Search Publications
A Global Two-temperature Corona and Inner Heliosphere Model: A Comprehensive Validation Study
Fedorov, A.; Llebaria, A.; Lamy, P. L. +9 more
The recent solar minimum with very low activity provides us a unique opportunity for validating solar wind models. During CR2077 (2008 November 20 through December 17), the number of sunspots was near the absolute minimum of solar cycle 23. For this solar rotation, we perform a multi-spacecraft validation study for the recently developed three-dim…
Broadband Spectral Analysis of the Galactic Ridge X-Ray Emission
Makishima, Kazuo; Nakazawa, Kazuhiro; Yuasa, Takayuki
Detailed spectral analysis of the Galactic X-ray background emission, or the Galactic Ridge X-ray Emission (GRXE), is presented. To study the origin of the emission, broadband and high-quality GRXE spectra were produced from 18 pointing observations with Suzaku in the Galactic bulge region, with a total exposure of 1 Ms. The spectra were successfu…
Search for Gamma-ray Emission from X-Ray-selected Seyfert Galaxies with Fermi-LAT
Ozaki, M.; Troja, E.; Caraveo, P. A. +133 more
We report on a systematic investigation of the γ-ray properties of 120 hard X-ray-selected Seyfert galaxies classified as "radio-quiet" objects, utilizing the three-year accumulation of Fermi Large Area Telescope (LAT) data. Our sample of Seyfert galaxies is selected using the Swift Burst Alert Telescope 58 month catalog, restricting the analysis …
Tracing the Gas to the Virial Radius (R 100) in a Fossil Group
Humphrey, Philip J.; Buote, David A.; Brighenti, Fabrizio +3 more
We present a Chandra, Suzaku, and ROSAT study of the hot intragroup medium (IGrM) of the relaxed fossil group/poor cluster RX J1159+5531. This group exhibits an advantageous combination of flat surface brightness profile, high luminosity, and optimal distance, allowing the gas to be detected out to the virial radius (R vir≡ R 108
Analyzing Star Cluster Populations with Stochastic Models: The Hubble Space Telescope/Wide Field Camera 3 Sample of Clusters in M83
Whitmore, Bradley C.; Chandar, Rupali; Fouesneau, Morgan +1 more
The majority of clusters in the universe have masses well below 105 M ⊙. Hence, their integrated fluxes and colors can be affected by the presence or absence of a few bright stars introduced by stochastic sampling of the stellar mass function. Specific methods are being developed to extend the analysis of cluster energy distr…
Star-Galaxy Classification in Multi-band Optical Imaging
Hogg, David W.; Fadely, Ross; Willman, Beth
Ground-based optical surveys such as PanSTARRS, DES, and LSST will produce large catalogs to limiting magnitudes of r >~ 24. Star-galaxy separation poses a major challenge to such surveys because galaxies—even very compact galaxies—outnumber halo stars at these depths. We investigate photometric classification techniques on stars and galaxies w…
A Population of z > 2 Far-infrared Herschel-SPIRE-selected Starbursts
Berta, S.; Magnelli, B.; Lutz, D. +29 more
We present spectroscopic observations for a sample of 36 Herschel-SPIRE 250-500 µm selected galaxies (HSGs) at 2 < z < 5 from the Herschel Multi-tiered Extragalactic Survey. Redshifts are confirmed as part of a large redshift survey of Herschel-SPIRE-selected sources covering ~0.93 deg2 in six extragalactic legacy fields. Ob…
Multiwavelength Observations of V2775 Ori, an Outbursting Protostar in L 1641: Exploring the Edge of the FU Orionis Regime
Henning, Thomas; Manoj, P.; Kounkel, Marina +9 more
Individual outbursting young stars are important laboratories for studying the physics of episodic accretion and the extent to which this phenomenon can explain the luminosity distribution of protostars. We present new and archival data for V2775 Ori (HOPS 223), a protostar in the L 1641 region of the Orion molecular clouds that was discovered by …
Flare-generated Type II Burst without Associated Coronal Mass Ejection
Zhukov, A. N.; Magdalenić, J.; Vršnak, B. +2 more
We present a study of the solar coronal shock wave on 2005 November 14 associated with the GOES M3.9 flare that occurred close to the east limb (S06° E60°). The shock signature, a type II radio burst, had an unusually high starting frequency of about 800 MHz, indicating that the shock was formed at a rather low height. The position of the radio so…
The Birth of an Ultraluminous X-Ray Source in M83
Soria, Roberto; Blair, William P.; Whitmore, Bradley C. +4 more
A previously undetected (LX < 1036 erg s-1) source in the strongly star-forming galaxy M83 entered an ultraluminous state between 2009 August and 2010 December. It was first seen with Chandra on 2010 December 23 at LX ≈ 4 × 1039 erg s-1 and has remained ultraluminous through our …