Abstract visibility
Abstract text size

Papers for Thursday, Jan 12 2023

Papers with local authors

A. Albert, R. Alfaro, J.C. Arteaga-Velázquez, E. Belmont-Moreno, T. Capistrán, A. Carramiñana, S. Casanova, J. Cotzomi, S. Coutiño de León, E. De la Fuente, R. Diaz Hernandez, M.A. DuVernois, J.C. Díaz-Vélez, C. Espinoza, K.L. Fan, N. Fraija, K. Fang, J.A. García-González, F. Garfias, Armelle Jardin-Blicq, M.M. González, J.A. Goodman, J.P. Harding, S. Hernandez, D. Huang, F. Hueyotl-Zahuantitla, A. Iriarte, V. Joshi, A. Lara, J. Lee, H. León Vargas, J.T. Linnemann, A.L. Longinotti, G. Luis-Raya, K. Malone, O. Martinez, J. Martínez-Castro, J.A. Matthews, J.A. Morales-Soto, E. Moreno, M. Mostafá, A. Nayerhoda, L. Nellen, M. Newbold, M.U. Nisa, Y. Pérez Araujo, E.G. Pérez-Pérez, C.D. Rho, D. Rosa-González, M. Schneider, et al.
0 votes
Paper 60 — arXiv:2301.04646
0 votes
Paper 60 — arXiv:2301.04646

Extended very-high-energy (VHE; 0.1-100~TeV) $\gamma$-ray emission has been observed around several middle-aged pulsars and referred to as ``TeV halos". Their formation mechanism remains under debate. It is also unknown whether they are ubiquitous or related to certain subgroup of pulsars. With 2321 days of observation, the High Altitude Water Cherenkov (HAWC) Gamma-Ray Observatory detected VHE $\gamma$-ray emission at the location of the radio-quiet pulsar PSR J0359+5414 with $>6\sigma$ significance. By performing likelihood tests with different spectral and spatial models and comparing the TeV spectrum with multi-wavelength observations of nearby sources, we show that this excess is consistent with a TeV halo associated with PSR J0359+5414, though future observation of HAWC and multi-wavelength follow-ups are needed to confirm this nature. This new halo candidate is located in a non-crowded region in the outer Galaxy. It shares similar properties to the other halos but its pulsar is younger and radio-quiet. Our observation implies that TeV halos could commonly exist around pulsars and their formation does not depend on the configuration of the pulsar magnetosphere.

All other papers

A. Posner, N. Arge, K. Cho, B. Heber, F. Effenberger, T. Y. Chen, S. Krucker, P. Kühl, O. Malandraki, Y.-D. Park, A. Pulkkinen, N. Raouafi, S. K. Solanki, O. C. StCyr, R. D. Strauss

Heliophysics 2050 White Paper

This white paper recognizes gaps in observations that will, when addressed, much improve solar radiation hazard and geomagnetic storm forecasting. Radiation forecasting depends on observations of the entire "Solar Radiation Hemisphere" that we will define. Mars exploration needs strategic placement of radiation-relevant observations. We also suggest an orbital solution that will improve geomagnetic storm forecasting through improved in situ and solar/heliospheric remote sensing.

Ryan Volz, Philip J. Erickson, Scott E. Palo, Jorge L. Chau, Juha Vierinen, Thomas Y. Chen

Heliophysics 2050 Workshop

Our current sampling of the near-Earth space environment is wholly insufficient to measure the highly variable processes therein and make predictions on par with lower atmospheric weather. We sketch out the scientific rationale for a network of radio instruments delivering dense observations of the near-Earth space environment and the broad steps necessary to implement wide-scale coverage in the next 30 years.

Jonathan J. Davies, Andrew Pontzen, Robert A. Crain

11 pages, 5 figures. Submitted to MNRAS, comments welcome

The fates of massive galaxies are tied to the evolution of their central supermassive black holes (BHs), due to the influence of AGN feedback. Correlations within simulated galaxy populations suggest that the masses of BHs are governed by properties of their host dark matter haloes, such as the binding energy and assembly time, at a given halo mass. However, the full picture must be more complex as galaxy mergers have also been shown to influence the growth of BHs and the impact of AGN. In this study, we investigate this problem by using the genetic modification technique to adjust the assembly history of a Milky Way-like galaxy simulated with the EAGLE model. We change the halo assembly time (and hence the binding energy) in the absence of any disruptive merger events, and find little change in the integrated growth of the BH. We attribute this to the angular momentum support provided by a galaxy disc, which reduces the inflow of gas towards the BH and effectively decouples the BH's growth from the properties of the halo. Introducing major mergers into the assembly history disrupts the disc, causing the BH to grow $\approx 4\times$ more massive and inject feedback that reduces the halo baryon fraction by a factor of $\approx 2$ and quenches star formation. Merger events appear to be essential to the diversity in BH masses in EAGLE, and we show that they can also significantly increase the halo binding energy, potentially explaining the correlation between these quantities.

M. Libralato, E. Vesperini, A. Bellini, A. P. Milone, R. P. van der Marel, G. Piotto, J. Anderson, A. Aparicio, B. Barbuy, L. R. Bedin, T. M. Brown, S. Cassisi, D. Nardiello, A. Sarajedini, M. Scalco

10 pages, 4 figures, 2 tables. Accepted for publication on ApJ

Our understanding of the kinematic properties of multiple stellar populations (mPOPs) in Galactic globular clusters (GCs) is still limited compared to what we know about their chemical and photometric characteristics. Such limitation arises from the lack of a comprehensive observational investigation of this topic. Here we present the first homogeneous kinematic analysis of mPOPs in 56 GCs based on high-precision proper motions computed with Hubble Space Telescope data. We focused on red-giant-branch stars, for which the mPOP tagging is clearer, and measured the velocity dispersion of stars belonging to first (1G) and second generations (2G). We find that 1G stars are generally kinematically isotropic even at the half-light radius, whereas 2G stars are isotropic at the center and become radially anisotropic before the half-light radius. The radial anisotropy is induced by a lower tangential velocity dispersion of 2G stars with respect to the 1G population, while the radial component of the motion is comparable. We also show possible evidence that the kinematic properties of mPOPs are affected by the Galactic tidal field, corroborating previous observational and theoretical results suggesting a relation between the strength of the external tidal field and some properties of mPOPs. Although limited to the GCs' central regions, our analysis leads to new insights into the mPOP phenomenon, and provides the motivation for future observational studies of the internal kinematics of mPOPs.

Lichen Liang, Robert Feldmann, Norman Murray, Desika Narayanan, Christopher C. Hayward, Daniel Anglés-Alcázar, Luigi Bassini, Alexander J. Richings, Claude-André Faucher-Giguère, Dongwoo T. Chung, Jennifer Y. H. Chan, Onur Çatmabacak, Dušan Kereš, Philip F. Hopkins

42 page, 25 figures, 8 tables and 8 appendices. Key figures: fig. 16 & 17. Comments are welcome

Observations of local star-forming galaxies (SFGs) show a tight correlation between their singly ionized carbon line luminosity ($L_{\rm [C_{II}]}$) and star formation rate (SFR), suggesting that $L_{\rm [C_{II}]}$ may be a useful SFR tracer for galaxies. Some other galaxy populations, however, are found to have lower $L_{\rm [C_{II}]}{}/{}\rm SFR$ than the local SFGs, including the infrared-luminous, starburst galaxies at low and high redshifts, as well as some moderately star-forming galaxies at the epoch of re-ionization (EoR). The origin of this `$\rm [C_{II}]$ deficit' is unclear. In this work, we study the $L_{\rm [C_{II}]}$-SFR relation of galaxies using a sample of $z=0-8$ galaxies with $M_*\approx10^7-5\times10^{11}\,M_\odot$ extracted from cosmological volume and zoom-in simulations from the Feedback in Realistic Environments (FIRE) project. We find a simple analytic expression for $L_{\rm [C_{II}]}$/SFR of galaxies in terms of the following parameters: mass fraction of $\rm [C_{II}]$-emitting gas ($f_{\rm [C_{II}]}$), gas metallicity ($Z_{\rm gas}$), gas density ($n_{\rm gas}$) and gas depletion time ($t_{\rm dep}{}={}M_{\rm gas}{}/{}\rm SFR$). We find two distinct physical regimes, where $t_{\rm dep}$ ($Z_{\rm gas}$) is the main driver of the $\rm [C_{II}]$ deficit in $\rm H_2$-rich ($\rm H_2$-poor) galaxies. The observed $\rm [C_{II}]$ deficit of IR-luminous galaxies and early EoR galaxies, corresponding to the two different regimes, is due to short gas depletion time and low gas metallicity, respectively. Our result indicates that $\rm [C_{II}]$ deficit is a common phenomenon of galaxies, and caution needs to be taken when applying a constant $L_{\rm [C_{II}]}$-to-SFR conversion factor derived from local SFGs to estimate cosmic SFR density at high redshifts and interpret data from upcoming $\rm [C_{II}]$ line intensity mapping experiments.

Elliot Y. Davies, Adam M. Dillamore, Eugene Vasiliev, Vasily Belokurov

5 pages, 7 figures, submitted to MNRAS

In a galaxy merger, the stars tidally stripped from the satellite and accreted onto the host galaxy undergo phase mixing and form finely-grained structures in the phase space. However, these fragile structures may be destroyed in the subsequent galaxy evolution, in particular, by a rotating bar that appears well after the merger is completed. In this work, we investigate the survivability of phase-space structures in the presence of a bar. We find that a bar with amplitude and pattern speed similar to those of the Milky Way would blur and destroy a substantial amount of the substructure that consists of particles with pericentre radii comparable to the bar length. While this appears to be in tension with the recent discovery of phase-space chevrons in \textit{Gaia} DR3 data, the most prominent chevrons in our simulations can still be recovered when applying the same analysis procedure as in observations. Moreover, the smoothing effect is less pronounced in the population of stars whose angular momenta have the opposite sign to the bar pattern speed.

Chad Bustard, S. Peng Oh

Submitted to ApJ, 21 pages, 12 figures

While it is well-known that cosmic rays (CRs) can gain energy from turbulence via second order Fermi acceleration, how this energy transfer affects the turbulent cascade remains largely unexplored. Here, we show that damping and steepening of the compressive turbulent power spectrum are expected once the damping time $t_{\rm damp} \sim \rho v^{2}/\dot{E}_{\rm CR} \propto E_{\rm CR}^{-1}$ becomes comparable to the turbulent cascade time. Magnetohydrodynamic (MHD) simulations of stirred compressive turbulence in a gas-CR fluid with diffusive CR transport show clear imprints of CR-induced damping, saturating at $\dot{E}_{\rm CR} \sim \tilde{\epsilon}$, where $\tilde{\epsilon}$ is the turbulent energy input rate. In that case, almost all the energy in large scale motions is absorbed by CRs and does not cascade down to grid scale. This ``divergence-cleaning" should render small-scale turbulence largely solenoidal and could suppress fluctuations important for thermal instability. The lack of small-scale compressive modes is also problematic for hypothesized resonant scattering of $E > 300$ GeV CRs, when self-confinement is inefficient. When CR transport is streaming dominated, CRs also damp large scale motions, with kinetic energy reduced by up to to an order of magnitude in realistic $E_{\rm CR} \sim E_{\rm g}$ scenarios, but turbulence (with a reduced amplitude) still cascades down to small scales with the same power spectrum. Such large scale damping implies that turbulent velocities obtained from the observed velocity dispersion may significantly underestimate the turbulent forcing rate, i.e. $\tilde{\epsilon} \gg \rho v^{3}/L$. These findings motivate future, higher resolution simulations with a mixture of turbulent driving modes.

