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Papers for Wednesday, Feb 10 2021

Papers with local authors

E. Iodice, M. Spavone, M.A. Raj, M. Capaccioli, M. Cantiello, VEGAS science team
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Paper 49 — arXiv:2102.04950
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Paper 49 — arXiv:2102.04950

We present the first data release (DR1) of the VST Early-type GAlaxy Survey (VEGAS). This is a deep multi-band (u'g'r'i') imaging survey, carried out with the ESO VLT Survey Telescope (VST). To date, using about 90% of the total observing time, VEGAS has already collected 43 targets (groups and clusters of galaxies) covering a total area on the sky of about 95 square degrees. Taking advantage of the wide (1 deg^2) field-of-view of OmegaCAM@VST, the long integration time and the wide variety of targets, VEGAS has proven to be a gold mine to explore the structure of galaxies down to the faintest surface brightness levels of about 27-30 mag/arcsec^2 in the SDSS g' band, for the dense clusters of galaxies and for the unexplored poor groups of galaxies. Based on the analysed data, VEGAS allowed us to i) study the galaxy outskirts, detect the intra-cluster light and low-surface brightness features in the intra-cluster/group space, ii) trace the mass assembly in galaxies, by estimating the accreted mass fraction in the stellar halos and provide results that can be directly compared with the predictions of galaxy formation models, iii) trace the spatial distribution of candidate globular clusters, and iv) detect the ultra-diffuse galaxies. With the DR1, we provide the reduced VST mosaics of 10 targets, which have been presented in the VEGAS publications. The data products are available via the ESO Science Portal (see this http URL).

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I combine duplicate spectroscopic stellar parameter estimates in the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) Data Release 6 Low Resolution Spectral Survey A, F, G, and K Type stellar parameter catalog. Combining repeat measurements results in a factor of two improvement in the precision of the spectroscopic stellar parameter estimates. Moreover, this trivializes the process of performing coordinate-based cross-matching with other catalogs. Similarly, I combine duplicate stellar abundance estimates for the Xiang et al. catalog which was produced using LAMOST Data Release 5 Low Resolution Spectral Survey data. These data have numerous applications in stellar, galactic, and exoplanet astronomy. The catalogs I produce are available as machine-readable tables at https://doi.org/10.7281/T1/QISGRU .

Guy Nir, Eran O. Ofek, Avishay Gal-Yam

Recently Jiang et al. reported the discovery of a possible short duration transient, detected in a single image, spatially associated with a z~11 galaxy. Jiang et al. and Kahn et al. suggested the transient originates from a Gamma-Ray Burst (GRB), while Padmanabhan & Loeb argued the flash is consistent with a supernova shock breakout event of a 300 M_sun population III star. Jiang et al. argued against the possibility that this event originated from light reflected off a satellite. Here we show that reflection of sunlight from a high-orbit satellite or a piece of space debris is a valid and reasonable explanation. As shown in recent works, the rate of point-like satellite reflections, brighter than 11th magnitude, is >10 deg^{-2} day^-1 near the equatorial plane. At higher declinations the rate is 5--50 times lower, but still significant: about four orders of magnitudes higher than the rate estimated for GRBs.

Sho Fujibayashi, Koh Takahashi, Yuichiro Sekiguchi, Masaru Shibata

7 pages, 4 figures, submitted to ApJ. Comments are welcome

Long-term neutrino-radiation hydrodynamics simulations in full general relativity are performed for rotating massive stars that are evolved from He-stars with their initial masses of $20$ and $32M_\odot$. It is shown that if the collapsing stellar core has sufficient angular momentum, the rotationally-supported proto-neutron star (PNS) survives for seconds accompanying the formation of a massive torus of mass larger than $1\,M_\odot$. Subsequent mass accretion onto the central region produces a massive and compact central object, and eventually enhances the neutrino luminosity beyond $10^{53}$ erg/s, resulting in a very delayed neutrino-driven explosion in particular toward the polar direction. The kinetic energy of the explosion can be appreciably higher than $10^{52}$ erg for a massive progenitor star and compatible with that of energetic supernovae like broad-line type-Ic supernovae. By the subsequent accretion, the massive PNS collapses eventually into a rapidly spinning black hole, which could be a central engine for gamma-ray bursts if a massive torus surrounds it.

Guido Roberts-Borsani, Tommaso Treu, Charlotte Mason, Kasper B. Schmidt, Tucker Jones, Adriano Fontana

13 pages, 7 figures. Accepted for publication in ApJ

The past decade has seen impressive progress in the detection of $z>7$ galaxies with the Hubble Space Telescope, however little is known about their properties. The James Webb Space Telescope will revolutionise the high-$z$ field by providing NIR (i.e., rest-frame optical) data of unprecedented depth and spatial resolution. Measuring galaxy quantities such as resolved stellar ages or gas metallicity gradients traditionally requires spectroscopy, as broad-band imaging filters are generally too coarse to fully isolate diagnostics such as the 4000 \r{A} (rest-frame) break, continuum emission from aged stars, and key emission lines (e.g., [OII], [OIII], H$\beta$). However, in this paper, we show that adding NIRCam images through a strategically chosen medium-band filter to common wide-band filters sets adopted by ERS and GTO programs delivers tighter constraints on these galactic properties. To constrain the choice of filter, we perform a systematic investigation of which combinations of wide-band filters from ERS and GTO programs and single medium-band filters offer the tightest constraints on several galaxy properties at redshifts $z\sim7-11$. We employ the JAGUAR extragalactic catalogs to construct statistical samples of physically-motivated mock photometry and conduct SED-fitting procedures to evaluate the accuracy of galaxy property (and photo-$z$) recovery with a simple star-formation history model. We find that adding $>4.1 \mu$m medium filters at comparable depth to the broad-band filters can significantly improve photo-$z$s and yield close to order-of-magnitude improvements in the determination of quantities such as stellar ages, metallicities, SF-related quantities and emission line fluxes at $z\sim8$. For resolved sources, the proposed approach enables spatially-resolved determination of these quantities that would be prohibitive with slit spectroscopy.

James. W. Nightingale, Richard G. Hayes, Matthew Griffiths

Published in the Journal of Open Source Software

A major trend in academia and data science is the rapid adoption of Bayesian statistics for data analysis and modeling, leading to the development of probabilistic programming languages (PPL). A PPL provides a framework that allows users to easily specify a probabilistic model and perform inference automatically. PyAutoFit is a Python-based PPL which interfaces with all aspects of the modeling (e.g., the model, data, fitting procedure, visualization, results) and therefore provides complete management of every aspect of modeling. This includes composing high-dimensionality models from individual model components, customizing the fitting procedure and performing data augmentation before a model-fit. Advanced features include database tools for analysing large suites of modeling results and exploiting domain-specific knowledge of a problem via non-linear search chaining. Accompanying PyAutoFit is the autofit workspace (see https://github.com/Jammy2211/autofit_workspace), which includes example scripts and the HowToFit lecture series which introduces non-experts to model-fitting and provides a guide on how to begin a project using PyAutoFit. Readers can try PyAutoFit right now by going to the introduction Jupyter notebook on Binder (see https://mybinder.org/v2/gh/Jammy2211/autofit_workspace/HEAD) or checkout our readthedocs(see https://pyautofit.readthedocs.io/en/latest/) for a complete overview of PyAutoFit's features.

Particles may be accelerated in magnetized coronae via magnetic reconnections and/or plasma turbulence, leading to high-energy neutrinos and soft gamma rays. We evaluate the detectability of neutrinos from nearby bright Seyfert galaxies identified by X-ray measurements. In the disk-corona model, we find that NGC 1068 is the most promising Seyfert galaxy in the Northern sky, where IceCube is the most sensitive, and show prospects for the identification of aggregated neutrino signals from Seyfert galaxies bright in X-rays. Moreover, we demonstrate that nearby Seyfert galaxies are promising targets for the next generation of neutrino telescopes such as KM3NeT and IceCube-Gen2. For KM3NeT, Cen A can be the most promising source in the Southern sky if a significant fraction of the observed X-rays come from the corona, and it could be identified in few years of KM3NeT operation. Our results reinforce the idea that hidden cores of supermassive black holes are the dominant sources of the high-energy neutrino emission and underlines the necessity of better sensitivity to medium-energy ranges in future neutrino detectors for identifying the origin of high-energy cosmic neutrinos.

Ilya S. Khrykin, Joseph F. Hennawi, Gabor Worseck, Frederick B. Davies

14 pages, 10 figures, submitted to MNRAS

Understanding the growth of the supermassive black holes powering luminous quasars, their co-evolution with host galaxies, and impact on the surrounding intergalactic medium depends sensitively on the duration of quasar accretion episodes. Unfortunately, this time-scale, known as the quasar lifetime, $t_{\rm Q}$, is still uncertain by orders of magnitude ($t_{\rm Q}\simeq 0.01~{\rm Myr}-1~{\rm Gyr}$). However, the extent of the He II Ly$\alpha$ proximity zones in the absorption spectra of $z_{\rm qso}\sim3-4$ quasars constitutes a unique probe, providing sensitivity to lifetimes up to $\sim 30$ Myr. Our recent analysis of $22$ archival He II proximity zone spectra reveals a surprisingly broad range of emission timescales, indicating that some quasars turned on $\lesssim 1$ Myr ago, whereas others have been shining for $\gtrsim 30$ Myr. Determining the underlying quasar lifetime distribution (QLD) from proximity zone measurements is a challenging task owing to: 1) the limited sensitivity of individual measurements; 2) random sampling of the quasar light curves; 3) density fluctuations in the quasar environment; and 4) the inhomogeneous ionization state of He II in a reionizing IGM. We combine a semi-numerical He II reionization model, hydrodynamical simulations post-processed with ionizing radiative transfer, and a novel statistical framework to infer the QLD from an ensemble of proximity zone measurements. Assuming a log-normal QLD, we infer a mean $\langle {\rm log}_{10}\left(t_{\rm Q}/{\rm Myr}\right)\rangle=0.22^{+0.22}_{-0.25}$ and standard deviation $\sigma_{{\rm log}_{10}t_{\rm Q}}=0.80^{+0.37}_{-0.27}$. Our results allow us to estimate the probability of detecting young quasars with $t_{\rm Q}\leq0.1$ Myr from their proximity zone sizes yielding $p\left(\leq 0.1~{\rm Myr}\right)=0.19^{+0.11}_{-0.09}$, which is broadly consistent with recent determination at $z\sim 6$.

M. Wienen, F. Wyrowski, C. M. Walmsley, T. Csengeri, T. Pillai, A. Giannetti, K. M. Menten

Deuteration has been used as a tracer of the evolutionary phases of low- and high-mass star formation. The APEX Telescope Large Area Survey (ATLASGAL) provides an important repository for a detailed statistical study of massive star-forming clumps in the inner Galactic disc at different evolutionary phases. We study the amount of deuteration using NH2D in a representative sample of high-mass clumps discovered by the ATLASGAL survey covering various evolutionary phases of massive star formation. Unbiased spectral line surveys at 3 mm were thus conducted towards ATLASGAL clumps between 85 and 93 GHz with the Mopra telescope and from 84 to 115 GHz using the IRAM 30m telescope. A subsample was followed up in the NH2D transition at 74 GHz with the IRAM 30m telescope. We determined the deuterium fractionation from the column density ratio of NH2D and NH3 and measured the NH2D excitation temperature for the first time from the simultaneous modelling of the 74 and 110 GHz line using MCWeeds. We find a large range of the NH2D to NH3 column density ratio up to 1.6+/-0.7 indicating a high degree of NH3 deuteration in a subsample of the clumps. Our analysis yields a clear difference between NH3 and NH2D rotational temperatures for a fraction of the sources. We therefore advocate observation of the NH2D transitions at 74 and 110 GHz simultaneously to determine the NH2D temperature directly. We determine a median ortho-to-para column density ratio of 3.7+/-1.2. The high detection rate of NH2D confirms a high deuteration previously found in massive star-forming clumps. Using the excitation temperature of NH2D instead of NH3 is needed to avoid an overestimation of deuteration. We measure a higher detection rate of NH2D in sources at early evolutionary stages. The deuterium fractionation shows no correlation with evolutionary tracers such as the NH3 (1,1) line width, or rotational temperature.

