Search for compton-backscattered annihilation radiation from the galactic center with the OSSE

D. M. Smith; M. Leventhal; N. Gehrels; J. Tueller; W. N. Johnson; R. L. Kinzer; J. D. Kurfess; M. S. Strickman; D. A. Grabelsky; W. R. Purcell; M. P. Ulmer; G. V. Jung

doi:10.1086/175507

Search for compton-backscattered annihilation radiation from the galactic center with the OSSE

D. M. Smith^*, M. Leventhal, N. Gehrels, J. Tueller, W. N. Johnson, R. L. Kinzer, J. D. Kurfess, M. S. Strickman, D. A. Grabelsky, W. R. Purcell, M. P. Ulmer, G. V. Jung

^*Corresponding author for this work

Physics and Astronomy

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Abstract

An emission feature near 170 keV, interpreted as Compton-backscattered 511 keV positron-annihilation radiation has been reported twice by balloon-borne germanium spectrometers from within ∼15° of the Galactic center (Leventhal, MacCallum, & Stang 1978; Smith et al. 1993). Upper limits on this feature set by HEAO 3 (Mahoney, Ling, & Wheaton 1993) and other instruments indicate that it must be transient. We have searched data from the Oriented Scintillation Spectrometer Experiment (OSSE) on the Compton Gamma Ray Observatory (CGRO) for this feature, using daily spectral accumulations from all pointings near the Galactic center up to 1993 August, and covering most of the region viewed by the balloon instruments. We find no evidence for backscatter emission. Under the hypothesis that the source is 1E 1740.7-2942 the OSSE data set (186 days) disagrees with the balloon measurements with 99.3% confidence. The average daily 3 σ OSSE upper limit on backscatter flux from 1E 1740.7-2942 is 6.8 × 10^-4 photons cm^-2 s^-1, compared to the 1.3 × 10^-3 photons cm^-2 reported by the balloon observations. We also saw no evidence in 186 days for linelike emission from the point source EXS 1737.9-2952 recently discovered by Grindlay, Covault & Manandhar (1993). This source exhibited bright emission from 83-111 keV, which has been interpreted as doubly backscattered 511 keV radiation. The average daily 3 σ upper limit from OSSE for this line is 9.8 × 10^-4 photons cm^-2 s^-1, or ∼8% of the reported flux.

Original language	English (US)
Pages (from-to)	117-123
Number of pages	7
Journal	Astrophysical Journal
Volume	443
Issue number	1
DOIs	https://doi.org/10.1086/175507
State	Published - Apr 10 1995

Keywords

Galaxy: center
Gamma-rays: observations

ASJC Scopus subject areas

Astronomy and Astrophysics
Space and Planetary Science

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10.1086/175507

Cite this

@article{bd7c91080e934aa4b0f94e18d5c98311,

title = "Search for compton-backscattered annihilation radiation from the galactic center with the OSSE",

abstract = "An emission feature near 170 keV, interpreted as Compton-backscattered 511 keV positron-annihilation radiation has been reported twice by balloon-borne germanium spectrometers from within ∼15° of the Galactic center (Leventhal, MacCallum, & Stang 1978; Smith et al. 1993). Upper limits on this feature set by HEAO 3 (Mahoney, Ling, & Wheaton 1993) and other instruments indicate that it must be transient. We have searched data from the Oriented Scintillation Spectrometer Experiment (OSSE) on the Compton Gamma Ray Observatory (CGRO) for this feature, using daily spectral accumulations from all pointings near the Galactic center up to 1993 August, and covering most of the region viewed by the balloon instruments. We find no evidence for backscatter emission. Under the hypothesis that the source is 1E 1740.7-2942 the OSSE data set (186 days) disagrees with the balloon measurements with 99.3% confidence. The average daily 3 σ OSSE upper limit on backscatter flux from 1E 1740.7-2942 is 6.8 × 10-4 photons cm-2 s-1, compared to the 1.3 × 10-3 photons cm-2 reported by the balloon observations. We also saw no evidence in 186 days for linelike emission from the point source EXS 1737.9-2952 recently discovered by Grindlay, Covault & Manandhar (1993). This source exhibited bright emission from 83-111 keV, which has been interpreted as doubly backscattered 511 keV radiation. The average daily 3 σ upper limit from OSSE for this line is 9.8 × 10-4 photons cm-2 s-1, or ∼8% of the reported flux.",

keywords = "Galaxy: center, Gamma-rays: observations",

author = "Smith, {D. M.} and M. Leventhal and N. Gehrels and J. Tueller and Johnson, {W. N.} and Kinzer, {R. L.} and Kurfess, {J. D.} and Strickman, {M. S.} and Grabelsky, {D. A.} and Purcell, {W. R.} and Ulmer, {M. P.} and Jung, {G. V.}",

year = "1995",

month = apr,

day = "10",

doi = "10.1086/175507",

language = "English (US)",

volume = "443",

pages = "117--123",

journal = "Astrophysical Journal",

issn = "0004-637X",

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TY - JOUR

T1 - Search for compton-backscattered annihilation radiation from the galactic center with the OSSE

AU - Smith, D. M.