Kristen. B. W. McQuinn, Yao-Yuan Mao, Matthew R. Buckley, David Shih, Roger E. Cohen, Andrew E. Dolphin

15 pages, 10 figures, 2 tables

We report the discovery of an ultrafaint dwarf (UFD) galaxy, Pegasus W, located on the far side of the Milky Way-M31 system and outside the virial radius of M31. The distance to the galaxy is 915 (+60/-91) kpc, measured using the luminosity of horizontal branch (HB) stars identified in Hubble Space Telescope optical imaging. The galaxy has a half-light radius (r_h) of 100 (+11/-13) pc, M_V = -7.20 (+0.17/-0.16) mag, and a present-day stellar mass of 6.5 (+1.1/-1.4) x 10^4 Msun. We identify sources in the color-magnitude diagram (CMD) that may be younger than ~500 Myr suggesting late-time star formation in the UFD galaxy, although further study is needed to confirm these are bona fide young stars in the galaxy. Based on fitting the CMD with stellar evolution libraries, Pegasus W shows an extended star formation history (SFH). Using the tau_90 metric (defined as the timescale by which the galaxy formed 90% of its stellar mass), the galaxy was quenched only 7.4 (+2.2/-2.6) Gyr ago, which is similar to the quenching timescale of a number of UFD satellites of M31 but significantly more recent than the UFD satellites of the Milky Way. Such late-time quenching is inconsistent with the more rapid timescale expected by reionization and suggests that, while not currently a satellite of M31, Pegasus W was nonetheless slowly quenched by environmental processes.

Vasily Kokorev, Shuowen Jin, Georgios E. Magdis, Karina I. Caputi, Francesco Valentino, Pratika Dayal, Maxime Trebitsch, Gabriel Brammer, Seiji Fujimoto, Franz Bauer, Edoardo Iani, Kotaro Kohno, David Blanquez Sese, Carlos Gómez-Guijarro

14 pages, 5 figures, 1 table. Submitted to ApJL

Using the novel $JWST$/NIRCam observations in the Abell 2744 field, we present a first spatially resolved overview of an $HST$-dark galaxy, spectroscopically confirmed at $z=2.58$ with magnification $\mu\approx1.9$. While being largely invisible at $\sim$1 $\mu$m with NIRCAM, except for sparse clumpy sub-structures, the object is well-detected and resolved in the long-wavelength bands with a spiral shape clearly visible in F277W. By combining ancillary ALMA and $Herschel$ data, we infer that this object is an edge-on dusty spiral with an intrinsic stellar mass log$(M_*/M_\odot)\sim11.6$ and a dust-obscured SFR$\sim 560~M_\odot$~yr$^{-1}$. A massive quiescent galaxy (log$(M_*/M_\odot)\sim11.1$) with tidal features lies 2".0 away ($r$$\sim$9 kpc), at a consistent redshift as inferred by $JWST$ photometry, indicating a potential major merger. The dusty spiral lies on the main-sequence of star formation, and shows high dust attenuation in the optical ($3<A_{\rm V}<4.5$). In the far-infrared, its integrated dust SED is optically thick up to $\lambda_0 \sim 500$ $\mu$m, further supporting the extremely dusty nature. Spatially resolved analysis of the $HST$-dark galaxy reveals a largely uniform $A_{\rm V}\sim 4$ area spanning $\sim$57 kpc$^2$, which spatially matches to the ALMA 1 mm continuum emission. Accounting for the surface brightness dimming and the depths of current $JWST$ surveys, unlensed analogs of the $HST$-dark galaxy at $z>4$ will remain detectable only in F356W and F444W, and become totally $JWST$-dark at $z\sim6$. This implies that discovering typical dusty star-forming galaxies in the Epoch of Reionization is a challenging task for $JWST$.

Wolfgang Brandner, Per Calissendorff, Taisiya Kopytova

Accepted for publication in AJ, 8 pages, 5 figures, full Table 1 will be available in machine readable format (mrt)

The determination of the astrophysical properties of stars remains challenging, and frequently relies on the application of stellar models. Stellar sequences in nearby open clusters provide some of the best means to test and calibrate stellar evolutionary models and isochrones, and to use these models to assign astrophysical properties consistently to a large sample of stars. We aim at updating the single star sequence of members of the Hyades cluster, identifying the best-fitting isochrones, and determining the astrophysical properties of the stars. The Gaia Catalogue of Nearby Stars provides a comprehensive sample of high-probability members of the Hyades cluster. We apply a multi-step method to flag photometric outliers, and to identify bonafide single stars and likely binary and multiple systems. The single stars define a tight sequence, which in the mass range 0.12 to 2.2 Msun is well-fitted by PARSEC isochrones for a supersolar metallicity of [M/H] = +0.18 +- 0.03 and an age of 775 +- 25 Myr. The isochrones enable us to assign mass, effective temperature, luminosity, and surface gravity to each of the 600 bonafide single main-sequence stars. The observed sequence validates the PARSEC isochrones. The derived stellar properties can serve as benchmarks for atmospheric and evolutionary models, and for all-sky catalogs of stellar astrophysical properties. The stellar properties are also relevant for studies of exoplanet properties among Hyades exoplanet hosts.

Dimitri Veras, Aaron J. Rosengren

Accepted for publication in MNRAS

Many potential mechanisms for delivering planetary debris to within a few Roche radii of white dwarfs rely on gravitational scattering events that feature perturbers which are giant planets or terrestrial planets. However, the population of these planets orbiting white dwarfs is still unknown, and for a substantial fraction of white dwarfs the largest planetary survivors of stellar evolution may be sub-terrestrial mass minor planets. Here, we attempt to identify the smallest mass perturbers that could pollute white dwarfs. Through computationally expensive numerical simulations of both unstable and stable configurations of minor planets, we find that this critical lower bound equals approximately one Luna mass. Further, we find that as this mass limit is approached from above, the typical cooling age at which white dwarf pollution occurs increases. Consequently, there is a two order-of-magnitude range of perturber masses between Earth and its moon that has remained largely unexplored in white dwarf pollution studies, despite the potential formation of thousands of such Luna-sized objects in these systems.

Prantik Sarmah, Sovan Chakraborty, Jagdish C. Joshi

8 pages, 4 figures

Recently, Large High Altitude Air Shower Observatory (LHAASO) has detected several Galactic point sources of ultra high energy (UHE; $E_{\gamma}> 100$ TeV) gamma-rays. These gamma-rays are possibly created in leptonic or hadronic interactions of cosmic rays (CRs) of PeV energies. In the hadronic channel ($p-p$ interaction), the gamma-rays are accompanied by neutrinos. The detection of neutrinos is therefore crucial in understanding CR acceleration in such objects. To estimate the neutrino flux, we adopt the two LHAASO sources (J2226+6057, J1908+0621) found to be spatially associated with the Supernova remnants (SNR G106.3+2.7, SNR G40.5-0.5). For these two sources, the detected TeV-PeV gamma-ray spectra are found to be unusually hard (with spectral index $\sim$ 1.8). We develop a model of gamma-ray and neutrino emission based on the above two prototypes. The neutrino fluxes from these two sources are found to be below the IceCube sensitivity, but are detectable in upcoming IceCube-Gen2 and KM3NeT experiments. We further estimate the neutrino fluxes from similar other 10 LHAASO PeVatron sources and most of them are found to be detectable in IceCube-Gen2 and KM3NeT. Finally, we explore our model parameters, in particular the spectral power law index and estimate the future potential of the neutrino detectors to probe CR acceleration in such Galactic sources.

Miguel Videla, Rene A. Mendez, Jorge F. Silva, Marcos E. Orchard

Accepted for publication to PASP. 23 pages, 2 Tables, 9 Figures, 2 Appendices

The optimal instant of observation of astrophysical phenomena for objects that vary on human time-sales is an important problem, as it bears on the cost-effective use of usually scarce observational facilities. In this paper we address this problem for the case of tight visual binary systems through a Bayesian framework based on the maximum entropy sampling principle. Our proposed information-driven methodology exploits the periodic structure of binary systems to provide a computationally efficient estimation of the probability distribution of the optimal observation time. We show the optimality of the proposed sampling methodology in the Bayes sense and its effectiveness through direct numerical experiments. We successfully apply our scheme to the study of two visual-spectroscopic binaries, and one purely astrometric triple hierarchical system. We note that our methodology can be applied to any time-evolving phenomena, a particularly interesting application in the era of dedicated surveys, where a definition of the cadence of observations can have a crucial impact on achieving the science goals.

Maria Werhahn, Philipp Girichidis, Christoph Pfrommer, Joseph Whittingham

18 pages, 11 figures, submitted to MNRAS, comments are welcome!

Cosmic rays (CRs) are ubiquitous in the interstellar medium (ISM) of nearby galaxies, but many of their properties are not well-constrained. Gamma-ray observations provide a powerful tool in this respect, allowing us to constrain both the interaction of CR protons with the ISM and their transport properties. To help better understand the link between observational signatures and CR physics, we use a series of magneto-hydrodynamical (MHD) AREPO simulations of isolated galaxies performed using spectrally-resolved CR transport in every computational cell, with subsequent gamma-ray emission calculated using the CRAYON+ (Cosmic RAY emissiON) code. In each of our simulated halos, modelling the energy-dependent spatial diffusion of CRs leads to a more extended distribution of high-energy (~100 GeV) gamma rays compared to that predicted by a 'grey' steady-state model, which is especially visible in the corresponding emission maps and radial profiles. Despite this, the total gamma-ray spectra can often be well approximated by the steady-state model, although recovering the same spectral index typically requires a minor variation of the energy dependence of the diffusion coefficient. Our simulations reproduce the observed spectral indices and gamma-ray spectra of nearby star-forming galaxies and also match recent observations of the far infrared--gamma-ray relation. We find, however, that the spectrally resolved model yields marginally smaller luminosities for lower star formation rates compared to grey simulations of CRs. Our work highlights the importance of modelling spectrally resolved CR transport for an accurate prediction of spatially resolved high-energy gamma-ray emission, as will be probed by the upcoming Cherenkov Telescope Array observatory.

K. Anastasopoulou, G. Ponti, M. C. Sormani, N. Locatelli, F. Haberl, M. R. Morris, E. M. Churazov, R. Schödel, C. Maitra, S. Campana, E. M. Di Teodoro, C. Jin, I. Khabibullin, S. Mondal, M. Sasaki, Y. Zhang, X. Zheng

21 pages, 11 figures, 7 tables, accepted for publication in A&A

The diffuse Fe XXV (6.7 keV) line emission observed in the Galactic ridge is widely accepted to be produced by a superposition of a large number of unresolved X-ray point sources. In the very central degrees of our Galaxy, however, the existence of an extremely hot ($\sim$7 keV) diffuse plasma is still under debate. In this work we measure the Fe XXV line emission using all available XMM-Newton observations of the Galactic centre (GC) and inner disc ($-10^{\circ}$$<\ell<10^{\circ}$, $-2^{\circ}<b<2^{\circ}$). We use recent stellar mass distribution models to estimate the amount of X-ray emission originating from unresolved point sources, and find that within a region of $\ell=\pm1^{\circ}$ and $b=\pm0.25^\circ$ the 6.7 keV emission is 1.3 to 1.5 times in excess of what is expected from unresolved point sources. The excess emission is enhanced towards regions where known supernova remnants are located, suggesting that at least a part of this emission is due to genuine diffuse very hot plasma. If the entire excess is due to very hot plasma, an energy injection rate of at least $\sim6\times10^{40}$ erg s$^{-1}$ is required, which cannot be provided by the measured supernova explosion rate or past Sgr A$^{*}$ activity alone. However, we find that almost the entire excess we observe can be explained by assuming GC stellar populations with iron abundances $\sim$1.9 times higher than those in the bar/bulge, a value that can be reproduced by fitting diffuse X-ray spectra from the corresponding regions. Even in this case, a leftover X-ray excess is concentrated within $\ell=\pm0.3^{\circ}$ and $b=\pm0.15^\circ$, corresponding to a thermal energy of $\sim2\times10^{52}$ erg, which can be reproduced by the estimated supernova explosion rate in the GC. Finally we discuss a possible connection to the observed GC Fermi-LAT excess.