David Valcin, Raul Jimenez, Licia Verde, Jose Luis Bernal, Benjamin D. Wandelt

submitted to JCAP

The dominant systematic uncertainty in the age determination of galactic globular clusters is the depth of the convection envelope of the stars. This parameter is partially degenerate with metallicity which is in turn degenerate with age. However, if the metal content, distance and extinction are known, the position and morphology of the red giant branch in a color-magnitude diagram are mostly sensitive to the value of the depth of the convective envelope. Therefore, using external, precise metallicity determinations this degeneracy and thus the systematic error in age, can be reduced. Alternatively, the morphology of the red giant branch of globular clusters color magnitude diagram can also be used to achieve the same. We demonstrate that globular cluster red giant branches are well fitted by values of the depth of the convection envelope consistent with those obtained for the Sun and this finding is robust to the adopted treatment of the stellar physics. With these findings, the uncertainty in the depth of the convection envelope is no longer the dominant contribution to the systematic error in the age determination of the oldest globular clusters, reducing it from $0.5$ to $0.23$ or $0.33$ Gyr, depending on the methodology adopted: i.e., whether resorting to external data (spectroscopic metallicity determinations) or relying solely on the morphology of the clusters's color-magnitude diagrams. This results in an age of the Universe $t_{\rm U}=13.5^{+0.16}_{-0.14} {\rm (stat.)} \pm 0.23(0.33) ({\rm sys.})$ at 68\% confidence level, accounting for the formation time of globular clusters and its uncertainty. An uncertainty of 0.27(0.36) Gyr if added in quadrature. This agrees well with $13.8 \pm 0.02$ Gyr, the cosmological model-dependent value inferred by the Planck mission assuming the $\Lambda$CDM model.

E. Dartois, M. Chabot, T. Id Barkach, H. Rothard, P. Boduch, B. Augé, A.N. Agnihotri

To appear in Astronomy & Astrophysics

Cosmic-ray-induced sputtering is one of the important desorption mechanisms at work in astrophysical environments. The chemical evolution observed in high-density regions, from dense clouds to protoplanetary disks, and the release of species condensed on dust grains, is one key parameter to be taken into account in interpretations of both observations and models. This study is part of an ongoing systematic experimental determination of the parameters to consider in astrophysical cosmic ray sputtering. As was already done for water ice, we investigated the sputtering yield as a function of ice mantle thickness for the two next most abundant species of ice mantles, carbon monoxide and carbon dioxide, which were exposed to several ion beams to explore the dependence with deposited energy. These ice sputtering yields are constant for thick films. It decreases rapidly for thin ice films when reaching the impinging ion sputtering desorption depth. An ice mantle thickness dependence constraint can be implemented in the astrophysical modelling of the sputtering process, in particular close to the onset of ice mantle formation at low visual extinctions.

Nicole Reindl, Veronika Schaffenroth, Semih Filiz, Stephan Geier, Ingrid Pelisoli, S. O. Kepler

24 pages, accepted for publication in A&A

About 10% of all stars exhibit absorption lines of ultra-high excited (UHE) metals (e.g. OVIII) in their optical spectra when entering the white dwarf cooling sequence. The recent discovery of a both spectroscopic and photometric variable UHE white dwarf led to the speculation that the UHE lines might be created in a shock-heated circumstellar magnetosphere. We investigate (multi-band) light curves from several ground- and space-based surveys of all 16 currently known UHE white dwarfs (including one newly discovered) and eight white dwarfs that show only the HeII line problem, as both phenomena are believed to be connected. We find that $75^{+8}_{-13}$% of the UHE white dwarfs, and $75^{+9}_{-19}$% of the HeII line problem white dwarfs are significantly photometrically variable, with periods ranging from 0.22d to 2.93d and amplitudes from a few tenth to a few hundredth mag. The high variability rate is in stark contrast to the variability rate amongst normal hot white dwarfs (we find $9^{+4}_{-2}$%), marking UHE and HeII line problem white dwarfs as a new class of variable stars. The period distribution of our sample agrees with both the orbital period distribution of post-common envelope binaries and the rotational period distribution of magnetic white dwarfs if we assume that the objects in our sample will spin-up as a consequence of further contraction. The lack of increasing photometric amplitudes towards longer wavelengths, as well as the non-detection of optical emission lines arising from the highly irradiated face of a hypothetical secondary in the optical spectra of our stars, makes it seem unlikely that an irradiated late type companion is the origin of the photometric variability. Instead, we believe that spots on the surfaces of these stars and/or geometrical effects of circumstellar material might be responsible. (abridged)

Rohini S. Giles, Thomas K. Greathouse, Joshua A. Kammer, G. Randall Gladstone, Bertrand Bonfond, Vincent Hue, Denis C. Grodent, Jean-Claude Gérard, Maarten H. Versteeg, Scott J. Bolton, John E. P. Connerney, Steven M. Levin

Accepted in GRL. 21 pages, 3 figures

The UVS instrument on the Juno mission recorded transient bright emission from a point source in Jupiter's atmosphere. The spectrum shows that the emission is consistent with a 9600-K blackbody located 225 km above the 1-bar level and the duration of the emission was between 17 ms and 150 s. These characteristics are consistent with a bolide in Jupiter's atmosphere. Based on the energy emitted, we estimate that the impactor had a mass of 250-5000 kg, which corresponds to a diameter of 1-4 m. By considering all observations made with Juno UVS over the first 27 perijoves of the mission, we estimate an impact flux rate of 24,000 per year for impactors with masses greater than 250-5000 kg.

A. Minelli, A. Mucciarelli, D. Romano, M. Bellazzini, L. Origlia, F. R. Ferraro

21 pages, 8 figures, Accepted for publication by ApJ

Similarities in the chemical composition of two of the closest Milky Way satellites, namely the Large Magellanic Cloud (LMC) and the Sagittarius (Sgr) dwarf galaxy, have been proposed in the literature, suggesting similar chemical enrichment histories between the two galaxies. This proposition, however, rests on different abundance analyses, which likely introduce various systematics that hamper a fair comparison among the different data sets. In order to bypass this issue (and highlight real similarities and differences between their abundance patterns), we present a homogeneous chemical analysis of 30 giant stars in LMC, 14 giant stars in Sgr and 14 giants in the Milky Way, based on high-resolution spectra taken with the spectrograph UVES-FLAMES. The LMC and Sgr stars, in the considered metallicity range ([Fe/H]>-1.1 dex), show very similar abundance ratios for almost all the elements, with differences only in the heavy s-process elements Ba, La and Nd, suggesting a different contribution by asymptotic giant branch stars. On the other hand, the two galaxies have chemical patterns clearly different from those measured in the Galactic stars, especially for the elements produced by massive stars. This finding suggests the massive stars contributed less to the chemical enrichment of these galaxies with respect to the Milky Way. The derived abundances support similar chemical enrichment histories for the LMC and Sgr.

Yvette C. Perrott (1 and 2), Marcos López-Caniego (3), Ricardo T. Génova-Santos (4 and 5), Jose Alberto Rubiño-Martín (4 and 5), Mark Ashdown (1 and 6), Diego Herranz (7), Anne Lähteenmäki (8 and 9), Anthony N. Lasenby (1 and 6), Carlos H. López-Caraballo (4 and 5 and 10), Frédérick Poidevin (4 and 5), Merja Tornikoski (8) ((1) Astrophysics Group, Cavendish Laboratory, (2) School of Chemical and Physical Sciences, Victoria University of Wellington, (3) European Space Agency, ESAC, (4) Instituto de Astrofísica de Canarias (IAC), (5) Universidad de La Laguna, Dpto. Astrofísica, (6) Kavli Institute for Cosmology, University of Cambridge, (7) Instituto de Física de Cantabria (CSIC-Universidad de Cantabria), (8) Aalto University Metsähovi Radio Observatory, (9) Aalto University Department of Electronics and Nanoengineering, (10) INFN Sezione di Milano)

17 pages, 14 figures, accepted to MNRAS

We observed 51 sources in the Q-U-I JOint TEnerife (QUIJOTE) cosmological fields which were brighter than 1 Jy at 30 GHz in the Planck Point Source Catalogue (version 1), with the Very Large Array at 28 -- 40 GHz, in order to characterise their high-radio-frequency variability and polarization properties. We find a roughly log-normal distribution of polarization fractions with a median of 2%, in agreement with previous studies, and a median rotation measure (RM) of $\approx$ 1110 rad m$^{-2}$ with one outlier up to $\approx$ 64000 rad m$^{-2}$ which is among the highest RMs measured in quasar cores. We find hints of a correlation between the total intensity flux density and median polarization fraction. We find 59% of sources are variable in total intensity, and 100% in polarization at $3\sigma$ level, with no apparent correlation between total intensity variability and polarization variability. This indicates that it will be difficult to model these sources without simultaneous polarimetric monitoring observations and they will need to be masked for cosmological analysis.

Ryan Magee, Deep Chatterjee, Leo P. Singer, Surabhi Sachdev, Manoj Kovalam, Geoffrey Mo, Stuart Anderson, Patrick Brady, Patrick Brockill, Kipp Cannon, Tito Dal Canton, Qi Chu, Patrick Clearwater, Alex Codoreanu, Marco Drago, Patrick Godwin, Shaon Ghosh, Giuseppe Greco, Chad Hanna, Shasvath J. Kapadia, Erik Katsavounidis, Victor Oloworaran, Alexander E. Pace, Fiona Panther, Anwarul Patwary, Roberto De Pietri, Brandon Piotrzkowski, Tanner Prestegard, Luca Rei, Anala K. Sreekumar, Marek J. Szczepańczyk, Vinaya Valsan, Aaron Viets, Madeline Wade

Gravitational-wave observations became commonplace in Advanced LIGO-Virgo's recently concluded third observing run. 56 non-retracted candidates were identified and publicly announced in near real time. Gravitational waves from binary neutron star mergers, however, remain of special interest since they can be precursors to high-energy astrophysical phenomena like $\gamma$-ray bursts and kilonovae. While late-time electromagnetic emissions provide important information about the astrophysical processes within, the prompt emission along with gravitational waves uniquely reveals the extreme matter and gravity during - and in the seconds following - merger. Rapid communication of source location and properties from the gravitational-wave data is crucial to facilitate multi-messenger follow-up of such sources. This is especially enabled if the partner facilities are forewarned via an early-warning (pre-merger) alert. Here we describe the commissioning and performance of such a low-latency infrastructure within LIGO-Virgo. We present results from an end-to-end mock data challenge that detects binary neutron star mergers and alerts partner facilities before merger. We set expectations for these alerts in future observing runs.

Andrea Gebek, Jorryt Matthee

16 pages, 12 figures, 4 tables. Submitted to MNRAS. Comments/hints for missing citations are very welcome!

