Search Publications
Testing the blazar spectral sequence: X-ray-selected blazars
Maraschi, L.; Ghisellini, G.; Tavecchio, F. +2 more
We present simultaneous optical and X-ray data from Swift for a sample of radio-loud flat-spectrum quasars selected from the Einstein Medium Sensitivity Survey (EMSS). We present also a complete analysis of Swift and INTEGRAL data on four blazars recently discussed as possibly challenging the trends of the hypothesized `blazar spectral sequence'. …
The Spectral Lag of GRB 060505: A Likely Member of the Long-Duration Class
McGlynn, S.; McBreen, S.; Foley, S. +7 more
Two long γ-ray bursts, GRB 060505 and GRB 060614, occurred in nearby galaxies at redshifts of 0.089 and 0.125, respectively. Due to their proximity and durations, deep follow-up campaigns to search for supernovae (SNe) were initiated. However, none were found in either case, to limits more than 2 orders of magnitude fainter than the prototypical G…
An X-Ray Survey of Wolf-Rayet Stars in the Magellanic Clouds. I. The Chandra ACIS Data Set
Guerrero, Martín A.; Chu, You-Hua
Wolf-Rayet (WR) stars are evolved massive stars with strong fast stellar winds. WR stars in our Galaxy have shown three possible sources of X-ray emission associated with their winds: shocks in the winds, colliding stellar winds, and wind-blown bubbles; however, quantitative analyses of observations are often hampered by uncertainties in distances…
Suzaku Spectroscopy of an X-Ray Reflection Nebula and a New Supernova Remnant Candidate in the SgrB1 Region
Koyama, Katsuji; Nakajima, Hiroshi; Matsumoto, Hironori +7 more
We made a 100 ks observation of the Sagittarius (Sgr) B1 region at (l, b) = (0°.5, -0°.1) near to the Galactic center (GC) with the Suzaku/XIS. Emission lines of SXV, FeI, FeXXV, and FeXXVI were clearly detected in the spectrum. We found that the FeXXV and FeXXVI line emissions smoothly distribute over the SgrB1 and B2 regions connecting from the …
In-Orbit Timing Calibration of the Hard X-Ray Detector on Board Suzaku
Dotani, Tadayasu; Enoto, Teruaki; Yamaoka, Kazutaka +28 more
The hard X-ray detector (HXD) aboard the X-ray satellite Suzaku is designed to have a good timing capability with a 61µs time resolution. In addition to detailed descriptions of the HXD timing system, results of in-orbit timing calibration and the performance of the HXD are summarized. The relative accuracy of time measurements of the HXD ev…
Chandra ACIS Survey of M33 (ChASeM33): A First Look
Blair, William P.; Hughes, John P.; Sasaki, Manami +22 more
We present an overview of the Chandra ACIS Survey of M33 (ChASeM33): A Deep Survey of the Nearest Face-on Spiral Galaxy. The 1.4 Ms survey covers the galaxy out to R ≈ 18'(≈ 4 kpc) . These data provide the most intensive, high spatial resolution assessment of the X-ray source populations available for the confused inner regions of M33. Mosaic imag…
Submillimeter Structure of the Disk of the Butterfly Star
Stapelfeldt, K. R.; Wolf, S.; Beuther, H. +2 more
We present a spatially resolved 894 µm map of the circumstellar disk of the Butterfly Star in Taurus (IRAS 04302+2247), obtained with the Submillimeter Array (SMA). The predicted and observed radial brightness profiles agree well in the outer disk region but differ in the inner region with an outer radius of ~80-120 AU. In particular, we fin…
Suzaku Observations of the North Polar Spur: Evidence for Nitrogen Enhancement
Miller, Eric D.; Katsuda, Satoru; Kokubun, Motohide +10 more
We present observations of the North Polar Spur (NPS) using the X-ray Imaging Spectrometer (XIS) aboard the Suzaku X-ray satellite. The NPS is a large region of enhanced soft X-ray and radio emission projected above the plane of the Galaxy, likely produced by a series of supernovae and stellar winds from the nearby Sco-Cen OB association. The exce…
Unveiling the Important Role of Groups in the Evolution of Massive Galaxies: Insights from an Infrared Passive Sequence at Intermediate Redshift
Wilman, D. J.; Mulchaey, J. S.; Balogh, M. L. +6 more
The most massive galaxies in the universe are also the oldest. To overturn this apparent contradiction with hierarchical growth models we focus on the group-scale halos that host most of these galaxies. Our z ~ 0.4 group sample is selected in redshift space from the CNOC2 redshift survey. A stellar mass-selected M*gtrsim 2 × 1010
The long-term X-ray variability properties of AGNs in the Lockman Hole region
Papadakis, I. E.; Georgantopoulos, I.; Markowitz, A. +2 more
Context: We present the results from a detailed X-ray variability analysis of 66 AGN in the Lockman Hole, which have optical spectroscopic identifications.
Aims: We compare, quantitatively, their variability properties with the properties of local AGN, and we study the “variability - luminosity” relation as a function of redshift, and the “var…