E. Leitinger, H. Baumgardt, I. Cabrera-Ziri, M. Hilker, E. Pancino

26 pages, 29 figures. Accepted by MNRAS

The majority of Galactic globular clusters (GCs) contain multiple stellar populations displaying specific chemical abundance variations. In particular, GCs generally contain a `primordial' population with abundances similar to field stars, along with an `enriched' population exhibiting light element anomalies. In this paper we present a homogeneous and wide-view analysis of multiple stellar populations in 28 Galactic GCs. By using a combination of HST photometry together with wide-field, ground-based photometry we are able to analyse between 84% and 99% of all stars in each cluster. For each GC, we classify stars into separate sub-populations using the well-established $C_{\rm{UBI}}$ colour index, and investigate the spatial distributions of these populations. Our results show that dynamically young GCs can contain either centrally concentrated enriched or primordial populations, or no centrally concentrated population. Dynamically old GCs show fully mixed populations as expected. The existence of clusters born with centrally concentrated primordial (and homogeneously mixed) populations exacerbates the mass-budget problem facing many cluster formation scenarios. The diversity in these results also highlights the need for additional theories that can account for the wide variety of initial conditions that we find. We finally investigate the enriched star fraction as a function of different global parameters in our GC sample, using also data for young and low-mass clusters from the Small- and Large Magellanic Clouds and confirm earlier results that the enriched star fraction strongly correlates with the initial mass of a cluster.

Alexandre Adam, Laurence Perreault-Levasseur, Yashar Hezaveh, Max Welling

13+7 pages, 13 figures; Submitted to The Astrophysical Journal. arXiv admin note: text overlap with arXiv:2207.01073

Modeling strong gravitational lenses in order to quantify the distortions in the images of background sources and to reconstruct the mass density in the foreground lenses has been a difficult computational challenge. As the quality of gravitational lens images increases, the task of fully exploiting the information they contain becomes computationally and algorithmically more difficult. In this work, we use a neural network based on the Recurrent Inference Machine (RIM) to simultaneously reconstruct an undistorted image of the background source and the lens mass density distribution as pixelated maps. The method iteratively reconstructs the model parameters (the image of the source and a pixelated density map) by learning the process of optimizing the likelihood given the data using the physical model (a ray-tracing simulation), regularized by a prior implicitly learned by the neural network through its training data. When compared to more traditional parametric models, the proposed method is significantly more expressive and can reconstruct complex mass distributions, which we demonstrate by using realistic lensing galaxies taken from the IllustrisTNG cosmological hydrodynamic simulation.

Chima D. McGruder, Mercedes López-Morales, Rafael Brahm, Andrés Jordán

ACCEPT by ApJL Jan 9th 2023

Studies of exoplanetary atmospheres have found no definite correlations between observed high altitude aerosols and other system parameters. This could be, in part, because of the lack of homogeneous exoplanet samples for which specific parameters can be isolated and inspected. Here we present a set of seven exoplanets with very similar system parameters. We analyze existing photometric timeseries, Gaia parallax, and high-resolution spectroscopic data to produce a new set of homogeneous stellar, planetary, and orbital parameters for these systems. With this we confirm that most measured parameters for all systems are very similar, except for the host stars' metallicities and possibly high energy irradiation levels, which require UV and X-ray observations to constrain. From the sample, WASP-6b, WASP-96b and WASP-110b, have observed transmission spectra that we use to estimate their aerosol coverage levels using the Na I doublet 5892.9{\AA}. We find a tentative correlation between the metallicity of the host stars and the planetary aerosol levels. The trend we find with stellar metallicity can be tested by observing transmission spectra of the remaining planets in the sample. Based on our prediction, WASP-25b and WASP-55b should have higher levels of aerosols than WASP-124b and HATS-29b. Finally, we highlight how targeted surveys of alike planets like the ones presented here might prove key for identifying driving factors for atmospheric properties of exoplanets in the future and could be used as a sample selection criterium for future observations with e.g. JWST, ARIEL, and the next generation of ground-based telescopes.

Jennifer I-Hsiu Li, Yue Shen, Luis C. Ho, W. N. Brandt, Catherine J. Grier, Patrick B. Hall, Y. Homayouni, Anton M. Koekemoer, Donald P. Schneider, Jonathan R. Trump

23 pages, 10 figures (Fig 9 is the key figure). Submitted to ApJ. The full figure set and ancillary data products can be found at this ftp URL

We measure the correlation between black-hole mass $M_{\rm BH}$ and host stellar mass $M_*$ for a sample of 38 broad-line quasars at $0.2\lesssim z\lesssim 0.8$ (median redshift $z_{\rm med}=0.5$). The black-hole masses are derived from a dedicated reverberation mapping program for distant quasars, and the stellar masses are estimated from two-band optical+IR HST imaging. Most of these quasars are well centered within $\lesssim 1$kpc from the host galaxy centroid, with only a few cases in merging/disturbed systems showing larger spatial offsets. Our sample spans two orders of magnitude in stellar mass ($\sim 10^9-10^{11}\,M_\odot$) and black-hole mass ($\sim 10^7-10^9\,M_\odot$), and reveals a significant correlation between the two quantities. We find a best-fit intrinsic (i.e., selection effects corrected) $M_{\rm BH}-M_{\rm *,host}$ relation of $\log (M_{\rm BH}/M_{\rm \odot})=7.01_{-0.33}^{+0.23} + 1.74_{-0.64}^{+0.64}\log (M_{\rm *,host}/10^{10}M_{\rm \odot})$, with an intrinsic scatter of $0.47_{-0.17}^{+0.24}$dex. Decomposing our quasar hosts into bulges and disks, there is a similar $M_{\rm BH}-M_{\rm *,bulge}$ relation with a slightly larger scatter, likely caused by systematic uncertainties in the bulge-disk decomposition. The $M_{\rm BH}-M_{\rm *,host}$ relation at $z_{\rm med}=0.5$ is similar to that in local quiescent galaxies, with negligible evolution over the redshift range probed by our sample. With direct black-hole masses from reverberation mapping and a large dynamical range of the sample, selection biases do not appear to affect our conclusions significantly. Our results, along with other samples in the literature, suggest that the locally-measured black-hole mass$-$host stellar mass relation is already in place at $z\sim 1$.

Chris Finlay, Bruce A. Bassett, Martin Kunz, Nadeem Oozeer

19 pages, 16 figures, 4 tables

Radio interferometry calibration and Radio Frequency Interference (RFI) removal are usually done separately. Here we show that jointly modelling the antenna gains and RFI has significant benefits when the RFI follows precise trajectories, such as for satellites. One surprising benefit is improved calibration solutions, by leveraging the RFI signal itself. We present TABASCAL (TrAjectory BAsed RFI Subtraction and CALibration), a new algorithm that jointly models the RFI signal & trajectory as well as the calibration parameters in post-correlation visibilities. TABASCAL can use either optimisation or fully Bayesian statistical methods to find calibration solutions in contaminated data that would otherwise be thrown away. We test TABASCAL on simulated MeerKAT calibration observations contaminated by satellite-based RFI with amplitudes varying between -20 dB and 15 dB relative to a 1 Jy source. We obtain gain estimates that are both unbiased and up to an order of magnitude better constrained compared to the case of no RFI. TABASCAL can be further applied to an adjacent target observation: using 5 minutes of calibration data resulted in an image with about half the noise compared to using purely flagged data, and only 23% higher than an uncontaminated observation. The source detection threshold and recovered flux distribution of TABASCAL-processed data was on par with uncontaminated data. In contrast, RFI flagging alone resulted in consistent underestimation of source fluxes and less sources detected. For a mean RFI amplitude of 17 Jy, using TABASCAL leads to less than 1% loss of data compared to 75% data loss from ideal $3\sigma$ flagging, a significant increase in data available for science analysis. Although we have examined the case of satellite RFI, TABASCAL should work for any RFI moving on parameterizable trajectories, such as planes or objects fixed to the ground.

J. Lustig-Yaeger, G. Fu, E. M. May, K. N. Ortiz Ceballos, S. E. Moran, S. Peacock, K. B. Stevenson, M. López-Morales, R. J. MacDonald, L. C. Mayorga, D. K. Sing, K. S. Sotzen, J. A. Valenti, J. Adams, M. K. Alam, N. E. Batalha, K. A. Bennett, J. Gonzalez-Quiles, J. Kirk, E. Kruse, J. D. Lothringer, Z. Rustamkulov, H. R. Wakeford

A co-first author paper Lustig-Yaeger and Fu et al., Under review in Nature Astronomy, Comments welcome

The critical first step in the search for life on exoplanets over the next decade is to determine whether rocky planets transiting small M-dwarf stars possess atmospheres and, if so, what processes sculpt them over time. Because of its broad wavelength coverage and improved resolution compared to previous methods, spectroscopy with JWST offers a new capability to detect and characterize the atmospheres of Earth-sized, M-dwarf planets. Here we use JWST to independently validate the discovery of LHS 475b, a warm (586 K), 0.99 Earth-radius exoplanet, interior to the habitable zone, and report a precise 2.9-5.3 um transmission spectrum. With two transit observations, we rule out primordial hydrogen-dominated and cloudless pure methane atmospheres. Thus far, the featureless transmission spectrum remains consistent with a planet that has a high-altitude cloud deck (similar to Venus), a tenuous atmosphere (similar to Mars), or no appreciable atmosphere at all (akin to Mercury). There are no signs of stellar contamination due to spots or faculae. Our observations demonstrate that JWST has the requisite sensitivity to constrain the secondary atmospheres of terrestrial exoplanets with absorption features <50 ppm, and that our current atmospheric constraints speak to the nature of the planet itself, rather than instrumental limits.

