Search Publications
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 …
Measuring the Physical Conditions in High-redshift Star-forming Galaxies: Insights from KBSS-MOSFIRE
Pettini, Max; Steidel, Charles C.; Rudie, Gwen C. +2 more
We use photoionization models that are designed to reconcile the joint rest-UV-optical spectra of high-z star-forming galaxies to self-consistently infer the gas chemistry and nebular ionization and excitation conditions for ∼150 galaxies from the Keck Baryonic Structure Survey (KBSS), using only observations of their rest-optical nebular spectra.…
BANYAN. XIII. A First Look at Nearby Young Associations with Gaia Data Release 2
Faherty, Jacqueline K.; Gagné, Jonathan
In this paper, we examine the nearest 100 pc entries in Data Release 2 of Gaia to identify previously unrecognized candidate members in young associations. We analyze 695 952 stars with the BANYAN Σ Bayesian classification software and discover 898 new high-likelihood candidate members that span a wide range of properties, from spectral types B9 t…
The Brightest Galaxies in the Dark Ages: Galaxies’ Dust Continuum Emission during the Reionization Era
Finkelstein, Steven L.; Casey, Caitlin M.; Zavala, Jorge A. +6 more
Though half of cosmic starlight is absorbed by dust and reradiated at long wavelengths (3 µm-3 mm), constraints on the infrared through the millimeter galaxy luminosity function (or the “IRLF”) are poor in comparison to the rest-frame ultraviolet and optical galaxy luminosity functions, particularly at z ≳ 2.5. Here, we present a backward ev…
The MOSDEF Survey: Significant Evolution in the Rest-frame Optical Emission Line Equivalent Widths of Star-forming Galaxies at z = 1.4-3.8
Barro, Guillermo; Siana, Brian; Shapley, Alice E. +13 more
We use extensive spectroscopy from the MOSFIRE Deep Evolution Field survey to investigate the relationships between rest-frame optical emission line equivalent widths (W) and a number of galaxy and interstellar medium (ISM) characteristics for a sample of 1134 star-forming galaxies at redshifts 1.4 ≲ z ≲ 3.8. We examine how the equivalent widths o…
Off the Beaten Path: Gaia Reveals GD-1 Stars outside of the Main Stream
Price-Whelan, Adrian M.; Bonaca, Ana
Tidally disrupted globular clusters are transformed into thin, dynamically cold streams of stars that are extremely valuable tracers of the large- and small-scale distribution of mass in the Galaxy. Using data from the Gaia second data release combined with Pan-STARRS photometry, we present a sample of highly probable members of the longest cold s…