The ratio of $\alpha$-elements to iron in galaxies holds valuable information about the star-formation history since their enrichment occurs on different timescales. The fossil record of stars in galaxies has mostly been excavated for passive galaxies, since the light of star-forming galaxies is dominated by young stars which have much weaker atmospheric absorption features. Here we use the cosmological EAGLE simulation to investigate the origin of variations in $\alpha$-enhancement among star-forming galaxies at $z=0$. The definition of $\alpha$-enhancement in a composite stellar population is ambiguous. We elucidate two definitions - termed 'mean' and 'galactic' $\alpha$-enhancement - in more detail. While a star-forming galaxy has a high 'mean' $\alpha$-enhancement when its stars formed rapidly, a galaxy with a large 'galactic' $\alpha$-enhancement generally had a delayed star formation history. We find that absorption-line strengths of Mg and Fe correlate with variations in $\alpha$-enhancement. These correlations are strongest for the 'galactic' $\alpha$-enhancement. However, we show that these are mostly caused by other effects which are cross-correlated with $\alpha$-enhancement, such as variations in the light-weighted age. This severely complicates the retrieval of $\alpha$-enhancements in star-forming galaxies. The ambiguity is not severe for passive galaxies and we confirm that spectral variations in these galaxies are caused by measurable variations in $\alpha$-enhancements. We suggest that this more complex coupling between $\alpha$-enhancement and star formation histories can guide the interpretation of new observations of star-forming galaxies.

M. M. Lisakov (1 and 2), E. V. Kravchenko (3, 2 and 4), A. B. Pushkarev (5, 2 and 3), Y. Y. Kovalev (2, 3 and 1), T. K. Savolainen (6, 7 and 1), M. L. Lister (8) ((1) Max-Planck-Institut für Radioastronomie, (2) Astro Space Center, Lebedev Physical Institute, Russian Academy of Sciences, (3) Moscow Institute of Physics and Technology, (4) INAF Istituto di Radioastronomia, (5) Crimean Astrophysical Observatory, (6) Aalto University Department of Electronics and Nanoengineering, (7) alto University Metsähovi Radio Observatory, (8) Department of Physics and Astronomy, Purdue University)

10 pages, 9 figures. Accepted to the Astrophysical Journal

In recent studies, several AGN have exhibited gradients of the Faraday Rotation Measure (RM) transverse to their parsec-scale jet direction. Faraday rotation likely occurs as a result of a magnetized sheath wrapped around the jet. In the case of 3C 273, using Very Long Baseline Array multi-epoch observations at 5, 8 and 15 GHz in 2009--2010, we observe that the jet RM has changed significantly towards negative values compared with that previously observed. These changes could be explained by a swing of the parsec-scale jet direction which causes synchrotron emission to pass through different portions of the Faraday screen. We develop a model for the jet-sheath system in 3C 273 where the sheath is wider than the single-epoch narrow relativistic jet. We present our oversized sheath model together with a derived wide jet full intrinsic opening angle $\alpha_\mathrm{int}=2.1^\circ$ and magnetic field strength $B_{||}=3$ $\mu$G and thermal particle density $N_\mathrm{e}=125~\mathrm{cm}^{-3}$ at the wide jet--sheath boundary 230 pc downstream (deprojected) from its beginning. Most of the Faraday rotation occurs within the innermost layers of the sheath. The model brings together the jet direction swing and long-term RM evolution and may be applicable to other AGN jets that exhibit changes of their apparent jet direction.

T. C. Scott, Chandreyee Sengupta, P. Lagos, Aeree Chung, O. Ivy Wong

13 pages , 8 Figures

We report on the first resolved HI observations of two blue ultra-diffuse galaxies (UDGs)using the Giant Metrewave Radio Telescope (GMRT). These observations add to the sofar limited number of UDGs with resolved HI data. The targets are from contrasting non-cluster environments: UDG-B1 is projected in the outskirts of Hickson Compact Group 25 and Secco-dI-2 (SdI-2) is an isolated UDG. These UDGs also have contrasting effective radii with Re of 3.7 kpc (similar to the Milky Way) and 1.3 kpc respectively. SdI-2 has an unusually large MHI/M* ratio =28.9, confirming a previous single dish HI observation. Both galaxies display HI morphological and kinematic signatures consistent with a recent tidal interaction, which is also supported by observations from other wavelengths, including optical spectroscopy. Within the limits of the observations' resolution, our analysis indicates that SdI-2 is dark matter-dominated within its HI radius and this is also likely to be the case for UDG-B1. Our study highlights the importance of high spatial and spectral resolution HI observations for the study of the dark matter properties of UDGs.

Sunjung Kim, Ji-Hoon Ha, Dongsu Ryu, Hyesung Kang

13 pages, 7 figures

Microinstabilities play important roles in both entropy generation and particle acceleration in collisionless shocks. Recent studies have suggested that in the transition zone of quasi-perpendicular ($Q_{\perp}$) shocks in the high-beta ($\beta=P_{\rm gas}/P_{\rm B}$) intracluster medium (ICM), the ion temperature anisotropy due to the reflected-gyrating ions could trigger the Alfv\'en ion cyclotron (AIC) instability and the ion-mirror instability, while the electron temperature anisotropy induced by magnetic field compression could excite the whistler instability and the electron-mirror instability. Adopting the numerical estimates for ion and electron temperature anisotropies found in particle-in-cell (PIC) simulations of $Q_{\perp}$-shocks with sonic Mach numbers, $M_{\rm s}=2-3$, we carry out a linear stability analysis for these microinstabilities. The kinetic properties of the microinstabilities and the ensuing plasma waves on both ion and electron scales are described for wide ranges of parameters, including the dependence on $\beta$ and the ion-to-electron mass ratio. In addition, the nonlinear evolution of induced plasma waves are examined by performing 2D PIC simulations with periodic boundary conditions. We find that for $\beta\approx 20-100$, the AIC instability could induce ion-scale waves and generate shock surface ripples in supercritical shocks above the AIC critical Mach number, $M_{\rm AIC}^{*} \approx 2.3$. Also electron-scale waves are generated primarily by the whistler instability in these high-$\beta$ shocks. The resulting multi-scale waves from electron to ion scales are thought to be essential in electron injection to the diffusive shock acceleration mechanism in $Q_{\perp}$-shocks in the ICM.

Fabian Menezes, Caius L. Selhorst, Carlos Guillermo Giménez de Castro, Adriana Valio

10 pages, 5 figure, 3 tables, 1 equation

At subterahertz frequencies -- \textit{i.e.}, millimeter and submillimeter wavelengths -- there is a gap of measurements of the solar radius as well as other parameters of the solar atmosphere. As the observational wavelength changes, the radius varies because the altitude of the dominant electromagnetic radiation is produced at different heights in the solar atmosphere. Moreover, radius variations throughout long time series are indicative of changes in the solar atmosphere that may be related to the solar cycle. Therefore, the solar radius is an important parameter for the calibration of solar atmospheric models enabling a better understanding of the atmospheric structure. In this work we use data from the Solar Submillimeter-wave Telescope (SST) and from the Atacama Large Millimeter/submillimeter Array (ALMA), at the frequencies of 100, 212, 230, and 405 GHz, to measure the equatorial and polar radii of the Sun. The radii measured with extensive data from the SST agree with the radius-vs-frequency trend present in the literature. The radii derived from ALMA maps at 230 GHz also agree with the radius-vs-frequency trend, whereas the 100-GHz radii are slightly above the values reported by other authors. In addition, we analyze the equatorial and polar radius behavior over the years, by determining the correlation coefficient between solar activity and subterahertz radii time series at 212 and 405 GHz (SST). The variation of the SST-derived radii over 13 years are correlated to the solar activity when considering equatorial regions of the solar atmosphere, and anticorrelated when considering polar regions. The ALMA derived radii time series for 100 and 230 GHz show very similar behaviors with those of SST.

Daikichi Seki, Kenichi Otsuji, Takako T. Ishii, Ayumi Asai, Kiyoshi Ichimoto

accepted for publication in Earth, Planets and Space

It is widely recognised that filament disappearances or eruptions are frequently associated with Coronal Mass Ejections (CMEs). Since CMEs are a major source of disturbances of the space environment surrounding the Earth, it is important to investigate these associations in detail for the better prediction of CME occurrence. However, the proportion of filament disappearances associated with CMEs is under debate. The estimates range from $\sim$10% to $\sim$90% and could be affected by the manners to select the events. In this study, we aim to reveal what parameters control the association between filament eruptions and CMEs. We analysed the relationships between CME associations and the physical parameters of filaments including their length, maximum ascending velocity, and direction of eruptions using 28 events of filament eruptions observed in H$\alpha$. We found that the product of the maximum radial velocity and the filament length is well correlated with the CME occurrence. If the product is larger than 8.0$\times$10$^{6}$ km$^{2}$ s$^{-1}$, the filament will become a CME with a probability of 93%, and if the product is smaller than this value, it will not become a CME with a probability of 100%. We suggest a kinetic-energy threshold above which filament eruptions are associated with CMEs. Our findings also suggest the importance of measuring the velocity vector of filament eruption in three-dimensional space for the better prediction of CME occurrence.

Phased array radar systems have a wide variety of applications in engineering and physics research. Phased array design usually requires numerical modeling with expensive commercial computational packages. Using the open-source MIT Electrogmagnetic Equation Propagation (MEEP) package, a set of phased array designs is presented. Specifically, one and two-dimensional arrays of Yagi-Uda and horn antennas were modeled in the bandwidth [0.1 - 5] GHz, and compared to theoretical expectations in the far-field. Precise matches between MEEP simulation and radiation pattern predictions at different frequencies and beam angles are demonstrated. Given that the computations match the theory, the effect of embedding a phased array within a medium of varying index of refraction is then computed. Understanding the effect of varying index on phased arrays is critical for proposed ultra-high energy neutrino observatories which rely on phased array detectors embedded in natural ice. Future work will develop the phased array concepts with parallel MEEP, in order to increase the detail, complexity, and speed of the computations.

Leping Li, Hardi Peter, Lakshmi Pradeep Chitta, Hongqiang Song

17 pages, 2 tables, 8 figures, accepted for publication in ApJ

Coronal condensation and rain are a crucial part of the mass cycle between the corona and chromosphere. In some cases, condensation and subsequent rain originate in the magnetic dips formed during magnetic reconnection. This provides a new and alternative formation mechanism for coronal rain. Until now, only off-limb, rather than on-disk, condensation events during reconnection have been reported. In this paper, employing extreme-ultraviolet (EUV) images of the Solar Terrestrial Relations Observatory (STEREO) and Solar Dynamics Observatory (SDO), we investigate the condensations facilitated by reconnection from 2011 July 14 to 15, when STEREO was in quadrature with respect to the Sun-Earth line. Above the limb, in STEREO/EUV Imager (EUVI) 171 \AA~images, higher-lying open structures move downward, reconnect with the lower-lying closed loops, and form dips. Two sets of newly reconnected structures then form. In the dips, bright condensations occur in EUVI 304 \AA~images repeatedly which then flow downward to the surface. In the on-disk observations by SDO/Atmospheric Imaging Assembly (AIA) in the 171 \AA~channel, these magnetic structures are difficult to identify. Dark condensations appear in AIA 304 \AA~images, and then move to the surface as on-disk coronal rain. The cooling and condensation of coronal plasma is revealed by the EUV light curves. If only the on-disk observations would be available, the relation between the condensations and reconnection, shown clearly by the off-limb observations, would not be identified. Thus, we suggest that some on-disk condensation events seen in transition region and chromospheric lines may be facilitated by reconnection.

