New Evidence for Black Hole Event Horizons from [ITAL]Chandra[/ITAL]

Garcia, M. R.; McClintock, Jeffrey E.; Narayan, Ramesh; Callanan, P. J.; Barret, D.; Murray, Stephen S.

doi:10.1086/320494

Cited by 231 publications

(292 citation statements)

References 36 publications

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“…an order of magnitude than the quiescent emission of black hole transients in similar binary systems (Garcia et al 2001), pointing to the role of the neutron star surface in producing the quiescent emission. Numerous observations during quiescent periods also revealed that there is a soft thermal component in the X-ray spectra, characterized by blackbody temperatures of 0.1 − 0.3 keV, in a fraction of sources (see Figure 6 and Table 2).…”

Section: Accreting Neutron Stars In Quiescencementioning

confidence: 94%

Surface emission from neutron stars and implications for the physics of their interiors

Özel

2012

Rep. Prog. Phys.

124

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Abstract. Neutron stars are associated with diverse physical phenomena that take place in conditions characterized by ultrahigh densities as well as intense gravitational, magnetic, and radiation fields. Understanding the properties and interactions of matter in these regimes remains one of the challenges in compact object astrophysics. Photons emitted from the surfaces of neutron stars provide direct probes of their structure, composition, and magnetic fields. In this review, I discuss in detail the physics that governs the properties of emission from the surfaces of neutron stars and their various observational manifestations. I present the constraints on neutron star radii, core and crust composition, and magnetic field strength and topology obtained from studies of their broadband spectra, evolution of thermal luminosity, and the profiles of pulsations that originate on their surfaces.

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Section: Accreting Neutron Stars In Quiescencementioning

confidence: 94%

Surface emission from neutron stars and implications for the physics of their interiors

Özel

2012

Rep. Prog. Phys.

124

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“…Accordingly, L j;rad ¼ 0:05 ; L j;tot only accounts for the partially self-absorbed synchrotron emission from the jet. Quiescent X-ray luminosities for V404 Cyg are from Garcia et al (2001), Kong et al (2002), and Hynes et al (2004); for XTE J1118+480 from McClintock et al (2004); and for A0620À00 from Kong et al (2002) and Gallo et al (2006). large luminosity difference between A0620À00 (L X /L Edd ' 10 À8 ) and other sources whose hard-state spectra were successfully fitted by the jet model, such as XTE J1118+480 (Markoff et al 2001), GX 339À4, and Cygnus XY1 (both Markoff et al 2005), simultaneous VLA and Chandra observations of A0620À00 in quiescence have shown that the nonlinear radio/X-ray correlation for hard-state BHBs appears unbroken all the way down to 10 À8 L Edd , which argues for no substantial difference between the hard and quiescent states ; but see Xue &Cui 2007 andGallo 2007). On the other hand, recent high-statistics X-ray observations of hard-state BHBs seem to show that a geometrically thin disk is present and already extends close to the innermost stable orbit at 10 À3 L Edd (Miller et al 2006b(Miller et al , 2006aRykoff et al 2007).…”

Section: Application To A0620à00mentioning

confidence: 95%

The Spectral Energy Distribution of Quiescent Black Hole X‐Ray Binaries: New Constraints fromSpitzer

Gallo¹,

Migliari²,

Markoff³

et al. 2007

ApJ

110

174

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Among the various issues that remain open in the field of accretion onto black hole X-ray binaries (BHBs) is the question of how gas accretes at very low Eddington ratios, in the so-called quiescent regime. While there is general agreement that X-rays are produced by a population of high-energy electrons near the BH, there is controversy concerning the modeling of the contributions of inflowing versus outflowing particles and their relative energy budget. Recent Spitzer observations of three quiescent BHBs have shown evidence for excess emission with respect to the Rayleigh-Jeans tail of the companion star between 8Y24 m. We suggest that synchrotron emission from a partially self-absorbed outflow might be responsible for the observed mid-IR excess, in place of, or in addition to, thermal emission from circumbinary material. If so, then the jet synchrotron luminosity, integrated from radio to near-IR frequencies, exceeds the measured 2Y10 keV luminosity by a factor of a few in these systems. In turn, the mechanical power stored in the jet exceeds the bolometric X-ray luminosity by at least 4 orders of magnitude. We compile the broadband spectral energy distribution (SED) of A0620À00, the lowest Eddington-ratio stellar mass BH with a known radio counterpart, by means of simultaneous radio, optical, and X-ray observations, and the archival Spitzer data. We are able to fit the SED of A0620À00 with a maximally jet-dominated model, in which the radio through the soft X-rays are dominated by synchrotron emission, while the hard X-rays are dominated by inverse Compton at the jet base. The fitted parameters land in a range of values reminiscent of the Galactic center supermassive black hole Sgr A Ã . Most notably, the inferred ratio of the jet acceleration rate to local cooling rates is 2 orders of magnitude weaker than higher luminosity, hard-state sources.

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“…Furthermore, it is claimed that a discrepancy between the quiescent luminosities of black hole and neutron star X-ray binaries provides evidence for the existence of event horizons in black holes (Garcia et al 2001). Accurate luminosity measurements are required to test this claim.…”

Section: Precise Distances and Luminositiesmentioning

confidence: 99%

Science at Very High Angular Resolution with the Square Kilometre Array

Godfrey

Bignall

Tingay

et al. 2012

Publ. – Astron. Soc. Aust

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Preliminary specifications for the Square Kilometre Array (SKA) call for 25% of the total collecting area of the dish array to be located at distances greater than 180 km from the core, with a maximum baseline of at least 3000 km. The array will provide angular resolution y t 40-2 mas at 0.5-10 GHz with image sensitivity reaching t50 nJy beam À1 in an 8-hour integration with 500-MHz bandwidth. Given these specifications, the high-angular-resolution component of the SKA will be capable of detecting brightness temperatures t200 K with milliarcsecond-scale angular resolution. The aim of this article is to bring together in one place a discussion of the broad range of new and important high-angular-resolution science that will be enabled by the SKA, and in doing so, address the merits of long baselines as part of the SKA. We highlight the fact that high angular resolution requiring baselines greater than 1000 km provides a rich science case with projects from many areas of astrophysics, including important contributions to key SKA science.

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New Evidence for Black Hole Event Horizons from [ITAL]Chandra[/ITAL]

Cited by 231 publications

References 36 publications

Surface emission from neutron stars and implications for the physics of their interiors

Surface emission from neutron stars and implications for the physics of their interiors

The Spectral Energy Distribution of Quiescent Black Hole X‐Ray Binaries: New Constraints fromSpitzer

Science at Very High Angular Resolution with the Square Kilometre Array

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