DISSECTING THE REGION OF 3EG J1837-0423 AND HESS J1841-055 WITH<i>INTEGRAL</i>

Sguera, V.; Romero, Gustavo E.; Bazzano, A.; Masetti, N.; Bird, A. J.; Bassani, L.

doi:10.1088/0004-637x/697/2/1194

Cited by 42 publications

(55 citation statements)

References 68 publications

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“…This corroborated the evidence that AX J1841.0−0536 is a member of the SFXT class, as proposed by Negueruela et al (2006b), at a distance of 3.2 +2.0 −1.5 kpc (Nespoli et al 2008). Several flares have been seen by INTEGRAL (Sguera et al 2006(Sguera et al , 2009, MAXI (Negoro et al 2010), Swift (e.g. Romano et al 2011b), and XMM-Newton (Bozzo et al 2011).…”

Section: Ax J18410−0536mentioning

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and ∼1.5 × 10 −9 erg cm −2 s −1 (orbital timescale, averaging ∼800 s); the great majority of these flares are unpublished.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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Section: Ax J18410−0536mentioning

confidence: 99%

The 100-monthSwiftcatalogue of supergiant fast X-ray transients

Romano¹,

Krimm²,

Palmer³

et al. 2014

A&A

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“…In particular, hard fast X-ray transients might form a new class of Galactic MeV emitters, as was argued by Sguera et al (2009) for the SFXT AX J1841.0-0536.…”

Section: Discussionmentioning

confidence: 88%

“…As was argued by Sguera et al (2009), a promising approach to explaining the production of relativistic particles capable of generating a transient γ-ray source, under the particular conditions imposed by the SFXTs, is the formation of a transient jet powered by a magnetic tower. Such an outflow could carry away a considerable fraction of the accreting material (Kato 2007).…”

Section: Igr J17354-3255mentioning

confidence: 99%

“…These possible associations raise the possibility that SFXT might also produce radiation at energies above 100 MeV. Recently, Sguera et al (2009) developed a model for the γ-ray emission from SFXT AX J1841.0-0536 based on the hypothesis that the high-energy radiation is originated from the cooling of relativistic particles accelerated in a collimated outflow from the NS. Although jets have been confirmed in some NSs that belong to low-mass X-ray binaries (LMXBs), in highmass X-ray binaries (HMXBs) that host an NS no jet has been A&A 565, A122 (2014) detected so far, although currently a possible jet origin is discussed for HMXB LS I +61 303 for its γ-ray emission (Romero et al 2007).…”

Section: Introductionmentioning

confidence: 99%

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Exploring jet-launching conditions for supergiant fast X-ray transients

García

Aguilera

Romero

2014

A&A

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Context. In the magneto-centrifugal mechanism for jet formation, accreting neutron stars are assumed to produce relativistic jets only if their surface magnetic field is weak enough (B ∼ 10 8 G). However, the most common manifestation of neutron stars are pulsars, whose magnetic field distribution peaks at B ∼ 10 12 G. If the neutron star magnetic field has at least this strength at birth, it must decay considerably before jets can be launched in binary systems. Aims. We study the magnetic field evolution of a neutron star that accretes matter from the wind of a high-mass stellar companion so that we can constrain the accretion rate and the impurities in the crust, which are necessary conditions for jet formation. Methods. We solved the induction equation for the diffusion and convection of the neutron star magnetic field confined to the crust, assuming spherical accretion in a simpliflied one-dimensional treatment. We incorporated state-of-the-art microphysics, including consistent thermal evolution profiles, and assumed two different neutron star cooling scenarios based on the superfluidity conditions at the core. Results. We find that in this scenario, magnetic field decay at long timescales is governed mainly by the accretion rate, while the impurity content and thermal evolution of the neutron star play a secondary role. For accretion ratesṀ > ∼ 10 −10 M yr −1 , surface magnetic fields can decay up to four orders of magnitude in ∼10 7 yr, which is the timescale imposed by the evolution of the high-mass stellar companion in these systems. Based on these results, we discuss the possibility of transient jet-launching in strong windaccreting high-mass binary systems like supergiant fast X-ray transients.

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“…It is usually thought that accreting models in high-mass binaries require black holes, but NS with low magnetic field can produce powerful jets (e.g. Sguera et al 2009). The magnetic field can decay in a few million years because of the contamination of the NS's crust by impurities contained in the accreting inflow.…”

Section: Models With Accretionmentioning

confidence: 99%