A. Williamson, C. W. James, S. J. Tingay, S. J. McSweeney, S. M. Ord

9 pages, 8 figures. To be published in the Journal of Astronomical Instrumentation

The radio-wavelength detection of extensive air showers (EAS) initiated by cosmic-ray interactions in the Earth's atmosphere is a promising technique for investigating the origin of these particles and the physics of their interactions. The Low Frequency Array (LOFAR) and the Owens Valley Long Wavelength Array (OVRO-LWA) have both demonstrated that the dense cores of low frequency radio telescope arrays yield detailed information on the radiation ground pattern, which can be used to reconstruct key EAS properties and infer the primary cosmic-ray composition. Here, we demonstrate a new observation mode of the Murchison Widefield Array (MWA), tailored to the observation of the sub-microsecond coherent bursts of radiation produced by EAS. We first show how an aggregate 30.72 MHz bandwidth (3072x 10 kHz frequency channels) recorded at 0.1 ms resolution with the MWA's voltage capture system (VCS) can be synthesised back to the full bandwidth Nyquist resolution of 16.3 ns. This process, which involves `inverting' two sets of polyphase filterbanks, retains 90.5% of the signal-to-noise of a cosmic ray signal. We then demonstrate the timing and positional accuracy of this mode by resolving the location of a calibrator pulse to within 5 m. Finally, preliminary observations show that the rate of nanosecond radio-frequency interference (RFI) events is 0.1 Hz, much lower than that found at the sites of other radio telescopes that study cosmic rays. We conclude that the identification of cosmic rays at the MWA, and hence with the low-frequency component of the Square Kilometre Array, is feasible with minimal loss of efficiency due to RFI.

Yoshiki Toba, Yoshihiro Ueda, Poshak Gandhi, Claudio Ricci, Denis Burgarella, Veronique Buat, Tohru Nagao, Shinki Oyabu, Hideo Matsuhara, Bau-Ching Hsieh

20 pages, 14 figures, and 4 tables, accepted for publication in ApJ. Physical properties (e.g., BH mass, Eddington ratio, IR luminosity) of 37,181 quasars at z < 0.7 selected from the SDSS DR16 will be available as a Machine-readable table

We revisit the dependence of covering factor (CF) of dust torus on physical properties of active galactic nuclei (AGNs) by taking into account an AGN polar dust emission. The CF is converted from a ratio of infrared (IR) luminosity contributed from AGN dust torus ($L_{\rm IR}^{\rm torus}$) and AGN bolometric luminosity ($L_{\rm bol}$), by assuming a non-linear relation between luminosity ratio and intrinsic CF. We select 37,181 type 1 quasars at $z < 0.7$ from the Sloan Digital Sky Survey Data Release 16 quasar catalog. Their $L_{\rm bol}$, black hole mass ($M_{\rm BH}$), and Eddington ratio ($\lambda_{\rm Edd}$) are derived by spectral fitting with QSFit. We conduct spectral energy distribution decomposition by using X-CIGALE with clumpy torus and polar dust model to estimate $L_{\rm IR}^{\rm torus}$ without being affected by the contribution of stellar and AGN polar dust to IR emission. For 5720 quasars whose physical quantities are securely determined, we perform a correlation analysis on CF and (i) $L_{\rm bol}$, (ii) $M_{\rm BH}$, and (iii) $\lambda_{\rm Edd}$. As a result, anti-correlations for CF-$L_{\rm bol}$, CF-$M_{\rm BH}$, and CF-$\lambda_{\rm Edd}$ are confirmed. We find that incorporating the AGN polar dust emission makes those anti-correlations stronger which are compared to those without considering it. This indicates that polar dust wind provably driven by AGN radiative pressure is one of the key components to regulate obscuring material of AGNs.

Enrique Macias, Osmar Guerra-Alvarado, Carlos Carrasco-Gonzalez, Alvaro Ribas, Catherine C. Espaillat, Jane Huang, Sean M. Andrews

22 pages, 17 figures, accepted for publication in A&A

We present Atacama Large Millimeter Array (ALMA) observations of TW Hya at 3.1 mm with $\sim50$ milliarcsecond resolution. These new data were combined with archival high angular resolution ALMA observations at 0.87 mm, 1.3 mm, and 2.1 mm. We analyze these multi-wavelength data to infer a disk radial profile of the dust surface density, maximum particle size, and slope of the particle size distribution. Most previously known annular substructures in the disk of TW Hya are resolved at the four wavelengths. Inside the inner 3 au cavity, the 2.1 mm and 3.1 mm images show a compact source of free-free emission, likely associated with an ionized jet. Our multi-wavelength analysis of the dust emission shows that the maximum particle size in the disk of TW Hya is $>1$ mm. The inner 20 au are completely optically thick at all four bands, which results in the data tracing different disk heights at different wavelengths. Coupled with the effects of dust settling, this prevents the derivation of accurate density and grain size estimates in these regions. At $r>20$ au, we find evidence of the accumulation of large dust particle at the position of the bright rings, indicating that these are working as dust traps. The total dust mass in the disk is between 250 and 330 $M_{\oplus}$, which represents a gas-to-dust mass ratio between 50 and 70. Our mass measurement is a factor of 4.5-5.9 higher than the mass that one would estimate using the typical assumptions of large demographic surveys. Our results indicate that the ring substructures in TW Hya are ideal locations to trigger the streaming instability and form new generations of planetesimals.

M. B. Pandge, Biny Sebastian, Ruchika Seth, Somak Raychaudhury

13 pages, 13 figures, 7 Tables

We present a detailed analysis of a cool-core galaxy cluster Abell~3017, at a redshift of $z\!=\! 0.219$, which has been identified to be merging with its companion cluster Abell~3016. This study has made use of X-ray ({\it Chandra}), UV (GALEX), optical (ESO/VLT), mid-infrared (WISE), and radio uGMRT observations of this cluster. Using various image processing techniques, such as unsharp masking, 2-d fits using Beta models, contour binning and the use of surface brightness profiles, we show the existence of a pair of X-ray cavities, at a projected distance of ~$\sim$20\arcsec (70\,kpc) and ~$\sim$16\arcsec (57\,kpc), respectively from the core of Abell~3017. We also detect an excess of X-ray emission, relatively hotter than that of the surroundings, towards the south, at $\sim$25\arcsec (88\, kpc) from the core of the cluster, indicating the existence of an in-falling galaxy group. We find that the radio lobes are responsible for the observed X-ray cavities detected in this system. The lower values of mid-IR WISE color [W1-W2] and [W2-W3] imply that the central BCG of Abell~3017 is a star-forming galaxy. The current star formation rate of the central BCG, estimated from the ${\rm H\alpha}$ and {\it GALEX} FUV luminosities, are equal to be $\sim 5.06\pm 0.78$ \Msun yr$^{-1}$ and $\sim 9.20\pm 0.81$ \Msun yr$^{-1}$, respectively. We detect, for the first time, a radio phoenix $\sim$150\,kpc away from the radio core, with a spectral index of ($\alpha \!\leq\! -1.8$). We also report the detection of $\rm~Pa_\alpha$ emission in this cluster using ESO VLT {\tt SINFONI} imaging data.

Subhashree Swain, P. Shalima, K.V.P. Latha, Krishna B. S. Swamy

21 pages, 24 figures, accepted for publication in MNRAS

We model the near infrared SED of NGC 4151 with a 3-D radiative transfer SKIRT code, using which torus only (TO) and Ring And Torus (RAT) scenarios are studied. In the RAT models, a graphite ring-like structure (clumpy or smooth), is incorporated between the torus and the accretion disk. We vary the inclination angle $(i)$, inner radius (of the torus and the ring, $R_{\rm in, t}$ and $R_{\rm in, r}$ respectively), torus half-opening angle ($\sigma $), optical depth ($\tau_{9.7, \rm t} $ of the torus and $\tau_{9.7, \rm r} $ of the ring ) and the dust clump size ($R_{\rm clump}$). We perform a statistical analysis of the parameter space and find that all the models are able to explain the flat NIR SED of NGC 4151 with minor differences in the derived parameters. For the TO model, we get, $R_{\rm in, t}=0.1$ pc, $\sigma = 30^\circ $, $i = 53^\circ $, $\tau_{9.7, \rm t}=10$ and the clumpsize, $R_{\rm clump}$ =0.4 pc. For the smooth RAT model, $R_{\rm in, \rm r}=0.04$ pc, $\tau_{9.7, \rm total}$ = 11 and for the clumpy RAT model, $R_{\rm in, r} = 0.04$ pc/0.06 pc and $\tau_{9.7, \rm total}=20$. The $R_{\rm in, t}$ from the TO model does not agree with the NIR observations ($\sim 0.04$ pc). Hence, the most likely scenario is that a hot graphite ring is located at a distance 0.04 pc from the centre, composed of a smooth distribution of dust followed by a dusty torus at 0.1 pc with ISM type of grains.

Sihe Chen, Eliot F. Young, Leslie A. Young, Tanguy Bertrand, François Forget, Yuk L. Yung

Pluto's atmospheric profiles (temperature and pressure) have been studied for decades from stellar occultation lightcurves. In this paper, we look at recent Pluto Global Climate Model (GCM) results (3D temperature, pressure, and density fields) from Bertrand et al. (2020) and use the results to generate model observer's plane intensity fields (OPIF) and lightcurves by using a Fourier optics scheme to model light passing through Pluto's atmosphere (Young, 2012). This approach can accommodate arbitrary atmospheric structures and 3D distributions of haze. We compared the GCM model lightcurves with the lightcurves observed during the 15-AUG-2018 Pluto stellar occultation. We find that the climate scenario which best reproduces the observed data includes an N2 ice mid-latitude band in the southern hemisphere. We have also studied different haze and P/T ratio profiles: the haze effectively reduces the central flash strength, and a lower P/T ratio both reduces the central flash strength and incurs anomalies in the shoulders of the central flash.

context{ The high energy emission regions of rotation powered pulsars are studied using folded light curves (FLCs) and phase resolved spectra (PRS).} aims{ This work uses the NICER observatory to obtain the highest resolution FLC and PRS of the Crab pulsar at soft X-ray energies.} methods{ NICER has accumulated about 347 kilo seconds of data on the Crab pulsar. The data are processed using the standard analysis pipeline. Stringent filtering is done for spectral analysis. The individual detectors are calibrated in terms of long time light curve (LTLC), raw spectrum and deadtime. The arrival times of the photons are referred to the solar system's barycenter, and the rotation frequency nu and its time derivative nu_dot are used to derive the rotation phase of each photon.} results{ The LTLCs, raw spectra and deadtimes of the individual detectors are statistically similar; the latter two show no evolution with epoch; detector deadtime is independent of photon energy. The deadtime for the Crab pulsar, taking into account the two types of deadtime, is only about 7% to 8% larger than that obtained using the cleaned events. Detector 00 behaves slightly differently from the rest, but can be used for spectral work. The PRS of the two peaks of the crab pulsar are obtained at a resolution of better than 1/512 in rotation phase. The FLC very close to the first peak rises slowly and falls faster, opposite in behavior to that seen further away from the peak. The spectral index of the PRS is almost constant very close to the first peak.} conclusions{ The high resolution FLC and PRS of the first peak of the Crab pulsar provide important constraints for the formation of caustics in the emission zone.}

Ashutosh Tripathi, Askar B. Abdikamalov, Dimitry Ayzenberg, Cosimo Bambi, Honghui Liu

12 pages, 8 figures

In a previous paper, we presented an extension of our reflection model RELXILL_NK to include the finite thickness of the accretion disk following the prescription in Taylor & Reynolds (2018). In this paper, we apply our model to fit the 2013 simultaneous observations by NuSTAR and XMM-Newton of the supermassive black hole in MCG-06-30-15 and the 2019 NuSTAR observation of the Galactic black hole in EXO 1846-031. The high-quality data of these spectra had previously led to precise black hole spin measurements and very stringent constraints on possible deviations from the Kerr metric. We find that the disk thickness does not change previous results found with a model employing an infinitesimally thin disk.

