corroborated by the concrete examples associated with different forms of the smearing functions. While the backgrounds obtained in this manner might seem technically regular, the evolution of the curvature inhomogeneities restrict the ranges of the solutions that turn out to be unsuitable even for a limited description of the pre-inflationary initial data. It is however not excluded that a class of scenarios (mainly associated with the curvature bounces) could indeed avoid the potential instabilities.

Victor J. H. Trees, Stephan R. de Roode, Job I. Wiltink, Jan Fokke Meirink, Ping Wang, Piet Stammes, A. Pier Siebesma

Clouds affected by solar eclipses could influence the reflection of sunlight back into space and might change local precipitation patterns. Satellite cloud retrievals have so far not taken into account the lunar shadow, hindering a reliable spaceborne assessment of the eclipse-induced cloud evolution. Here we use satellite cloud measurements during three solar eclipses between 2005 and 2016 that have been corrected for the partial lunar shadow together with large-eddy simulations to analyze the eclipse-induced cloud evolution. Our corrected data reveal that, over cooling land surfaces, shallow cumulus clouds start to disappear at very small solar obscurations. Our simulations explain that the cloud response was delayed and was initiated at even smaller solar obscurations. We demonstrate that neglecting the disappearance of clouds during a solar eclipse could lead to a considerable overestimation of the eclipse-related reduction of net incoming solar radiation. These findings should spur cloud model simulations of the direct consequences of sunlight-intercepting geoengineering proposals, for which our results serve as a unique benchmark.

Anne-Katherine Burns, Venus Keus, Marc Sher, Tim M.P. Tait

12 pages, 4 figures

Recently, the EMPRESS collaboration has included new data in the extraction of the primordial He-4 abundance from Big Bang Nucleosynthesis (BBN), resulting in a determination that differs from the previous value and from theoretical expectations. There have been several studies attempting to explain this anomaly which involve variation of fundamental constants between the time of BBN and the present. Since the Higgs vacuum expectation value (vev) is the only dimensionful parameter of the Standard Model and it is already known to vary during the electroweak phase transition, we consider the possibility that the vev is slightly different during BBN compared to its present value. A modification of the vev changes not only particle masses but also affects, through mass thresholds, the QCD confinement scale. We use the recently developed PRyMordial program to study this variation and its impact on the He-4 and deuterium abundances. We find that bounds on |dv/v| are approximately 0.01, and that the EMPRESS result can be explained within 2 sigma if -0.03 < dv/v < -0.01, but at the cost of worsening the current 2 sigma discrepancy in the deuterium abundance to over 3 sigma.

Recently, using Bayesian Machine Learning, a deviation from the cold dark matter model on cosmological scales has been put forward. Such model might replace a proposed non-gravitational interaction between dark energy and dark matter, and help solve the H0 tension problem. The idea behind the learning procedure relied there on a generated expansion rate, while the real expansion rate was just used to validate the learned results. In the present work, however, the emphasis is put on a Gaussian Process (GP) with the available H(z) data confirming the possible existence of the already learned deviation. Three cosmological scenarios are considered: a simple one, with equation of state parameter for dark matter ωdm=ω00, and two other models, with corresponding parameters ωdm=ω0+ω1z and ωdm=ω0+ω1z/(1+z). The constraints obtained on the free parameters ω0 and ω1 hint towards a dynamical nature of the deviation. The dark energy dynamics is also reconstructed, revealing interesting aspects connected with the H0 tension problem. It is concluded, however, that improved tools and more data are needed, in order to reach a better understanding of the reported deviation.