Soft X-ray spectrum of a hot plasma

Raymond, J. C.; Smith, Barham W.

doi:10.1086/190486

Cited by 1,322 publications

(1,022 citation statements)

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“…Also, the best-fitting photon index, À ¼ 0:46 AE 0:09, was unusually hard; the typical photon index for a radio-quiet QSO is in the range À ¼ 1:7-2.3 (e.g., Reeves & Turner 2000;George et al 2000). As Mrk 231 hosts a starburst ring within 1 00 of its nucleus (Bryant & Scoville 1996;Carilli et al 1998;Taylor et al 1999), a plausi- ble additional component to add is a Raymond-Smith thermal plasma (Raymond & Smith 1977). The plasma abundance was initially fixed at solar, a reasonable value for an energetic starburst hosting a luminous QSO.…”

Section: Basic Spectral Modelingmentioning

confidence: 99%

X‐Raying the Ultraluminous Infrared Starburst Galaxy and Broad Absorption Line QSO Markarian 231 withChandra

Gallagher

Brandt

Chartas

et al. 2002

ApJ

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With 40 ks of Chandra ACIS-S3 exposure, new information on both the starburst and QSO components of the X-ray emission of Markarian 231, an ultraluminous infrared galaxy and broad absorption line QSO, has been obtained. The bulk of the X-ray luminosity is emitted from an unresolved nuclear point source, and the spectrum is remarkably hard, with the majority of the flux emitted above 2 keV. Most notably, significant nuclear variability (a decrease of $45% in approximately 6 hr) at energies above 2 keV indicates that Chandra has probed within light-hours of the central black hole. Although we concur with Maloney & Reynolds that the direct continuum is not observed, this variability coupled with the 188 eV upper limit on the equivalent width of the Fe K emission line argues against the reflection-dominated model put forth by these authors based on their ASCA data. Instead, we favor a model in which a small, Compton-thick absorber blocks the direct X-rays, and only indirect, scattered X-rays from multiple lines of sight can reach the observer. Extended soft, thermal emission encompasses the optical extent of the galaxy and exhibits resolved structure. An off-nuclear X-ray source with a 0.35-8.0 keV luminosity of L X ¼ 7 Â 10 39 ergs s À1 , consistent with the ultraluminous X-ray sources in other nearby starbursts, is detected. We also present an unpublished Faint Object Spectrograph spectrum from the Hubble Space Telescope archive showing the broad C iv absorption.

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Section: Basic Spectral Modelingmentioning

confidence: 99%

X‐Raying the Ultraluminous Infrared Starburst Galaxy and Broad Absorption Line QSO Markarian 231 withChandra

Gallagher

Brandt

Chartas

et al. 2002

ApJ

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“…clouds at lower speeds. The former possibility gives higher maximum temperatures, T-10" K. The real spectrum of a hot shocked zone C is not a simple continuum, but also includes ionizing emission lines and "edges"; see Cox and Daltabuit (1971), Raymond and Smith (1977), Daltabuit, Cox, and MacAlpine (1978), and Shull and McKee (1979 (Grandi, 1978) may arise in shock-heated gas. Krolik, McKee, and Tarter (1978) have pointed out that radio-frequency waves can heat the gas.…”

Section: E Dust In Quasarsmentioning

confidence: 99%

The emission lines of quasars and similar objects

1979

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Much of our information about quasars is derived from their emission-line spectra. The analysis of such spectra has become an intricate subject which differs considerably from traditional, low-density nebular astrophysics. This review is intended to explain our present understanding of the situation, including some aspects of galactic nuclei whose luminosities are more modest than quasars. Quasars line-emitting regions are probably photoionized (even if supplementary heating processes also occur). So fax, models have been constructed which include ionization and thermal equilibria, the transfer of resonance-line and related photons, and the likely effects of absorption and scattering by dust grains. From comparisons between emission-line intensities produced in these models and observed quasars spectra, it appears that certain densities and pressures and size scales occur in or around quasars. The relative abundances of elements are not very far from solar values, although it is suspected that heavy elements -carbon, nitrogen, and oxygen in particular -are moderately "overabundant" in quasars. The emission-line intensities also provide indirect information about quasars ultraviolet and soft-x-ray continua; there are hints that photons with energies between 20 and 300 eV -which are not directly observable -may even represent the peak of the luminous output of a typical quasar. Finally, some gas-dynamical questions, while extremely important, are very difficult to answer, because of a lack of observables. CONTENTS 715

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“…Stellar coronal X-ray spectra are measured in low-mass stars and are reasonably well described as a Raymond-Smith plasma (Raymond & Smith 1977). These X-ray spectra are distinct from those calculated from ADAFs, which consist of a featureless continuum from the Compton-scattered optical/UV emission and weak line emission that does not appear detectable with the current generation of detectors (Narayan & Raymond 1999).…”

Section: Black Hole Transients In Quiescence: Advection Dominated Accmentioning

confidence: 86%

Transient Low-Mass X-Ray Binaries in Quiescence

Bildsten¹,

Rutledge²

2001

The Neutron Star—Black Hole Connection

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We summarize the quiescent X-ray observations of transient low-mass X-ray binaries. These observations show that, in quiescence, binaries containing black holes are fainter than those containing neutron stars. This has triggered a number of theoretical ideas about what causes the quiescent Xray emission. For black hole binaries, the options are accretion onto the black hole or coronal emission from the rapidly rotating stellar companion. There are more possibilities for the neutron stars; accretion, thermal emission from the surface or non-thermal emission from a "turned-on" radio pulsar. We review recent theoretical work on these mechanisms and note where current observations can distinguish between them. We highlight the re-analysis of the quiescent neutron star emission by Rutledge and collaborators that showed thermal emission to be a predominant contributor in many of these systems. Our knowledge of these binaries is bound to dramatically improve now that the Chandra and XMM-Newton satellites are operating successfully,

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Soft X-ray spectrum of a hot plasma

Cited by 1,322 publications

References 0 publications

X‐Raying the Ultraluminous Infrared Starburst Galaxy and Broad Absorption Line QSO Markarian 231 withChandra

X‐Raying the Ultraluminous Infrared Starburst Galaxy and Broad Absorption Line QSO Markarian 231 withChandra

The emission lines of quasars and similar objects

Transient Low-Mass X-Ray Binaries in Quiescence

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