Safae Dahmani, Amine Bouali, Imad El Bojaddaini, Ahmed Errahmani, Taoufik Ouali

11 pages, 4 figures

The discrepancy between Planck data and direct measurements of the current expansion rate $H_0$ and the matter fluctuation amplitude $S_8$ has become one of the most intriguing puzzles in cosmology nowadays. The $H_0$ tension has reached $4.2\sigma$ in the context of standard cosmology i.e $\Lambda$CDM. Therefore, explanations to this issue are mandatory to unveil its secrets. Despite its success, $\Lambda$CDM is unable to give a satisfying explanation to the tension problem. Unless some systematic errors might be hidden in the observable measurements, physics beyond the standard model of cosmology must be advocated. In this perspective, we study a phantom dynamical dark energy model as an alternative to $\Lambda$CDM in order to explain the aforementioned issues. This phantom model is characterised by one extra parameter, $\Omega_{pdde}$, compared to $\Lambda$CDM. We obtain a strong positive correlation between $H_0$ and $\Omega_{pdde}$, for all data combinations. Using Planck measurements together with BAO and Pantheon, we find that the $H_0$ and the $S_8$ tensions are $3\sigma$ and $2.6\sigma$, respectively. By introducing a prior on the absolute magnitude, $M_B$, of the SN Ia, the $H_0$ tension decreases to $2.27\sigma$ with $H_0 = 69.76_{-0.82}^{+0.75}$ km s$^{-1}$ Mpc$^{-1}$ and the $S_8$ tension reaches the value $2.37\sigma$ with $S_8 =0.8269_{-0.012}^{+0.011}$.

Jean-Baptiste Ruffio, Katelyn Horstman, Dimitri Mawet, Lee J. Rosenthal, Konstantin Batygin, Jason J. Wang, Maxwell Millar-Blanchaer, Ji Wang, Benjamin J. Fulton, Quinn M. Konopacky, Shubh Agrawal, Lea A. Hirsch, Andrew W. Howard, Sarah Blunt, Eric Nielsen, Ashley Baker, Randall Bartos, Charlotte Z. Bond, Benjamin Calvin, Sylvain Cetre, Jacques-Robert Delorme, Greg Doppmann, Daniel Echeverri, Luke Finnerty, Michael P. Fitzgerald, Nemanja Jovanovic, Ronald López, Emily C. Martin, Evan Morris, Jacklyn Pezzato, Garreth Ruane, Ben Sappey, Tobias Schofield, Andrew Skemer, Taylor Venenciano, J. Kent Wallace, Nicole L. Wallack, Peter Wizinowich, Jerry W. Xuan

Accepted to AJ (Jan 10, 2023)

The detection of satellites around extrasolar planets, so called exomoons, remains a largely unexplored territory. In this work, we study the potential of detecting these elusive objects from radial velocity monitoring of self-luminous directly imaged planets. This technique is now possible thanks to the development of dedicated instruments combining the power of high-resolution spectroscopy and high-contrast imaging. First, we demonstrate a sensitivity to satellites with a mass ratio of 1-4% at separations similar to the Galilean moons from observations of a brown-dwarf companion (HR 7672 B; Kmag=13; 0.7" separation) with the Keck Planet Imager and Characterizer (KPIC; R~35,000 in K band) at the W. M. Keck Observatory. Current instrumentation is therefore already sensitive to large unresolved satellites that could be forming from gravitational instability akin to binary star formation. Using end-to-end simulations, we then estimate that future instruments such as MODHIS, planned for the Thirty Meter Telescope, should be sensitive to satellites with mass ratios of ~1e-4. Such small moons would likely form in a circumplanetary disk similar to the Jovian satellites in the solar system. Looking for the Rossiter-McLaughlin effect could also be an interesting pathway to detecting the smallest moons on short orbital periods. Future exomoon discoveries will allow precise mass measurements of the substellar companions that they orbit and provide key insight into the formation of exoplanets. They would also help constrain the population of habitable Earth-sized moons orbiting gas giants in the habitable zone of their stars.

The surface chemical compositions of stars are affected by physical processes which bring the products of thermonuclear burning to the surface. Despite their potential in understanding the structure and evolution of stars, elemental abundances are available for only a few high-mass binary stars. We aim to enlarge this sample by determining the physical properties and photospheric abundances for four eclipsing binary systems containing high-mass stars: V1034 Sco, GL Car, V573 Car and V346 Cen. The components have masses 8-17 Msun and effective temperatures from 22500 to 32200 K, and are all on the main sequence. We present new high-resolution and high signal-to-noise spectroscopy from HARPS, and analyse them using spectral disentangling and NLTE spectral synthesis. We model existing light curves and new photometry from the TESS satellite, We measure the stellar masses to 0.6-2.0 percent precision, radii to 0.8-1.7 percent precision, effective temperatures to 1.1-1.6 percent precision, and abundances of C, N, O, Mg and Si. The abundances are similar to those found in our previous studies of high-mass eclipsing binaries; our sample now comprises 25 high-mass stars in 13 binary systems. We also find tidally-excited pulsations in V346 Cen. We reinforce our previous conclusions: interior chemical element transport is not as efficient in binary star components as in their single-star counterparts in the same mass regime and evolutionary stage, possibly due to the effects of tidal forces. Our ultimate goal is to provide a larger sample of OB-type stars in binaries which would enable a thorough comparison to stellar evolutionary models, as well as to single high-mass stars.

A. Escorza (ESO Chile), R. J. De Rosa (ESO Chile)

Accepted for publication in Astronomy & Astrophysics

Masses are one of the most difficult stellar properties to measure. In the case of the white-dwarf companions of Barium stars, the situation is worse. These stars are dim, cool, and difficult to observe via direct methods. However, Ba stars were polluted by the Asymptotic Giant Branch progenitors of these WDs with matter rich in heavy elements, and the properties of their WD companions contain key information about binary interaction processes involving AGB stars and about the slow-neutron-capture(s)-process of nucleosynthesis. We aim to determine accurate and assumption-free masses for the WD companions of as many Ba stars as possible. We want to provide new observational constraints that can help us learn about the formation and evolution of these post-interaction binary systems and about the nucleosynthesis processes that took place in the interiors of their AGB progenitors. We combined archival radial-velocity data with Hipparcos and Gaia astrometry using the software package orvara, a code designed to simultaneously fit a single Keplerian model to any combination of these types of data using a parallel-tempering Markov chain Monte Carlo method. We adopted Gaussian priors for the Ba star masses and for the parallaxes, and assumed uninformative priors for the orbital elements and the WD masses. We determined new orbital inclinations and companion masses for 60 Ba star systems, including a couple of new orbits and several improved orbits for the longest-period systems. We also unravelled a triple system that was not known before and constrained the orbits and the masses of the two companions. (Continued in the manuscript)

Dante V. Gomez-Navarro, Alejandro Aviles, Axel de la Macorra

17 pages, 7 figures

We study dark energy cosmological models, extensions of the standard model of particles, characterized by having an extra relativistic energy density at very early times, and that rapidly dilute after a phase transition occurs. These models generate well localized features (or bumps) in the matter power spectrum for modes crossing the horizon around and before the phase transition epoch. This is because the presence of the additional energy component enhances the growth of matter fluctuations during the radiation dominated epoch. Instead of considering a particular model, we focus on a parametric family of Gaussian bumps in the matter power spectrum, which otherwise would be a $\Lambda$CDM one. We study the evolution of such bump cosmologies and their effects in the halo mass function and halo power spectrum using N-body simulations, the halo-model based HMcode method, and the peak background split framework. The bumps are subject to different nonlinear effects that become physically well understood, and from them we are able to predict that the most distinctive features will show up for intermediate halo masses $10^{12.3} \,h^{-1}M_{\odot} < M < 10^{13.6} \,h^{-1}M_{\odot}$. Out of this range, we expect halos are not significantly affected regardless of the location of the primordial bump in the matter power spectrum. Our analytical results are accurate and in very satisfactory agreement with the simulated data.

Stellar activity mitigation is one of the major challenges for the detection of earth-like exoplanets in radial velocity (RV) measurements. Several promising techniques are now investigating the use of spectral time-series, to differentiate between stellar and planetary perturbations. In this paper, we present a new version of the Spot Oscillation And Planet (SOAP) 2.0 code that can model stellar activity at the spectral level using graphical processing units (GPUs). We take advantage of the computational power of GPUs to optimise the computationally expensive algorithms behind the original SOAP 2.0 code. We develope GPU kernels that allow to model stellar activity on any given wavelength range. In addition to the treatment of stellar activity at the spectral level, SOAP-GPU also includes the change of spectral line bisectors from center to limb, and can take as input PHOENIX spectra to model the quiet photosphere, spots and faculae, which allow to simulate stellar activity for a wide space in stellar properties. Benchmark calculations show that for the same accuracy, this new code improves the computational speed by a factor of 60 compared with a modified version of SOAP 2.0 that generates spectra, when modeling stellar activity on the full visible spectral range with a resolution of R=115'000. Although the code now includes the variation of spectral line bisector with center to limb angle, the effect on the derived RVs is small. The publicly available SOAP-GPU code allows to efficiently model stellar activity at the spectral level, which is essential to test further stellar activity mitigation techniques working at the level of spectral timeseries not affected by other sources of noise. Besides a huge gain in performance, SOAP-GPU also includes more physics and is able to model different stars than the Sun, from F to K dwarfs, thanks to the use of the PHOENIX spectral library.

A Radio interferometer comprises several antennas, spared over a large area. Say ALMA(Atacama Large Millimeter/submillimeter Array), VLA(very large array), VLBA(Very Long Baseline Array), GMRT(Giant Metrewave Radio Telescope), MWA( Murchison Widefield Array), EHT(Event Horizon Telescope), and the SKA(Square Kilometer Array), the name itself speaks about square-kilometres of area. Most radio observatories are constructed or constitute giant dish antennas, and few constitute an extensive array of antennas. However, what if a simple antenna like Dipole, Loop or Yagi-UDA is considered an element of an interferometer? Then how does it affect the visibility of the instrument? Yes, it will be less, but how weak? Furthermore, what is the math to reach it? These questions pushed for this work. Here, one can find the detailed derivation starting from a simple Young's double slit experiment to a radio interferometer intensity distribution in terms of the Gain of the antenna element. This literature aided in understanding the interferometer of yagi antennas of Gain 11dBi, resulting in a visibility of 0.0714. This clarity was insignificant in the current work. Hence using this work, one can design and construct a suited interferometer for their requirement.

J. R. Fuentes, A. Cumming, M. Castro-Tapia, E. H. Anders

Submitted to ApJ. Comments are welcome

We investigate heat transport associated with compositionally-driven convection driven by crystallization at the ocean-crust interface in accreting neutron stars, or growth of the solid core in cooling white dwarfs. We study the effect of thermal diffusion and rapid rotation on the convective heat transport, using both mixing length theory and numerical simulations of Boussinesq convection. We determine the heat flux, composition gradient and P\'eclet number (the ratio of thermal diffusion time to convective turnover time) as a function of the composition flux. We find that the ratio between the heat flux and composition flux is independent of P\'eclet number, because the loss of heat from convecting fluid elements due to thermal diffusion is offset by the smaller composition gradient needed to overcome the reduced thermal buoyancy. We find two regimes of convection with a rapid transition between them as the composition flux increases. We discuss the implications for neutron star and white dwarf cooling. Convection in neutron stars spans both regimes. We find rapid mixing of neutron star oceans, with a convective turnover time of order weeks to minutes depending on rotation. Except during the early stages of core crystallization, white dwarf convection is in the thermal-diffusion-dominated fingering regime. We find convective velocities much smaller than recent estimates for crystallization-driven dynamos. The small fraction of energy carried as kinetic energy calls into question the effectiveness of crystallization-driven dynamos as an explanation for observed white dwarf magnetic fields.

