Astronomical Informant

2022-06-24 05:36:51 arXiv:The effect of stellar multiplicity on the formation and evolution of planetary systems is complex. At a demographic level, campaigns with both high-resolution imaging and radial velocity observations indicate that planet formation is strongly disrupted by close binaries, while being relatively unaffected by wide companions. However, the magnitude and distance-limited nature of those tools mean that large ranges of mass ratios and separations remain largely unexplored. The Early Data Release 3 (EDR3) from the Gaia Mission includes radial velocity measurements of over 6.5 million targets, which we employ to explore the effect of binary companions within a statistical framework called paired. These companions present as a source of excess radial velocity noise in the Gaia catalog, when compared to the typical noise for stars of similar spectral type and magnitude. Within this framework, we examine the evidence for stellar multiplicity among the stars surveyed by NASA's Kepler and TESS missions. We use radial velocity errors published in Gaia EDR3 to estimate the probability of an unresolved stellar companion for a large subset of the Kepler and TESS Input Catalog stars, where possible benchmarking our inferred radial velocity semi-amplitudes against the those from ground-based radial velocity surveys. We determine that we are typically sensitive out to several AU and mass ratios $>0.1$, dependent upon the stellar magnitude. We aim for paired to be a useful community tool for the exploration of the effects of binarity on planets at a population level, and for efficient identification of false-positive transit candidates.

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2022-06-24 04:48:40 ATel 15463: A Supernova in a Magnified Multiply Imaged Galaxy at Redshift z=1.76
https://www.astronomerstelegram.org/?read=15463

We report the detection of a supernova candidate in a galaxy at redshift z=1.76 that is multiply imaged by foreground RX J1347-1145 (z=0.451) galaxy cluster. ... Aprire / Come

2022-06-24 04:36:32 arXiv:The Wess Zumino Dark Radiation (WZDR) model first proposed in arXiv:2111.00014 shows great promise as a well-motivated simple explanation of the Hubble tension between local and CMB-based measurements. In this work we investigate the assumptions made in the original proposal and confront the model with additional independent data sets. We show that the original assumptions can have an impact on the overall results but are usually well motivated. We further demonstrate that the preference for negative $\Omega_k$ remains at a similar level as for the $\Lambda$CDM model, while the $A_L$ tension is slightly reduced. Furthermore, the tension between Planck data for $\ell < 800$ and $\ell \geq 800$ is significantly reduced for the WZDR model. The independent data sets show slightly more permissive bounds on the Hubble parameter, allowing the tension to be further reduced to $2.1 \sigma$ (CMB-independent) or $1.9\sigma$ (ACT+WMAP). However, no combination shows a large preference for the presence of WZDR. We also investigate whether additional dark radiation -- dark matter interactions can help in easing the $S_8$ tension as well. We find that the CMB data are too restrictive on this additional component as to allow a significant decrease in the clustering.

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2022-06-24 04:36:30 arXiv:ASASSN-14ko is a nuclear transient at the center of the AGN ESO 253-G003 that undergoes periodic flares. Optical flares were first observed in 2014 by the All-Sky Automated Survey for Supernovae (ASAS-SN) and their peak times are well-modeled with a period of $115.2^{+1.3}_{-1.2}$ days and period derivative of $-0.0026 \pm 0.0006$. Here we present ASAS-SN, Chandra, HST/STIS, NICER, Swift, and TESS data for the flares that occurred in December 2020, April 2021, July 2021, and November 2021. The HST/STIS UV spectra evolve from blue shifted broad absorption features to red shifted broad emission features over $\sim$10 days. The Swift UV/optical light curves peaked as predicted by the timing model, but the peak UV luminosities varied between flares and the UV flux in July 2021 was roughly half the brightness of all other peaks. The X-ray luminosities consistently decreased and the spectra became harder during the UV/optical rise but apparently without changes in absorption. Finally, two high-cadence TESS light curves from December 2020 and November 2018 showed that the slopes during the rising and declining phases changed over time, which indicates some stochasticity in the flare's driving mechanism. ASASSN-14ko remains observationally consistent with a repeating partial tidal disruption event, but, these rich multi-wavelength data are in need of a detailed theoretical model.

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2022-06-24 04:36:29 arXiv:Modeling of strong gravitational lenses is a necessity for further applications in astrophysics and cosmology. Especially with the large number of detections in current and upcoming surveys such as the Rubin Legacy Survey of Space and Time (LSST), it is timely to investigate in automated and fast analysis techniques beyond the traditional and time consuming Markov chain Monte Carlo sampling methods. Building upon our convolutional neural network (CNN) presented in Schuldt et al. (2021b), we present here another CNN, specifically a residual neural network (ResNet), that predicts the five mass parameters of a Singular Isothermal Ellipsoid (SIE) profile (lens center $x$ and $y$, ellipticity $e_x$ and $e_y$, Einstein radius $\theta_E$) and the external shear ($\gamma_{ext,1}$, $\gamma_{ext,2}$) from ground-based imaging data. In contrast to our CNN, this ResNet further predicts a 1$\sigma$ uncertainty for each parameter. To train our network, we use our improved pipeline from Schuldt et al. (2021b) to simulate lens images using real images of galaxies from the Hyper Suprime-Cam Survey (HSC) and from the Hubble Ultra Deep Field as lens galaxies and background sources, respectively. We find overall very good recoveries for the SIE parameters, while differences remain in predicting the external shear. From our tests, most likely the low image resolution is the limiting factor for predicting the external shear. Given the run time of milli-seconds per system, our network is perfectly suited to predict the next appearing image and time delays of lensed transients in time. Therefore, we also present the performance of the network on these quantities in comparison to our simulations. Our ResNet is able to predict the SIE and shear parameter values in fractions of a second on a single CPU such that we are able to process efficiently the huge amount of expected galaxy-scale lenses in the near future.

