Search Publications
Evidence for a Supernova Associated with the X-Ray Flash 020903
Covino, S.; Becker, A. C.; Filippenko, A. V. +24 more
We present ground-based and Hubble Space Telescope optical observations of the X-ray flash (XRF) 020903, covering 300 days. The afterglow showed a very rapid rise in the first day, followed by a relatively slow decay in the next few days. There was a clear bump in the light curve after ~25 days, accompanied by a drastic change in the spectral ener…
Rings and Bent Chain Galaxies in the GEMS and GOODS Fields
Elmegreen, Bruce G.; Elmegreen, Debra Meloy
Twenty-four galaxies with rings or partial rings were studied in the GEMS and GOODS fields out to z~1.4. Most resemble local collisional ring galaxies in morphology, size, and clumpy star formation. Clump ages range from 108 to 109 yr, and clump masses go up to several × 108 Msolar, based on color evolut…
A Multi-Wavelength Study of the Compact M1 Flare on October 22, 2002
Mason, H. E.; Schmieder, B.; Berlicki, A. +1 more
In this paper we present a further study of the Ml class flare observed on October 22, 2002. We focus on the SOHO Coronal Diagnostic Spectrometer (CDS) spectral observations performed during a multi-wavelength campaign with TRACE and ground-based instruments (VTT, THEMIS). Strong blue-shifts are observed in the CDS coronal lines in flare kernels d…
Cyclotron Resonance Energies at a Low X-Ray Luminosity: A0535+262 Observed with Suzaku
Mukai, K.; Yonetoku, D.; Mihara, T. +28 more
The binary X-ray pulsar A0535+262 was observed with the Suzaku X-ray observatory on 2005 September 14 for a net exposure of 22 ks. The source was in the declining phase of a minor outburst, exhibiting 3-50 keV luminosity of ~3.7×1035 ergs s-1 at an assumed distance of 2 kpc. In spite of the very low source intensity (about 30…
Cosmic-ray diffusion near the Bohm limit in the Cassiopeia A supernova remnant
Stage, M. D.; Allen, G. E.; Houck, J. C. +1 more
The acceleration of cosmic rays in our Galaxy by means of diffusive shock (Fermi) acceleration is believed to occur primarily in supernova remnants (SNRs). Despite considerable theoretical work, the precise details are still unknown, in part because of the difficulty in directly observing nucleons that are accelerated to TeV energies in-and affect…
First results of the XI Groups Project: studying an unbiased sample of galaxy groups
Raychaudhury, Somak; Mulchaey, John S.; Ponman, Trevor J. +2 more
X-ray observations of hot, intergalactic gas in galaxy groups provide a useful means of characterizing the global properties of groups. However, X-ray studies of large group samples have typically involved very shallow X-ray exposures or have been based on rather heterogeneous samples. Here we present the first results of the XI (XMM/IMACS) Groups…
On the Feedback from Super Stellar Clusters. I. The Structure of Giant H II Regions and H II Galaxies
Tenorio-Tagle, Guillermo; Muñoz-Tuñón, Casiana; Pérez, Enrique +2 more
We review the structural properties of giant extragalactic H II regions and H II galaxies based on two-dimensional hydrodynamic calculations and propose an evolutionary sequence that accounts for their observed detailed structure. The model assumes a massive and young stellar cluster surrounded by a large collection of clouds. These are thus expos…
XMM-Newton observations of a sample of γ-ray loud active galactic nuclei
Maraschi, L.; Tagliaferri, G.; Ghisellini, G. +7 more
Aims.To understand the nature of γ-ray loud active galactic nuclei (AGN) and the mechanisms for the generation of high-energy γ-rays.
Methods: .We performed a homogeneous and systematic analysis of simultaneous X-ray and optical/UV properties of a group of 15 γ-ray loud AGN, using observations performed with XMM-Newton. The sample is composed …
Relationships Among Magnetic Clouds, CMES, and Geomagnetic Storms
Gopalswamy, N.; Lepping, R. P.; Wu, C. C.
During solar cycle 23, 82 interplanetary magnetic clouds (MCs) were identified by the Magnetic Field Investigation (MFI) team using Wind (1995 - 2003) solar wind plasma and magnetic field data from solar minimum through the maximum of cycle 23. The average occurrence rate is 9.5 MCs per year for the overall period. It is found that some of the ano…
The role of the wind-transported dust in slope streaks activity: Evidence from the HRSC data
Mangold, N.; Forget, F.; Neukum, G. +7 more
Slope streaks are gravity-driven albedo features observed on martian slopes since the Viking missions. The debated mechanism of formation could involve alternatively dry granular flow or wet mass wasting. A systematic mapping of slope streaks from the High Resolution Stereo Camera is presented in this paper. Two regions known for their slope strea…