E. M. Gutiérrez, L. Combi, G. E. Romero, M. Campanelli

14 pages, 12 figures, submitted to MNRAS

Supermassive black hole binaries (SMBHBs) are natural by-products of galaxy mergers and are expected to be powerful multi-messenger sources. They can be powered by the accretion of matter and shine throughout the electromagnetic spectrum similarly to normal active galactic nuclei (AGNs). Current electromagnetic observatories have good chances to detect and identify these systems in the near future, but we need precise observational indicators to distinguish single AGNs from SMBHBs. In this work, we propose a novel electromagnetic signature from SMBHBs: periodic flares caused by the interaction between the jets launched by the black holes. We investigate close black hole binaries accreting matter from a circumbinary disc and the mini-discs formed around each hole, and launching magnetically-dominated jets in the direction of their spin through the Blandfor--Znajeck mechanism. If the spins are slightly inclined, the two jets will encounter each other once per orbit. We argue that this interaction may trigger strong magnetic reconnection events where particles are accelerated and form plasmoids that emit non-thermal radiation. We model the evolution of these particles and calculate the radiative output obtaining spectra and light curves at different wavelengths. We show that these flares can significantly shine in radio, soft X-rays, and \gamma rays, providing a periodic multi-wavelength electromagnetic signature for SMBHBs.

This work presents the model of an ejecta cloud distribution to characterise the plume generated by the impact of a projectile onto asteroids surfaces. A continuum distribution based on the combination of probability density functions is developed to describe the size, ejection speed, and ejection angles of the fragments. The ejecta distribution is used to statistically analyse the fate of the ejecta. By combining the ejecta distribution with a space-filling sampling technique, we draw samples from the distribution and assigned them a number of \emph{representative fragments} so that the evolution in time of a single sample is representative of an ensemble of fragments. Using this methodology, we analyse the fate of the ejecta as a function of different modelling techniques and assumptions. We evaluate the effect of different types of distributions, ejection speed models, coefficients, etc. The results show that some modelling assumptions are more influential than others and, in some cases, they influence different aspects of the ejecta evolution such as the share of impacting and escaping fragments or the distribution of impacting fragments on the asteroid surface.

Carlos E. Chavez, Andres Aviles, Nikolaos Georgakarakos, Cesar Ramos, Hector Aceves, Gagik Tovmassian, Sergey Zharikov

16 pages, 5 figures

A very long term variability (VLPP), with period of 875 days, was observed in the long-term light curve of FS Aurigae in 2011. This periodicity was calculated on 6 cycles. We re-examine the periodicity with new observations over of the past 5 yrs. A total of 18 yrs of observations confirm the hypothesis of a third body perturbing in a secular way the cataclysmic variable (CV). Improvements to the model such as eccentric and inclined orbits for the third body and a binary post-Newtonian correction are considered. We confirm the VLPP of FS Aur and find the new period of 857 $\pm$ 78 days. The secular perturbations are most efficient when the mass of the third body is M=29 MJ, much less than the 50 MJ reported in 2011. We estimate the effect of the third body on the mass transfer rate and the brightness of the system. We consider alternative scenarios for the VLPP. The new data and analysis supports the hypothesis that FS Aur is a CV in a triple system.

Pattana Chintarungruangchai, Ing-Guey Jiang, Jun Hashimoto, Yu Komatsu, Mihoko Konishi

30 pages, 12 figures, 1 table, published by New Astronomy

The method of direct imaging has detected many exoplanets and made important contribution to the field of planet formation. The standard method employs angular differential imaging (ADI) technique, and more ADI image frames could lead to the results with larger signal-to-noise-ratio (SNR). However, it would need precious observational time from large telescopes, which are always over-subscribed. We thus explore the possibility to generate a converter which can increase the SNR derived from a smaller number of ADI frames. The machine learning technique with two-dimension convolutional neural network (2D-CNN) is tested here. Several 2D-CNN models are trained and their performances of denoising are presented and compared. It is found that our proposed Modified five-layer Wide Inference Network with the Residual learning technique and Batch normalization (MWIN5-RB) can give the best result. We conclude that this MWIN5-RB can be employed as a converter for future observational data.

Miguel Gracia-Linares, Francisco S. Guzmán

9 pages, 10 figures. Accepted for publication in MNRAS

We present the accretion of magnetized supersonic winds onto a rotating black hole in three dimensions. We select representative spin-wind orientations in order to illustrate its effects on the evolution and morphology of the shock cone. The most important finding in the magnetized case, unlike the purely hydrodynamical scenario, is the formation of rarified spots where the magnetic field pressure dominates over the gas pressure. In these rarified spots we find the formation of eddies within the shock cone.

Mehmet Sarp Yalim, Gary P. Zank, Mahboubeh Asgari-Targhi

23 pages, 6 figures, 1 table, The Astrophysical Journal, in press

The transport of waves and turbulence beyond the photosphere is central to the coronal heating problem. Turbulence in the quiet solar corona has been modeled on the basis of the nearly incompressible magnetohydrodynamic (NI MHD) theory to describe the transport of low-frequency turbulence in open magnetic field regions. It describes the evolution of the coupled majority quasi-2D and minority slab component, driven by the magnetic carpet and advected by a subsonic, sub-Alfvenic flow from the lower corona. In this paper, we couple the NI MHD turbulence transport model with an MHD model of the solar corona to study the heating problem in a coronal loop. In a realistic benchmark coronal loop problem, we find that a loop can be heated to ~1.5 million K by transport and dissipation of MHD turbulence described by the NI MHD model. We also find that the majority 2D component is as important as the minority slab component in the heating of the coronal loop. We compare our coupled MHD/NI MHD model results with a reduced MHD (RMHD) model. An important distinction between these models is that RMHD solves for small-scale velocity and magnetic field fluctuations and obtains the actual viscous/resistive dissipation associated with their evolution whereas NI MHD evolves scalar moments of the fluctuating velocity and magnetic fields and approximates dissipation using an MHD turbulence phenomenology. Despite the basic differences between the models, their simulation results match remarkably well, yielding almost identical heating rates inside the corona.

James G. Rogers, Hilke E. Schlichting, James E. Owen

15 pages, 2 figures. Submitted to ApJL

The population of small, close-in exoplanets is bifurcated into super-Earths and sub-Neptunes. We calculate physically motivated mass-radius relations for sub-Neptunes, with rocky cores and H/He dominated atmospheres, accounting for their thermal evolution, irradiation and mass-loss. For planets $\lesssim 10~$M$_\oplus$, we find that sub-Neptunes retain atmospheric mass fractions that scale with planet mass and show that the resulting mass-radius relations are degenerate with results for `water-worlds' consisting of a 1:1 silicate-to-ice composition ratio. We further demonstrate that our derived mass-radius relation is in excellent agreement with the observed exoplanet population orbiting M-dwarfs and that planet mass and radii alone are insufficient to determine the composition of some sub-Neptunes. Finally, we highlight that current exoplanet demographics show an increase in the ratio of super-Earths to sub-Neptunes with both stellar mass (and therefore luminosity) and age, which are both indicative of thermally driven atmospheric escape processes. Therefore, such processes should not be ignored when making compositional inferences in the mass-radius diagram.

Johannes Heyl, Thanja Lamberts, Serena Viti, Jonathan Holdship

11 pages, 3 figures, accepted for publication in MNRAS

The impact of including the reactions of C and CH with molecular hydrogen in a gas-grain network is assessed via a sensitivity analysis. To this end, we vary 3 parameters, namely, the efficiency for the reaction \ce{C + H2 -> CH2}, and the cosmic ray ionisation rate, with the third parameter being the final density of the collapsing dark cloud. A grid of 12 models is run to investigate the effect of all parameters on the final molecular abundances of the chemical network. We find that including reactions with molecular hydrogen alters the hydrogen economy of the network; since some species are hydrogenated by molecular hydrogen, atomic hydrogen is freed up. The abundances of simple molecules produced from hydrogenation, such as \ce{CH4}, \ce{CH3OH} and \ce{NH3}, increase, and at the same time, more complex species such as glycine and its precursors see a significant decrease in their final abundances. We find that the precursors of glycine are being preferentially hydrogenated, and therefore glycine itself is produced less efficiently.

Gravitational-wave now became one of the important observational methods for studying the Universe since its first detection. However, the ground-based observatories have an inherent barrier to their detection frequency band due to the seismic and gravity gradient noises nearby the perturbation of the surroundings. A recent intriguing development of artificial structures for media called metamaterial is opening a new branch of wave mechanics and its application in various fields, in particular, suggesting a novel way of mitigating noises by controlling the media structure for propagating waves. In this paper, we propose a novel framework for handling noises in ground-based gravitational wave detectors by using wave mechanics under metamaterial media. Specifically, we suggest an application of the bandgap engineering technique for mitigating the underground effects of acoustic noises resulting from the seismic vibration in the KAGRA gravitational wave observatory.

Chris Nolting, Jay Ball, Tri Nguyen

12 pages, 5 figures, submitted to ApJ. Animated versions of the figures can be found at: this https URL

Jet precession is sometimes invoked to explain asymmetries in radio galaxy (RG) jets and "X/S/Z-shape" radio galaxies, caused by the presence of a binary black hole companion to the source active galactic nucleus (AGN) or by accretion instabilities. We present a series of simulations of radio galaxy jet precession to examine how these sources would evolve over time, including a passive distribution of cosmic ray electrons (CRe) so we can model radio synchrotron emissions and create synthetic radio maps of the sources. We find that a single source viewed from different angles can result in differing RG morphological classifications, confusing physical implications of these classifications. Additionally, the jet trajectories can become unstable due to their own self-interactions and lead to "reorientation events" that may look like the effects of external dynamics such as shocks, winds, or cold fronts in the medium. Finally, something akin to an "Odd Radio Circle" may be observed in the case of viewing the radio remnant of such a precessing source from a line of sight near the precession axis.

Harry Desmond, Deaglan J. Bartlett, Pedro G. Ferreira

12+4 pages, 4 figures, 3 tables; MNRAS submitted

We apply a new method for learning equations from data -- Exhaustive Symbolic Regression (ESR) -- to late-type galaxy dynamics as encapsulated in the radial acceleration relation (RAR). Relating the centripetal acceleration due to baryons, $g_\text{bar}$, to the total dynamical acceleration, $g_\text{obs}$, the RAR has been claimed to manifest a new law of nature due to its regularity and tightness, in agreement with Modified Newtonian Dynamics (MOND). Fits to this relation have been restricted by prior expectations to particular functional forms, while ESR affords an exhaustive and nearly prior-free search through functional parameter space to identify the equations optimally trading accuracy with simplicity. Working with the SPARC data, we find the best functions typically satisfy $g_\text{obs} \propto g_\text{bar}$ at high $g_\text{bar}$, although the coefficient of proportionality is not clearly unity and the deep-MOND limit $g_\text{obs} \propto \sqrt{g_\text{bar}}$ as $g_\text{bar} \to 0$ is little evident at all. By generating mock data according to MOND with or without the external field effect, we find that symbolic regression would not be expected to identify the generating function or reconstruct successfully the asymptotic slopes. We conclude that the limited dynamical range and significant uncertainties of the SPARC RAR preclude a definitive statement of its functional form, and hence that this data alone can neither demonstrate nor rule out law-like gravitational behaviour.