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2022-06-24 04:36:23 arXiv:Entropy production is a necessary ingredient for addressing the over-population of thermal relics. It is widely employed in particle physics models for explaining the origin of dark matter. A long-lived particle that decays to the known particles, while dominating the universe, plays the role of the dilutor. We point out the impact of its partial decay to dark matter on the primordial matter power spectrum. For the first time, we derive a stringent limit on the branching ratio of the dilutor to dark matter from large scale structure observation using the SDSS data. This offers a novel tool for testing models with a dark matter dilution mechanism. We apply it to the left-right symmetric model and show that it firmly excludes a large portion of parameter space for right-handed neutrino warm dark matter.

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2022-06-23 10:50:44 ATel 15457: Swift detects rapid outburst decay from MAXI J1957+032
https://www.astronomerstelegram.org/?read=15457

A new outburst of the faint X-ray transient MAXI J1957+032 was detected by the MAXI/GSC nova alert system which triggered on this source at 17:26 UT on June 18, 2022 (ATel #15440). ... Aprire / Come

2022-06-23 05:36:39 arXiv:Conferences and workshops shape scientific discourse. The Kavli Institute for Theoretical Physics (KITP) hosts long-term workshops to stimulate scientific collaboration that would not otherwise have taken place. One goal of KITP programs is to increase diversity in the next generation of scientists. In this analysis, we examine gender trends in authorship of papers generated as a result of the KITP program \textit{Probes of Transport in Stars}, which ran from October 11th, 2021 to December 17th, 2021. While 38\% of workshop participants were women, only 19\% of publications produced between December 1st, 2021 and June 3rd, 2022 had female first-authors. Further, of these early publications, 61\% had all-male author lists. Among publications resulting from the KITP program, the proportions of both male first-author papers and papers with all-male author lists are higher than predicted by models that take into account the gender distribution of the KITP participants. These results motivate more thorough investigations of collaboration networks at scientific conferences and workshops. Importantly, they also suggest that programs, conferences, and workshops of any kind need to take steps beyond those implemented in this KITP program to enable more diverse collaborations and address gender disparities in science.

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2022-06-22 06:36:11 arXiv:We present a catalog of 1.4 million photometrically-selected quasar candidates in the southern hemisphere over the $\sim 5000\,{\rm deg^2}$ Dark Energy Survey (DES) wide survey area. We combine optical photometry from the DES second data release (DR2) with available near-infrared (NIR) and the all-sky unWISE mid-infrared photometry in the selection. We build models of quasars, galaxies, and stars with multivariate Skew-t distributions in the multi-dimensional space of relative fluxes as functions of redshift (or color for stars) and magnitude. Our selection algorithm assigns probabilities for quasars, galaxies, and stars, and simultaneously calculates photometric redshifts (photo-$z$) for quasar and galaxy candidates. Benchmarking on spectroscopically confirmed objects, we successfully classify (with photometry) 94.7% of quasars, 99.3% of galaxies, and 96.3% of stars when all IR bands (NIR $YJHK$ and WISE $W1W2$) are available. The classification and photo-$z$ regression success rates decrease when fewer bands are available. Our quasar (galaxy) photo-$z$ quality, defined as the fraction of objects with the difference between the photo-$z$ $z_p$ and the spectroscopic redshift $z_s$, $|\Delta z| = |z_s - z_p|/(1 + z_s)\le 0.1$, is 92.2% (98.1%) when all IR bands are available, decreasing to 72.2% (90.0%) using optical DES data only. Our photometric quasar catalog achieves estimated completeness of 89% and purity of 79% at $r<21.5$ (0.68 million quasar candidates), with reduced completeness and purity at $21.5
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2022-06-22 05:37:11 arXiv:We present optical spectropolarimetry of the tidal disruption event (TDE) AT 2019qiz on days $+0$ and $+29$ relative to maximum brightness. Continuum polarization, which informs the shape of the electron-scattering surface, was found to be consistent with 0 per cent at peak brightness. On day $+29$, the continuum polarization rose to $\sim 1$ per cent, making this the first reported spectropolarimetric evolution of a TDE. These findings are incompatible with a naked eccentric disc that lacks significant mass outflow. Instead, the spectropolarimetry paints a picture wherein, at maximum brightness, high-frequency emission from the accretion disc is reprocessed into the optical band by a nearly spherical, optically thick, electron-scattering photosphere located far away from the black hole. We estimate the radius of the scattering photosphere to be $\sim 100\rm\, au$ at maximum brightness -- significantly larger than the tidal radius ($\sim 1\rm\, au$) and the thermalisation radius ($\sim 30\rm\, au$) where the optical continuum is formed. A month later, as the fallback rate drops and the scattering photosphere recedes, the continuum polarization increases, revealing a moderately aspherical interior. We also see evidence for smaller-scale density variations in the scattering photosphere, inferred from the scatter of the data in the Stokes $q-u$ plane. On day $+29$, the H$\alpha$ emission-line peak is depolarized to $\sim 0.3$ per cent (compared to $\sim 1$ per cent continuum polarization), and displays a gradual rise toward the line's redder wavelengths. This observation indicates the H$\alpha$ line formed near the electron-scattering radius.

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