Mirjana Pović

Proceedings paper of the International Astronomical Union Symposium 367: Education and Heritage in the Era of Big Data in Astronomy

Africa has amazing potential due to natural (such as dark sky) and human resources for scientific research in astronomy and space science. At the same time, the continent is still facing many difficulties, and its countries are now recognising the importance of astronomy, space science and satellite technologies for improving some of their principal socio-economic challenges. The development of astronomy in Africa (including Ethiopia) has grown significantly over the past few years, and never before it was more possible to use astronomy for education, outreach, and development as it is now. However, much still remains to be done. This paper will summarise the recent developments in astronomy research and education in Africa and Ethiopia and will focus on how working together on the development of science and education can we fight poverty in the long term and increase our possibilities of attaining the United Nations Sustainable Development Goals in future for benefit of all.

Supriyo Ghosh, Soumen Mondal, Ramkrishna Das, Somnath Dutta

14 pages, 7 figures, 5 tables. Accepted for publication in AJ

We present the time-dependent properties of a poorly known OH/IR star $-$ IRAS 18278+0931 (hereafter, IRAS 18+09) towards the Ophiuchus constellation. We have carried out long-term optical/near-infrared (NIR) photometric and spectroscopic observations to study the object. From optical $R$- and $I$-band light curves, the period of IRAS 18+09 is estimated to be 575 $\pm$ 30 days and the variability amplitudes range from $\Delta$R $\sim$ 4.0 mag to $\Delta$I $\sim$ 3.5 mag. From the standard Period-Luminosity (PL) relations, the distance ($D$) to the object, 4.0 $\pm$ 1.3 kpc, is estimated. Applying this distance in the radiative transfer model, the spectral energy distribution (SED) are constructed from multi-wavelength photometric and IRAS-LRS spectral data which provides the luminosity, optical depth, and gas mass-loss rate (MLR) of the object to be 9600 $\pm$ 500 $L_{\odot}$, 9.1 $\pm$ 0.6 at 0.55 $\mu$m and 1.0$\times$10$^{-6}$ M$_\odot$ yr$^{-1}$, respectively. The current mass of the object infers in the range 1.0 $-$ 1.5 $M_\odot$ assuming solar metallicity. Notably, the temporal variation of atomic and molecular features (e.g., TiO, Na I, Ca I, CO, H$_2$O) over the pulsation cycle of the OH/IR star illustrates the sensitivity of the spectral features to the dynamical atmosphere as observed in pulsating AGB stars.

Eddie Ross, William J. Chaplin, Steven J. Hale, Rachel Howe, Yvonne P. Elsworth, Guy R. Davies, Martin Bo Nielsen

Accepted for publication in MNRAS; 9 pages, 7 figures, 1 table

We have used very high-cadence (sub-minute) observations of the solar mean magnetic field (SMMF) from the Birmingham Solar Oscillations Network (BiSON) to investigate the morphology of the SMMF. The observations span a period from 1992--2012, and the high-cadence observations allowed the exploration of the power spectrum up to frequencies in the mHz range. The power spectrum contains several broad peaks from a rotationally-modulated (RM) component, whose linewidths allowed us to measure, for the first time, the lifetime of the RM source. There is an additional broadband, background component in the power spectrum which we have shown is an artefact of power aliasing due to the low fill of the data. The sidereal rotation period of the RM component was measured as $25.23 \pm 0.11$ days and suggests that the signal is sensitive to a time-averaged latitude of $\sim 12^{\circ}$. We have also shown the RM lifetime to be $139.6 \pm 18.5$ days. This provides evidence to suggest the RM component of the SMMF is connected to magnetic flux concentrations (MFCs) and active regions (ARs) of magnetic flux, based both on its lifetime and location on the solar disc.

J. R. Callingham, B. J. S. Pope, A. D. Feinstein, H. K. Vedantham, T. W. Shimwell, P. Zarka, C. Tasse, L. Lamy, K. Veken, S. Toet, J. Sabater, P. N. Best, R. J. van Weeren, H. J. A. Röttgering, T. P. Ray

Accepted for publication in A&A, 16 pages, 7 figures, 2 tables

Recently detected coherent low-frequency radio emission from M dwarf systems shares phenomenological similarities with emission produced by magnetospheric processes from the gas giant planets of our Solar System. Such beamed electron-cyclotron maser emission can be driven by a star-planet interaction or a breakdown in co-rotation between a rotating plasma disk and a stellar magnetosphere. Both models suggest that the radio emission could be periodic. Here we present the longest low-frequency interferometric monitoring campaign of an M dwarf system, composed of twenty-one $\approx$8 hour epochs taken in two series of observing blocks separated by a year. We achieved a total on-source time of 6.5 days. We show that the M dwarf binary CR Draconis has a low-frequency 3$\sigma$ detection rate of 90$^{+5}_{-8}$% when a noise floor of $\approx$0.1 mJy is reached, with a median flux density of 0.92 mJy, consistent circularly polarised handedness, and a median circularly polarised fraction of 66%. We resolve three bright radio bursts in dynamic spectra, revealing the brightest is elliptically polarised, confined to 4 MHz of bandwidth centred on 170 MHz, and reaches a flux density of 205 mJy. The burst structure is mottled, indicating it consists of unresolved sub-bursts. Such a structure shares a striking resemblance with the low-frequency emission from Jupiter. We suggest the near-constant detection of high brightness temperature, highly-circularly-polarised radiation that has a consistent circular polarisation handedness implies the emission is produced via the electron-cyclotron maser instability. Optical photometric data reveal the system has a rotation period of 1.984$\pm$0.003 days. We observe no periodicity in the radio data, but the sampling of our radio observations produces a window function that would hide the near two-day signal.

K. D. Gazeas, G. A. Loukaidou, P. G. Niarchos, S. Palafouta, D. Athanasopoulos, A. Liakos, S. Zola, A. Essam, P. Hakala

16 pages, 10 figure, 2 tables

Binary and multiple stellar systems are numerous in our solar neighborhood with 80 per cent of the solar-type stars being members of systems with high order multiplicity. The Contact Binaries Towards Merging (CoBiToM) Project is a programme that focuses on contact binaries and multiple stellar systems, as a key for understanding stellar nature. The goal is to investigate stellar coalescence and merging processes, as the final state of stellar evolution of low-mass contact binary systems. Obtaining observational data of approximately 100 eclipsing binaries and multiple systems and more than 400 archival systems, the programme aspires to give insights for their physical and orbital parameters and their temporal variations, e.g. the orbital period modulation, spot activity etc. Gravitational phenomena in multiple-star environments will be linked with stellar evolution. A comprehensive analysis will be conducted, in order to investigate the possibility of contact binaries to host planets, as well as the link between inflated hot Jupiters and stellar mergers. The innovation of CoBiToM Project is based on a multi-method approach and a detailed investigation, that will shed light for the first time on the origin of stellar mergers and rapidly rotating stars. In this work we describe the scientific rationale, the observing facilities to be used and the methods that will be followed to achieve the goals of CoBiToM Project and we present the first results as an example of the current research on evolution of contact binary systems.

Joanna K. Barstow

Invited review article for Astronomy & Geophysics, author's own version. Version of record: this https URL

In recent years, a vast increase in spectroscopic observations of transiting exoplanets has for the first time allowed us to search for broad trends in their atmospheric properties. Analysis of these observations has revealed that, even for the highly irradiated hot Jupiters, aerosol is a common presence and must be accounted for in modelling efforts. An additional challenge for hot Jupiters is the large variation in temperature across the planet, which is likely to result in partial or patchy cloud cover. As our observational capability is due to increase further with the launch of the James Webb Space Telescope, anticipated in autumn 2021, community efforts are underway to prepare modelling and analysis tools capable of recovering information about variable and patchy cloud coverage on hot exoplanets

F. Cangemi, T. Beuchert, T. Siegert, J. Rodriguez, V. Grinberg, R. Belmont, C. Gouiffès, I. Kreykenbohm, P. Laurent, K. Pottschmidt, J. Wilms

12 pages, 7 figures. Accepted for a publication in A&A

0.1-10 MeV observations of the black hole microquasar Cygnus X-1 have shown the presence of a spectral feature in the form of a power law in addition to the standard black body and Comptonization components observed by INTEGRAL. This so-called "high-energy tail" has recently been shown to be strong in its hard spectral state and interpreted as high-energy part of the emission from a compact jet. This result was, however, obtained from a data set dominated by hard state observations. In the soft state, only upper limits on the presence and hence the potential parameters of a high-energy tail could be derived. Using an extended data set we aim at obtaining better constraints on the properties of this spectral component in both states. We make use of data obtained from 15 years of observations with the INTEGRAL satellite. The data set is separated into the different states and we analyse stacked state-resolved spectra obtained from the X-ray monitors, the gamma-ray imager, and the gamma-ray spectrometer onboard. A high-energy component is detected in both states confirming its earlier detection in the hard state and its suspected presence in the soft state with INTEGRAL. We first characterize the high-energy tail components in the two states through a model-independent, phenomenological analysis. We then apply physical models based on hybrid Comptonization. The spectra are well modeled in all cases, with a similar goodness of the fits. While in the phenomenological approach the high-enery tail has similar indices in both states, the fits with the physical models seem to indicate different properties. We discuss the potential origins of the high-energy components in both states, and favor an interpretation where the part of the high-energy component is due to a compact jet in the hard state and hybrid Comptonization in either a magnetised or non-magnetised corona in the soft state.

Accurate constraints on curvature provide a powerful probe of inflation. However, curvature constraints based on specific assumptions of dark energy may lead to unreliable conclusions when used to test inflation models. To avoid this, it is important to obtain constraints that are independent on assumptions for dark energy. In this paper, we investigate such constraints on curvature from the geometrical probe constructed from galaxy-lensing cross-correlations. We study comprehensively the cross-correlations of galaxy with magnification, measured from type Ia supernovae's brightnesses ("$g\kappa^{\rm SN}$"), with shear ("$g\kappa^{\rm g}$"), and with CMB lensing ("$g\kappa^{\rm CMB}$"). We find for the LSST and Stage IV CMB surveys, "$g\kappa^{\rm SN}$" , "$g\kappa^{\rm g}$" and "$g\kappa^{\rm CMB}$" can be detected with signal-to-noise ratio $S/N=104,\ 2291,\ 1842$ respectively. When combined with supernovae Hubble diagram ("SN") to constrain curvature, we find galaxy-lensing cross-correlation becomes increasingly important with more degrees of freedom allowed in dark energy. Without any priors, we obtain error on $\Omega_K$ of $0.723$ from "SN + $g\kappa^{\rm SN}$", $0.0417$ from "SN + $g\kappa^{\rm g}$", and $0.04$ from "SN + $g\kappa^{\rm g}$ + $g\kappa^{\rm CMB}$" for the LSST and Stage IV CMB surveys. The last one is more competitive than a Stage IV BAO survey ("BAO"). When galaxy-lensing cross-correlations are added to the combined probe of "SN + BAO + CMB", where "CMB" stands for Planck measurement for the CMB acoustic scale, we obtain constraint on $\Omega_K$ of $0.0013$, which is a factor of 7 improvement from "SN + BAO + CMB". We study improvements in these results from increasing the high redshift extension of supernovae.

