1,520 research outputs found
Analysis and interpretation of diffuse x-ray emission using data from the Einstein satellite
An ambitious program to create a powerful and accessible archive of the HEAO-2 Imaging Proportional Counter (IPC) database was outlined. The scientific utility of that database for studies of diffuse x ray emissions was explored. Technical and scientific accomplishments are reviewed. Three papers were presented which have major new scientific findings relevant to the global structure of the interstellar medium and the origin of the cosmic x ray background. An all-sky map of diffuse x ray emission was constructed
A complete database for the Einstein imaging proportional counter
A complete database for the Einstein Imaging Proportional Counter (IPC) was completed. The original data that makes up the archive is described as well as the structure of the database, the Op-Ed analysis system, the technical advances achieved relative to the analysis of (IPC) data, the data products produced, and some uses to which the database has been put by scientists outside Columbia University over the past year
The x ray population in globular clusters and three crab-like SNR in the large Magellanic cloud
This document is to serve as the requisite Final Technical Report on grant NAG5-1557 which was awarded under the NASA ROSAT Guest Investigator Program to Columbia University. In response to the NASA Research Anouncement describing the first round of Guest Investigations to be carried out under the U.S.-German ROSAT Program (AO-1), the PI submitted several proposals, three of which were accepted in part: (1) the x-ray population of globular clusters; (2) three crab-like SNR in the Large Magellanic Cloud; and (3) x rays from nearby radio pulsars. The status of these three programs as of 31 May 1993, the termination date of the grant, is reported
Discovery of a Pulsar Candidate Associated with the TeV Gamma-ray Source HESS J1813-178
We present a Chandra X-ray observation of G12.82-0.02, a shell-like radio
supernova remnant coincident with the TeV gamma-ray source HESS J1813-178. We
resolve the X-ray emission from the co-located ASCA source into a compact
object surrounded by structured diffuse emission that fills the interior of the
radio shell. The morphology of the diffuse emission strongly resembles that of
a pulsar wind nebula. The spectrum of the compact source is well-characterized
by a power-law with index approx. 1.3, typical of young and energetic
rotation-powered pulsars. For a distance of 4.5 kpc, consistent with the X-ray
absorption, the 2-10 keV X-ray luminosity of the putative pulsar and nebula is
L(PSR) = 3.2E33 erg/s and L(PWN) = 1.4E34 erg/s, respectively. Both the flux
ratio of L(PWN)/L(PSR) = 4.3 and the total luminosity of this system imply a
pulsar spin-down power greater then 1E37 erg/s, on a par with the top ten most
energetic young pulsars in the Galaxy. We associate the putative pulsar with
the radio remnant and the TeV source and discuss the origin of the gamma-ray
emission.Comment: 3 Pages, 3 Figures. Latex, aipproc.cls. To be published in "The
Proceedings of the First International GLAST Symposium" (Held Febuary 5-8,
2007, Stanford Univ., USA), AIP, Eds. S. Ritz, P.F. Michelson, and C. Meegan.
Updated coordinate
Will GRB 990123 Perform an Encore?
The recent gamma ray burst, GRB 990123, has an absorption redshift z_s=1.60,
implying an apparent energy , and a peak luminosity
, assuming isotropic emission. This energy is
ten times larger than hitherto measured and in excess of the rest mass of the
sun. Optical observations have revealed an associated galaxy displaced from the
line of sight by . This raises the possibility that the burst is
enhanced by gravitational lensing. We argue that existing observations probably
only allow magnifications if the galaxy is at z_d=1.60 and the burst
originates at much higher redshift. It should be possible to exclude this
possibility by examining the burst time structure. If, as we anticipate,
multiple imaging can be excluded, GRB 990123 remains the most intrinsically
luminous event yet observed in its entirety.Comment: Accepted by MNRAS: 4 pages, latex, no figure
Far infrared observations of crab-like supernova remnants
Using the Infrared Astronomy Satellite (IRAS) data, an investigation was begun of the far infrared properties of Crab-like supernova remnants and other synchrotron nebulae. Both the co-added scanning data and, where available, pointed observations were examined. To date infrared emission was found from two Crab-like remnants: G24.7+0.6 in which the infrared source near the center of the object was shown to be a compact HII region with EM greater than or approximately 10 to the 7th pc/cm(6); and G0.9+0.1 where a marginal detection of a 25 micron source coincident with the remnant core was used to set limits on the energetics of this synchrotron nebula. Further work, in progress under a second year of this program, should yield additional information concerning the distribution of initial pulsar spin periods and the evolution of synchrotron nebulae
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