Measurement of the 0.3-8.5 MeV Galactic gamma-ray spectrum from the Galactic center direction

Harris, M J; Share, G. H.; Leising, M. D.; Kinzer, R. L.; Messina, D. C.

doi:10.1086/169250

Cited by 27 publications

(26 citation statements)

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“…The longitude distribution has an e †ective width of D10¡ FWHM about the center. This narrow component is consistent with OSSE mapping observations of the 0.511 MeV (Harris et al 1990) of the Ñux from the broad Galactic center region (130¡ FWHM circular Ðeld of view). The hatched areas represent the range of systematic uncertainties in the SMM Ñux, while the Ðtted components of the OSSE spectrum are shown as in Fig.…”

Section: Observation and Data Analysissupporting

confidence: 88%

“…The Galactic center region positron annihilation line and continuum components appear to come principally from a central bulge that is sharply peaked toward the center in both latitude and longitude, and a ridge component extending to at least D^35¡ in longitude (Kinzer et al 1996(Kinzer et al , 1998. There also appears to be broadly distributed positron annihilation emission underlying these narrow components (e.g., Harris et al 1990 ;Harris et al 1998). The narrow 1.809 MeV 26Al line follows a broad longitude distribution which is consistent with the CO distribution (e.g., Diehl et al 1995).…”

Section: Introductionmentioning

confidence: 57%

“…Additional insight into the overall distribution of lowenergy gamma rays from the Galactic center direction comes from comparing the small Ðeld of view OSSE observations of the Galactic plane toward the center (di †erential relative to intensities at^10¡ in latitude) with similar but integral observations made with the very broad Ðeld of view Gamma Ray Spectrometer (GRS) instrument on the Solar Maximum Mission satellite (Harris et al 1990), as shown in Figure 5. The average of the measurements from the two OSSE observations at l \ 0¡, b \ 0¡ is indicated in the Ðgure by the Ðlled circles, with the best-Ðt model and its separate components shown as in Figure 1a.…”

Section: Observation and Data Analysismentioning

confidence: 99%

“…uum (e.g., Leventhal, MacCallum, & Stang 1978 ;Riegler et al 1985 ;Harris et al 1990 ;Gehrels et al 1991 ;Slassi et al 1991 ;Smith et al 1993 ;Mahoney, Ling, & Wheaton 1993 ;Kinzer et al 1996Kinzer et al , 1999 ; (3) a 511 keV positron annihilation line (e.g., Johnson, Harnden, & Haymes 1972 ;Leventhal et al 1978 ;Riegler et al 1981 ;Share et al 1988 ;Gehrels et al 1991 ;Slassi et al 1991 ;Purcell et al 1993Purcell et al , 1996Kinzer et al 1996Kinzer et al , 1999 ; (4) a 1.809 MeV 26Al line (e.g., Mahoney et al 1984 ;Share et al 1985 ;Diehl et al 1995) ; and (5) a component resulting from cosmic rays interacting with the interstellar gas and photon Ðelds (e.g., Harris et al 1990 ;Bloemen et al 1994Bloemen et al , 1997Strong et al 1994Strong et al , 1996.…”

Section: Introductionmentioning

confidence: 99%

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Gamma‐Ray Emission from the Inner Galactic Ridge

Kinzer

Purcell

Kurfess

1999

ApJ

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We present measurements of the 0.05È10 MeV gamma-ray spectra as a function of longitude from the inner Galactic ridge using the Oriented Scintillation Spectrometer Experiment (OSSE) on the Compton Gamma Ray Observatory. The di †erential continuum emission relative to intensities at^10¡ Galactic latitude appears to be a composite of at least three independent components : a soft low-energy component with a broad longitude distribution and with spectra well approximated by an exponentially absorbed power law ; a hard component with a similarly broad longitude distribution modeled by a power law from D200 keV to 10 MeV with photon index D[1.75 ; and strong positron annihilation line and continuum contributions observed toward the center with intensities that decrease rapidly with longitude distance from the center. Although OSSE cannot distinguish between a simple one-component latitude distribution and a more complicated one with, for example, broad and narrow latitude components, an "" e †ective ÏÏ 5¡È6¡ FWHM Gaussian latitude width gives a spectrum and intensity for the power-law component that agrees with extrapolations of measurements at higher energies using a cosmic-ray interaction model. However, the latitude distribution of the emission is not well measured. Near the Galactic center, bright variable sources contribute signiÐcantly to the low-energy spectrum. When account is taken of these variable-source contributions, both the soft low-energy and hard powerlaw components show a consistent longitude distribution that follows the Galactic matter distribution as evidenced by the Galactic CO distribution. These results, in conjunction with previous measurements, provide new information for determining the Galactic cosmic-ray electron spectrum at lower energies.

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Section: Observation and Data Analysissupporting

confidence: 88%

Section: Introductionmentioning

confidence: 57%

Section: Observation and Data Analysismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Gamma‐Ray Emission from the Inner Galactic Ridge

Kinzer

Purcell

Kurfess

1999

ApJ

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“…However, we should note that the difference in the morphology of the EGRET Galactic gamma-ray background and hard X-ray (17-60 keV) ridge emission observed by IBIS/ISGRI cannot by itself be considered as a strong argument against the hypothesis of the cosmic ray origin for the GRXE. Indeed, if the hard X-ray background emission of the Galaxy were dominated by bremsstrahlung of low energy ( < ∼ 0.5 MeV) cosmic ray electrons (see, e.g., Stecker 1977;Mandrou et al 1980;Sacher & Schoenfelder 1984;Harris et al 1990), then these electrons might be confined to an almost immediate vicinity of their birthplace if the interstellar magnetic field is sufficiently tangled. 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 11 11 11 11 11 11 11 11 11 11 11 11 11 11 11 11 11 11 11 11 11 X−ray sources Weak Cosmic ray induced background Positron annihilation Fig.…”

Section: )mentioning

confidence: 99%

Hard X-ray emission from the Galactic ridge

Krivonos

Revnivtsev

Churazov

et al. 2006

A&A

123

144

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We present results of a study of the Galactic ridge X-ray emission (GRXE) in hard X-rays performed with the IBIS telescope aboard INTEGRAL. The imaging capabilities of this coding aperture telescope make it possible to account for the flux from bright Galactic point sources whereas the wide field of view permits us to collect large flux from the underlying GRXE. Extensive study of the IBIS/ISGRI detector background allowed us to construct a model that predicts the detector count rate with ∼1−2% accuracy in the energy band 17-60 keV. The derived longitude and latitude profiles of the ridge emission are in good agreement with the Galactic distribution of stars obtained from infrared observations. This, along with the measured hard X-ray spectrum of the Galactic ridge emission strongly indicates its stellar origin. The derived unit stellar mass emissivity of the ridge in the energy band 17-60 keV, (0.9−1.2) × 10 27 erg s −1 M −1 (assuming a bulge mass of 1−1.3 × 10 10 M ), agrees with that of local (in the Solar neigborhood) accreting magnetic white dwarf binaries -dominant contributors to the GRXE at these energies. In addition, the shape of the obtained GRXE spectrum can be used to determine the average mass of white dwarfs in such systems in the Galaxy as ∼0.5 M . The total hard X-ray luminosity of the GRXE is L 17−60 keV = (3.7 ± 0.2) × 10 37 erg s −1 in the 17-60 keV band. At energies 70-200 keV no additional contribution to the total emission of the Galaxy apart from the detected point sources is seen.

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