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Galaxy Morphology Network: A Convolutional Neural Network Used to Study Morphology and Quenching in ∼100,000 SDSS and ∼20,000 CANDELS Galaxies
Schawinski, Kevin; Urry, C. Megan; Powell, Meredith C. +3 more
We examine morphology-separated color-mass diagrams to study the quenching of star formation in ∼100,000 (z ∼ 0) Sloan Digital Sky Survey (SDSS) and ∼20,000 (z ∼ 1) Cosmic Assembly Near-Infrared Deep Extragalactic Legacy Survey (CANDELS) galaxies. To classify galaxies morphologically, we developed Galaxy Morphology Network (GAMORNET), a convolutio…
Primordial black holes and gravitational waves in nonstandard cosmologies
Mohanty, Subhendra; Parashari, Priyank; Bhattacharya, Sukannya
For primordial black holes (PBHs) to form a considerable fraction of cold dark matter, the required amplitude of primordial scalar perturbations is quite large (Pζ(k )∼10-2) if PBH is formed in radiation epoch. In alternate cosmological histories, where additional epoch of arbitrary equation of state precede radiation epoch, …
Detection of PAH Absorption and Determination of the Mid-infrared Diffuse Interstellar Extinction Curve from the Sight Line toward Cyg OB2-12
Draine, B. T.; Hensley, Brandon S.
The sight line toward the luminous blue hypergiant Cyg OB2-12 is widely used to study interstellar dust on account of its large extinction (AV ≃ 10 mag) and the fact that this extinction appears to be dominated by dust typical of the diffuse interstellar medium. We present a new analysis of archival Infrared Space Observatory Short Wave…
The Tidal Disruption Event AT 2018hyz II: Light-curve modelling of a partially disrupted star
Eftekhari, Tarraneh; Berger, Edo; Chornock, Ryan +18 more
AT 2018hyz (= ASASSN-18zj) is a tidal disruption event (TDE) located in the nucleus of a quiescent E+A galaxy at a redshift of z = 0.04573, first detected by the All-Sky Automated Survey for Supernovae (ASAS-SN). We present optical+UV photometry of the transient, as well as an X-ray spectrum and radio upper limits. The bolometric light curve of AT…
The Colors and Sizes of Recently Quenched Galaxies: A Result of Compact Starburst before Quenching
Bell, Eric F.; D'Eugenio, Francesco; Franx, Marijn +11 more
We analyze the colors and sizes of 32 quiescent (UVJ-selected) galaxies with strong Balmer absorption (EW(Hδ) ≥ 4 Å) at z ∼ 0.8 drawn from DR2 of the LEGA-C survey to test the hypothesis that these galaxies experienced compact, central starbursts before quenching. These recently quenched galaxies, usually referred to as post-starburst galaxies, sp…
A closer look at the spur, blob, wiggle, and gaps in GD-1
Gieles, M.; Erkal, D.; de Boer, T. J. L.
The GD-1 stream is one of the longest and coldest stellar streams discovered to date, and one of the best objects for constraining the dark matter properties of the Milky Way. Using data from Gaia DR2, we study the proper motions (PMs), distance, morphology, and density of the stream to uncover small-scale perturbations. The PM cleaned data show a…
Clouds of Fluffy Aggregates: How They Form in Exoplanetary Atmospheres and Influence Transmission Spectra
Okuzumi, Satoshi; Tazaki, Ryo; Ohno, Kazumasa
Transmission spectrum surveys have suggested the ubiquity of high-altitude clouds in exoplanetary atmospheres. Theoretical studies have investigated the formation processes of the high-altitude clouds; however, cloud particles have been commonly approximated as compact spheres, which is not always true for solid mineral particles that likely const…
The unusual broad-band X-ray spectral variability of NGC 1313 X-1 seen with XMM-Newton, Chandra, and NuSTAR
Harrison, F. A.; Stern, D.; Fabian, A. C. +19 more
We present results from the major coordinated X-ray observing programme on the ULX NGC 1313 X-1 performed in 2017, combining XMM-Newton, Chandra, and NuSTAR, focusing on the evolution of the broad-band (∼0.3-30.0 keV) continuum emission. Clear and unusual spectral variability is observed, but this is markedly suppressed above ∼10-15 keV, qualitati…
Searching for ultra-fast outflows in AGN using variability spectra
Schartel, N.; Santos-Lleó, M.; Buisson, D. J. K. +9 more
We present a qualitative search for ultra-fast outflows (UFOs) in excess variance spectra of radio-quiet active galactic nuclei (AGNs). We analyse 42 sources from the spectroscopic UFO detection sample, and an additional 22 different sources from the variability sample. A total of 58 sources have sufficient observational data from XMM-Newton EPIC-…
Investigating the Effect of Galaxy Interactions on the Enhancement of Active Galactic Nuclei at 0.5 < z < 3.0
Hathi, Nimish P.; Kartaltepe, Jeyhan S.; Kocevski, Dale D. +30 more
Galaxy interactions and mergers are thought to play an important role in the evolution of galaxies. Studies in the nearby universe show a higher fraction of active galactic nuclei (AGNs) in interacting and merging galaxies than in their isolated counterparts, indicating that such interactions are important contributors to black hole growth. To inv…