Oleksandra Ivanova, Yury Skorov, Pavlo Korsun, Viktor Afanasiev, Jürgen Blum

9 pages, 4 figures, 2 tables

We investigated three comets, which are active at large heliocentric distances, using observations obtained at the 6-m BTA telescope (SAO RAS, Russia) in the photometric mode of the focal reducer SCORPIO. The three comets, 29P/Schwassmann-Wachmann 1, C/2003 WT42 (LINEAR), and C/2002 VQ94 (LINEAR), were observed after their perihelion passages at heliocentric distances between 5.5 and 7.08 AU. The dust production rates in terms of Afrho was measured for these comets. Using the retrieved values, an average dust production rate was derived under different model assumptions. A tentative calculation of the total mass loss of the comet nucleus within a certain observation period was executed. We calculated the corresponding thickness of the depleted uppermost layer where high-volatile ices completely sublimated. The results obtained in our study strongly support the idea that the observed activity of Comet SW1 requires a permanent demolition of the upper surface layers.

We present BALRoGO: Bayesian Astrometric Likelihood Recovery of Galactic Objects, a public code to measure the centers, effective radii, and bulk proper motions of Milky Way globular clusters and Local Group dwarf spheroidals, whose data are mixed with Milky Way field stars. Our approach presents innovative methods such as surface density fits allowing for strong interloper contamination and proper motion fits using a Pearson VII distribution for interlopers, instead of classic Gaussian-mixture recipes. We also use non-parametric approaches to represent the color-magnitude diagram of such stellar systems based in their membership probabilities, previously derived from surface density and proper motion fits. The robustness of our method is verified by comparing its results with previous estimates from the literature as well as by testing it on mock data from N-body simulations. We applied BALRoGO to Gaia EDR3 data for over one hundred Milky Way globular clusters and nine Local Group dwarf spheroidals, and we provide positions, effective radii, and bulk proper motions. Finally, we make our algorithm available as an open source software.

Akaash Srikanth, Bharat Chandra, Binukumar G Nair, Nirmal K, Margarita Safonova, Shanti Prabha, Rekhesh Mohan, Jayant Murthy, Rajini G.K

High-altitude balloon experiments are becoming very popular among universities and research institutes as they can be used for testing instruments eventually intended for space, and for simple astronomical observations of Solar System objects like the Moon, comets, and asteroids, difficult to observe from the ground due to atmosphere. Further, they are one of the best platforms for atmospheric studies. In this experiment, we build a simple 1U CubeSat and, by flying it on a high-altitude balloon to an altitude of about 30 km, where the total payload weighted 4.9 kg and examine how some parameters, such as magnetic field, humidity, temperature or pressure, vary as a function of altitude. We also calibrate the magnetometer to remove the hard iron and soft iron errors. Such experiments and studies through a stratospheric balloon flights can also be used to study the performance of easily available commercial sensors in extreme conditions as well. We present the results of the first flight, which helped us study the functionality of the various sensors and electronics at low temperatures reaching about -40 degrees Celsius. Further the motion of the payload has been tracked throughout this flight. This experiment took place on 8 March 2020 from the CREST campus of the Indian Institute of Astrophysics, Bangalore. Using the results from this flight, we identify and rectify the errors to obtain better results from the subsequent flights.

We have analysed the Ca-K images obtained at Kodaikanal Observatory as a function of latitude and time for the period of 1913 - 2004 covering the Solar Cycle 15 to 23. We have classified the chromospheric activity into plage, Enhanced Network (EN), Active Network (AN), and Quiet Network (QN) areas to differentiate between large strong active and small weak active regions. The strong active regions represent toroidal and weak active regions poloidal component of the magnetic field. We find that plages areas mostly up to 50 deg latitude belt vary with about 11-year Solar Cycle. We also find that weak activity represented by EN, AN and QN varies with about 11-year with significant amplitude up to about 50 deg latitude in both the hemispheres. The amplitude of variation is minimum around 50 deg latitude and again increases by small amount in the polar region. In addition, the plots of plages, EN, AN and QN as a function of time indicate the maximum of activity at different latitude occur at different epoch. To determine the phase difference for the different latitude belts, we have computed the cross-correlation coefficients of other latitude belts with 35 deg latitude belt. We find that activity shifts from mid-latitude belts towards equatorial belts at fast speed at the beginning of Solar Cycle and at slower speed as the cycle progresses. The speed of shift varies between approximately 19 and 3 m/s considering all the data for the observed period. This speed can be linked with speed of meridional flows those believed to occur between convection zone and the surface of the Sun.

L. Moscadelli, H. Beuther, A. Ahmadi, C. Gieser, F. Massi, R. Cesaroni, Á. Sánchez-Monge, F. Bacciotti, M.T. Beltrán, T. Csengeri, R. Galván-Madrid, Th. Henning, P.D. Klaassen, R. Kuiper, S. Leurini, S.N. Longmore, L.T. Maud, T. Möller, A. Palau, T. Peters, R.E. Pudritz, A. Sanna, D. Semenov, J.S. Urquhart, J.M. Winters, H. Zinnecker

25 pages, 16 figures

In the massive star-forming region IRAS 21078+5211, a highly fragmented cluster (0.1~pc in size) of molecular cores is observed, located at the density peak of an elongated (1~pc in size) molecular cloud. A small (1~km/s per 0.1~pc) LSR velocity (Vlsr) gradient is detected across the axis of the molecular cloud. Assuming we are observing a mass flow from the harboring cloud to the cluster, we derive a mass infall rate of about 10^{-4}~M_{sun}~yr^{-1}. The most massive cores (labeled 1, 2, and 3) are found at the center of the cluster, and these are the only ones that present a signature of protostellar activity in terms of emission from high-excitation molecular lines or a molecular outflow. We reveal an extended (size about 0.1~pc), bipolar collimated molecular outflow emerging from core 1. We believe this is powered by a (previously discovered) compact (size <= 1000~au) radio jet, ejected by a YSO embedded in core 1 (named YSO-1), since the molecular outflow and the radio jet are almost parallel and have a comparable momentum rate. By means of high-excitation lines, we find a large (14~km/s over 500~au) Vlsr gradient at the position of YSO-1, oriented approximately perpendicular to the radio jet. Assuming this is an edge-on, rotating disk and fitting a Keplerian rotation pattern, we determine the YSO-1 mass to be 5.6+/-2.0~M_{sun}. The water masers (previously observed with VLBI) emerge within 100-300~au from YSO-1 and are unique tracers of the jet kinematics. Their three-dimensional (3D) velocity pattern reveals that the gas flows along, and rotates about, the jet axis. We show that the 3D maser velocities are fully consistent with the magneto-centrifugal disk-wind models predicting a cylindrical rotating jet. Under this hypothesis, we determine the jet radius to be about 16~au and the corresponding launching radius and terminal velocity to be about 2.2~au and 200~km/s, respectively.

Yan Li, Rong-Feng Shen

16 pages, 6 Figures. Accepted for publication in ApJ

Compact binary mergers that involve at least one neutron star, either binary neutron star or black hole--neutron star coalescences, are thought to be the potential sources of electromagnetic emission due to the material ejected during the merger or those left outside the central object after the merger. Since the intensity of these electromagnetic transients decay rapidly with time, one should pay more attention to early emissions from such events, which are useful in revealing the nature of these mergers. In this work, we study the early emission of kilonovae, short $\gamma$-ray bursts and cocoons that could be produced in those mergers. We estimate their luminosities and time scales as functions of the chirp mass which is the most readily constrained parameter from the gravitational wave detections of these events. We focus on the range of chirp mass as $1.3M_{\odot} -2.7M_{\odot}$ which is compatible with one of the merging component being a so-called `mass gap' black hole. We show that the electromagnetic observation of these transients could be used to distinguish the types of the mergers when the detected chirp mass falls in the range of $1.5M_{\odot}-1.7M_{\odot}$. Applying our analysis to the sub-threshold GRB GBM-190816, we found that for this particular event the effective spin should be larger than 0.6 and the mass of the heavier object might be larger than 5.5$M_{\odot}$ for the SFHo equation of state.

E. R. Alonso, L. Kolesniková, A. Belloche, S. Mata, R. T. Garrod, A. Jabri, I. León, J.-C. Guillemin, H. S. P. Müller, K. M. Menten, J. L. Alonso

The article will be published as a regular paper in Astronomy and Astrophysics

For all the amides detected in the interstellar medium (ISM), the corresponding nitriles or isonitriles have also been detected in the ISM, some of which have relatively high abundances. Among the abundant nitriles for which the corresponding amide has not yet been detected is cyanoacetylene (HCCCN), whose amide counterpart is propiolamide (HCCC(O)NH$_2$). With the aim of supporting searches for this amide in the ISM, we provide a complete rotational study of propiolamide from 6 GHz to 440 GHz using rotational spectroscopic techniques in the frequency and time domain. We identified and measured more than 5500 distinct frequency lines of propiolamide and obtained accurate sets of spectroscopic parameters for the ground state and the three low-lying excited vibrational states. We used the ReMoCA spectral line survey performed with the Atacama Large Millimeter/submillimeter Array toward the star-forming region Sgr B2(N) to search for propiolamide. We report the nondetection of propiolamide toward the hot cores Sgr B2(N1S) and Sgr B2(N2). We find that propiolamide is at least 50 and 13 times less abundant than acetamide in Sgr B2(N1S) and Sgr B2(N2), respectively, indicating that the abundance difference between both amides is more pronounced by at least a factor of 8 and 2, respectively, than for their corresponding nitriles. Although propiolamide has yet to be included in astrochemical modeling networks, the observed upper limit to the ratio of propiolamide to acetamide seems consistent with the ratios of related species as determined from past simulations.

Fiorenzo Vincenzo, Todd A. Thompson, David H. Weinberg, Emily J. Griffith, James W. Johnson, Jennifer A. Johnson

9 pages, 5 figures

We test the hypothesis that the observed first-peak (Sr, Y, Zr) and second-peak (Ba) s-process elemental abundances in low metallicity Milky Way stars ($\text{[Fe/H]} \lesssim -0.5$), and the abundances of the intervening elements Mo and Ru, can be explained by a pervasive r-process contribution that originates in neutrino-driven winds from highly-magnetic and rapidly rotating proto-neutron stars (proto-NSs). To this end, we construct chemical evolution models that incorporate recent calculations of proto-NS yields in addition to contributions from AGB stars, Type Ia supernovae, and two alternative sets of yields for massive star winds and core collapse supernovae. For non-rotating massive star yields from either set, models without proto-NS winds underpredict the observed s-process peak abundances by $0.3$-$1\,\text{dex}$ at low metallicity, and they severely underpredict Mo and Ru at all metallicities. Models that include the additional wind yields predicted for proto-NSs with spin periods $P \sim 2$-$5\,\text{ms}$ fit the observed trends for all these elements well. Alternatively, models that omit proto-NS winds but adopt yields of rapidly rotating massive stars, with $v_{\rm rot}$ between $150$ and $300\,\text{km}\,\text{s}^{-1}$, can explain the observed abundance levels reasonably well for $\text{[Fe/H]}<-2$. These models overpredict [Sr/Fe] and [Mo/Fe] at higher metallicities, but with a tuned dependence of $v_{\rm rot}$ on stellar metallicity they might achieve an acceptable fit at all [Fe/H]. If many proto-NSs are born with strong magnetic fields and short spin periods, then their neutrino-driven winds provide a natural source for Sr, Y, Zr, Mo, Ru, and Ba in low metallicity stellar populations. Spherical winds from unmagnetized proto-NSs, on the other hand, overproduce the observed Sr, Y, and Zr abundances by a large factor.

