A gamma-ray flare from PKS 2255-282

D. J. Macomb; N. Gehrels; C. R. Shrader

doi:10.1086/306869

A gamma-ray flare from PKS 2255-282

D. J. Macomb, N. Gehrels, C. R. Shrader

Physics Department

NASA Goddard Space Flight Center

Research output: Contribution to journal › Article › peer-review

7 Scopus citations

Abstract

A gamma-ray flare from the quasar PKS 2255-282 was detected in 1997 December by the EGRET instrument on board the Compton Gamma Ray Observatory (CGRO). Previously undetected at gamma-ray energies, the source remained bright for 2 weeks of observations with weak evidence of gamma-ray variability within the flare observation. The average flux was (1.6 ± 0.3) x 10^-6 cm^-2 s^-1 above 100 MeV with a hard power-law index of 1.7 ± 0.3. This places the outburst among the brightest detected by EGRET. A later Rossi X-Ray Timing Explorer (RXTE) observation revealed a simple power-law spectrum with photon index 1.8 and 2-10 keV flux of 1.44 x 10^-11 ergs cm^-2 s^-1. This paper describes the CGRO and RXTE observations and data analysis, the source identification, and gamma-ray variability. We also consider the broadband spectrum, albeit on the basis of nonsimultaneous multiwavelength measurements, and the nature of the outburst from this source in the context of other known gamma-ray blazars.

Original language	English
Pages (from-to)	652-655
Number of pages	4
Journal	Astrophysical Journal
Volume	513
Issue number	2 PART 1
DOIs	https://doi.org/10.1086/306869
State	Published - 10 Mar 1999

Keywords

Gamma rays: observations
Quasars: individual (PKS 2255-282)
X-rays: galaxies

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10.1086/306869

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title = "A gamma-ray flare from PKS 2255-282",

abstract = "A gamma-ray flare from the quasar PKS 2255-282 was detected in 1997 December by the EGRET instrument on board the Compton Gamma Ray Observatory (CGRO). Previously undetected at gamma-ray energies, the source remained bright for 2 weeks of observations with weak evidence of gamma-ray variability within the flare observation. The average flux was (1.6 ± 0.3) x 10-6 cm-2 s-1 above 100 MeV with a hard power-law index of 1.7 ± 0.3. This places the outburst among the brightest detected by EGRET. A later Rossi X-Ray Timing Explorer (RXTE) observation revealed a simple power-law spectrum with photon index 1.8 and 2-10 keV flux of 1.44 x 10-11 ergs cm-2 s-1. This paper describes the CGRO and RXTE observations and data analysis, the source identification, and gamma-ray variability. We also consider the broadband spectrum, albeit on the basis of nonsimultaneous multiwavelength measurements, and the nature of the outburst from this source in the context of other known gamma-ray blazars.",

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author = "Macomb, {D. J.} and N. Gehrels and Shrader, {C. R.}",

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doi = "10.1086/306869",

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T1 - A gamma-ray flare from PKS 2255-282

AU - Macomb, D. J.

AU - Gehrels, N.

AU - Shrader, C. R.

PY - 1999/3/10

Y1 - 1999/3/10

N2 - A gamma-ray flare from the quasar PKS 2255-282 was detected in 1997 December by the EGRET instrument on board the Compton Gamma Ray Observatory (CGRO). Previously undetected at gamma-ray energies, the source remained bright for 2 weeks of observations with weak evidence of gamma-ray variability within the flare observation. The average flux was (1.6 ± 0.3) x 10-6 cm-2 s-1 above 100 MeV with a hard power-law index of 1.7 ± 0.3. This places the outburst among the brightest detected by EGRET. A later Rossi X-Ray Timing Explorer (RXTE) observation revealed a simple power-law spectrum with photon index 1.8 and 2-10 keV flux of 1.44 x 10-11 ergs cm-2 s-1. This paper describes the CGRO and RXTE observations and data analysis, the source identification, and gamma-ray variability. We also consider the broadband spectrum, albeit on the basis of nonsimultaneous multiwavelength measurements, and the nature of the outburst from this source in the context of other known gamma-ray blazars.

AB - A gamma-ray flare from the quasar PKS 2255-282 was detected in 1997 December by the EGRET instrument on board the Compton Gamma Ray Observatory (CGRO). Previously undetected at gamma-ray energies, the source remained bright for 2 weeks of observations with weak evidence of gamma-ray variability within the flare observation. The average flux was (1.6 ± 0.3) x 10-6 cm-2 s-1 above 100 MeV with a hard power-law index of 1.7 ± 0.3. This places the outburst among the brightest detected by EGRET. A later Rossi X-Ray Timing Explorer (RXTE) observation revealed a simple power-law spectrum with photon index 1.8 and 2-10 keV flux of 1.44 x 10-11 ergs cm-2 s-1. This paper describes the CGRO and RXTE observations and data analysis, the source identification, and gamma-ray variability. We also consider the broadband spectrum, albeit on the basis of nonsimultaneous multiwavelength measurements, and the nature of the outburst from this source in the context of other known gamma-ray blazars.

KW - Gamma rays: observations

KW - Quasars: individual (PKS 2255-282)

KW - X-rays: galaxies

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U2 - 10.1086/306869

DO - 10.1086/306869

M3 - Article

AN - SCOPUS:0033540920

SN - 0004-637X

VL - 513

SP - 652

EP - 655

JO - Astrophysical Journal

JF - Astrophysical Journal

IS - 2 PART 1

ER -

A gamma-ray flare from PKS 2255-282

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Keywords

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