Search Publications
Black Hole Mass and Bulge Luminosity for Low-mass Black Holes
Ho, Luis C.; Greene, Jenny E.; Jiang, Yan-Fei
We study the scaling between bulge magnitude and central black hole (BH) mass in galaxies with virial BH masses <~ 106 M sun. Based on careful image decomposition of a snapshot Hubble Space Telescope I-band survey, we found that these BHs are found predominantly in galaxies with pseudobulges. Here we show that the M B…
Evidence Against an Edge-on Disk Around the Extrasolar Planet, 2MASS 1207 b and a New Thick-cloud Explanation for Its Underluminosity
Pascucci, Ilaria; Apai, Dániel; Biller, Beth A. +3 more
Since the discovery of the first directly imaged, planetary-mass object, 2MASS 1207 b, several works have sought to explain a disparity between its observed temperature and luminosity. Given its known age, distance, and spectral type, 2MASS 1207 b is underluminous by a factor of ~10 (~2.5 mag) when compared to standard models of brown-dwarf/giant-…
Spatially Resolved Nonthermal Line Broadening during the Impulsive Phase of a Solar Flare
Milligan, Ryan O.
This paper presents a detailed study of excess line broadening in extreme ultraviolet (EUV) emission lines during the impulsive phase of a C-class solar flare. In this work, which utilizes data from the EUV Imaging Spectrometer on board Hinode, the broadened line profiles were observed to be cospatial with the two hard X-ray footpoints as observed…
Can the Soft X-Ray Opacity Toward High-redshift Sources Probe the Missing Baryons?
Laor, Ari; Behar, Ehud; Dar, Arnon +1 more
Observations with the Swift satellite of X-ray afterglows of more than a hundred gamma-ray bursts (GRBs) with known redshift reveal ubiquitous soft X-ray absorption. The directly measured optical depth τ at a given observed energy is found to be constant on average at redshift z > 2, i.e., langτ(0.5 keV)rang z > 2 = 0.40 ± 0.02. S…
A Deep Chandra ACIS Study of NGC 4151. II. The Innermost Emission Line Region and Strong Evidence for Radio Jet-NLR Cloud Collision
Elvis, Martin; Zezas, Andreas; Risaliti, Guido +4 more
We have studied the X-ray emission within the inner ~150 pc radius of NGC 4151 by constructing high spatial resolution emission line images of blended O VII, O VIII, and Ne IX. These maps show extended structures that are spatially correlated with the radio outflow and optical [O III] emission. We find strong evidence for jet-gas cloud interaction…
Empirical Reconstruction and Numerical Modeling of the First Geoeffective Coronal Mass Ejection of Solar Cycle 24
Howard, R. A.; Rouillard, A. P.; Wood, B. E. +2 more
We analyze the kinematics and morphology of a coronal mass ejection (CME) from 2010 April 3, which was responsible for the first significant geomagnetic storm of solar cycle 24. The analysis utilizes coronagraphic and heliospheric images from the two STEREO spacecraft, and coronagraphic images from SOHO/LASCO. Using an empirical three-dimensional …
A Compton-thick Active Galactic Nucleus at z ~ 5 in the 4 Ms Chandra Deep Field South
Ptak, A.; Brandt, W. N.; Fiore, F. +13 more
We report the discovery of a Compton-thick active galactic nucleus (AGN) at z = 4.76 in the 4 Ms Chandra Deep Field South. This object was selected as a V-band dropout in HST/ACS images and previously recognized as an AGN from optical spectroscopy. The 4 Ms Chandra observations show a significant (~4.2σ) X-ray detection at the V-band dropout posit…
X-ray Emission from Two Infrared-selected Galaxy Clusters at z > 1.4 in the IRAC Shallow Cluster Survey
Stern, D.; Vikhlinin, A.; Dey, A. +17 more
We report the X-ray detection of two z > 1.4 infrared-selected galaxy clusters from the IRAC Shallow Cluster Survey (ISCS). We present new data from the Hubble Space Telescope and the W. M. Keck Observatory that spectroscopically confirm cluster ISCS J1432.4+3250 at z = 1.49, the most distant of 18 confirmed z > 1 clusters in the ISCS to dat…
Temperature Distribution of a Non-flaring Active Region from Simultaneous Hinode XRT and EIS Observations
DeLuca, Edward E.; Landi, Enrico; Testa, Paola +2 more
We analyze coordinated Hinode X-ray Telescope (XRT) and Extreme Ultraviolet Imaging Spectrometer (EIS) observations of a non-flaring active region to investigate the thermal properties of coronal plasma taking advantage of the complementary diagnostics provided by the two instruments. In particular, we want to explore the presence of hot plasma in…
Plasma Heating During a Coronal Mass Ejection Observed By the Solar and Heliospheric Observatory
Raymond, J. C.; Korreck, K. E.; Murphy, N. A.
We perform a time-dependent ionization analysis to constrain plasma heating requirements during a fast partial halo coronal mass ejection (CME) observed on 2000 June 28 by the Ultraviolet Coronagraph Spectrometer (UVCS) aboard the Solar and Heliospheric Observatory (SOHO). We use two methods to derive densities from the UVCS measurements, includin…