Evidence for X-Radiation from the Radio Galaxy M87

Bradt, H.; Mayer, W.; Naranan, S.; Rappaport, S.; Spada, G.

doi:10.1086/180125

Cited by 54 publications

(21 citation statements)

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“…At the present time the X-ray source in Virgo is the only one which has been identified as an extragalactic object with reasonable certainty on the basis of rocket surveys [14,15,16] in the 1-10 keV region. 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.…”

Section: Extragalactic Sourcesmentioning

confidence: 71%

“…The experiment of Bradt et al [16], which placed M-87 in the 6 deg 2 uncertainty area around the measured position of the X-ray source, also scanned the position of 3C273 and found a 3a upper limit consistent with the intensity claimed for it by Friedman et al [15]. However, an optimal analysis of the raw data subsequently published by Friedman et al [21], reveals that the counting rate peak attributed to 3C273 contained a number of counts above background which was less than one standard deviation of the Poisson distribution.…”

Section: Extragalactic Sourcesmentioning

confidence: 99%

See 1 more Smart Citation

Studies of discrete cosmic X-ray sources at M.I.T.: (Invited discourse)

Clark¹

1970

Symp. - Int. Astron. Union

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Section: Extragalactic Sourcesmentioning

confidence: 71%

Section: Extragalactic Sourcesmentioning

confidence: 99%

Studies of discrete cosmic X-ray sources at M.I.T.: (Invited discourse)

Clark¹

1970

Symp. - Int. Astron. Union

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“…There is evidence that Cygnus X-2 is correctly identified (GIAcCONI et al, 1967a, b). It is probable that M-87 (BYRAM et al, 1966;FRIEDMAN and BYRAM, 1967;BRADT et al, 1967) and possibly GX3 + 1 (BLANCO et al, 1968;BRADT et al, 1968) are correctly identified. None of the approximately 30 other sources can be associated with a visible or radio object with any degree of confidence.…”

Section: Dn (E)/de = Lie Exp (-E/kt)mentioning

confidence: 98%

Grazing-incidence telescopes for X-ray astronomy

Giacconi¹,

Reidy²,

Vaiana³

et al. 1969

Space Sci Rev

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~'~,,~ 16-31 32-63 64-127 m 128-255 lllg 256-511 counts in 140 msec The above sequence of maps was obtained from the X-ray Spectroheliograph of American Science and Engineering, Cambridge, Massachusetts, on board t he NASA satellite OSO-IV. The instrumentation uses inaage-forming grazing optics and transmission filters. The maps were obtained through 1.0 • 10 3 cm of thinly aluminized Mylar which, together with the optical system, yields an effective band pass of approximately 3 A to 15 A. Picture elements are approximately 0.9 by 0.75 arc min; instrument resolution is 1 arc rain. Times of data acquisition over the picture element of the flare, relative to 0846 UT, 28 October 1967, are approximately --100, 0, 10, 20, 30, 40, 100, and 230 rain, for 1 through 8 respectively. The peak counting rate (Figure 4) corresponds to an incident intensity of about 5 • 104 photons/cm 2 sec within the wavelength band. The incident energy per unit area within this band, integrated over the life of the flare, was roughly 0.3 erg/cm 2. The flare is identified with the if flare first observed at 0854 UT. The higher number density of the lighter gray tones towards the right of each map is due to spacecraft-generated noise; the condition causing it was later corrected.Abstract. We review the progress made at our laboratory over the past several years in developing grazing-incidence imaging X-ray optics. Mirrors, detection systems and dispersion techniques are discussed and experimental results are given. We discuss the application of two telescope systems to a number of experimental observations in X-ray astronomy.

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“…Sky surveys at high sensitivity are best accomplished from satellites. The spectrum of the X-ray source which has been associated with the object M-87 (Bradt et al, 1967) is of considerable interest since it is the only known extra-galactic X-ray source. This very weak X-ray source, y 1^ of the Crab Nebula at 3 keV, may be observed at balloon altitude with sufficiently sensitive technique if the spectrum is not too soft.…”

Section: Other Sourcesmentioning

confidence: 99%

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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Evidence for X-Radiation from the Radio Galaxy M87

Cited by 54 publications

References 0 publications

Studies of discrete cosmic X-ray sources at M.I.T.: (Invited discourse)

Studies of discrete cosmic X-ray sources at M.I.T.: (Invited discourse)

Grazing-incidence telescopes for X-ray astronomy

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

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