Search Publications
UVIT Open Cluster Study. I. Detection of a White Dwarf Companion to a Blue Straggler in M67: Evidence of Formation through Mass Transfer
Jadhav, Vikrant V.; Puzia, Thomas H.; Simunovic, Mirko +7 more
The old open cluster M67, populated with blue straggler stars (BSSs), is a well-known test bed to study the BSS formation pathways. Here, we report the first direct detection of a white dwarf (WD) companion to a BSS in M67, using far-UV images from the Ultra-Violet Imaging telescope on ASTROSAT. Near-simultaneous observations in three far-UV bands…
Space Telescope and Optical Reverberation Mapping Project. VIII. Time Variability of Emission and Absorption in NGC 5548 Based on Modeling the Ultraviolet Spectrum
Im, M.; Malkan, M. A.; Geier, S. +164 more
We model the ultraviolet spectra of the Seyfert 1 galaxy NGC 5548 obtained with the Hubble Space Telescope during the 6 month reverberation mapping campaign in 2014. Our model of the emission from NGC 5548 corrects for overlying absorption and deblends the individual emission lines. Using the modeled spectra, we measure the response to continuum v…
Buried Black Hole Growth in IR-selected Mergers: New Results from Chandra
Ellison, Sara L.; Ricci, Claudio; Blecha, Laura +8 more
Observations and theoretical simulations suggest that a significant fraction of merger-triggered accretion onto supermassive black holes is highly obscured, particularly in late-stage galaxy mergers, when the black hole is expected to grow most rapidly. Starting with the Wide-Field Infrared Survey Explorer all-sky survey, we identified a populatio…
Comparing the Quenching Times of Faint M31 and Milky Way Satellite Galaxies
Lewis, Geraint F.; Dolphin, Andrew E.; Skillman, Evan D. +8 more
We present the star formation histories (SFHs) of 20 faint M31 satellites (-12 ≲ M V ≲ -6) that were measured by modeling sub-horizontal branch depth color-magnitude diagrams constructed from Hubble Space Telescope (HST) imaging. Reinforcing previous results, we find that virtually all galaxies quenched between 3 and 9 Gyr ago, indepe…
Extremely Low Molecular Gas Content in a Compact, Quiescent Galaxy at z = 1.522
Franx, Marijn; Bezanson, Rachel; Weiner, Benjamin +4 more
One of the greatest challenges to theoretical models of massive galaxy formation is the regulation of star formation at early times. The relative roles of molecular gas expulsion, depletion, and stabilization are uncertain as direct observational constraints of the gas reservoirs in quenched or quenching galaxies at high redshift are scant. We pre…
The TRGB Distance to the Second Galaxy “Missing Dark Matter”: Evidence for Two Groups of Galaxies at 13.5 and 19 Mpc in the Line of Sight of NGC 1052
Trujillo, Ignacio; Monelli, Matteo
A second galaxy “missing dark matter” (NGC 1052-DF4) has been reported recently. Here we show, using the location of the tip of the red giant branch (TRGB), that the distance to this galaxy is 14.2 ± 0.7 Mpc. This locates the galaxy 6 Mpc closer than previously determined. We also analyze the distances to the brightest galaxies in the field of vie…
RELICS: Strong Lensing Analysis of MACS J0417.5-1154 and Predictions for Observing the Magnified High-redshift Universe with JWST
Ouchi, Masami; Mahler, Guillaume; Frye, Brenda L. +37 more
Strong gravitational lensing by clusters of galaxies probes the mass distribution at the core of each cluster and magnifies the universe behind it. MACS J0417.5-1154 at z = 0.443 is one of the most massive clusters known based on weak lensing, X-ray, and Sunyaev-Zel’dovich analyses. Here we compute a strong lens model of MACS J0417 based on Hubble…
The Extremely Luminous Quasar Survey in the Sloan Digital Sky Survey Footprint. III. The South Galactic Cap Sample and the Quasar Luminosity Function at Cosmic Noon
Fan, Xiaohui; McGreer, Ian D.; Huang, Yun-Hsin +11 more
We have designed the Extremely Luminous Quasar Survey (ELQS) to provide a highly complete census of unobscured UV-bright quasars during the cosmic noon, z = 2.8-5.0. Here we report the discovery of 70 new quasars in the ELQS South Galactic Cap (ELQS-S) quasar sample, doubling the number of known extremely luminous quasars in 4237.3 deg2…
TESS Asteroseismology of the Known Red-giant Host Stars HD 212771 and HD 203949
Stock, Stephan; Reffert, Sabine; Chaplin, William J. +45 more
The Transiting Exoplanet Survey Satellite (TESS) is performing a near all-sky survey for planets that transit bright stars. In addition, its excellent photometric precision enables asteroseismology of solar-type and red-giant stars, which exhibit convection-driven, solar-like oscillations. Simulations predict that TESS will detect solar-like oscil…
Record-breaking Coronal Magnetic Field in Solar Active Region 12673
Fleishman, Gregory D.; Anfinogentov, Sergey A.; Stupishin, Alexey G. +1 more
The strongest magnetic fields on the Sun are routinely detected at dark sunspots. The magnitude of the field is typically about 3000 G, with only a few exceptions that reported the magnetic field in excess of 5000 G. Given that the magnetic field decreases with height in the solar atmosphere, no coronal magnetic field above ∼2000 G has ever been r…