F. Kahraman Alivacus, T. Pawar, K. G. Hełminiak, G. Handler, A. Moharana, F. Alicavus, P. De Cat, F. Leone, G. Catanzaro, M. Giarrusso, N. Ukita, E. Kambe

Accepted for publication in MNRAS

The pulsating eclipsing binaries are remarkable systems that provide an opportunity to probe the stellar interior and to determine the fundamental stellar parameters precisely. Especially the detached eclipsing binary systems with (a) pulsating component(s) are significant objects to understand the nature of the oscillations since the binary effects in these systems are negligible. Recent studies based on space data have shown that the pulsation mechanisms of some oscillating stars are not completely understood. Hence, comprehensive studies of a number of pulsating stars within detached eclipsing binaries are important. In this study, we present a detailed analysis of the pulsating detached eclipsing binary system AI Hya which was studied by two independent groups with different methods. We carried out a spectroscopic survey to estimate the orbital parameters via radial velocity measurements and the atmospheric parameters of each binary component using the composite and/or disentangled spectra. We found that the more luminous component of the system is a massive, cool and chemically normal star while the hotter binary component is a slightly metal-rich object. The fundamental parameters of AI Hya were determined by the analysis of binary variations and subsequently used in the evolutionary modelling. Consequently, we obtained the age of the system as 850 $\pm$ 20 Myr and found that both binary components are situated in the Delta Scuti instability strip. The frequency analysis revealed pulsation frequencies between the 5.5 - 13.0 d$^{-1}$ and we tried to estimate which binary component is the pulsating one. However, it turned out that those frequencies could originate from both binary components.

Divya Rawat, Mariano Méndez, Federico García, Diego Altamirano, Konstantinos Karpouzas, Liang Zhang, Kevin Alabarta, Tomaso M. Belloni, Pankaj Jain, Candela Bellavita

15 pages, 8 figures, accepted for publication in MNRAS

We present a detailed spectral and temporal analysis of the black-hole candidate MAXI~J1535$-$571 using NICER observations in September and October 2017. We focus specifically on observations in the hard-intermediate state when the source shows type-C quasi-periodic oscillations (QPOs). We fitted the time-averaged spectrum of the source and the rms and phase-lag spectra of the QPO with a one-component time-dependent Comptonization model. We found that the corona contracts from $\sim 10^4$ to $\sim 3 \times 10^3$ km as the QPO frequency increases from $\sim 1.8$ Hz to $\sim 9.0$ Hz. The fits suggest that the system would consists of two coronas, a small one that dominates the time-averaged spectrum and a larger one, possibly the jet, that dominates the rms and lag spectra of the QPO. We found a significant break in the relation of the spectral parameters of the source and the properties of the QPO, including its lag spectra, with QPO frequency. The change in the relations happens when the QPO frequency crosses a critical frequency $\nu_c \approx 3.0$ Hz. Interestingly, the QPO reaches this critical frequency simultaneously as the radio emission from the jet in this source is quenched.

J. Blanco-Pozo, M. Perger, M. Damasso, G. Anglada Escudé, I. Ribas, D. Baroch, J. A. Caballero, C. Cifuentes, S.V. Jeffers, M. Lafarga, A. Kaminski, S. Kaur, E. Nagel, V. Perdelwitz, M. Pérez-Torres, A. Sozzetti, D. Viganò, P. J. Amado, G. Andreuzzi, E. L. Brown, F. Del Sordo, S. Dreizler, D. Galadí-Enríquez, A. P. Hatzes, M. Kürster, A. F. Lanza, A. Melis, E. Molinari, D. Montes, M. Murgia, E. Pallé, L. Peña-Moñino, D. Perrodin, M. Pilia, E. Poretti, A. Quirrenbach, A. Reiners, A. Schweitzer, M. R. Zapatero Osorio, M. Zechmeister

18 pages, 11 figures. Accepted version, A&A (2023)

Detecting a planetary companion in a short-period orbit through radio emission from the interaction with its host star is a new prospect in exoplanet science. Recently, a tantalising signal was found close to the low-mass stellar system GJ 1151 using LOFAR observations. We studied spectroscopic time-series data of GJ 1151 in order to search for planetary companions, investigate possible signatures of stellar magnetic activity, and to find possible explanations for the radio signal. We used the combined radial velocities measured from spectra acquired with the CARMENES, HARPS-N, and HPF instruments, extracted activity indices from those spectra in order to mitigate the impact of stellar magnetic activity on the data, and performed a detailed analysis of Gaia astrometry and all available photometric time series coming from the MEarth and ASAS-SN surveys. We found a M$>$10.6 M$_{\oplus}$ companion to GJ 1151 in a 390d orbit at a separation of 0.57 au. Evidence for a second modulation is also present; this could be due to long-term magnetic variability or a second (substellar) companion. The star shows episodes of elevated magnetic activity, one of which could be linked to the observed LOFAR radio emission. We show that it is highly unlikely that the detected GJ 1151 b, or any additional outer companion is the source of the detected signal. We cannot firmly rule out the suggested explanation of an undetected short-period planet that could be related to the radio emission, as we establish an upper limit of 1.2 M$_{\oplus}$ for the minimum mass.

Neutral hydrogen (HI) intensity mapping (IM) survey is generally regarded as a promising tool to explore the expansion history of the universe. In this work, we investigate the capability of MeerKAT HI IM observation in interferometric mode to estimate the power spectrum and constrain cosmological parameters in typical dark energy models. Besides, a novel approach of delay spectrum is employed, which can achieve separating the weak HI signal from the foreground in the frequency space. We find that the different survey fields have a great influence on the fractional errors on power spectrum $\Delta P/P$ in a limited observational time of 10 h. With the integration time increasing from 10 h to 10000 h, $\Delta P/P$ becomes distinctly smaller until the cosmic variance begins to dominate. In the total 10000 h observation, the lower $\Delta P/P$ in low $k$ can be achieved when tracking 100 points for MeerKAT L-band and 10 points for MeerKAT UHF-band. Through simulating 10000 h HI IM survey, we obtain $\sigma(\Omega_{\rm m})=0.044$ and $\sigma(H_0)=2.8~{\rm km\ s^{-1}\ Mpc^{-1}}$ with MeerKAT L-band, which are worse than the results of $\sigma(\Omega_{\rm m})=0.028$ and $\sigma(H_0)=2.0~{\rm km\ s^{-1}\ Mpc^{-1}}$ with MeerKAT UHF-band in the $\Lambda$CDM model. However, in the $w$CDM and CPL models, MeerKAT shows a limited capability of constraining dark-energy equation of state, even though combined with Planck data. Our analysis is shown to be a useful guide for the near future MeerKAT observations in HI IM survey.

F. Z. Majidi, J. M. Alcala', A. Frasca, S. Desidera, C. F. Manara, G. Beccari, V. D'Orazi, A. Bayo, K. Biazzo, R. Claudi, E. Covino, G. Mantovan, M. Montalto, D. Nardiello, G. Piotto, E. Rigliaco

20 pages, 15 Tables, 13 Figures, accepted for publication in A&A

We characterize twelve young stellar objects (YSOs) located in the Lupus I region, spatially overlapping with the Upper Centaurus Lupus (UCL) sub-stellar association. The aim of this study is to understand whether the Lupus I cloud has more members than what has been claimed so far in the literature and gain a deeper insight into the global properties of the region. We selected our targets using Gaia DR2 catalog, based on their consistent kinematic properties with the Lupus I bona fide members. In our sample of twelve YSOs observed by X-Shooter, we identified ten Lupus I members. We could not determine the membership status of two of our targets, namely Gaia DR2 6014269268967059840 and 2MASS J15361110-3444473 due to technical issues. We found out that four of our targets are accretors, among them 2MASS J15551027-3455045, with a mass of ~0.03 M_Sun, is one of the least massive accretors in the Lupus complex to date. Several of our targets (including accretors) are formed in-situ and off-cloud with respect to the main filaments of Lupus I, hence, our study may hint that there are diffused populations of M-dwarfs around Lupus I main filaments. In this context, we would like to emphasize that our kinematic analysis with Gaia catalogs played a key role in identifying the new members of the Lupus I cloud.

Andreas Morlok, Aleksandra N. Stojic, Iris Weber, Harald Hiesinger, Michael Zanetti, Joern Helbert

We have analyzed 14 impact melt glass samples, covering the compositional range from highly felsic to mafic/basaltic, as part of our effort to provide mid-infrared spectra (7-14 micron) for MERTIS (Mercury Radiometer and Thermal Infrared Spectrometer), an instrument onboard of the ESA/JAXA BepiColombo mission. Since Mercury was exposed to many impacts in its history, and impact glasses are also common on other bodies, powders of tektites (Irghizite, Libyan Desert Glass, Moldavite, Muong Nong, Thailandite) and impact glasses (from the Dellen, El'gygytgyn, Lonar, Mien, Mistastin, and Popigai impact structures) were analyzed in four size fractions of (0-25, 25-63, 93-125 and 125-250 micron) from 2.5 to 19 micron in bi-directional reflectance. The characteristic Christiansen Feature (CF) is identified between 7.3 micron (Libyan Desert Glass) and 8.2 micron (Dellen). Most samples show mid-infrared spectra typical of highly amorphous material, dominated by a strong Reststrahlen Band (RB) between 8.9 micron (Libyan Desert Glass) and 10.3 micron (Dellen). Even substantial amounts of mineral fragments hardly affect this general band shape. Comparisons of the SiO2 content representing the felsic/mafic composition of the samples with the CF shows felsic/intermediate glass and tektites forming a big group, and comparatively mafic samples a second one. An additional sign of a highly amorphous state is the lack of features at wavelengths longer than about 15 micron. The tektites and two impact glasses, Irghizite and El'gygytgyn respectively, have much weaker water features than most of the other impact glasses.

W. Benbow, A. Brill, M. Capasso, J. L. Christiansen, A. J. Chromey, M. K. Daniel, M. Errando, A. Falcone, K. A Farrell, Q. Feng, J. P. Finley, G. M Foote, L. Fortson, A. Furniss, G. Gallagher, A. Gent, C. Giuri, O. Gueta, W. F Hanlon, D. Hanna, T. Hassan, O. Hervet, J. Hoang, J. Holder, G. Hughes, T. B. Humensky, W. Jin, P. Kaaret, M. Kertzman, D. Kieda, T. K. Kleiner, N. Korzoun, F. Krennrich, S. Kumar, M. J. Lang, M. Lundy, G. Maier, C. E McGrath, M. J Millard, C. L. Mooney, P. Moriarty, R. Mukherjee, D. Nieto, M. Nievas-Rosillo, S. O'Brien, R. A. Ong, A. N. Otte, D. Pandel, N. Park, S. R. Patel, S. Patel, K. Pfrang, A. Pichel, M. Pohl, R. R. Prado, E. Pueschel, J. Quinn, K. Ragan, P. T. Reynolds, D. Ribeiro, G. T. Richards, E. Roache, A. C. Rovero, C. Rulten, J. L. Ryan, I. Sadeh, et al. (16 additional authors not shown)

The ground-based gamma-ray observatory VERITAS (Very Energetic Radiation Imaging Telescope Array System) is sensitive to photons of astrophysical origin with energies in the range between $\approx 85$ GeV to $\approx 30$ TeV. The instrument consists of four 12-m diameter imaging Cherenkov telescopes operating at the Fred Lawrence Whipple Observatory (FLWO) in southern Arizona. VERITAS started four-telescope operations in 2007 and collects about 1100 hours of good-weather data per year. The VERITAS collaboration has published over 100 journal articles since 2008 reporting on gamma-ray observations of a large variety of objects: Galactic sources like supernova remnants, pulsar wind nebulae, and binary systems; extragalactic sources like star forming galaxies, dwarf-spheroidal galaxies, and highly-variable active galactic nuclei. This note presents VTSCat: the catalog of high-level data products from all VERITAS publications.

