Search Publications
Identifying Candidate Optical Variables Using Gaia Data Release 2
Strader, Jay; Andrew, Shion; Swihart, Samuel J.
Gaia is undertaking a deep synoptic survey of the Galaxy, but photometry from individual epochs has, as of yet, only been released for a minimal number of sources. We show that it is possible to identify variable stars in Gaia Data Release 2 by selecting stars with unexpectedly large photometric uncertainties given their brightness and number of o…
Star Formation in a Strongly Magnetized Cloud
Caselli, Paola; Arce, Héctor G.; Tan, Jonathan C. +6 more
We study star formation in the Center Ridge 1 (CR1) clump in the Vela C giant molecular cloud, selected as a high column density region that shows the lowest level of dust continuum polarization-angle dispersion, likely indicating that the magnetic field is relatively strong. We observe the source with the Atacama Large Millimeter/submillimeter Ar…
Probing the Disk-Corona Systems and Broad-line Regions of Changing-look Quasars with X-Ray and Optical Observations
Green, Paul J.; Anderson, Scott F.; Eracleous, Michael +8 more
"Changing-look" quasars are a new class of highly variable active galactic nuclei that have changed their spectral type over surprisingly short timescales of just a few years. The origin of this phenomenon is debated, but is likely to reflect some change in the accretion flow. To investigate the disk-corona systems in these objects, we measure opt…
The Star Formation History of a Post-starburst Galaxy Determined from Its Cluster Population
Chandar, Rupali; French, K. Decker; Mok, Angus +2 more
The recent star formation histories (SFHs) of post-starburst galaxies have been determined almost exclusively from detailed modeling of their composite starlight. This has provided important but limited information on the number, strength, and duration of bursts of star formation. In this work, we present a direct and independent measure of the re…
Local Analogs to High-redshift Galaxies. I. Characterization of Dust Emission and Star Formation History
Wiklind, Tommy; Eufrasio, Rafael T.; Motiño Flores, Skarleth M.
Star-forming dwarf galaxies have properties similar to those expected in high-redshift galaxies. Hence, these local galaxies may provide insights into the evolution of the first galaxies and the physical processes at work. We present a sample of 11 potential local analogs to high-z (LAHz) galaxies. The sample consists of blue compact dwarf galaxie…
Multiwavelength Quasi-periodic Pulsations in a Stellar Superflare
Nakariakov, Valery M.; Kolotkov, Dmitrii Y.; Holt, Robin +1 more
We present the first multiwavelength simultaneous detection of quasi-periodic pulsations (QPPs) in a superflare (more than a thousand times stronger than known solar flares) on a cool star, in soft X-rays (SXRs, with XMM-Newton) and white light (WL, with Kepler). It allowed for the first ever analysis of oscillatory processes in a stellar flare si…
Chandra, NuSTAR, and Optical Observations of the Cataclysmic Variables IGR J17528-2022 and IGR J20063+3641
Mori, Kaya; Thorstensen, John R.; Halpern, Jules P. +5 more
We report on Chandra, NuSTAR, and MDM observations of two International Gamma-ray Astrophysics Laboratory (INTEGRAL) sources, namely IGR J17528-2022 and IGR J20063+3641. IGR J17528-2022 is an unidentified INTEGRAL source, while IGR J20063+3641 was recently identified as a magnetic cataclysmic variable (mCV) by Halpern et al. The Chandra observatio…
A Giant Loop of Ionized Gas Emerging from the Tumultuous Central Region of IC 5063
Ho, Luis C.; Elvis, Martin; Fischer, Travis C. +6 more
The biconical radiation pattern extending from an active galactic nucleus (AGN) may strongly photoionize the circumnuclear interstellar medium (ISM) and stimulate emission from the narrow-line region (NLR). Observations of the NLR may provide clues to the structure of dense material that preferentially obscures the bicone at certain angles, and ma…
FOXSI-2 Solar Microflares. II. Hard X-ray Imaging Spectroscopy and Flare Energetics
Krucker, Säm; Ryan, Daniel F.; Musset, Sophie +7 more
We study the nature of energy release and transfer for two sub-A class solar microflares observed during the second Focusing Optics X-ray Solar Imager (FOXSI-2) sounding rocket flight on 2014 December 11. FOXSI is the first solar-dedicated instrument to utilize focusing optics to image the Sun in the hard X-ray (HXR) regime, sensitive to energies …
Implications of Increased Central Mass Surface Densities for the Quenching of Low-mass Galaxies
Papovich, Casey; Pérez-González, Pablo G.; Bell, Eric F. +12 more
We use the Cosmic Assembly Deep Near-infrared Extragalactic Legacy Survey data to study the relationship between quenching and the stellar mass surface density within the central radius of 1 kpc (Σ1) of low-mass galaxies (stellar mass M* ≲ 109.5 M⊙) at 0.5 ≤ z < 1.5. Our sample is mass complete down t…