Search Publications
A New Population of Compton-thick AGNs Identified Using the Spectral Curvature above 10 keV
Harrison, F. A.; Stern, D.; Alexander, D. M. +19 more
We present a new metric that uses the spectral curvature (SC) above 10 keV to identify Compton-thick active galactic nuclei (AGNs) in low-quality Swift/Burst Alert Telescope (BAT) X-ray data. Using NuSTAR, we observe nine high SC-selected AGNs. We find that high-sensitivity spectra show that the majority are Compton-thick (78% or 7/9) and the rema…
Globular Clusters Indicate That Ultra-diffuse Galaxies Are Dwarfs
Beasley, Michael A.; Trujillo, Ignacio
We present an analysis of archival HST/ACS imaging in the F475W (g 475), F606W (V 606), and F814W (I 814) bands of the globular cluster (GC) system of a large (3.4 kpc effective radius) ultra-diffuse galaxy (DF17) believed to be located in the Coma Cluster of galaxies. We detect 11 GCs down to the 5σ completeness l…
A Universal Density Structure for Circumgalactic Gas
Stern, Jonathan; Hennawi, Joseph F.; Prochaska, J. Xavier +1 more
We develop a new method to constrain the physical conditions in the cool (∼104 K) circumgalactic medium (CGM) from measurements of ionic column densities by assuming that the cool CGM spans a large range of gas densities and that small high-density clouds are hierarchically embedded in large low-density clouds. The new method combines t…
Balloon-Borne Submillimeter Polarimetry of the Vela C Molecular Cloud: Systematic Dependence of Polarization Fraction on Column Density and Local Polarization-Angle Dispersion
Ward-Thompson, Derek; Fissel, Laura M.; Nakamura, Fumitaka +27 more
We present results for Vela C obtained during the 2012 flight of the Balloon-borne Large Aperture Submillimeter Telescope for Polarimetry. We mapped polarized intensity across almost the entire extent of this giant molecular cloud, in bands centered at 250, 350, and 500 µm. In this initial paper, we show our 500 µm data smoothed to a r…
Highest Redshift Image of Neutral Hydrogen in Emission: A CHILES Detection of a Starbursting Galaxy at z = 0.376
Strader, Jay; Scoville, Nick; Yun, Min S. +32 more
Our current understanding of galaxy evolution still has many uncertainties associated with the details of the accretion, processing, and removal of gas across cosmic time. The next generation of radio telescopes will image the neutral hydrogen (H I) in galaxies over large volumes at high redshifts, which will provide key insights into these proces…
Spectroscopic Indication of a Centi-parsec Supermassive Black Hole Binary in the Galactic Center of NGC 5548
Ho, Luis C.; Zhang, Zhi-Xiang; Du, Pu +8 more
As a natural consequence of cosmological hierarchical structure formation, sub-parsec supermassive black hole binaries (SMBHBs) should be common in galaxies but thus far have eluded spectroscopic identification. Based on four decades of optical spectroscopic monitoring, we report that the nucleus of NGC 5548, a nearby Seyfert galaxy long suspected…
KMOS3D: Dynamical Constraints on the Mass Budget in Early Star-forming Disks
Übler, Hannah; van Dokkum, Pieter G.; Bender, Ralf +26 more
We exploit deep integral-field spectroscopic observations with KMOS/Very Large Telescope of 240 star-forming disks at 0.6\lt z\lt 2.6 to dynamically constrain their mass budget. Our sample consists of massive (≳ {10}9.8 {M}⊙ ) galaxies with sizes {R}e≳ 2 {kpc}. By contrasting the observed velocity and dispersion p…
Slipping Magnetic Reconnection, Chromospheric Evaporation, Implosion, and Precursors in the 2014 September 10 X1.6-Class Solar Flare
Polito, Vanessa; Del Zanna, Giulio; Aulanier, Guillaume +7 more
We investigate the occurrence of slipping magnetic reconnection, chromospheric evaporation, and coronal loop dynamics in the 2014 September 10 X-class flare. Slipping reconnection is found to be present throughout the flare from its early phase. Flare loops are seen to slip in opposite directions toward both ends of the ribbons. Velocities of 20-4…
A Coherent Study of Emission Lines from Broadband Photometry: Specific Star Formation Rates and [O III]/Hβ Ratio at 3 > z > 6
Ilbert, O.; Silverman, J. D.; Salvato, M. +14 more
We measure the Hα and [O III] emission line properties as well as specific star formation rates (sSFRs) of spectroscopically confirmed 3 < z < 6 galaxies in COSMOS from their observed colors versus redshift evolution. Our model describes consistently the ensemble of galaxies including intrinsic properties (age, metallicity, star formation hi…
"Refsdal" Meets Popper: Comparing Predictions of the Re-appearance of the Multiply Imaged Supernova Behind MACSJ1149.5+2223
Sharon, K.; Diego, J. M.; Zitrin, A. +25 more
Supernova “Refsdal,” multiply imaged by cluster MACS1149.5+2223, represents a rare opportunity to make a true blind test of model predictions in extragalactic astronomy, on a timescale that is short compared to a human lifetime. In order to take advantage of this event, we produced seven gravitational lens models with five independent methods, bas…