Orbital parameters of V 0332+53 from 2015 giant outburst data

Doroshenko, V.; Tsygankov, Sergey S.; Santangelo, A.

doi:10.1051/0004-6361/201527756

Cited by 23 publications

(26 citation statements)

References 18 publications

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“…4.1) and hence decreases the e-folding times to 14.3 hr and 5.6 hr. The blue vertical dashed lines represent times of the periastron passage, according to the orbital ephemeris, obtained by Raichur & Paul (2010) for 4U 0115+63 and Doroshenko et al (2016) for V 0332+53.…”

Section: Resultsmentioning

confidence: 99%

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Propeller effect in two brightest transient X-ray pulsars: 4U 0115+63 and V 0332+53

Tsygankov

Lutovinov

Doroshenko

et al. 2016

A&A

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105

111

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Aims. We present the results of the monitoring programmes performed with the Swift/XRT telescope and aimed specifically to detect an abrupt decrease of the observed flux associated with a transition to the propeller regime in two well-known X-ray pulsars 4U 0115+63 and V 0332+53. Methods. Both sources form binary systems with Be optical companions and undergo so-called giant outbursts every 3-4 years. The current observational campaigns were performed with the Swift/XRT telescope in the soft X-ray band (0.5-10 keV) during the declining phases of the outbursts exhibited by both sources in 2015.Results. The transitions to the propeller regime were detected at the threshold luminosities of (1.4 ± 0.4) × 10 36 erg s −1 and (2.0 ± 0.4) × 10 36 erg s −1 for 4U 0115+63 and V 0332+53, respectively. Spectra of the sources are shown to be significantly softer during the low state. In both sources, the accretion at rates close to the aforementioned threshold values briefly resumes during the periastron passage following the transition into the propeller regime. The strength of the dipole component of the magnetic field required to inhibit the accretion agrees well with estimates based on the position of the cyclotron lines in their spectra, thus excluding presence of a strong multipole component of the magnetic field in the vicinity of the neutron star.

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Section: Resultsmentioning

confidence: 99%

“…Both sources form binary systems with Be optical companions (Be/XRP) and undergo the so-called giant outbursts every 3-4 years. The current observational campaigns were performed during the declining phases of their outbursts in 2015 (Nakajima et al 2015a,b;Doroshenko et al 2015b). …”

Section: Introductionmentioning

confidence: 99%

Propeller effect in two brightest transient X-ray pulsars: 4U 0115+63 and V 0332+53

Tsygankov

Lutovinov

Doroshenko

et al. 2016

A&A

Self Cite

105

111

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“…The 1-day sensitivity (for 15-50 keV) of the BAT is 5.3 mCrab (∼7 × 10 −11 erg cm −2 s −1 ; Krimm et al 2013), limiting the peak brightness of these episodes to LX 4 × 10 35 erg s −1 (assuming a distance of 7 kpc for both sources). Those rebrightening events occurred at times of periastron passage of the neutron star (based on the ephemerides of Doroshenko et al (2015b) and Raichur & Paul (2010); dotted lines in Figure 1). Therefore, these are likely related to type-I outbursts, albeit much fainter.…”

Section: Observations Analysis and Resultsmentioning

confidence: 99%

Meta-stable low-level accretion rate states or neutron star crust cooling in the Be/X-ray transients V0332+53 and 4U 0115+63

Wijnands

Degenaar

2016

Monthly Notices of the Royal Astronomical Society: Letters

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The Be/X-ray transients V0332+53 and 4U 0115+63 exhibited giant, type-II outbursts in 2015. Here we present Swift/XRT follow-up observations at the end of those outbursts. Surprisingly, the sources did not decay back to their known quiescent levels but stalled at a (slowly decaying) meta-stable state with luminosities a factor ∼10 above that observed in quiescence. The spectra in these states are considerably softer than the outburst spectra and appear to soften in time when the luminosity decreases. The physical mechanism behind these metastable states is unclear and they could be due to low-level accretion (either directly onto the neutron stars or onto their magnetospheres) or due to cooling of the accretion-heated neutron star crusts. Based on the spectra, the slowly decreasing luminosities, and the spectral softening, we favour the crust cooling hypothesis but we cannot exclude the accretion scenarios. On top of this meta-stable state, weak accretion events were observed that occurred at periastron passage and may thus be related to regular type-I outbursts.

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“…An enhancement of the X-ray luminosity that repeats periodically at intervals of P orb in wind-fed systems with high eccentricity can be explained with the higher accretion rate at the periastron passage of the pulsar, where the circumstellar wind is denser and slower (e.g., Waters et al 1989;Raguzova & Lipunov 1998). An accretion disk around the NS of V0332+53 is expected to form during giant outbursts as indicated by the strong spin-up of the NS (Doroshenko et al 2016). The timescale needed for the gravitationally captured material to spiral-in and fall onto the NS is of the order of > ∼ 10-100 days and depends on the dimensions of the disk and its viscosity properties (Shakura & Sunyaev 1973).…”

Section: Outburst Profilesmentioning

confidence: 99%

“…In June 2015, V0332+53 underwent a new giant outburst (Nakajima et al 2015;Doroshenko et al 2015), anticipated by a brightening in the optical band that was probably associated with the donor star disc (Camero-Arranz et al 2015). During this outburst, INTEGRAL carried out four observations between July 17 and October 9, covering both the rise and the decay of the outburst.…”

Section: Introductionmentioning

confidence: 99%

Two giant outbursts of V0332+53 observed with INTEGRAL

Ferrigno

Ducci

Bozzo

et al. 2016

A&A

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Context. In July 2015, the high-mass X-ray binary V0332+53 underwent a giant outburst, a decade after the previous one. V0332+53 hosts a strongly magnetized neutron star. During the 2004-2005 outburst, an anti-correlation between the centroid energy of its fundamental cyclotron resonance scattering features (CRSFs) and the X-ray luminosity was observed. Aims. The long (≈100 d) and bright (L x ≈ 10 38 erg s −1 ) 2015 outburst provided the opportunity to study the unique properties of the fundamental CRSF during another outburst and to study its dependence on the X-ray luminosity. Methods. The source was observed by the INTEGRAL satellite for ∼330 ks. We exploit the spectral resolution at high energies of the SPectrometer on INTEGRAL (SPI) and the Joint European X-ray Monitors to characterize its spectral properties, focusing in particular on the CRSF-luminosity dependence. We complement the data of the 2015 outburst with those collected by SPI in [2004][2005], which have so far been left unpublished. Results. We find a highly significant anti-correlation of the centroid energy of the fundamental CRSF and the 3-100 keV luminosity of E 1 ∝ −0.095(8)L 37 keV. This trend is observed for both outbursts. We confirm the correlation between the width of the fundamental CRSF and the X-ray luminosity previously found in the JEM-X and IBIS dataset of the 2004-2005 outburst. By exploiting the RXTE/ASM and Swift/BAT monitoring data, we also report on the detection of a ∼34 d modulation superimposed on the mean profiles and roughly consistent with the orbital period of the pulsar. We discuss possible interpretations of such variability.

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Orbital parameters of V 0332+53 from 2015 giant outburst data

Cited by 23 publications

References 18 publications

Propeller effect in two brightest transient X-ray pulsars: 4U 0115+63 and V 0332+53

Propeller effect in two brightest transient X-ray pulsars: 4U 0115+63 and V 0332+53

Meta-stable low-level accretion rate states or neutron star crust cooling in the Be/X-ray transients V0332+53 and 4U 0115+63

Two giant outbursts of V0332+53 observed with INTEGRAL

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