EGRET/COMPTEL observations of an unusual, steep-spectrum gamma-ray source

Thompson, D. J.; Bertsch, D. L.; Hartman, R. C.; Collmar, W.; Johnson, W. N.
April 2000
AIP Conference Proceedings;2000, Vol. 510 Issue 1, p479
Academic Journal
During analysis of sources below the threshold of the third EGRET catalog, we have discovered a source, named GRO J1400-3956 based on the best position, with a remarkably steep spectrum. Archival analysis of COMPTEL data shows that the spectrum must have a strong turn-over in the energy range between COMPTEL and EGRET. The EGRET data show some evidence of time variability, suggesting an AGN, but the spectral change of slope is larger than that seen for most gamma-ray blazars. The sharp cutoff resembles the high-energy spectral breaks seen in some gamma-ray pulsars. There have as yet been no OSSE observations of this source. © 2000 American Institute of Physics.


Related Articles

  • Optical studies of potential counterparts for unidentified EGRET sources. Carramin˜ana, A.; Chavushyan, V.; Zharikov, S.; Reimer, O.; Brazier, K. T. S. // AIP Conference Proceedings;2000, Vol. 510 Issue 1, p494 

    We present optical observations of candidate X-ray counterparts for the EGRET sources 3EG J2020+4017, 3EG J0010+7309 and 3EG J1835+5918. Preliminary spectroscopic observations of the late-type star coincident with the X-ray counterpart of 3EG J2020+4017, the γ-Cygni source, show no evidence...

  • Science with the International Gamma-Ray Astrophysics Laboratory INTEGRAL. Winkler, Christoph; Hermsen, Wim // AIP Conference Proceedings;2000, Vol. 510 Issue 1, p676 

    The International Gamma-Ray Astrophysics Laboratory (INTEGRAL), to be launched in 2001, is dedicated to the fine spectroscopy (ΔE: 2 keV FWHM @ 1.3 MeV) and fine imaging (angular resolution: 12′ FWHM) of celestial gamma-ray sources in the energy range 15 keV to 10 MeV with concurrent...

  • Event-by-Event Energy Estimation and Spectral Determination with Milagro. Allen, Branden T.; Yodh, Gaurang B. // AIP Conference Proceedings;2007, Vol. 921 Issue 1, p528 

    The observed characteristics of a TeV gamma ray shower which triggers Milagro depend on core location, zenith angle, and primary energy. An algorithm to estimate the primary energy on an event-by-event basis based upon observed quantities has been devised. This algorithm is applied to signals...

  • Observing peculiar γ-ray pulsars with AGILE. Pilia, M.; Pellizzoni, A. // AIP Conference Proceedings;8/18/2011, Vol. 1357 Issue 1, p229 

    The AGILE γ-ray satellite provides large sky exposure levels (≥109 cm2 s per year on the Galactic Plane) with sensitivity peaking at E ∼100 MeV where the bulk of pulsar energy output is typically released. Its ∼1 μs absolute time tagging capability makes it perfectly suited...

  • Demystifying an unidentified EGRET source by VHE gamma-ray observations. Reimer, Olaf; Funk, Stefan // Astrophysics & Space Science;May2007, Vol. 309 Issue 1-4, p203 

    In a novel approach in observational high-energy gamma-ray astronomy, observations carried out by imaging atmospheric Cherenkov telescopes provide necessary templates to pinpoint the nature of intriguing, yet unidentified EGRET gamma-ray sources. Using GeV-photons detected by EGRET and taking...

  • Status and Prospects of Fermi LAT Pulsar Blind Searches. Parkinson, P. M. Saz // AIP Conference Proceedings;8/18/2011, Vol. 1357 Issue 1, p48 

    Blind Searches of Fermi Large Area Telescope (LAT) data have resulted in the discovery of 24 γ-ray pulsars in the first year of survey operations, most of which remain undetected in radio, despite deep radio follow-up searches. I summarize the latest Fermi LAT blind search efforts and...

  • EGRET unidentified sources. Grenier, Isabelle A. // AIP Conference Proceedings;2000, Vol. 515 Issue 1, p261 

    Nearly 60% of the EGRET sources are still defeating our attempts at identifying them. The present strategy to elucidate their nature is three-fold: search for counterparts at other wavelengths; search for temporal signatures characteristic of pulsars, binaries or flaring sources; correlation...

  • Could the unidentified EGRET sources in the Gould Belt be of pulsar origin? Zhang, Bing; Harding, Alice K. // AIP Conference Proceedings;2001, Vol. 558 Issue 1, p767 

    We explore the possibility, within the polar cap model, that at least some of the recently identified new population of EGRET sources in the Gould Belt sources are γ-ray pulsars, viewed at large angles to the magnetic axis, such that the line-of-sight misses both the bright gamma-ray double...

  • Artifact sources near bright EGRET pulsars. Thompson, D. J.; Bertsch, D. L.; Hartman, R. C. // AIP Conference Proceedings;2001, Vol. 587 Issue 1, p668 

    As noted in the Third EGRET Catalog, six sources near the bright Vela pulsar are thought to be artifacts: 3EG J0824-4610, 3EG J0827-4247, 3EG J0828-4954, 3EG J0841- 4356, 3EG J0848-4429, and 3EG J0859-4257. This conclusion is based on analysis of phase-resolved maps of the pulsar region. The...


Read the Article


Sorry, but this item is not currently available from your library.

Try another library?
Sign out of this library

Other Topics