AU - Leventhal, M.

AU - Gehrels, N.

AU - Tueller, J.

AU - Johnson, W. N.

AU - Kinzer, R. L.

AU - Kurfess, J. D.

AU - Strickman, M. S.

AU - Grabelsky, D. A.

AU - Purcell, W. R.

AU - Ulmer, M. P.

AU - Jung, G. V.

PY - 1995/4/10

Y1 - 1995/4/10

N2 - An emission feature near 170 keV, interpreted as Compton-backscattered 511 keV positron-annihilation radiation has been reported twice by balloon-borne germanium spectrometers from within ∼15° of the Galactic center (Leventhal, MacCallum, & Stang 1978; Smith et al. 1993). Upper limits on this feature set by HEAO 3 (Mahoney, Ling, & Wheaton 1993) and other instruments indicate that it must be transient. We have searched data from the Oriented Scintillation Spectrometer Experiment (OSSE) on the Compton Gamma Ray Observatory (CGRO) for this feature, using daily spectral accumulations from all pointings near the Galactic center up to 1993 August, and covering most of the region viewed by the balloon instruments. We find no evidence for backscatter emission. Under the hypothesis that the source is 1E 1740.7-2942 the OSSE data set (186 days) disagrees with the balloon measurements with 99.3% confidence. The average daily 3 σ OSSE upper limit on backscatter flux from 1E 1740.7-2942 is 6.8 × 10-4 photons cm-2 s-1, compared to the 1.3 × 10-3 photons cm-2 reported by the balloon observations. We also saw no evidence in 186 days for linelike emission from the point source EXS 1737.9-2952 recently discovered by Grindlay, Covault & Manandhar (1993). This source exhibited bright emission from 83-111 keV, which has been interpreted as doubly backscattered 511 keV radiation. The average daily 3 σ upper limit from OSSE for this line is 9.8 × 10-4 photons cm-2 s-1, or ∼8% of the reported flux.

AB - An emission feature near 170 keV, interpreted as Compton-backscattered 511 keV positron-annihilation radiation has been reported twice by balloon-borne germanium spectrometers from within ∼15° of the Galactic center (Leventhal, MacCallum, & Stang 1978; Smith et al. 1993). Upper limits on this feature set by HEAO 3 (Mahoney, Ling, & Wheaton 1993) and other instruments indicate that it must be transient. We have searched data from the Oriented Scintillation Spectrometer Experiment (OSSE) on the Compton Gamma Ray Observatory (CGRO) for this feature, using daily spectral accumulations from all pointings near the Galactic center up to 1993 August, and covering most of the region viewed by the balloon instruments. We find no evidence for backscatter emission. Under the hypothesis that the source is 1E 1740.7-2942 the OSSE data set (186 days) disagrees with the balloon measurements with 99.3% confidence. The average daily 3 σ OSSE upper limit on backscatter flux from 1E 1740.7-2942 is 6.8 × 10-4 photons cm-2 s-1, compared to the 1.3 × 10-3 photons cm-2 reported by the balloon observations. We also saw no evidence in 186 days for linelike emission from the point source EXS 1737.9-2952 recently discovered by Grindlay, Covault & Manandhar (1993). This source exhibited bright emission from 83-111 keV, which has been interpreted as doubly backscattered 511 keV radiation. The average daily 3 σ upper limit from OSSE for this line is 9.8 × 10-4 photons cm-2 s-1, or ∼8% of the reported flux.

KW - Galaxy: center

KW - Gamma-rays: observations

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DO - 10.1086/175507

M3 - Article

AN - SCOPUS:11944269281

SN - 0004-637X

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JO - Astrophysical Journal

JF - Astrophysical Journal

IS - 1

ER -

Search for compton-backscattered annihilation radiation from the galactic center with the OSSE

Abstract

Keywords

ASJC Scopus subject areas

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