Search Publications
A First Spectroscopic Measurement of the Magnetic-field Strength for an Active Region of the Solar Corona
Brage, Tomas; Si, Ran; Li, Wenxian +3 more
For all involved in astronomy, the importance of monitoring and determining astrophysical magnetic-field strengths is clear. It is also a well-known fact that the corona magnetic fields play an important part in the origin of solar flares and the variations of space weather. However, after many years of solar corona studies, there is still no dire…
NICER Observation of the Temporal and Spectral Evolution of Swift J1818.0-1607: A Missing Link between Magnetars and Rotation-powered Pulsars
Enoto, Teruaki; Sakamoto, Takanori; Ray, Paul S. +13 more
We report on the hard X-ray burst and the first ∼100 days of NICER monitoring of the soft X-ray temporal and spectral evolution of the newly discovered magnetar Swift J1818.0-1607. The burst properties are typical of magnetars with a duration of T90 = 10 ± 4 ms and a temperature of kT = 8.4 ± 0.7 keV. The 2-8 keV pulse shows a broad, si…
SuperBoRG: Exploration of Point Sources at z ∼ 8 in HST Parallel Fields
Treu, T.; Mason, C. A.; Trenti, M. +7 more
To extend the search for quasars in the epoch of reionization beyond the tip of the luminosity function, we explore point-source candidates at redshift z ∼ 8 in SuperBoRG, a compilation of ∼0.4 deg2 archival medium-deep (mF160W ∼ 26.5 ABmag, 5σ) parallel infrared (IR) images taken with the Hubble Space Telescope (HST). Initia…
A Second Look at 12 Candidate Dual AGNs Using BAYMAX
Greene, Jenny E.; Comerford, Julia M.; Barrows, R. Scott +5 more
We present an analysis of 12 optically selected dual active galactic nucleus (AGN) candidates at z < 0.34. Each candidate was originally identified via double-peaked [O III] λ5007 emission lines and received follow-up Chandra and Hubble Space Telescope (HST) observations. Because the X-ray data are low-count (<100 counts) with small separati…
The Lyman Continuum Escape Fraction of Galaxies and AGN in the GOODS Fields
Koekemoer, Anton M.; Conselice, Christopher J.; Hathi, Nimish +13 more
We present our analysis of the Lyman continuum (LyC) emission and escape fraction of 111 spectroscopically verified galaxies with and without active galactic nuclei (AGN) from 2.26 < z < 4.3. We extended our ERS sample from Smith et al. with 64 galaxies in the GOODS North and South fields using WFC3/UVIS F225W, F275W, and F336W mosaics we in…
The Chemical Signatures of Planetary Engulfment Events in Binary Systems
Nagar, Tushar; Spina, Lorenzo; Karakas, Amanda I.
Planetary engulfment events involve the chemical assimilation of a planet into a star’s external layer. This can cause a change in the chemical pattern of the stellar atmosphere in a way that mirrors the composition of the rocky object engulfed, with the refractory elements being more abundant than the volatiles. Due to these stellar chemical chan…
Two Major Constraints on the Inner Radii of Accretion Disks
Zdziarski, Andrzej A.; De Marco, Barbara
The Stefan-Boltzmann law yields a fundamental constraint on the geometry of inner accretion disks in black hole X-ray binaries. It follows from considering the irradiating flux and the effective temperature of the inner parts of the disk, which implies that a strong quasi-thermal component with the average energy higher than that of a blackbody at…
Discovery of the Optical Afterglow and Host Galaxy of Short GRB 181123B at z = 1.754: Implications for Delay Time Distributions
Cenko, S. B.; Berger, E.; Cucchiara, A. +19 more
We present the discovery of the optical afterglow and host galaxy of the Swift short-duration gamma-ray burst (SGRB) GRB 181123B. Observations with Gemini-North starting ≈9.1 hr after the burst reveal a faint optical afterglow with i ≈ 25.1 mag at an angular offset of 0"59 ± 0"16 from its host galaxy. Using grizYJHK observations, we measure a phot…
The M Supergiant High-mass X-Ray Binary 4U 1954+31
Habel, Nolan; Fekel, Francis C.; Hinkle, Kenneth H. +5 more
The X-ray binary 4U 1954+31 has been classified as a low-mass X-ray binary containing an M giant and a neutron star (NS). It has also been included in the rare class of X-ray symbiotic binaries. The Gaia parallax, infrared colors, spectral type, abundances, and orbital properties of the M star demonstrate that the cool star in this system is not a…
The MASSIVE Survey. XV. A Stellar Dynamical Mass Measurement of the Supermassive Black Hole in Massive Elliptical Galaxy NGC 1453
Ma, Chung-Pei; Greene, Jenny E.; Blakeslee, John P. +4 more
We present a new stellar dynamical mass measurement (M_{BH}) of the supermassive black hole (SMBH) in NGC 1453, a fast-rotating massive elliptical galaxy in the MASSIVE survey. We measure stellar kinematics in 135 spatial bins in the central 1.5 kpc × 2 kpc region of the galaxy using high signal-to-noise ratio (S/N ∼ 130) spectra from the Gemini-N…