Search Publications
Scaling Relations and X-Ray Properties of Moderate-luminosity Galaxy Clusters from 0.3 < z < 0.6 with XMM-Newton
Donahue, Megan; Conselice, Christopher J.; Hoekstra, Henk +4 more
We present new X-ray temperatures and improved X-ray luminosity estimates for 15 new and archival XMM-Newton observations of galaxy clusters at intermediate redshift with mass and luminosities near the galaxy group/cluster division ({M}2500 < 2.4 × 1014 h70-1 {M}_⊙, L < 2 × 1044 erg s
Steadily Increasing Star Formation Rates in Galaxies Observed at 3 <~ z <~ 5 in the CANDELS/GOODS-S Field
Ferguson, Henry C.; Giavalisco, Mauro; Somerville, Rachel S. +3 more
We investigate the star formation histories (SFHs) of high redshift (3 <~ z <~ 5) star-forming galaxies selected based on their rest-frame ultraviolet (UV) colors in the CANDELS/GOODS-S field. By comparing the results from the spectral-energy-distribution-fitting analysis with two different assumptions about the SFHs—i.e., exponentially decl…
Fifty M31 Black Hole Candidates Identified by Chandra and XMM-Newton
Murray, S. S.; Garcia, M. R.; Barnard, R. +1 more
Over approximately the last five years, we have identified ~35 black hole candidates (BHCs) in M31 from their X-ray spectra. Our BHCs exhibited 0.3-10 keV spectra consistent with the X-ray binary (XB) hard state at luminosities that are above the upper limit for neutron star (NS) XBs. When our BHC spectra were modeled with a disk blackbody + black…
Oblique Alfvén Instabilities Driven by Compensated Currents
De Keyser, J.; Malovichko, P.; Voitenko, Y.
Compensated-current systems created by energetic ion beams are widespread in space and astrophysical plasmas. The well-known examples are foreshock regions in the solar wind and around supernova remnants. We found a new oblique Alfvénic instability driven by compensated currents flowing along the background magnetic field. Because of the vastly di…
Heating and Dynamics of Two Flare Loop Systems Observed by AIA and EIS
Ding, M. D.; Li, Y.; Qiu, J.
We investigate heating and evolution of flare loops in a C4.7 two-ribbon flare on 2011 February 13. From Solar Dynamics Observatory/Atmospheric Imaging Assembly (AIA) imaging observations, we can identify two sets of loops. Hinode/EUV Imaging Spectrometer (EIS) spectroscopic observations reveal blueshifts at the feet of both sets of loops. The evo…
An Upper Bound from Helioseismology on the Stochastic Background of Gravitational Waves
Roth, Markus; Siegel, Daniel M.
The universe is expected to be permeated by a stochastic background of gravitational radiation of astrophysical and cosmological origin. This background is capable of exciting oscillations in solar-like stars. Here we show that solar-like oscillators can be employed as giant hydrodynamical detectors for such a background in the µHz to mHz fr…
Spectral Analysis in Orbital/Superorbital Phase Space and Hints of Superorbital Variability in the Hard X-Rays of LS I +61°303
Torres, Diego F.; Li, Jian; Zhang, Shu
We present an INTEGRAL spectral analysis in the orbital/superorbital phase space of LS I +61°303. A hard X-ray spectrum with no cutoff is observed at all orbital/superorbital phases. The hard X-ray index is found to be uncorrelated with the radio index (non-simultaneously) measured at the same orbital and superorbital phases. In particular, the ab…
Maser and Infrared Studies of Oxygen-rich Late/Post-asymptotic Giant Branch Stars and Water Fountains: Development of a New Identification Method
Yung, Bosco H. K.; Nakashima, Jun-ichi; Henkel, Christian
We explored an efficient method to identify evolved stars with oxygen-rich envelopes in the late asymptotic giant branch (AGB) or post-AGB phase of stellar evolution, which include a rare class of objects—the "water fountains (WF)." Our method considers the OH and H2O maser spectra, the near-infrared Q-parameters (these are color indice…
Where are the Mini Kreutz-family Comets?
Kracht, Rainer; Ye, Quan-Zhi; Hui, Man-To +1 more
The Kreutz family of sungrazing comets contains over 2000 known members, many of which are believed to be under ~100 m sizes (mini comets) and have only been studied at small heliocentric distances (r H) with space-based SOHO/STEREO spacecraft. To understand the brightening process of mini Kreutz comets, we conducted a survey using CFHT…
Near-infrared Structure of Fast and Slow-rotating Disk Galaxies
Bershady, Matthew A.; Schechtman-Rook, Andrew
We investigate the stellar disk structure of six nearby edge-on spiral galaxies using high-resolution JHK s-band images and three-dimensional radiative transfer models. To explore how mass and environment shape spiral disks, we selected galaxies with rotational velocities between 69 km s-1 <V rot < 245 km s