Leon Ofman, Therese A. Kucera, C. Richard DeVore

We investigate the properties of nonlinear fast magnetosonic (NFM) waves in a solar prominence, motivated by recent high-resolution and high-cadence Hinode/SOT observations of small-scale oscillations in a prominence pillar. As an example, we analyze the details of the 2012 February 14 Hinode/SOT observations of quasi-periodic propagating features consistent with NFM waves, imaged in emission in Ca~II and in the far blue wing of H_alpha. We perform wavelet analysis and find oscillations in the 1-3 min period range. Guided by these observations, we model the NFM waves with a three-dimensional magnetohydrodynamics (3D MHD) model, extending previous 2.5D MHD studies. The new model includes the structure of the high-density, low-temperature material of the prominence pillar embedded in the hot corona, in both potential and non-force-free sheared magnetic field configurations. The nonlinear model demonstrates the effects of mode coupling and the propagating density compressions associated with linear and NFM waves. The guided fast magnetosonic waves, together with density compressions and currents, are reproduced in the 3D pillar structure. We demonstrate or the first time the dynamic effects of the Lorentz force due to the magnetic shear in the non-force-free field on the pillar structure and on the propagation of the waves. The insights gained from the 3D MHD modeling are useful for improving coronal seismology of prominence structures that exhibit fast MHD wave activity.

X. Astiasarain, L. Tibaldo., P. Martin, J. Knödlseder, Q. Remy

Accepted for publication in A&A. The main results will be made available in machine-readable format upon publication

Star-forming regions may play an important role in the life cycle of Galactic cosmic rays. Gamma-ray observations of Cygnus X have revealed the presence of an excess of hard-spectrum gamma-ray emission, possibly related to a cocoon of freshly accelerated particles. Based on ~13 years of observations with the Fermi-Large Area Telescope (LAT), we performed an improved spectro-morphological characterisation of the residual emission including the cocoon. The best-fit model for the cocoon includes two main emission components: an extended component FCES G78.74+1.56, described by a 2D Gaussian of extension $r_{68} = 4.4^\circ \pm 0.1^\circ\,^{+0.1^\circ}_{-0.1^\circ}$, and a central component FCES G80.00+0.50, traced by the distribution of ionised gas within the borders of the photo-dissociation regions. The two have significantly different spectra. An additional extended emission component FCES G78.83+3.57, located on the edge of the central cavities in Cygnus X and with a spectrum compatible with that of FCES G80.00+0.50, is likely related to the cocoon. For the two main components, spectra and radial-azimuthal profiles of the emission can be accounted for in a diffusion-loss framework involving one single population of non-thermal particles. Particles span the full extent of FCES G78.74+1.56 as a result of diffusion from a central source, and give rise to source FCES G80.00+0.50 by interacting with ionised gas in the innermost region. For this simple diffusion-loss model, viable setups can be very different in terms of energetics, transport conditions, and timescales involved, and both hadronic and leptonic scenarios are possible. The solutions range from long-lasting particle acceleration, possibly in prominent star clusters such as Cyg OB2 and NGC 6910, to a more recent and short-lived release of particles within the last 10-100 kyr, likely from a supernova remnant. (Abridged)

K. É. Gabányi, S. Belladitta, S. Frey, G. Orosz, L. I. Gurvits, K. Rozgonyi, T. An, H. Cao, Z. Paragi, K. Perger

8 pages, 4 figures, accepted for publication in PASA

Active galactic nuclei (AGN) have been observed as far as redshift z~7. They are crucial in investigating the early Universe as well as the growth of supermassive black holes at their centres. Radio-loud AGN with their jets seen at a small viewing angle are called blazars and show relativistic boosting of their emission. Thus, their apparently brighter jets are easier to detect in the high-redshift Universe. DES J014132.4-542749.9 is a radio-luminous but X-ray weak blazar candidate at z = 5. We conducted high-resolution radio interferometric observations of this source with the Australian Long Baseline Array at 1.7 and 8.5 GHz. A single, compact radio emitting feature was detected at both frequencies with a flat radio spectrum. We derived the milliarcsecond-level accurate position of the object. The frequency dependence of its brightness temperature is similar to that of blazar sources observed at lower redshifts. Based on our observations, we can confirm its blazar nature. We compared its radio properties with those of two other similarly X-ray-weak and radio-bright AGN, and found that they show very different relativistic boosting characteristics.

The exquisitely measured maps of fluctuations in the Cosmic Microwave Background (CMB) present the possibility to test the principle of Statistical Isotropy (SI) of the Universe through systematic observable measures for non-Statistical Isotropy (nSI) features in the data. Recent measurements of the CMB temperature field provide tantalizing evidence of the deviation from SI. A systematic approach based on strong mathematical formulation allows any nSI feature to be traced to known physical effects or observational artefacts. Unexplained nSI features could have immense cosmological ramifications for the standard model of cosmology. BipoSH (Bipolar Spherical Harmonics) provides a general formalism for quantifying the departure from statistical isotropy for a field on a 2D sphere. We adopt a known reduction of the BipoSH functions, dubbed Minimal Harmonics (Manakov et al. 1996). We demonstrate that this reduction technique of BipoSH leads to a new generalized set of isotropic angular correlation functions (mBipoSH) that are observable quantifications of nSI features in a sky map. We show that any nSI feature in the CMB map captured by BipoSH at the bipolar multiple $L$ with projection $M$ can be studied by $(L+1)$ mBipoSH angular correlation functions in case of even parity and by $L$ functions in case of odd parity. We present in this letter a novel observable quantification of deviation from statistical isotropy in terms of generalized angular correlation functions that are compact and complementary to the BipoSH spectra that generalize angular power spectrum CMB fluctuations.

G. B. Crew, C. Goddi, L. D. Matthews, H. Rottmann, A. Saez, I. Marti-Vidal

22 pages, 11 figures, 7 tables, accepted for publication in PASP

The development of the Atacama Large Millimeter/submillimeter Array (ALMA) phasing system (APS) has allowed ALMA to function as an extraordinarily sensitive station for very long baseline interferometry (VLBI) at frequencies of up to 230 GHz (~1.3 mm). Efforts are now underway to extend use of the APS to 345 GHz (~0.87 mm). Here we report a characterization of APS performance at 345 GHz based on a series of tests carried out between 2015-2021, including a successful global VLBI test campaign conducted in 2018 October in collaboration with the Event Horizon Telescope (EHT).

Sudipta Sikder, Rennan Barkana, Anastasia Fialkov, Itamar Reis

Submitted to MNRAS

The reported detection of the global 21-cm signal by the EDGES collaboration is significantly stronger than standard astrophysical predictions. One possible explanation is an early radio excess above the cosmic microwave background. Such a radio background could have been produced by high redshift galaxies, if they were especially efficient in producing low-frequency synchrotron radiation. We have previously studied the effects of such an inhomogeneous radio background on the 21-cm signal; however, we made a simplifying assumption of isotropy of the background seen by each hydrogen cloud. Here we perform a complete calculation that accounts for the fact that the 21-cm absorption occurs along the line of sight, and is therefore sensitive to radio sources lying behind each absorbing cloud. We find that the complete calculation strongly enhances the 21-cm power spectrum during cosmic dawn, by up to two orders of magnitude; on the other hand, the effect on the global 21-cm signal is only at the $5\%$ level. In addition to making the high-redshift 21-cm fluctuations potentially more easily observable, the line of sight radio effect induces a new anisotropy in the 21-cm power spectrum. While these effects are particularly large for the case of an extremely-enhanced radio efficiency, they make it more feasible to detect even a moderately-enhanced radio efficiency in early galaxies. This is especially relevant since the EDGES signal has been contested by the SARAS experiment.

Ziyong Wu, Liang Xiao, Xu Xiao, Jie Wang, Xi Kang, Yang Wang, Xin Wang, Le Zhang, Xiao-Dong Li

15 pages, 13 figures

The peculiar velocities of dark matter halos are crucial to study many issues in cosmology and galaxy evolution. In this study, by using the state-of-the-art deep learning technique, a UNet-based neural network, we propose to reconstruct the peculiar velocity field from the redshift-space distribution of dark matter halos. Through a point-to-point comparison and examination of various statistical properties, we demonstrate that, the reconstructed velocity field is in good agreement with the ground truth. The power spectra of various velocity field components, including velocity magnitude, divergence and vorticity, can be successfully recovered when $k\lesssim 1.1$ $h/\rm Mpc$ (the Nyquist frequency of the simulations) at about 80% accuracy. This approach is very promising and presents an alternative method to correct the redshift-space distortions using the measured 3D spatial information of halos. Additionally, for the reconstruction of the momentum field of halos, UNet achieves similar good results. Hence the applications in various aspects of cosmology are very broad, such as correcting redshift errors and improving measurements in the structure of the cosmic web, the kinetic Sunyaev-Zel'dovich effect, BAO reconstruction, etc.

Coronal flare emission is commonly observed to decay on timescales longer than those predicted by impulsively-driven, one-dimensional flare loop models. This discrepancy is most apparent during the gradual phase, where emission from these models decays over minutes, in contrast to the hour or more often observed. Magnetic reconnection is invoked as the energy source of a flare, but should deposit energy into a given loop within a matter of seconds. Models which supplement this impulsive energization with a long, persistent ad hoc heating have successfully reproduced long-duration emission, but without providing a clear physical justification. Here we propose a model for extended flare heating by the slow dissipation of turbulent Alfv\'en waves initiated during the retraction of newly-reconnected flux tubes through a current sheet. Using one-dimensional simulations, we track the production and evolution of MHD wave turbulence trapped by reflection from high-density gradients in the transition region. Turbulent energy dissipates through non-linear interaction between counter-propagating waves, modeled here using a phenomenological one-point closure model. AIA EUV light curves synthesized from the simulation were able to reproduce emission decay on the order of tens of minutes. We find this simple model offers a possible mechanism for generating the extended heating demanded by observed coronal flare emissions self-consistently from reconnection-powered flare energy release.

Benjamin Wehmeyer, Andrés Yagüe López, Benoit Côté, Maria K. Pető, Chiaki Kobayashi, Maria Lugaro

22 pages, 11 figures

While modelling the galactic chemical evolution (GCE) of stable elements provides insights to the formation history of the Galaxy and the relative contributions of nucleosynthesis sites, modelling the evolution of short-lived radioisotopes (SLRs) can provide supplementary timing information on recent nucleosynthesis. To study the evolution of SLRs, we need to understand their spatial distribution. Using a 3-dimensional GCE model, we investigated the evolution of four SLRs: Mn-53, Fe-60, Hf-182, and Pu-244 with the aim of explaining detections of recent (within the last $\approx$1-20 Myr) deposition of live Mn-53, Fe-60, and Pu-244 of extrasolar origin into deep-sea reservoirs. We find that core-collapse supernovae (CCSNe) are the dominant propagation mechanism of SLRs in the Galaxy. This results in the simultaneously arrival of these four SLRs on Earth, although they could have been produced in different astrophysical sites, which can explain why live extrasolar Mn-53, Fe-60, and Pu-244 are found within the same, or similar, layers of deep-sea sediments. We predict that Hf-182 should also be found in such sediments at similar depths.

