Search Publications
The Hα-based Star Formation Rate Density of the Universe at z = 0.84
Barro, Guillermo; Pérez-González, Pablo G.; Koo, David C. +5 more
We present the results of an Hα near-infrared narrowband survey searching for star-forming galaxies at redshift z = 0.84. This work is an extension of our previous narrowband studies in the optical at lower redshifts. After removal of stars and redshift interlopers (using spectroscopic and photometric redshifts), we build a complete sample of 165 …
X-Ray Properties of an Unbiased Hard X-Ray-detected Sample of Active Galactic Nuclei
Mushotzky, Richard F.; Tueller, Jack; Markwardt, Craig +1 more
The Swift gamma-ray observatory's Burst Alert Telescope (BAT) has detected a sample of AGNs based solely on their hard X-ray flux (14-195 keV). In this paper we present for the first time XMM-Newton X-ray spectra for 22 BAT AGNs with no previously analyzed X-ray spectra. If our sources are a representative sample of the BAT AGNs, as we claim, our …
3C 454.3 Reveals the Structure and Physics of Its "Blazar Zone"
Madejski, Greg M.; Sikora, Marek; Moderski, RafaŁ
Recent multiwavelength observations of 3C 454.3, in particular during its giant outburst in 2005, put severe constraints on the location of the "blazar zone," its dissipative nature, and high-energy radiation mechanisms. As the optical, X-ray, and millimeter light curves indicate, a significant fraction of the jet energy must be released in the vi…
The Extended HST Supernova Survey: The Rate of SNe Ia at z > 1.4 Remains Low
Riess, Adam G.; Strolger, Louis-Gregory; Dahlen, Tomas
We use the HST ACS imaging of the two GOODS fields during Cycles 11, 12, and 13 to derive the Type Ia supernova rate in four redshift intervals in the range 0.2 < z < 1.8. Compared to our previous results based on Cycle 11 observations only, we have increased the coverage of the search by a factor 2.7, making the total area searched equivale…
The Host Galaxy and Central Engine of the Dwarf Active Galactic Nucleus POX 52
Ho, Luis C.; Thornton, Carol E.; Barth, Aaron J. +2 more
We present new multiwavelength observations of the dwarf Seyfert 1 galaxy POX 52 in order to investigate the properties of the host galaxy and the active nucleus and to examine the mass of its black hole, previously estimated to be ~105 M⊙. HST ACS HRC images show that the host galaxy has a dwarf elliptical morphology (M…
Simultaneous Multiwavelength Observations of the Blazar 1ES 1959+650 at a Low TeV Flux
Maraschi, L.; Tagliaferri, G.; Ghisellini, G. +144 more
We present the results from a multiwavelength campaign on the TeV blazar 1ES 1959+650, performed in 2006 May. Data from the optical, UV, soft- and hard-X-ray, and very high energy (VHE) gamma-ray (E > 100 GeV) bands were obtained with the Suzaku and Swift satellites, the MAGIC telescope, and other ground-based facilities. The source spectral en…
The Rotating Nuclear Star Cluster in NGC 4244
Caldwell, Nelson; Seth, Anil C.; Debattista, Victor P. +2 more
We present observations of the nuclear star cluster in the nearby edge-on spiral galaxy NGC 4244 using the Gemini Near-Infrared Integral Field Spectrograph (NIFS) with laser guide star adaptive optics. From a previous study of edge-on galaxies, this nuclear star cluster was found to be one of a sample of clusters that appear flattened along the pl…
Spitzer/MIPS 24 µm Observations of Galaxy Clusters: An Increasing Fraction of Obscured Star-forming Members from z = 0.02 to z = 0.83
Saintonge, Amélie; Tran, Kim-Vy H.; Holden, Bradford P.
We study the mid-infrared properties of 1315 spectroscopically confirmed members in eight massive (Mvirgtrsim 5 × 1014 M⊙) galaxy clusters covering the redshift range from 0.02 to 0.83. The selected clusters all have deep Spitzer/MIPS 24 µm observations, Hubble and ground-based photometry, and extensive redsh…
Do All Flares Have White-Light Emission?
Mathioudakis, M.; Keenan, F. P.; Jess, D. B. +1 more
High-cadence, multiwavelength optical observations of a solar active region (NOAA AR 10969), obtained with the Swedish Solar Telescope, are presented. Difference imaging of white light continuum data reveals a white-light brightening, 2 minutes in duration, linked to a cotemporal and cospatial C2.0 flare event. The flare kernel observed in the whi…
Proplyds and Massive Disks in the Orion Nebula Cluster Imaged with CARMA and SMA
Carpenter, John M.; Wilner, D.; Eisner, J. A. +3 more
We imaged a 2' × 2' region of the Orion Nebula Cluster (ONC) in 1.3 mm wavelength continuum emission with the recently commissioned Combined Array for Research in Millimeter Astronomy (CARMA) and with the Submillimeter Array (SMA). Our mosaics include >250 known near-IR cluster members, of which 36 are so-called ``proplyds…