Search Publications
Chandra Identification of 26 New Black Hole Candidates in the Central Region of M31
Murray, S. S.; Garcia, M. R.; Barnard, R.
We have previously identified 10 M31 black hole candidates (BHCs) in M31 from their X-ray properties alone. They exhibit "hard state" emission spectra that are seen at luminosities lsim10% Eddington in X-ray binaries (XBs) containing a neutron star (NS) or black hole, at luminosities that significantly exceed the NS threshold. Nine of these are as…
VLT/X-Shooter Near-infrared Spectroscopy and HST Imaging of Gravitationally Lensed z ~ 2 Compact Quiescent Galaxies
Geier, S.; Toft, S.; Fynbo, J. P. U. +4 more
Quiescent massive galaxies at z ~ 2 are thought to be the progenitors of present-day massive ellipticals. Observations revealed them to be extraordinarily compact. Until now, the determination of stellar ages, star formation rates, and dust properties via spectroscopic measurements has been feasible only for the most luminous and massive specimens…
Signatures of Multiple Stellar Populations in Unresolved Extragalactic Globular/Young Massive Star Clusters
Zepf, Stephen E.; Peacock, Mark B.; Finzell, Thomas
We present an investigation of potential signatures of the formation of multiple stellar populations in recently formed extragalactic star clusters. All of the Galactic globular clusters for which good samples of individual stellar abundances are available show evidence for multiple populations. This appears to require that multiple episodes of st…
Reflection-dominated Nuclear X-Ray Emission in the Early-type Galaxy ESO 565-G019
Alexander, D. M.; Done, C.; Takahashi, T. +8 more
We present the discovery of a reflection-dominated active galactic nucleus (AGN) in the early-type radio-quiet galaxy ESO 565-G019 with Suzaku and Swift/Burst Alert Telescope. The source X-ray spectrum below 10 keV is characteristic of other Compton-thick (CT) AGNs, clearly showing an inverted continuum and prodigious fluorescence iron emission ab…
The INTEGRAL Source IGR J16328-4726: A High-mass X-Ray Binary from the BeppoSAX Era
Piro, L.; Bird, A. J.; Fiocchi, M. +5 more
We report on temporal and spectral analysis of the INTEGRAL fast transient candidate IGR J16328-4726 observed with BeppoSAX in 1998 and more recently with INTEGRAL. The MECS X-ray data show a frequent microactivity typical of the intermediate state of supergiant fast X-ray transients and a weak flare with a duration of ~4.6 ks. The X-ray emission …
WISE J233237.05-505643.5: A Double-peaked, Broad-lined Active Galactic Nucleus with a Spiral-shaped Radio Morphology
Tsai, Chao-Wei; Kong, Albert K. H.; Norris, Ray P. +14 more
We present radio continuum mapping, optical imaging, and spectroscopy of the newly discovered double-peaked, broad-lined active galactic nucleus (AGN) WISE J233237.05-505643.5 at redshift z = 0.3447. This source exhibits an FR-I and FR-II hybrid morphology, characterized by a bright core, jet, and Doppler-boosted lobe structures in Australian Tele…
Measurements of Anisotropic Ion Temperatures, Non-thermal Velocities, and Doppler Shifts in a Coronal Hole
Hahn, M.; Savin, D. W.
We present a new diagnostic allowing one to measure the anisotropy of ion temperatures and non-thermal velocities, as well as Doppler shifts with respect to the ambient magnetic field. This method provides new results, as well as an independent test for previous measurements obtained with other techniques. Our spectral data come from observations …
A Lyman Break Galaxy in the Epoch of Reionization from Hubble Space Telescope Grism Spectroscopy
Dickinson, Mark; Gardner, Jonathan P.; Hathi, Nimish +28 more
We present observations of a luminous galaxy at z = 6.573—the end of the reionization epoch—which has been spectroscopically confirmed twice. The first spectroscopic confirmation comes from slitless Hubble Space Telescope Advanced Camera for Surveys grism spectra from the PEARS survey (Probing Evolution And Reionization Spectroscopically), which s…
A Novel Approach to Constrain the Mass Ratio of Minor Mergers in Elliptical Galaxies: Application to NGC 4889, the Brightest Cluster Galaxy in Coma
Ho, Luis C.; Huang, Song; Peng, Chien Y. +1 more
Minor mergers are thought to be important for the buildup and structural evolution of massive elliptical galaxies. In this work, we report the discovery of a system of four shell features in NGC 4889, one of the brightest members of the Coma cluster, using optical images taken with the Hubble Space Telescope and the Sloan Digital Sky Survey. The s…
A Redline Starburst: CO(2-1) Observations of an Eddington-limited Galaxy Reveal Star Formation at Its Most Extreme
Moustakas, J.; Rudnick, G. H.; Krips, M. +6 more
We report observations of the CO(2-1) emission of SDSS J1506+54, a compact (r e ≈ 135 pc) starburst galaxy at z = 0.6. SDSS J1506+54 appears to be forming stars close to the limit allowed by stellar radiation pressure feedback models: the measured L_IR/L^{\prime }_CO\approx 1500 is one of the highest measured for any galaxy. With its co…