Shuang Du

4 pages, submitted to MNRASL, comments are welcome

Magnetars are the most strongly magnetized subclass of pulsars. Observed magnetar activities, such as glitches and bursts, have not yet been systematically explained. Inspired by the dynamo theory, in this letter, we suggest a uniform picture for illustrating these observations. We speculate that the perturbation of velocity fields in these magnetars due to glitches acts as the springhead for glitch-associated activities. We argue that comparing the spark frequencies of pulsed radio pulses before and after glitches may examine the imaginary picture.

Christian Ginski, Ryo Tazaki, Carsten Dominik, Tomas Stolker

Submitted to ApJ with parallel submission to arxiv for logistical reasons; We will update the arxiv submission with the final version once the manuscript was refereed and accepted by ApJ. Data files for all phase functions will be made available once refereeing is concluded. We welcome comments from the community

Dust particles are the building blocks from which planetary bodies are made. A major goal of the studies of planet-forming disks is to constrain the properties of dust particles and aggregates in order to trace their origin, structure, and the associated growth and mixing processes in the disk. Observations of scattering and/or emission of dust in a location of the disk often lead to degenerate information about the kind of particles, such as size, porosity, or fractal dimension of aggregates. Progress can be made by deriving the full (polarizing) scattering phase function of such particles at multiple wavelengths. This has now become possible by careful extraction from scattered light images. Such an extraction requires knowledge about the shape of the scattering surface in the disk and we discuss how to obtain such knowledge as well as the associated uncertainties. We use a sample of disk images from observations with VLT/SPHERE to, for the first time, extract the phase functions of a whole sample of disks with broad phase angle coverage. We find that polarized phase functions come in two categories. Comparing the extracted functions with theoretical predictions from rigorous T-Matrix computations of aggregates, we show that one category can be linked back to fractal, porous aggregates, while the other is consistent with more compact, less porous aggregates. We speculate that the more compact particles become visible in disks where embedded planets trigger enhanced vertical mixing.

Yashvi Sharma, Jesper Sollerman, Christoffer Fremling, Shrinivas R. Kulkarni, Kishalay De, Ido Irani, Steve Schulze, Nora Linn Strotjohann, Avishay Gal-Yam, Kate Maguire, Daniel A. Perley, Eric C. Bellm, Erik C. Kool, Thomas Brink, Rachel Bruch, Maxime Deckers, Richard Dekany, Alison Dugas, Samantha Goldwasser, Matthew J. Graham, Melissa L. Graham, Steven L. Groom, Matt Hankins, Jacob Jencson, Joel P. Johansson, Viraj Karambelkar, Mansi M. Kasliwal, Frank J. Masci, Michael S. Medford, James D. Neill, Guy Nir, Reed L. Riddle, Mickael Rigault, Tassilo Schweyer, Jacco H. Terwel, Lin Yan, Yi Yang, Yuhan Yao

26 pages, 14 figures, 5 tables. Submitted to ApJ

Among the supernovae (SNe) that show strong interaction with the circumstellar medium, there is a rare subclass of Type Ia supernovae, SNe Ia-CSM, that show strong narrow hydrogen emission lines much like SNe IIn but on top of a diluted over-luminous Type Ia spectrum. In the only previous systematic study of this class (Silverman et al. 2013), 16 objects were identified, 8 historic and 8 from the Palomar Transient Factory (PTF). Now using the successor survey to PTF, the Zwicky Transient Facility (ZTF), we have classified 12 additional objects of this type through the systematic Bright Transient Survey (BTS). In this study, we present and analyze the optical and mid-IR light curves, optical spectra, and host galaxy properties of this sample. Consistent with previous studies, we find the objects to have slowly evolving light curves compared to normal SNe Ia with peak absolute magnitudes between -19.1 and -21, spectra having weak H$\beta$, large Balmer decrements of ~7 and strong Ca NIR emission. Out of 10 SNe from our sample observed by NEOWISE, 9 have $3\sigma$ detections, along with some showing a clear reduction in red-wing of H$\alpha$, indicative of newly formed dust. We do not find our SN Ia-CSM sample to have a significantly different distribution of equivalent width of He I $\lambda5876$ than SNe IIn as observed in Silverman et al. 2013. The hosts tend to be late-type galaxies with recent star formation. We also derive a rate estimate of 29$^{+27}_{-21}$ Gpc$^{-3}$ yr$^{-1}$ for SNe Ia-CSM which is ~0.02--0.2 % of the SN Ia rate. This work nearly doubles the sample of well-studied Ia-CSM objects in Silverman et al. 2013, increasing the total number to 28.

Dennis van Dompseler, Christos Georgiou, Nora Elisa Chisari

13 pages, 8 figures

Massive elliptical galaxies align pointing towards each other in the structure of the Universe. Such alignments are well-described at large scales through a linear relation with respect to the tidal field of the large-scale structure. At such scales, galaxy alignments are sensitive to the presence of baryon acoustic oscillations (BAO). The shape of the BAO feature in galaxy alignment correlations differs from the traditional peak in the clustering correlation function. Instead, it appears as a trough feature at the BAO scale. In this work, we show that this feature can be explained by a simple toy model of tidal fields from a spherical shell of matter. This helps give a physical insight for the feature and highlights the need for tailored template-based identification methods for the BAO in alignment statistics. We also discuss the impact of projection baselines and photometric redshift uncertainties for identifying the BAO in intrinsic alignment measurements.

Jhan N. Martinez (1), Jose F. Rodriguez (1, 2), Yeinzon Rodriguez (1, 3), Gabriel Gomez (4) ((1) Universidad Industrial de Santander, (2) ICRANet, (3) Universidad Antonio Narino, (4) Universidad de Santiago de Chile)

LaTeX file in RevTeX 4.1 style, 20 pages, 11 figures

The generalized SU(2) Proca theory is a vector-tensor modified gravity theory where the action is invariant under both diffeomorphisms and global internal transformations of the SU(2) group. This work constitutes the first approach to investigate the physical properties of the theory at astrophysical scales. We have found solutions that naturally generalize the particle-like solutions of the Einstein-Yang-Mills equations, also known as gauge boson stars. Under the requirement that the solutions must be static, asymptotically flat, and globally regular, the t'Hooft-Polyakov magnetic monopole configuration for the vector field rises as one viable possibility. The solutions have been obtained analytically through asymptotic expansions and numerically by solving the boundary value problem. We have found new features in the solutions such as regions with negative effective energy density and imaginary effective charge. We have also obtained a new kind of globally charged solutions for some region in the parameter space of the theory. Furthermore, we have constructed equilibrium sequences and found turning points in some cases. These results hint towards the existence of stable solutions which are absent in the Einstein-Yang-Mills case.

Gonzalo Alonso-Álvarez, Katarina Bleau, James M. Cline

9 pages, 8 figures

A weakly coupled and light dark photon coupling to lepton charges $L_\mu-L_\tau$ is an intriguing dark matter candidate whose coherent oscillations alter the dispersion relations of leptons. We study how this effect modifies the dynamics of neutrino flavor conversions, focusing on atmospheric and solar oscillations. We analyze data from the T2K, SNO, and Super-Kamiokande experiments in order to obtain world-leading limits on the dark photon gauge coupling for masses below $\sim 10^{-11}\,\mathrm{eV}$. Degeneracies between shifts in the neutrino mass-squared differences and mixing angles and the new physics effect significantly relax the current constrains on the neutrino vacuum oscillation parameters.

Joshua Berger, Gilly Elor

6 pages, 3 figures, 4 tables. All data generated using this code is available upon request. The code itself can be downloaded from this https URL

We introduce and study the first class of signals that can probe the dark matter in Mesogenesis which will be observable at current and upcoming large volume neutrino experiments. The well-motivated Mesogenesis scenario for generating the observed matter-anti-matter asymmetry necessarily has dark matter charged under baryon number. Interactions of these particles with nuclei can induce nucleon decay with kinematics differing from sponanteous nucleon decay. We calculate the rate for this process and develop a simulation of the signal that includes important distortions due to nuclear effects. We estimate the sensitivity of DUNE, Super-Kamiokande, and Hyper-Kamiokande to this striking signal.

Salvatore Capozziello, Maria Caruana, Jackson Levi Said, Joseph Sultana

Teleparallel geometry offers a platform on which to build up theories of gravity where torsion rather than curvature mediates gravitational interaction. The teleparallel analogue of Horndeski gravity is an approach to teleparallel geometry where scalar-tensor theories are considered in this torsional framework. Being teleparallel gravity of lower order in dynamics, this turns out to be more general than metric Horndeski gravity. In other words, the class of teleparallel Horndeski gravity models is much broader than the standard metric one. In this work, we explore constraints on this wide range of models coming from ghost and Laplacian instabilities. The aim is to limit pathological branches of the theory by fundamental considerations. It is possible to conclude that a very large class of models results physically viable.

Leonardo Chataignier, Alexander Yu. Kamenshchik, Alessandro Tronconi, Giovanni Venturi

We analyze the consequences of different evolutions of the Hubble parameter on the spectrum of scalar inflationary perturbations. The analysis is restricted to inflationary phases described by a transient evolution, when uncommon features arise in the inflationary spectra which may lead to an amplitude enhancement. We then discuss how the spectrum is, respectively, amplified or blue-tilted in the presence or absence of a growing solution of the Mukhanov-Sasaki equation. The cases of general relativity with a minimally coupled inflaton and that of induced gravity are considered explicitly. Finally, some remarks on constant roll inflation are discussed.

Pieter Braat, Marieke Postma

17 pages, 14 pages appendices, 3 figures

Pions of a dark sector gauge group can be strongly interacting massive particle (SIMP) dark matter, produced by the freeze-out of $3 \to 2$ interactions, with naturally large self-interactions. We study if adding a dark photon to the set-up can do it all: i) maintain thermalization with the visible sector, ii) resonantly enhance the $3\to2$ interactions, thus allowing for a perturbative pion description, and iii) provide a velocity dependent self-interaction that can affect small scale structure formation. We find that this is marginally excluded, as the required kinetic mixing is too small to maintain thermal equilibrium with the SM. Dropping the small scale structure requirement iii), a viable setup is reproduced for dark charges of $\alpha_d = 0.01-1$ and a dark pion mass $m_\pi \geq 30$ MeV. Late time annihilations are non-negligible making the SIMP dark pion a bit WIMPy.

Xin An, Anton Artemyev, Vassilis Angelopoulos, Andrei Runov, Sergey Kamaletdinov

20 pages, 12 figures

Force-free current sheets are local plasma structures with field-aligned electric currents and approximately uniform plasma pressures. Such structures, widely found throughout the heliosphere, are sites for plasma instabilities and magnetic reconnection, the growth rate of which is controlled by the structure's current sheet configuration. Despite the fact that many kinetic equilibrium models have been developed for one-dimensional (1D) force-free current sheets, their two-dimensional (2D) counterparts, which have a magnetic field component normal to the current sheets, have not received sufficient attention to date. Here, using particle-in-cell simulations, we search for such 2D force-free current sheets through relaxation from an initial, magnetohydrodynamic equilibrium. Kinetic equilibria are established toward the end of our simulations, thus demonstrating the existence of kinetic force-free current sheets. Although the system currents in the late equilibrium state remain field aligned as in the initial configuration, the velocity distribution functions of both ions and electrons systematically evolve from their initial drifting Maxwellians to their final time-stationary Vlasov state. The existence of 2D force-free current sheets at kinetic equilibrium necessitates future work in discovering additional integrals of motion of the system, constructing the kinetic distribution functions, and eventually investigating their stability properties.