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Lyman-alpha spectroscopy of extreme [O III] emitting galaxies at z ≃ 2-3: implications for Lyα visibility and LyC leakage at z > 6
Charlot, Stéphane; Chevallard, Jacopo; Tang, Mengtao +3 more
Spectroscopic observations of massive z > 7 galaxies selected to have extremely large [O III] + H β equivalent width (EW ~1500 Å) have recently revealed large Ly α detection rates, in contrast to the weak emission seen in the general population. Why these systems are uniquely visible in Ly α at redshifts where the intergalactic medium (IGM) is …
Anomaly detection in the Zwicky Transient Facility DR3
Pruzhinskaya, M. V.; Malanchev, K. L.; Ishida, E. E. O. +12 more
We present results from applying the SNAD anomaly detection pipeline to the third public data release of the Zwicky Transient Facility (ZTF DR3). The pipeline is composed of three stages: feature extraction, search of outliers with machine learning algorithms, and anomaly identification with followup by human experts. Our analysis concentrates in …
Primordial black holes and secondary gravitational waves from the Higgs field
Gong, Yungui; Wang, Bin; Yi, Zhu +1 more
We devise a novel mechanism and for the first time demonstrate that the Higgs model in particle physics can drive the inflation to satisfy the cosmic microwave background observations and simultaneously enhance the curvature perturbations at small scales to explain the abundance of dark matter in our universe in the form of primordial black holes.…
Deep generative models for galaxy image simulations
Mandelbaum, Rachel; Lanusse, François; Freeman, Peter +3 more
Image simulations are essential tools for preparing and validating the analysis of current and future wide-field optical surveys. However, the galaxy models used as the basis for these simulations are typically limited to simple parametric light profiles, or use a fairly limited amount of available space-based data. In this work, we propose a meth…
Effect of binary evolution on the inferred initial and final core masses of hydrogen-rich, Type II supernova progenitors
Smith, N.; Renzo, M.; Zapartas, E. +3 more
The majority of massive stars, which are the progenitors of core-collapse supernovae (SNe), are found in close binary systems. In a previous work, we modeled the fraction of hydrogen-rich, Type II SN progenitors whose evolution is affected by mass exchange with their companion, finding this to be between ≈1/3 and 1/2 for most assumptions. Here we …
The R-Process Alliance: Chemodynamically Tagged Groups of Halo r-process-enhanced Stars Reveal a Shared Chemical-evolution History
Beers, Timothy C.; Holmbeck, Erika M.; Hansen, Terese T. +11 more
We derive dynamical parameters for a large sample of 446 r-process-enhanced (RPE) metal-poor stars in the halo and disk systems of the Milky Way, based on data releases from the R-Process Alliance, supplemented by additional literature samples. This sample represents more than a 10-fold increase in size relative to that previously considered by Ro…
White dwarf-main-sequence binaries from Gaia EDR3: the unresolved 100 pc volume-limited sample
Althaus, L. G.; Solano, E.; Rebassa-Mansergas, A. +6 more
We use the data provided by the Gaia Early Data Release 3 to search for a highly complete volume-limited sample of unresolved binaries consisting of a white dwarf and a main-sequence companion (i.e. WDMS binaries) within 100 pc. We select 112 objects based on their location within the Hertzsprung-Russell diagram, of which 97 are new identification…
ML-MOC: Machine Learning (kNN and GMM) based Membership determination for Open Clusters
Vaidya, Kaushar; Rao, Khushboo K.; Agarwal, Manan +1 more
The existing open-cluster membership determination algorithms are either prior dependent on some known parameters of clusters or are not automatable to large samples of clusters. In this paper, we present ML-MOC, a new machine-learning-based approach to identify likely members of open clusters using the Gaia DR2 data and no a priori information ab…
Ultraviolet spectra of extreme nearby star-forming regions: Evidence for an overabundance of very massive stars
Charlot, Stéphane; Chevallard, Jacopo; Stark, Daniel P. +3 more
As deep spectroscopic campaigns extend to higher redshifts and lower stellar masses, the interpretation of galaxy spectra depends increasingly upon models for very young stellar populations. Here we present new HST/COS ultraviolet spectroscopy of seven nearby (<120 Mpc) star-forming regions hosting very young stellar populations (~4-20 Myr) wit…
Light Elements in the Universe
Magrini, Laura; Randich, Sofia
Due to their production sites, as well as to how they are processed and destroyed in stars, the light elements are excellent tools to investigate a number of crucial issues in modern astrophysics: from stellar structure and non-standard processes at work in stellar interiors to age dating of stars; from pre-main sequence evolution to the star form…