Emission line features in the soft X-ray spectra of the North Polar Spur and the Cygnus Loop

Inoue, Hiroki; Koyama, K.; Matsuoka, M.; Ohashi, T.; Tanaka, Yuichi; Tsunemi, H.

doi:10.1086/158051

Cited by 33 publications

(15 citation statements)

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“…We found that the intensities below 2 keV in source-free regions in these fields are higher than the level of the "blank-sky" background, while the hard band intensities show no excess. By fitting the energy spectra of the soft excess component with the XSPEC Mekal model, we obtained the temperature to be ∼ 0.3 keV, consistent with the previous result for the Galactic soft emission from NPS (Inoue et al 1980). The surface brightness in the four nearby fields differ significantly, ranging in (5-10) ×10 −10 photons cm…”

Section: Background Estimationsupporting

confidence: 87%

Chandra and XMM-Newton Observations of the Group of Galaxies HCG 62

Ohashi

Morita

Ishisaki

et al. 2007

Eso Astrophysics Symposia

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We present results from Chandra and XMM-Newton observations of the bright group of galaxies HCG 62. There are two cavities at about 30 ′′ northeast and 20 ′′ southwest of the central galaxy in the Chandra image. The energy spectrum shows no significant change in the cavity compared with that in the surrounding region. The radial X-ray profile is described by a sum of 3-β components with core radii about 2, 10, and 160 kpc, respectively. We studied radial distributions of temperature and metal abundance with joint spectral fit for the Chandra and XMM-Newton data, and two temperatures were required in the inner r < 2 ′ (35 kpc) region. The sharp drop of temperature at r ∼ 5 ′ implies the gravitational mass density even lower than the gas density, suggesting the gas may not be in hydrostatic equilibrium. Fe and Si abundances are 1-2 solar at the center and drop to about 0.1 solar at r ∼ 10 ′ . O abundance is less than 0.5 solar and shows a flatter profile. Observed metal distribution supports the view that iron and silicon are produced by type Ia supernova in the central galaxy, while galactic winds by type II supernova have caused wide distribution of oxygen. The supporting mechanism of the cavity is discussed. Pressure for the sum of electrons and magnetic field is too low to displace the hot group gas, and the required pressure due to high energy protons are nearly 700 times higher than the electron pressure. This leaves the origin of the cavities a puzzle, and we discuss other possible origins of the cavities.

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Section: Background Estimationsupporting

confidence: 87%

Chandra and XMM-Newton Observations of the Group of Galaxies HCG 62

Ohashi

Morita

Ishisaki

et al. 2007

Eso Astrophysics Symposia

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“…In addition, the XRB below 2 keV shows a spectral excess above the power-law component of photon index 1.4 that well describes the spectrum above 2 keV (Hashinger 1992;Gendreau et al 1995;Chen et al 1997;Miyaji et al 1998;Parmar et al 1999). The excess component of the XRB is contributed by optically thin thermal emission having a temperature of ∼0.1 keV from an ionized gas surrounding the solar system, and an emission of temperature of ∼0.7 keV associated with our Galaxy (e.g., Sidher et al 1996;Parmar et al 1999;Kuntz, Snowden 2000), as evidenced by line emissions from OVII and CV (Inoue et al 1980;Rocchia et al 1984) and a shadowing study of XRB with cold clouds (Kerp 1994;Snowden et al 1997;Kerp et al 1999). In addition to these components, there may also be thermal emission from the hypothetical Local Group halo contributing to the soft XRB.…”

Section: Introductionmentioning

confidence: 90%

Search for hot gas in the local group with ASCA

Osone

Makishima

Matsuzaki

et al. 2000

Advances in Space Research

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An X-ray study was made to examine whether some part of the soft X-ray background is coming from hot gas in the Local Group. For this purpose, four consecutive pointings were made with ASCA toward a sky region between M 31 and M 33, which is close to the direction of the center of the Local Group. By comparing the X-ray surface brightness in this sky direction with that in another blank sky region near the north equatorial pole, an upper limit on any soft excess X-ray background was determined to be 2.8×10 −9 erg cm −2 s −1 sr −1 with a 90% confidence level statistical error. Assuming an optically thin thermal bremsstrahlung energy spectrum (Raymond-Smith model) for a temperature of 1 keV and a β-model electron density distribution for a core radius of 100 kpc for the X-ray halo, the upper limit of the central plasma density was obtained to be 1.3×10 −4 cm −3 . The plasma column density is too low to contribute significantly to the observed quadrupole anisotropy in the cosmic microwave background.

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“…Significant line emission by ionized oxygen (OVII at 0.574 keV and OVIII at 0.650 keV), indicating the existence of 2-3 million degree plasma even outside the region of Loop-I has been inferred from early rocket flights (Inoue et al, 1980, Rocchia et al, 1984. This "hard thermal" component on top of any reasonable extrapolation of the high-energy extragalactic power law (see above) has been confirmed by the analysis of many high-latitude ROSAT PSPC pointings across the sky (Hasinger 1992, Wang & McCray 1993, Georgantopoulos et al, 1995.…”

Section: The C-band Background: a "Soft Thermal Component"mentioning

confidence: 99%

The X-Ray Background

Hasinger

1996

Symp. - Int. Astron. Union

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Abstract.The recent progress in the measurement and understanding of the X-ray background is reviewd here. Particular emphasis is put on a discussion of the partially discrepant measurement of the X-ray background spectrum in the 0.5-3 keV range. New and important constraints on large scale structure are obtained from measurements of the smoothness of the XRB. Recently the first discovery of a signal in the angular correlation function of the XRB could be announced. Finally, various X-ray surveys and their identification content is summarized. The role of optically inactive galaxies as a major contributor to the faint X-ray source population which might produce a substantial fraction of the XRB is clarified.

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Emission line features in the soft X-ray spectra of the North Polar Spur and the Cygnus Loop

Cited by 33 publications

References 0 publications

Chandra and XMM-Newton Observations of the Group of Galaxies HCG 62

Chandra and XMM-Newton Observations of the Group of Galaxies HCG 62

Search for hot gas in the local group with ASCA

The X-Ray Background

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