Detection of Hard X-Radiation from Virgo

Haymes, R. C.; Ellis, Darwin V.; Fishman, G.; Glenn, S. W.; Kurfess, J. D.

doi:10.1086/180157

Cited by 18 publications

(4 citation statements)

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“…Recent high resolution satellite studies (Kellogg et al, 1971) 'have provided convincing evidence that the source coincides with the radio galaxy M-87 (Virgo A) and that M-84 and the quasar 30273 are other likely discrete source emitters in the direction of Virgo. Measurements of high energy (40-100 keV) X-rays from Virgo A have also been reported (Haymes et al, 1968;Fif^hman et al, 1970), but these measurements lack independent verification and, in fact, conflicting results have been reported (Peterson, 1970;McClintock et al, 1969;Webber and Reinert, 1970). Felton (1970) has summarized the existing observations over the entire electromagnetic spectrum of the "jet" of Virgo and finds that the data over 13 decades of energy are reasonably consistent with a single power law spectrum, given by N(E) = 8.2 x 10 -4 E-1.75 photons/(cm2 sec MeV).…”

Section: B) Virgo Smentioning

confidence: 98%

Gamma-Ray Observations of the Galactic Center and Some Possible Point Sources

Fichtel¹,

Hartman²,

Kniffen³

et al. 1972

ApJ

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A (.5 m by .5 m) digitized spark chamber gamma ray telescope was flown on three balloon flights to look at the galactic center region, Virgo, and the Crab. An excess flux above atmospheric background of over four standard deviations was found for gamma rays exceeding 100 MeV coming from the galactic center region, corresponding to a line intensity of (2.0 +0.6) x 10 -4 y's(cm2 rad see),but there was no statistically significant excess in the 50 to 100 MeV interval, with a 95% confidence limit for the ratio EJ(50 -100 MeV) /J(> 100 McV)]being 0.50. As a result, there is only a 6% chance that Compton or synchrotron radiation from electrons with a power law spectrum having an exponent of 2.6 could make as much as a 50% contribution to the gamma radiation in this energy range. No positive evidence was found for radiation from any of the sources M 87, 3C273, and the Crab Nebula, and 95% confidence upper limits for the gamma ray flux from these objects were set at 1.0 . 10 -5 , 1.0 . 10 -5 , and 6 . 10 -5 /(cm 2 sec) respectively. The M-87 limit eliminates the possibility that the power law spectrum observed at X-ray energies extends unchanged to the high energy gamma ray region.

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Section: B) Virgo Smentioning

confidence: 98%

Gamma-Ray Observations of the Galactic Center and Some Possible Point Sources

Fichtel¹,

Hartman²,

Kniffen³

et al. 1972

ApJ

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“…Although neither of these flights was sufficiently successful so that the ultimate sensitivity of the observation could be realized, significant upper limits have nevertheless been obtained, as shown in Figure 14. These upper limits, which are at a 3cr confidence level, seem to be significantly below the reported flux at 40 keV due to Haymes at Rice University (Haymes et al, 1968c). We therefore question the validity of the Rice observation.…”

Section: Other Sourcesmentioning

confidence: 54%

Properties of individual X-ray sources: (Invited discourse)

Peterson

1970

Symp. - Int. Astron. Union

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Abstract. Observations to determine the spectra and time variations of hard X-rays from cosmic sources have been made from balloons and from the OSO-III satellite. These data have been obtained using actively collimated scintillation counters with apertures between 6 and 24° FWHM, areas between 10 and 50 cm 2 and which operate over the 10-300 keV range. The Crab Nebula has been observed on three occasions over a 22-month period between September 1965 and July 1967. The power law spectrum has a number index of 2.0 ± 0.1. No long-term changes were observed over the 30-100keV range with a limit at 3%/yr. A balloon search with a 10 cm 2 Ge(Li) detector for X-ray lines at 62.5 keV, 110 keV and 180 keV due to heavy element radioactive decays which would be produced in the initial Crab explosion based on the Cf 254 hypothesis has resulted in upper limits at about 10" 3 y-rays cm 2 -sec. This is about a factor of 20 above the predicted levels. Simultaneous X-ray and optical observations of SCO XR-1 from OSO-III confirm that X-ray and optical flaring are indeed coincident phenomena, and that although the X-ray intensity increases about a factor of two during the flare, the equivalent temperature of the excess radiation is nearly the same as that of the quiescent object. Upper limits, 95% confidence, on the flux of M-87 at 40 keV have been obtained. These are inconsistent with the flux of 1.2 x 10~4 photons/cm 2 -sec-keV reported in the literature. CYG X-l has been observed to have a power law of number index 2.0 ± 0.2. The OSO-III has observed a number of sources in the southern skies including NOR XR-2 and the variable source Centaurus XR-2.

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“…These surveys showed signals with 3a significance or better from a source located within a small region containing M-87 but otherwise devoid of conspicuous objects. Haymes et al [17] recently reported a balloon observation of M-87 at energies above 30 keV which they interpreted as evidence for a continuation to 100 keV of the power law spectrum that fits the data for the emission of the jet from the visible to the soft X-ray region. There have been several reports of the detection of X-rays from other extragalactic sources, namely the radio galaxy Cyg A [18], the quasar 3C273 [15], and the Large Magellanic Cloud [19].…”

Section: Extragalactic Sourcesmentioning

confidence: 88%