Search Publications
Accretion Disk Reverberation with Hubble Space Telescope Observations of NGC 4593: Evidence for Diffuse Continuum Lags
Horne, Keith; Goad, Michael R.; Korista, Kirk T. +4 more
The Seyfert 1 galaxy NGC 4593 was monitored spectroscopically with the Hubble Space Telescope as part of a reverberation mapping campaign that also included Swift, Kepler, and ground-based photometric monitoring. During 2016 July 12-August 6, we obtained 26 spectra across a nearly continuous wavelength range of ∼1150-10000 Å. These were combined w…
The MOSDEF Survey: A Stellar Mass-SFR-Metallicity Relation Exists at z ∼ 2.3
Barro, Guillermo; Siana, Brian; Shapley, Alice E. +15 more
We investigate the nature of the relation among stellar mass, star formation rate, and gas-phase metallicity (the {M}* -SFR-Z relation) at high redshifts using a sample of 260 star-forming galaxies at z ∼ 2.3 from the MOSDEF survey. We present an analysis of the high-redshift {M}* -SFR-Z relation based on several emission-lin…
Apocenter Pile-up: Origin of the Stellar Halo Density Break
Belokurov, Vasily; Koposov, Sergey E.; Deason, Alis J. +1 more
We measure the orbital properties of halo stars using seven-dimensional information provided by Gaia and the Sloan Digital Sky Survey. A metal-rich population of stars, present in both local main sequence stars and more distant blue horizontal branch stars, have very radial orbits (eccentricity ∼0.9) and apocenters that coincide with the stellar h…
Scaling Relations Associated with Millimeter Continuum Sizes in Protoplanetary Disks
Wilner, David J.; Andrews, Sean M.; Ansdell, Megan +3 more
We present a combined, homogenized analysis of archival Submillimeter Array (SMA) and Atacama Large Millimeter/submillimeter Array (ALMA) observations of the spatially resolved 340 GHz (870 µm) continuum emission from 105 nearby protoplanetary disks. Building on the previous SMA survey, we infer surface brightness profiles using a simple mod…
The Extended Distribution of Baryons around Galaxies
Bregman, Joel N.; Anderson, Michael E.; Qu, Zhijie +5 more
We summarize and reanalyze observations bearing on missing galactic baryons, where we propose a consistent picture for halo gas in L ≳ L* galaxies. The hot X-ray-emitting halos are detected to 50-70 kpc, where typically M hot(<50 kpc) ∼ 5 × 109 M ⊙, and with density n ∝ r -3/2. When extrapolated to R …
Alternative Explanations for Extreme Supersolar Iron Abundances Inferred from the Energy Spectrum of Cygnus X-1
Gandhi, Poshak; Yamaoka, Kazutaka; Fürst, Felix +11 more
Here we study a 1-200 keV energy spectrum of the black hole binary Cygnus X-1 taken with NuSTAR and Suzaku. This is the first report of a NuSTAR observation of Cyg X-1 in the intermediate state, and the observation was taken during the part of the binary orbit where absorption due to the companion’s stellar wind is minimal. The spectrum includes a…
Nearby Early-type Galactic Nuclei at High Resolution: Dynamical Black Hole and Nuclear Star Cluster Mass Measurements
Böker, Torsten; Pechetti, Renuka; Caldwell, Nelson +12 more
We present a detailed study of the nuclear star clusters (NSCs) and massive black holes (BHs) of four of the nearest low-mass early-type galaxies: M32, NGC 205, NGC 5102, and NGC 5206. We measure the dynamical masses of both the BHs and NSCs in these galaxies using Gemini/NIFS or VLT/SINFONI stellar kinematics, Hubble Space Telescope (HST) imaging…
Observations of Turbulent Magnetic Reconnection within a Solar Current Sheet
Cheng, X.; Ding, M. D.; Zhang, J. +4 more
Magnetic reconnection is a fundamental physical process in various astrophysical, space, and laboratory environments. Many pieces of evidence for magnetic reconnection have been uncovered. However, its specific processes that could be fragmented and turbulent have been short of direct observational evidence. Here, we present observations of a supe…
Short GRBs: Opening Angles, Local Neutron Star Merger Rate, and Off-axis Events for GRB/GW Association
Li, Xiang; Yuan, Qiang; Jin, Zhi-Ping +7 more
The jet breaks in the afterglow light curves of short gamma-ray bursts (SGRBs), rarely detected so far, are crucial for estimating the half-opening angles of the ejecta (θ j) and hence the neutron star merger rate. In this work, we report the detection of jet decline behaviors in GRB 150424A and GRB 160821B, and find θ j ∼ 0.…
The MUSCLES Treasury Survey. V. FUV Flares on Active and Inactive M Dwarfs
Loyd, R. O. Parke; Redfield, Seth; Brown, Alexander +10 more
M dwarf stars are known for their vigorous flaring. This flaring could impact the climate of orbiting planets, making it important to characterize M dwarf flares at the short wavelengths that drive atmospheric chemistry and escape. We conducted a far-ultraviolet flare survey of six M dwarfs from the recent MUSCLES (Measurements of the Ultraviolet …