First Results from the All-Sky Monitor on the [ITAL]Rossi X-Ray Timing Explorer[/ITAL]

Levine, Alan M.; Bradt, H.; Cui, Wei; Jernigan, J. G.; Morgan, E.; Remillard, Ronald; Shirey, R.; Smith, D. A.

doi:10.1086/310260

Cited by 653 publications

(631 citation statements)

References 11 publications

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“…4.1.2 is shown in green. Bałucińska-Church et al (2000) have used mainly RXTEAll Sky Monitor (ASM; Levine et al 1996) data to show orbital variability in ASM-based hardness ratios and in dip (defined by a threshold ASM hardness ratio) occurrence, both peaking at superior conjunction consistent with the behavior of the absorption column density that we observe. They observe a peak in the dip occurence at φ orb = 0.95, but our sample is not large enough to track this possible assymetry of the N H distribution around φ orb = 0.…”

Section: Discussion and Comparison To Earlier Resultssupporting

confidence: 61%

Long term variability of Cygnus X-1

Grinberg

Leutenegger

Hell

et al. 2015

A&A

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Binary systems with an accreting compact object offer a unique opportunity to investigate the strong, clumpy, line-driven winds of early-type supergiants by using the compact object's X-rays to probe the wind structure. We analyze the two-component wind of HDE 226868, the O9.7Iab giant companion of the black hole Cyg X-1, using 4.77 Ms Rossi X-ray Timing Explorer (RXTE) observations of the system taken over the course of 16 years. Absorption changes strongly over the 5.6 d binary orbit, but also shows a large scatter at a given orbital phase, especially at superior conjunction. The orbital variability is most prominent when the black hole is in the hard X-ray state. Our data are poorer for the intermediate and soft state, but show signs for orbital variability of the absorption column in the intermediate state. We quantitatively compare the data in the hard state to a toy model of a focussed Castor-AbbottKlein wind: as it does not incorporate clumping, the model does not describe the observations well. A qualitative comparison to a simplified simulation of clumpy winds with spherical clumps shows good agreement in the distribution of the equivalent hydrogen column density for models with a porosity length on the order of the stellar radius at inferior conjunction; we conjecture that the deviations between data and model at superior conjunction could either be due to lack of a focussed wind component in the model or to a more complicated clump structure.

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Section: Discussion and Comparison To Earlier Resultssupporting

confidence: 61%

Long term variability of Cygnus X-1

Grinberg

Leutenegger

Hell

et al. 2015

A&A

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“…The HEXTE (Rothschild et al 1998) was constituted of 2 clusters of 4 NaI/CsI scintillation counters each, with a total collecting area of 2 × 800 cm 2 , sensitive in the 15-250 keV band, with a nominal energy resolution of 15% at 60 keV. The ASM (Levine et al 1996) scanned about 80% of the sky every orbit, allowing monitoring on time scales of 90 minutes or longer in the energy range 1.3-12.1 keV.…”

Section: Observations and Data Analysismentioning

confidence: 99%

The photon-index–time-lag correlation in black hole X-ray binaries

Reig

Kylafis

Papadakis

et al. 2017

Monthly Notices of the Royal Astronomical Society

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We have performed a timing and spectral analysis of a set of black-hole binaries to study the correlation between the photon index and the time lag of the hard photons with respect to the soft ones. We provide further evidence that the timing and spectral properties in black-hole X-ray binaries are coupled. In particular, we find that the average time lag increases as the X-ray emission becomes softer. Although a correlation between the hardness of the X-ray spectrum and the time (or phase) lag has been reported in the past for a handful of systems, our study confirms that this correlated behaviour is a global property of black-hole X-ray binaries. We also demonstrate that the photon-index -time-lag correlation can be explained as a result of inverse Comptonization in a jet.

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“…In 1.5-12 keV band, the Crab Nebula flux corresponds to about 75 ASM counts per second. A detailed description of ASM can be found in (Levine et al 1996). RXTE standard data products are collected directly from the HEASARC database.…”

Section: Datamentioning

confidence: 99%

The classification of flaring states of blazars

Resconi¹,

Franco

Groß

et al. 2009

A&A

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Aims. The time evolution of the electromagnetic emission from blazars, in particular high-frequency peaked sources (HBLs), displays irregular activity that has not yet been understood. In this work we report a methodology capable of characterizing the time behavior of these variable objects. Methods. The maximum likelihood blocks (MLBs) is a model-independent estimator that subdivides the light curve into time blocks, whose length and amplitude are compatible with states of constant emission rate of the observed source. The MLBs yield the statistical significance in the rate variations and strongly suppresses the noise fluctuations in the light curves. We applied the MLBs for the first time on the long term X-ray light curves (RXTE/ASM) of Mkn 421, Mkn 501, 1ES 1959+650, and 1ES 2155-304, more than 10 years of observational data (1996)(1997)(1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007). Using the MLBs interpretation of RXTE/ASM data, the integrated time flux distribution is determined for each single source considered. We identify in these distributions the characteristic level, as well as the flaring states of the blazars. Results. All the distributions show a significant component at negative flux values, most probably caused by an uncertainty in the background subtraction and by intrinsic fluctuations of RXTE/ASM. This effect concerns in particular short time observations. To quantify the probability that the intrinsic fluctuations give rise to a false identification of a flare, we study a population of very faint sources and their integrated time-flux distribution. We determine duty cycle or fraction of time a source spent in the flaring state of the source Mkn 421, Mkn 501, 1ES 1959+650 and 1ES 2155-304. Moreover, we study the random coincidences between flares and generic sporadic events such as high-energy neutrinos or flares in other wavelengths.

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First Results from the All-Sky Monitor on the [ITAL]Rossi X-Ray Timing Explorer[/ITAL]

Cited by 653 publications

References 11 publications

Long term variability of Cygnus X-1

Long term variability of Cygnus X-1

The photon-index–time-lag correlation in black hole X-ray binaries

The classification of flaring states of blazars

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