A DOUBLE-PEAKED OUTBURST OF A 0535+26 OBSERVED WITH
 INTEGRAL
 ,
 RXTE
 , AND
 SUZAKU

Caballero, I.; Pottschmidt, K.; Marcu, D. M.; Barragán, L.; Ferrigno, C.; Klochkov, D.; Heras, J. A. Zurita; Suchy, S.; Wilms, J.; Kretschmar, P.; Santangelo, A.; Kreykenbohm, I.; Fürst, Felix; Rothschild, R. E.; Staubert, R.; Finger, Mark H.; Camero-Arranz, A.; Makishima, Kazuo; Enoto, T.; Iwakiri, W.; Terada, Y.

doi:10.1088/2041-8205/764/2/l23

Cited by 32 publications

(45 citation statements)

References 37 publications

(48 reference statements)

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“…The observed decrease of the ratio implies an overall hardening of the spectrum with flux. A similar behavior is reported in Caballero et al (2013) for the normal double-peaked outburst of August 2009. The results of this analysis, i.e.…”

Section: Phase Averaged Spectrasupporting

confidence: 84%

A 0535+26 in the April 2010 outburst: probing the accretion regime at work

Müller

Klochkov

Caballero

et al. 2013

A&A

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Context. A number of accreting X-ray pulsars experience spectral changes, both on the long time scales and on the time scales of the neutron star spin period. The sources seem to form two distinct groups that differ by the type of the spectral variations with flux. Such a bimodality probably reflects two different regimes of accretion that may result in a particular pulsar depending on its luminosityso-called sub-and super-critical regimes. Aims. We investigated the behavior of the spectral parameters of the Be/X-ray binary system A 0535+26, as a function of flux and pulse phase. Methods. We used the data collected with INTEGRAL and RXTE during the April 2010 outburst of the source. We analyzed the phase-averaged and phase-resolved spectra and performed pulse-to-pulse spectral analysis of the pulsar. Results. Our analysis reveals variability in the continuum parameters of the source's pulse-averaged spectrum with flux. The pulseaveraged cyclotron line energy does not change with the source luminosity during the outburst, which is consistent with previous studies. Our pulse-phase resolved and pulse-to-pulse analyses reveal, however, indications for a positive correlation of the cyclotron line energy with flux, as well as a flux-dependence of the continuum parameters. Based on the observed behavior, we argue that A 0535+26 operates at the sub-critical accretion regime.

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Section: Phase Averaged Spectrasupporting

confidence: 84%

A 0535+26 in the April 2010 outburst: probing the accretion regime at work

Müller

Klochkov

Caballero

et al. 2013

A&A

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“…The mass and radius of the neutron star were assumed to be M = 1.5 M and R ns = 13 km, respectively , and the magnetic field was fixed to the value derived from the energy of the cyclotron line observed in 1A 0535+262. As discussed by Caballero et al (2013), the cyclotron line energy is observed at E ∼ 46 keV and does not change significantly with the luminosity. This implies that it most likely originates in the vicinity of the neutron star surface and, therefore, does provide an estimate of the magnetic field at the surface.…”

Section: Discussionmentioning

confidence: 66%

“…The magnetic field of the neutron star has been estimated to be B ∼ 5 × 10 12 G from the centroid energy of the so-called cyclotron resonance scattering feature (CRSF) observed at E cyc ∼ 45 keV in the X-ray spectrum of the pulsar. Unlike many other sources, 1A 0535+262 exhibits no significant variation of the line energy with luminosity, suggesting that the line is formed close to the surface of the neutron star (Caballero et al 2013).…”

Section: Introductionmentioning

confidence: 69%

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XMM-Newtonobservations of 1A 0535+262 in quiescence

Doroshenko

Santangelo

Doroshenko

et al. 2014

A&A

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Accretion onto magnetized neutron stars is expected to be centrifugally inhibited at low accretion rates. Several sources, however, are known to pulsate in quiescence at luminosities below the theoretical limit predicted for the onset of the centrifugal barrier. The source 1A 0535+262 is one of them. Here we present the results of an analysis of a ∼50 ks long XMM-Newton observation of 1A 0535+262 in quiescence. At the time of the observation, the neutron star was close to apastron, and the source had remained quiet for two orbital cycles. In spite of this, we detected a pulsed X-ray flux of ∼3 × 10 −11 erg cm −2 s −1 . Several observed properties, including the power spectrum, remained similar to those observed in the outbursts. Particularly, we have found that the frequency of the break detected in the quiescent noise power spectrum follows the same correlation with flux observed when the source is in outburst. This correlation has been associated with the truncation of the accretion disk at the magnetosphere boundary. We argue that our result, along with other arguments previously reported in the literature, suggests that the accretion in quiescence also proceeds from an accretion disk around the neutron star. The proposed scenario consistently explains the energy of the cyclotron line observed in 1A 0535+262, and the timing properties of the source including the spin frequency evolution within and between the outbursts, and the frequency of the break in power spectrum.

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“…11 for the sources with known positive and negative correlations (shown by blue and red points, respectively). Finally, it is worth to note that for some transient pulsars no dependence of the cyclotron energy on luminosity has been detected for a wide range of luminosities (see, e.g., Caballero et al, 2013, for A 0535+26). Apart from the transient BeXBs, Reig and Roche (1999) pointed out the existence of persistent sources of the same Be/X type, but with low luminosities (10 34 − 10 35 erg s −1 ).…”

Section: Be Systems X-ray Pulsars and Properties Of Cyclotron Absorpmentioning

confidence: 99%

High-mass X-ray binaries in the Milky Way

Walter

Lutovinov

Bozzo

et al. 2015

Astron Astrophys Rev

230

234

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High-mass X-ray binaries are fundamental in the study of stellar evolution, nucleosynthesis, structure and evolution of galaxies and accretion processes. Hard X-rays observations by INTEGRAL and Swift have broadened significantly our understanding in particular for the super-giant systems in the Milky Way, which number has increased by almost a factor of three. INTEGRAL played a crucial role in the discovery, study and understanding of heavily obscured systems and of fast X-ray transients. Most super-giant systems can now be classified in three categories: classical/obscured, eccentric and fast transient.The classical systems feature low eccentricity and variability factor of ∼ 10 3 , mostly driven by hydrodynamic phenomena occurring on scales larger than the accretion radius. Among them, systems with short orbital periods and close to Roche-Lobe overflow or with slow winds, appear highly obscured. In eccentric systems, the variability amplitude can reach even higher factors, because of the contrast of the wind density along the orbit. Four super-giant systems, featuring fast outbursts, very short orbital periods and anomalously low accretion rates, are not yet understood.Simulations of the accretion processes on relatively large scales have progressed and reproduce parts of the observations. The combined effects of wind

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A DOUBLE-PEAKED OUTBURST OF A 0535+26 OBSERVED WITH INTEGRAL , RXTE , AND SUZAKU

Cited by 32 publications

References 37 publications

A 0535+26 in the April 2010 outburst: probing the accretion regime at work

A 0535+26 in the April 2010 outburst: probing the accretion regime at work

XMM-Newtonobservations of 1A 0535+262 in quiescence

High-mass X-ray binaries in the Milky Way

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