Laura Wolz, Alkistis Pourtsidou, Kiyoshi W. Masui, Tzu-Ching Chang, Julian E. Bautista, Eva-Maria Mueller, Santiago Avila, David Bacon, Will J. Percival, Steven Cunnington, Chris Anderson, Xuelei Chen, Jean-Paul Kneib, Yi-Chao Li, Yu-Wei Liao, Ue-Li Pen, Jeffrey B. Peterson, Graziano Rossi, Donald P. Schneider, Jaswant Yadav, Gong-Bo Zhao

16 pages, 15 figures, 1 table; submitted to MNRAS

We present the joint analysis of Neutral Hydrogen (HI) Intensity Mapping observations with three galaxy samples: the Luminous Red Galaxy (LRG) and Emission Line Galaxy (ELG) samples from the eBOSS survey, and the WiggleZ Dark Energy Survey sample. The HI intensity maps are Green Bank Telescope observations of the redshifted 21cm emission on 100deg2 covering the redshift range $0.6<z<1.0$. We process the data by separating and removing the foregrounds with FastICA, and construct a transfer function to correct for the effects of foreground removal on the HI signal. We cross-correlate the cleaned HI data with the galaxy samples and study the overall amplitude as well as the scale-dependence of the power spectrum. We also qualitatively compare our findings with the predictions by a semi-analytic galaxy evolution simulation. The cross-correlations constrain the quantity $\Omega_{{HI}} b_{{HI}} r_{{HI},{opt}}$ at an effective scale $k_{eff}$, where $\Omega_{HI}$ is the HI density fraction, $b_{HI}$ is the HI bias, and $r_{{HI},{opt}}$ the galaxy-hydrogen correlation coefficient, which is dependent on the HI content of the optical galaxy sample. At $k_{eff}=0.31 \, h/{Mpc}$ we find $\Omega_{{HI}} b_{{HI}} r_{{HI},{Wig}} = [0.58 \pm 0.09 \, {(stat) \pm 0.05 \, {(sys)}}] \times 10^{-3}$ for GBT-WiggleZ, $\Omega_{{HI}} b_{{HI}} r_{{HI,{ELG}}} = [0.40 \pm 0.09 \, {(stat) \pm 0.04 \, {(sys)}}] \times 10^{-3}$ for GBT-ELG, and $\Omega_{{HI}} b_{{HI}} r_{{HI},{LRG}} = [0.35 \pm 0.08 \, {(stat) \pm 0.03 \, {(sys)}}] \times 10^{-3}$ for GBT-LRG, at $z\simeq 0.8$. We also report results at $k_{eff}=0.24 \, h/{Mpc}$ and $k_{eff}=0.48 \, h/{Mpc}$. With little information on HI parameters beyond our local Universe, these are amongst the most precise constraints on neutral hydrogen density fluctuations in an underexplored redshift range.

L. Harra, D. H. Brooks, S. D. Bale, C. H. Mandrini, K. Barczynski, R. Sharma, S. T. Badman, S. Vargas Dominguez, M. Pulupa

Context. To investigate the source of a type III radio burst storm during encounter 2 of NASA's Parker Solar Probe (PSP) mission. Aims. It was observed that in encounter 2 of NASA's Parker Solar Probe mission there was a large amount of radio activity, and in particular a noise storm of frequent, small type III bursts from 31st March to 6th April 2019. Our aim is to investigate the source of these small and frequent bursts. Methods. In order to do this, we analysed data from the Hinode EUV Imaging Spectrometer (EIS), PSP FIELDS, and the Solar Dynamics Observatory (SDO) Atmospheric Imaging Assembly (AIA). We studied the behaviour of active region 12737, whose emergence and evolution coincides with the timing of the radio noise storm and determined the possible origins of the electron beams within the active region. To do this, we probe the dynamics, Doppler velocity, non-thermal velocity, FIP bias, densities, and carry out magnetic modelling. Results. We demonstrate that although the active region on the disk produces no significant flares, its evolution indicates it is a source of the electron beams causing the radio storm. They most likely originate from the area at the edge of the active region that shows strong blue-shifted plasma. We demonstrate that as the active region grows and expands, the area of the blue-shifted region at the edge increases, which is also consistent with the increasing area where large-scale or expanding magnetic field lines from our modelling are anchored. This expansion is most significant between 1 and 4 April 2019, coinciding with the onset of the type III storm and the decrease of the individual burst's peak frequency, indicating the height at which the peak radiation is emitted increases as the active region evolves.

Bing Zhang, Yu Wang, Liang Li

8 pages, 3 figures, under review in ApJL

The jet composition and radiative efficiency of GRBs are poorly constrained from the data. If the jet composition is matter-dominated (i.e. a fireball), the GRB prompt emission spectra would include a dominant thermal component originating from the fireball photosphere, and a non-thermal component presumably originating from internal shocks whose radii are greater than the photosphere radius. We propose a method to directly dissect the GRB fireball energy budget into three components and measure their values by combining the prompt emission and early afterglow data. The measured parameters include the initial dimensionless specific enthalpy density ($\eta$), bulk Lorentz factors at the photosphere radius ($\Gamma_{\rm ph}$) and before fireball deceleration ($\Gamma_0$), the amount of mass loading ($M$), as well as the GRB radiative efficiency ($\eta_\gamma$). All the parameters can be derived from the data for a GRB with a dominant thermal spectral component, a deceleration bump feature in the early afterglow lightcurve, and a measured redshift. The results only weakly depend on the density $n$ of the interstellar medium when the composition ${\cal Y}$ parameter (typically unity) is specified.

Yuan-Sen Ting, David H. Weinberg

34 pages, 17 figures, submitted to ApJ

Some studies of stars' multi-element abundance distributions suggest at least 5-7 significant dimensions, but other studies show that the abundances of many elements can be predicted to high accuracy from [Fe/H] and [Mg/Fe] alone (or from [Fe/H] and age). We show that both propositions can be, and are, simultaneously true. We adopt a technique known as normalizing flow to reconstruct the probability distribution of Milky Way disk stars in the space of 15 elemental abundances measured by APOGEE. Conditioning on stellar parameters $T_{\rm eff}$ and $\log g$ minimizes the differential systematics. After conditioning on [Fe/H] and [Mg/H], the residual scatter for the best measured APOGEE elements is $\sigma_{[X/{\rm H}]} \lesssim 0.02$ dex, consistent with APOGEE's reported statistical uncertainties of $\sim 0.01 - 0.015$ dex and intrinsic scatter of $0.01-0.02$ dex. Despite the small scatter, residual abundances display clear correlations between elements, which are too large to be explained by measurement uncertainties or by the statistical noise from our finite sample size. We must condition on at least seven elements (e.g., Fe, Mg, O, Si, Ni, Ca, Al) to reduce residual correlations to a level consistent with observational uncertainties, and higher measurement precision for other elements would likely reveal additional dimensions. Our results demonstrate that cross-element correlations are a much more sensitive and robust probe of hidden structure than dispersion alone, and they can be measured precisely in a large sample even if star-by-star measurement noise is comparable to the intrinsic scatter. We conclude that many elements have an independent story to tell, even for a "mundane" sample of disk stars and elements produced mainly by core-collapse and Type Ia supernovae. The only way to learn these lessons is to measure the abundances directly, and not merely infer them.

The capacity to sense gradients efficiently and acquire information about the ambient environment confers many advantages like facilitating movement toward nutrient sources or away from toxic chemicals. The amplified dispersal evinced by organisms endowed with motility is possibly beneficial in related contexts. Hence, the connections between information acquisition, motility, and microbial size are explored from an explicitly astrobiological standpoint. By using prior theoretical models, the constraints on organism size imposed by gradient detection and motility are elucidated in the form of simple heuristic scaling relations. It is argued that environments such as alkaline hydrothermal vents, which are distinguished by the presence of steep gradients, might be conducive to the existence of "small" microbes (with radii of $\gtrsim 0.1$ $\mu$m) in principle, when only the above two factors are considered; other biological functions (e.g., metabolism and genetic exchange) could, however, regulate the lower bound on microbial size and elevate it. The derived expressions are potentially applicable to a diverse array of settings, including those entailing solvents other than water; for example, the lakes and seas of Titan. The paper concludes with a brief exposition of how this formalism may be of practical and theoretical value to astrobiology.

Ravi Kopparapu, Giada Arney, Jacob Haqq-Misra, Jacob Lustig-Yaeger, Geronimo Villanueva

Accepted to Astrophysical Journal (in press). 1-D photochemical code from 'Atmos' is available at: this https URL

Nitrogen dioxide (NO2) on Earth today has biogenic and anthropogenic sources. During the COVID-19 pandemic, observations of global NO2 emissions have shown significant decrease in urban areas. Drawing upon this example of NO2 as an industrial byproduct, we use a one-dimensional photochemical model and synthetic spectral generator to assess the detectability of NO2 as an atmospheric technosignature on exoplanets. We consider cases of an Earth-like planet around Sun-like, K-dwarf and M-dwarf stars. We find that NO2 concentrations increase on planets around cooler stars due to less short-wavelength photons that can photolyze NO2. In cloud-free results, present Earth-level NO2 on an Earth-like planet around a Sun-like star at 10pc can be detected with SNR ~5 within ~400 hours with a 15 meter LUVOIR-like telescope when observed in the 0.2 - 0.7micron range where NO2 has a strong absorption. However, clouds and aerosols can reduce the detectability and could mimic the NO2 feature. Historically, global NO2 levels were 3x higher, indicating the capability of detecting a 40-year old Earth-level civilization. Transit and direct imaging observations to detect infrared spectral signatures of NO2 on habitable planets around M-dwarfs would need several 100s of hours of observation time, both due to weaker NO2 absorption in this region, and also because of masking features by dominant H2O and CO2 bands in the infrared part of the spectrum. Non-detection at these levels could be used to place upper limits on the prevalence of NO2 as a technosignature.

L. E. Bleem, T. M. Crawford, B. Ansarinejad, B. A. Benson, S. Bocquet, J. E. Carlstrom, C. L. Chang, R. Chown, A. T. Crites, T. de Haan, M. A. Dobbs, W. B. Everett, E. M. George, R. Gualtieri, N. W. Halverson, G. P. Holder, W. L. Holzapfel, J. D. Hrubes, L. Knox, A. T. Lee, D. Luong-Van, D. P. Marrone, J. J. McMahon, S. S. Meyer, M. Millea, L. M. Mocanu, J. J. Mohr, T. Natoli, Y. Omori, S. Padin, C. Pryke, S. Raghunathan, C. L. Reichardt, J. E. Ruhl, K. K. Schaffer, E. Shirokoff, Z. Staniszewski, A. A. Stark, J. D. Vieira, R. Williamson

27 pages (including appendices), 7 figures

We present component-separated maps of the primary cosmic microwave background/kinematic Sunyaev-Zel'dovich (SZ) amplitude and the thermal SZ Compton-$y$ parameter, created using data from the South Pole Telescope (SPT) and the Planck satellite. These maps, which cover the $\sim$2500 square degrees of the Southern sky imaged by the SPT-SZ survey, represent a significant improvement over previous such products available in this region by virtue of their higher angular resolution (1.25 arcminutes for our highest resolution Compton-$y$ maps) and lower noise at small angular scales. In this work we detail the construction of these maps using linear combination techniques, including our method for limiting the correlation of our lowest-noise Compton-$y$ map products with the cosmic infrared background. We perform a range of validation tests on these data products to test our sky modeling and combination algorithms, and we find good performance in all of these tests. Recognizing the potential utility of these data products for a wide range of astrophysical and cosmological analyses, including studies of the gas properties of galaxies, groups, and clusters, we make these products publicly available at this http URL and on the NASA/LAMBDA website.

