<i>INTEGRAL</i> and<i>XMM-Newton</i> observations of AX J1845.0-0433

Heras, J. A. Zurita; Walter, R.

doi:10.1051/0004-6361:200810219

Cited by 18 publications

(19 citation statements)

References 33 publications

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“…The XRT/PC spectrum (T+848 to T+1891 s; 1043 s net exposure) shows a power law shape with N H = (1.4 +0.4 −0.3 ) × 10 22 cm −2 , Γ = 0.8 ± 0.2 and an average flux of F 2−10 keV = 8 × 10 −10 erg cm −2 s −1 (unabsorbed). These fluxes translate into a luminosity of L 2−10 keV = 1 × 10 36 erg s −1 (assuming the optical counterpart distance of 3.6 kpc, Coe et al, 1996), comparable with the one observed in previous outbursts of this source (Sguera et al, 2007a;Zurita Heras and Walter, 2009).…”

Section: Igr J16328−4726supporting

confidence: 81%

“…The absorbed power-law with a high energy cutoff yields a poorly constrained value of the cut-off energy. The absorbed power-law with an exponential cut-off, on (Bird et al, 2010;Baumgartner et al, 2010;Cusumano et al, 2010) was discovered in ASCA data (Yamauchi et al, 1995) as a source variable on timescales of tens of minutes and classified as a SFXT (Sguera et al, 2007a) with an O9.5I companion (Coe et al, 1996;Zurita Heras and Walter, 2009). AX J1845.0−0433 triggered the BAT on 2012 May 05 at 01:44:39 UT 4 (image trigger=521567, Romano et al, 2012a).…”

Section: Igr J16328−4726mentioning

confidence: 99%

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The Swift Supergiant Fast X-ray Transients Project: A review, new results and future perspectives

Romano

Mangano

Ducci

et al. 2013

Advances in Space Research

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We present a review of the Supergiant Fast X-ray Transients (SFXT) Project, a systematic investigation of the properties of SFXTs with a strategy that combines Swift monitoring programs with outburst follow-up observations. This strategy has quickly tripled the available sets of broad-band data of SFXT outbursts, and gathered a wealth of out-of-outburst data, which have led us to a broad-band spectral characterization, an assessment of the fraction of the time these sources spend in each phase, and their duty cycle of inactivity. We present some new observational results obtained through our outburst follow-ups, as fitting examples of the exceptional capabilities of Swift in catching bright flares and monitor them panchromatically.

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Section: Igr J16328−4726supporting

confidence: 81%

Section: Igr J16328−4726mentioning

confidence: 99%

The Swift Supergiant Fast X-ray Transients Project: A review, new results and future perspectives

Romano

Mangano

Ducci

et al. 2013

Advances in Space Research

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“…We verified a posteriori that results obtained from the fit to this spectrum were compatible with those obtained by using only the EPIC-pn spectrum. A fit to the summed EPIC spectrum was carried out simultaneously with the RGS and the IBIS/ISGRI spectra first by using the same spectral model considered by Zurita Heras & Walter (2009). This model comprises an emission from optically thin plasma at the lower energies (mekal in Xspec), a cut-off power-law to fit the data above ∼4 keV, and an edge at ∼7.9 keV.…”

Section: Igr J18450-0435mentioning

confidence: 99%

The accretion environment of supergiant fast X-ray transients probed withXMM-Newton

