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The Compact, Conical, Accretion-Disk Warm Absorber of the Seyfert 1 Galaxy NGC 4051 and Its Implications for IGM-Galaxy Feedback Processes
Elvis, Martin; Nicastro, Fabrizio; Mathur, Smita +4 more
Using a 100 ks XMM-Newton exposure of NGC 4051, we show that the time evolution of the ionization state of the X-ray absorbers in response to the rapid and highly variable X-ray continuum constrains all the main physical and geometrical properties of an AGN ``warm absorber'' wind. The absorber consists of two different ionization components, with …
Hα Tail, Intracluster H II Regions, and Star Formation: ESO 137-001 in Abell 3627
Sun, M.; Donahue, M.; Voit, G. M.
We present the discovery of a 40 kpc Hα tail and at least 29 emission-line objects downstream of a star-forming galaxy, ESO 137-001, in the rich, nearby cluster A3627. The galaxy is known to possess a dramatic 70 kpc X-ray tail. The detected Hα tail coincides positionally with the X-ray tail. The Hα emission in the galaxy is sharply truncated on t…
A New Population of High-Redshift Short-Duration Gamma-Ray Bursts
Cenko, S. B.; Peterson, B. A.; Price, P. A. +23 more
The redshift distribution of the short-duration gamma-ray bursts (GRBs) is a crucial, but currently fragmentary, clue to the nature of their progenitors. Here we present optical observations of nine short GRBs obtained with Gemini, Magellan, and the Hubble Space Telescope. We detect the afterglows and host galaxies of two short bursts, and host ga…
Leo A: A Late-blooming Survivor of the Epoch of Reionization in the Local Group
Dolphin, Andrew E.; Skillman, Evan D.; Cole, Andrew A. +8 more
As part of a major program to use isolated Local Group dwarf galaxies as near-field probes of cosmology, we have obtained deep images of the dwarf irregular galaxy Leo A with the Advanced Camera for Surveys aboard the Hubble Space Telescope. From these images we have constructed a color-magnitude diagram (CMD) reaching apparent [absolute] magnitud…
Binaries and the L Dwarf/T Dwarf Transition
Burgasser, Adam J.
High-resolution imaging has revealed an unusually high binary fraction among objects spanning the transition between the L dwarf and T dwarf spectral classes. In an attempt to reproduce and unravel the origins of this apparent binary excess, I present a series of Monte Carlo mass function and multiplicity simulations of field brown dwarfs in the v…
NICMOS Imaging of DRGs in the HDF-S: A Relation between Star Formation and Size at z ~ 2.5
Daddi, E.; Toft, S.; Rix, H. -W. +9 more
We present deep, high angular-resolution HST NICMOS imaging in the Hubble Deep Field South (HDF-S), focusing on a subset of 14 distant red galaxies (DRGs) at z~2.5 that have been preselected to have J-K>2.3. We find a clear trend between the rest-frame optical sizes of these sources and their luminosity-weighted stellar ages as inferred from th…
A Comparative Study between Eruptive X-Class Flares Associated with Coronal Mass Ejections and Confined X-Class Flares
Wang, Yuming; Zhang, Jie
We examine the two kinds of major energetic phenomena that occur in the solar atmosphere: eruptive and confined events. The former describes flares with associated coronal mass ejections (CMEs), while the latter denotes flares without associated CMEs. We find that about 90% of X-class flares are eruptive, but the remaining 10% are confined. To pro…
Evidence for a Population of High-Redshift Submillimeter Galaxies from Interferometric Imaging
Kohno, Kotaro; Wilner, David J.; Schinnerer, Eva +22 more
We have used the Submillimeter Array to image a flux-limited sample of seven submillimeter galaxies, selected by the AzTEC camera on the JCMT at 1.1 mm, in the COSMOS field at 890 µm with ~2" resolution. All of the sources-two radio-bright and five radio-dim-are detected as single point sources at high significance (>6 σ), with positions …
The White Dwarf Cooling Sequence of NGC 6397
Anderson, Jay; Dotter, Aaron; Rich, R. Michael +10 more
We present the results of a deep Hubble Space Telescope (HST) exposure of the nearby globular cluster NGC 6397, focussing attention on the cluster's white dwarf cooling sequence. This sequence is shown to extend over 5 mag in depth, with an apparent cutoff at magnitude F814W~27.6. We demonstrate, using both artificial star tests and the detectabil…
Probing the Dark Matter and Gas Fraction in Relaxed Galaxy Groups with X-Ray Observations from Chandra and XMM-Newton
Humphrey, Philip J.; Buote, David A.; Brighenti, Fabrizio +4 more
We present radial mass profiles within ~0.3rvir for 16 relaxed galaxy groups-poor clusters (kT range 1-3 keV) selected for optimal mass constraints from the Chandra and XMM-Newton data archives. After accounting for the mass of hot gas, the resulting mass profiles are described well by a two-component model consisting of dark matter, re…