You-Hua Chu, Jesus A. Toala, Martin A. Guerrero, Florian Bauer, Jana Bilikova, Robert A. Gruendl

Accepted for publication for The Astrophysical Journal

KPD 0005+5106, with an effective temperature of $\simeq$200,000 K, is one of the hottest white dwarfs (WDs). ROSAT unexpectedly detected "hard" ($\sim$1 keV) X-rays from this apparently single WD. We have obtained Chandra observations that confirm the spatial coincidence of this hard X-ray source with KPD 0005+5106. We have also obtained XMM-Newton observations of KPD 0005+5106, as well as PG 1159$-$035 and WD 0121$-$756, which are also apparently single and whose hard X-rays were detected by ROSAT at 3$\sigma$-4$\sigma$ levels. The XMM-Newton spectra of the three WDs show remarkably similar shapes that can be fitted by models including a blackbody component for the stellar photospheric emission, a thermal plasma emission component, and a power-law component. Their X-ray luminosities in the $0.6-3.0$ keV band range from $4\times10^{29}$ to $4\times10^{30}$ erg~s$^{-1}$. The XMM-Newton EPIC-pn soft-band ($0.3-0.5$ keV) lightcurve of KPD 0005+5106 is essentially constant, but the hard-band ($0.6-3.0$ keV) lightcurve shows periodic variations. An analysis of the generalized Lomb-Scargle periodograms for the XMM-Newton and Chandra hard-band lightcurves finds a convincing modulation (false alarm probability of 0.41%) with a period of 4.7$\pm$0.3 hr. Assuming that this period corresponds to a binary orbital period, the Roche radii of three viable types of companion have been calculated: M9V star, T brown dwarf, and Jupiter-like planet. Only the planet has a size larger than its Roche radius, although the M9V star and T brown dwarf may be heated by the WD and inflate past the Roche radius. Thus, all three types of companion may be donors to fuel accretion-powered hard X-ray emission.

E. Laplace, S. Justham, M. Renzo, Y. Götberg, R. Farmer, D. Vartanyan, S. E. de Mink

19 pages, 15 figures, 2 tables of main text. Submitted to A&A. A video and MESA inlists can be found at this https URL

The majority of massive stars live in binary or multiple systems and will interact during their lifetimes, which helps to explain the observed diversity of core-collapse supernovae. Donor stars in binary systems can lose most of their hydrogen-rich envelopes through mass transfer, which not only affects the surface properties, but also the core structure. However, most calculations of the core-collapse properties of massive stars rely on single-star models. We present a systematic study of the difference between the pre-supernova structures of single stars and stars of the same initial mass (11 - 21\Msun) that have been stripped due to stable post-main sequence mass transfer at solar metallicity. We present the pre-supernova core composition with novel diagrams that give an intuitive representation of the isotope distribution. As shown in previous studies, at the edge of the carbon-oxygen core, the binary-stripped star models contain an extended gradient of carbon, oxygen, and neon. This layer originates from the receding of the convective helium core during core helium burning in binary-stripped stars, which does not occur in single-star models. We find that this same evolutionary phase leads to systematic differences in the final density and nuclear energy generation profiles. Binary-stripped star models have systematically higher total masses of carbon at the moment of core collapse compared to single star models, which likely results in systematically different supernova yields. In about half of our models, the silicon-burning and oxygen-rich layers merge after core silicon burning. We discuss the implications of our findings for the explodability, supernova observations, and nucleosynthesis from these stars. Our models will be publicly available and can be readily used as input for supernova simulations. [Abridged]

Given the Loop-Quantum-Gravity (LQG) non-graph-changing Hamiltonian $\widehat{H[N]}$, the coherent state expectation value $\langle\widehat{H[N]}\rangle$ admits an semiclassical expansion in $\ell^2_{\rm p}$. In this paper, we compute explicitly the expansion of $\langle\widehat{H[N]}\rangle$ on the cubic graph to the linear order in $\ell^2_{\rm p}$, when the coherent state is peaked at the homogeneous and isotropic data of cosmology. In our computation, a powerful algorithm is developed to overcome the complexity in computing $\langle \widehat{H[N]} \rangle$. In particular, some key innovations in our algorithm substantially reduce the computational complexity in the Lorentzian part of $\langle\widehat{H[N]}\rangle$. In addition, some effects in cosmology from the quantum correction in $\langle\widehat{H[N]}\rangle$ are discussed at the end of this paper.

Given the non-graph-changing Hamiltonian $\widehat{H[N]}$ in Loop Quantum Gravity (LQG), $\langle\widehat{H[N]}\rangle$, the coherent state expectation value of $\widehat{H[N]}$, admits an semiclassical expansion in $\ell^2_{\rm p}$. In this paper, as presenting the detailed derivations of our previous work arXiv:2012.14242, we explicitly compute the expansion of $\langle\widehat{H[N]}\rangle$ to the linear order in $\ell^2_{\rm p}$ on the cubic graph with respect to the coherent state peaked at the homogeneous and isotropic data of cosmology. In our computation, a powerful algorithm is developed, supported by rigorous proofs and several theorems, to overcome the complexity in the computation of $\langle \widehat{H[N]} \rangle$. Particularly, some key innovations in our algorithm substantially reduce the complexity in computing the Lorentzian part of $\langle\widehat{H[N]}\rangle$. Additionally, some quantum correction effects resulted from $\langle\widehat{H[N]}\rangle$ in cosmology are discussed at the end of this paper.

In this Letter, we describe how a spectrum of entropic perturbations generated during a period of slow contraction can source a nearly scale-invariant spectrum of curvature perturbations on length scales larger than the Hubble radius during the transition from slow contraction to a classical non-singular bounce (the `graceful exit' phase). The sourcing occurs naturally through higher-order scalar field kinetic terms common to classical (non-singular) bounce mechanisms. We present a concrete example in which, by the end of the graceful exit phase, the initial entropic fluctuations have become negligible and the curvature fluctuations have a nearly scale-invariant spectrum with an amplitude consistent with observations.

Sven E. Vahsen, Ciaran A. J. O'Hare, Dinesh Loomba

45 pages, 8 figures. Invited review for Annual Review of Nuclear and Particle Science

Searches for dark matter-induced recoils have made impressive advances in the last few years. Yet the field is confronted by several outstanding problems. First, the inevitable background of solar neutrinos will soon inhibit the conclusive identification of many dark matter models. Second, and more fundamentally, current experiments have no practical way of confirming a detected signal's galactic origin. The concept of directional detection addresses both of these issues while offering opportunities to study novel dark matter and neutrino-related physics. The concept remains experimentally challenging, but gas time projection chambers are an increasingly attractive option, and when properly configured, would allow directional measurements of both nuclear and electron recoils. In this review, we reassess the required detector performance and survey relevant technologies. Fortuitously, the highly-segmented detectors required to achieve good directionality also enable several fundamental and applied physics measurements. We comment on near-term challenges and how the field could be advanced.

We examine the constraints on sub-GeV dark sector particles set by the proto-neutron star cooling associated with the core-collapse supernova event SN1987a. Considering explicitly a dark photon portal dark sector model, we compute the relevant interaction rates of dark photon ($A'$) and dark fermion ($\chi$) with the Standard Model particles as well as their self-interaction inside the dark sector. We find that even with a small dark sector fine structure constant $\alpha_D\ll 1$, dark sector self-interactions can easily lead to their own self-trapping. This effect strongly limits the energy luminosity carried away by dark sector particles from the supernova core and thus drastically affects the parameter space that can be constrained by SN1987a. We consider specifically two mass ratios $m_{A'}=3m_\chi$ and $3m_{A'}=m_\chi$ which represent scenarios where the decay of $A'$ to $\chi\bar\chi$ is allowed or not. We show that SN1987a can only place bounds on the dark sector when $\alpha_D\lesssim 10^{-15}$ ($10^{-7}$) for the former (latter) for $m_\chi\lesssim 20$ MeV. Furthermore, this evades the supernova bounds on the widely-examined dark photon parameter space completely if $\alpha_D\lesssim 10^{-7}$ for the former, while lifts the bounds when $\alpha_D\lesssim 10^{-7}$ if $m_\chi\lesssim 100$ MeV. Our findings thus imply that the existing supernova bounds on light dark particles can be generally evaded by a similar self-trapping mechanism. This also implies that non-standard strongly self-interacting neutrino is not consistent with the SN1987a observation. Same effects can also take place for other known stellar bounds on dark sector particles.

Tiberiu Harko, Haidar Sheikhahmadi

25 pages, 8 figures, accepted for publication in EPJC

We consider a warm inflationary scenario in which the two dominant matter components present in the early Universe, the scalar field, and the radiation fluid, evolve with different four-velocities. This cosmological system is mathematically equivalent to a single anisotropic fluid, evolving with a four-velocity that is a function of the two independent fluid four-velocities. Due to the presence of the anisotropic physical parameters, the overall cosmological evolution is also anisotropic. We derive the gravitational field equations of the noncomoving scalar field-radiation mixture for a Bianchi type I geometry. By considering that the decay of the scalar field is accompanied by a corresponding radiation generation, we formulate the basic equations of the warm inflationary model in the presence of two noncomoving components. By adopting the slow roll approximation, we perform a detailed comparison of the theoretical predictions of the warm inflationary scenario with noncomoving scalar field and radiation fluid with the observational data obtained by the Planck satellite, by investigating both the weak dissipation and strong dissipation limits. Constraints on the free parameters of the model are obtained in both cases. The functional forms of the scalar field potentials compatible with the noncomoving nature of warm inflation are also derived.

We consider dark matter which have non-zero electromagnetic form factors like electric/magnetic dipole moments and anapole moment for fermionic dark matter and Rayleigh form factor for scalar dark matter. We consider dark matter mass $m_\chi > \cal{ O}({\rm MeV})$ and put constraints on their mass and electromagnetic couplings from CMB and LSS observations. Fermionic dark matter with non-zero electromagnetic form factors can annihilate to $e^+ e^-$ and scalar dark matter can annihilate to $2\gamma$ at the time of recombination and distort the CMB. We analyze dark matter with multipole moments with Planck and BAO observations. We find upper bounds on anapole moment $g_{A}<7.163\times 10^{3}$ $\text{GeV}^{-2}$, electric dipole moment ${\cal D}<7.978\times 10^{-9}$ e-cm, magnetic dipole moment ${\mu}<2.959\times 10^{-7}$ $\mu_B$ and magnetic dipole moment for Rayleigh dark matter $\frac{g_A}{\Lambda_4^2}<1.085\times 10^{-2}$ $\text{GeV}^{-2}$ with $95\%$C.L.