Search Publications
Tracing the Cosmic Metal Evolution in the Low-redshift Intergalactic Medium
Shull, J. Michael; Danforth, Charles W.; Tilton, Evan M.
Using the Cosmic Origins Spectrograph aboard the Hubble Space Telescope, we measured the abundances of six ions (C III, C IV, Si III, Si IV, N V, and O VI) in the low-redshift (z <= 0.4) intergalactic medium (IGM). Both C IV and Si IV have increased in abundance by a factor of ~10 from z ≈ 5.5 to the present. We derive ion mass densities, ρ
Degree-scale Cosmic Microwave Background Polarization Measurements from Three Years of BICEP1 Data
Ade, P. A. R.; Bock, J. J.; Chiang, H. C. +31 more
BICEP1 is a millimeter-wavelength telescope designed specifically to measure the inflationary B-mode polarization of the cosmic microwave background at degree angular scales. We present results from an analysis of the data acquired during three seasons of observations at the South Pole (2006-2008). This work extends the two-year result published i…
Are X-Ray Emitting Coronae around Supermassive Black Holes Outflowing?
Wang, Jun-Xian; Zhu, Fei-Fan; Zhou, You-Yuan +2 more
Hard X-ray emission in radio-quiet active galactic nuclei (AGNs) is believed to be produced via inverse Compton scattering by hot and compact coronae near the supermassive black hole. However, the origin and physical properties of the coronae, including geometry, kinematics, and dynamics, remain poorly known. In this work, taking [O IV] 25.89 &mic…
A Magnified View of the Kinematics and Morphology of RCSGA 032727-132609: Zooming in on a Merger at z = 1.7
Rigby, Jane R.; Sharon, Keren; Gladders, Michael D. +1 more
We present a detailed analysis of multi-wavelength Hubble Space Telescope/Wide Field Camera 3 (WFC3) imaging and Keck/OSIRIS near-infrared adaptive optics-assisted integral field spectroscopy for a highly magnified lensed galaxy at z = 1.70. This young starburst is representative of ultraviolet-selected star-forming galaxies (SFGs) at z ~ 2 and co…
Interstellar and Ejecta Dust in the Cas A Supernova Remnant
Arendt, Richard G.; Hwang, Una; Rho, Jeonghee +2 more
Infrared continuum observations provide a means of investigating the physical composition of the dust in the ejecta and swept up medium of the Cas A supernova remnant (SNR). Using low-resolution Spitzer IRS spectra (5-35 µm), and broad-band Herschel PACS imaging (70, 100, and 160 µm), we identify characteristic dust spectra, associated…
A Molecular Line Scan in the Hubble Deep Field North
Daddi, E.; Maiolino, R.; Menten, K. M. +20 more
We present a molecular line scan in the Hubble Deep Field North (HDF-N) that covers the entire 3 mm window (79-115 GHz) using the IRAM Plateau de Bure Interferometer. Our CO redshift coverage spans z <~ 0.45, 1 <~ z <~ 1.9 and all z >~ 2. We reach a CO detection limit that is deep enough to detect essentially all z > 1 CO lines repo…
The Black Hole Mass of NGC 4151. II. Stellar Dynamical Measurement from Near-infrared Integral Field Spectroscopy
Peterson, Bradley M.; Pogge, Richard W.; Storchi-Bergmann, Thaisa +8 more
We present a revised measurement of the mass of the central black hole (M BH ) in the Seyfert 1 galaxy NGC 4151. The new stellar dynamical mass measurement is derived by applying an axisymmetric orbit-superposition code to near-infrared integral field data obtained using adaptive optics with the Gemini Near-infrared Integral Field Spect…
New Evidence for a Substellar Luminosity Problem: Dynamical Mass for the Brown Dwarf Binary Gl 417BC
Dupuy, Trent J.; Ireland, Michael J.; Liu, Michael C.
We present new evidence for a problem with cooling rates predicted by substellar evolutionary models that implies that model-derived masses in the literature for brown dwarfs and directly imaged planets may be too high. Based on our dynamical mass for Gl 417BC (L4.5+L6) and a gyrochronology system age from its young, solar-type host star, commonly…
Observational Characteristics of Coronal Mass Ejections without Low-coronal Signatures
Berghmans, D.; Seaton, D. B.; D'Huys, E. +1 more
Solar eruptions are usually associated with a variety of phenomena occurring in the low corona before, during, and after the onset of eruption. Though easily visible in coronagraph observations, so-called stealth coronal mass ejections (CMEs) do not obviously exhibit any of these low-coronal signatures. The presence or absence of distinct low-coro…
New Evidence for Efficient Collisionless Heating of Electrons at the Reverse Shock of a Young Supernova Remnant
Petre, Robert; Yamaguchi, Hiroya; Hughes, John P. +7 more
Although collisionless shocks are ubiquitous in astrophysics, certain key aspects of them are not well understood. In particular, the process known as collisionless electron heating, whereby electrons are rapidly energized at the shock front, is one of the main open issues in shock physics. Here, we present the first clear evidence for efficient c…