Search Publications
Another Nonsegregated Blue Straggler Population in a Globular Cluster: the Case of NGC 2419
Dalessandro, E.; Bellazzini, M.; Ferraro, F. R. +3 more
We have used a combination of ACS HST high-resolution and wide-field Subaru data in order to study the blue straggler star (BSS) population over the entire extension of the remote Galactic globular cluster NGC 2419. The BSS population presented here is among the largest ever observed in any stellar system, with more than 230 BSSs in the brightest …
Spitzer Mid-Infrared Spectroscopy of Infrared Luminous Galaxies at z ~ 2. III. Far-IR to Radio Properties and Optical Spectral Diagnostics
Choi, Philip; Helou, George; Lutz, Dieter +7 more
We present the FIR, millimeter, and radio photometry and optical and NIR spectroscopy of a sample of 48 z ~ 1-3 Spitzer-selected ULIRGs with IRS MIR spectra. Our goals are to compute their bolometric emission and to determine both the presence and relative strength of their AGN and starburst components. We find that strong-PAH sources tend to have…
Dark Matter and Baryons in the X-Ray Luminous Merging Galaxy Cluster RX J1347.5-1145
Treu, Tommaso; Bradač, Maruša; Schrabback, Tim +12 more
The galaxy cluster RX J1347.5-1145 is one of the most X-ray luminous and most massive clusters known. This makes it a prime target for studying issues addressing cluster formation and cosmology. Despite the naive expectation that mass estimation for this cluster should be straightforward (high mass and favorable redshift make it an efficient lens;…
A Comprehensive View of the 2006 December 13 CME: From the Sun to Interplanetary Space
Liu, Y.; Sauvaud, J. -A.; Luhmann, J. G. +7 more
The biggest halo coronal mass ejection (CME) since the Halloween storm in 2003, which occurred on 2006 December 13, is studied in terms of its solar source and heliospheric consequences. The CME was accompanied by an X3.4 flare, EUV dimmings, and coronal waves. It generated significant space weather effects such as an interplanetary shock, radio b…
A Giant Flare from a Soft Gamma Repeater in the Andromeda Galaxy (M31)
Hurley, K.; von Kienlin, A.; Frederiks, D. D. +6 more
The light curve, energy spectra, energetics, and IPN localization of an exceedingly intense, short-duration, hard-spectrum burst, GRB 070201, obtained from Konus-Wind, INTEGRAL (SPI-ACS), and MESSENGER data are presented. The total fluence of the burst and the peak flux are S = 2.00+ 0.10-0.26 × 10-5 erg cm-2<…
The Horizontal Internetwork Magnetic Field: Numerical Simulations in Comparison to Observations with Hinode
Rezaei, R.; Wedemeyer-Böhm, S.; Steiner, O. +1 more
Observations with the Hinode space observatory led to the discovery of predominantly horizontal magnetic fields in the photosphere of the quiet internetwork region. Here we investigate realistic numerical simulations of the surface layers of the Sun with respect to horizontal magnetic fields and compute the corresponding polarimetric response in t…
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…