Bozzo

Bernardini²,

Ferrigno

et al. 2017

A&A

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Context. Supergiant fast X-ray transients are a peculiar class of supergiant X-ray binaries characterized by a remarkable variability in the X-ray domain, widely ascribed to the accretion from a clumpy stellar wind. Aims. In this paper we performed a systematic and homogeneous analysis of the sufficiently bright X-ray flares observed with XMMNewton from the supergiant fast X-ray transients to probe spectral variations on timescales as short as a few hundred of seconds. Our ultimate goal is to investigate if SFXT flares and outbursts are triggered by the presence of clumps and eventually reveal whether strongly or mildly dense clumps are required. Methods. For all sources, we employ a technique developed by our group already exploited in a number of our previous papers, making use of an adaptive rebinned hardness ratio to optimally select the time intervals for the spectral extraction. A total of twelve observations performed in the direction of five SFXTs are reported, providing the largest sample of events available so far. Results. Using the original results reported here and those obtained with our technique from the analysis of two previously published XMM-Newton observations of IGR J17544-2619 and IGR J18410-0535, we show that both strongly and mildly dense clumps can trigger these events. In the former case, the local absorption column density may increase by a factor of ≫3, while in the latter case, the increase is only by a factor ∼2-3 (or lower). An increase in the absorption column density is generally recorded during the rise of the flares/outbursts, while a drop follows when the source achieves the peak flux. In a few cases, a re-increase of the absorption column density after the flare is also detected, and we discovered one absorption event related to the passage of an unaccreted clump in front of the compact object. Overall, there seems to be no obvious correlation between the dynamic ranges in the X-ray fluxes and absorption column densities in supergiant fast X-ray transients, with an indication that lower densities are recorded at the highest fluxes. Conclusions. The spectral variations measured in all sources are in agreement with the idea that the flares/outbursts are triggered by the presence of dense structures in the wind interacting with the X-rays from the compact object (leading to photoionization). The lack of correlation between the dynamic ranges in the X-ray fluxes and absorption column densities can be explained by the presence of accretion inhibition mechanism(s). Based on the knowledge acquired so far on the SFXTs, we propose a classification of the flares/outbursts from these sources to drive future observational investigations. We suggest that the difference between the classes of flares/outbursts is related to the fact that the mechanism(s) inhibiting accretion can be overcome more easily in some sources compared to others. We also investigate the possibility that different stellar wind structures, rather than clumps, could provide the means to temporarily overcome the...

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“…The source AX J1845.0−0433 was discovered in ASCA data (Yamauchi et al 1995) as a source variable on timescales of tens of minutes (Sguera et al 2007a;Zurita Heras & Walter 2009) and was classified as a SFXT with an O9.5I companion at a distance of 3.6 kpc (Coe et al 1996). It also triggered the Swift/BAT (Romano et al , 2012a.…”

Section: Ax J18450−0433mentioning

confidence: 99%

The 100-monthSwiftcatalogue of supergiant fast X-ray transients

Romano¹,

Krimm²,

Palmer³

et al. 2014

A&A

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Context. Supergiant fast X-ray transients (SFXTs) are high mass X-ray binaries (HMXBs) that are defined by their hard X-ray flaring behaviour. During these flares they reach peak luminosities of 10 36 -10 37 erg s −1 for a few hours (in the hard X-ray), which are much shorter timescales than those characterizing Be/X-ray binaries. Aims. We investigate the characteristics of bright flares (detections in excess of 5σ) for a sample of SFXTs and their relation to the orbital phase. Methods. We have retrieved all Swift/BAT Transient Monitor light curves and collected all detections in excess of 5σ from both dailyand orbital-averaged light curves in the time range of 2005 February 12 to 2013 May 31 . We also considered all on-board detections as recorded in the same time span and selected those in excess of 5σ and within 4 arcmin of each source in our sample.Results. We present a catalogue of over a thousand BAT flares from 11 SFXTs, down to 15-150 keV fluxes of ∼6 × 10 −10 erg cm −2 s −1(daily timescale) and ∼1.5 × 10 −9 erg cm −2 s −1 (orbital timescale, averaging ∼800 s); the great majority of these flares are unpublished. The catalogue spans 100 months. This population is characterized by short (a few hundred seconds) and relatively bright (in excess of 100 mCrab, 15-50 keV) events. In the hard X-ray, these flares last generally much less than a day. Clustering of hard X-ray flares can be used to indirectly measure the length of an outburst, even when the low-level emission is not detected. We construct the distributions of flares, of their significance (in terms of σ), and of their flux as a function of orbital phase to infer the properties of these binary systems. In particular, we observe a trend of clustering of flares at some phases as P orb increases, which is consistent with a progression from tight circular or mildly eccentric orbits at short periods to wider and more eccentric orbits at longer orbital periods. Finally, we estimate the expected number of flares for a given source for our limiting flux and provide the recipe for calculating them for the limiting flux of future hard X-ray observatories.

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INTEGRAL andXMM-Newton observations of AX J1845.0-0433

Cited by 18 publications

References 33 publications

The Swift Supergiant Fast X-ray Transients Project: A review, new results and future perspectives

The Swift Supergiant Fast X-ray Transients Project: A review, new results and future perspectives

The accretion environment of supergiant fast X-ray transients probed withXMM-Newton

The 100-monthSwiftcatalogue of supergiant fast X-ray transients

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