The<i>BeppoSAX</i>view of the galactic high-mass X-ray binary 4U 0114+65

Masetti, N.; Orlandini, M.; Fiume, D. Dal; Sordo, S. Del; Amati, L.; Frontera, F.; Palazzi, E.; Santangelo, A.

doi:10.1051/0004-6361:20053654

Cited by 23 publications

(42 citation statements)

References 38 publications

(74 reference statements)

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“…The OMC observed the optical companion of V 0332+53, BQ Cam at M V ∼ 15.4 ± 0.2 consistent with simultaneous ground based observations (Masetti et al 2005). The observations confirm that BQ Cam is in an excited state.…”

Section: Image Analysissupporting

confidence: 80%

INTEGRALobservation of V 0332+53 in outburst

Kreykenbohm

Mowlavï

Produit

et al. 2005

A&A

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Abstract.We present the analysis of a 100 ks INTEGRAL (3−100 keV) observation of the transient X-ray pulsar V 0332+53 in outburst. The source is pulsating at P Pulse = 4.3751 ± 0.0002 s with a clear double pulse from 6 keV to 60 keV. The average flux was ∼550 mCrab between 20 keV and 60 keV. We modeled the broad band continuum from 5 keV to 100 keV with a power-law modified by an exponential cut off. We observe three cyclotron lines: the fundamental line at 24.9 +0.1 −0.1 keV, the first harmonic at 50.5 +0.1 −0.1 keV as well as the second harmonic at 71.7 +0.7 −0.8 keV, thus confirming the discovery of the harmonic lines by Coburn et al. (2005) in RXTE data.

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Section: Image Analysissupporting

confidence: 80%

INTEGRALobservation of V 0332+53 in outburst

Kreykenbohm

Mowlavï

Produit

et al. 2005

A&A

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“…The measurement by Masetti et al (2005) shows that the disk was larger, hence the decrease in EW(Hα) after the X-ray outburst was more significant than what our data alone suggested. The low inclination of the system may also explain the smaller amplitude change in EW(Hα) after the outburst with respect to other systems, as pointed out in Sect.…”

Section: Circumstellar Disk and X-ray Variabilitycontrasting

confidence: 50%

“…However, we do not know whether EW(Hα) was larger before MJD 53 304 and smaller after MJD 53 670. To investigate this issue, we searched the literature for other measurements of EW(Hα) in the interval MJD 52 920-54 033 and found two values at MJD 53 378 (Masetti et al 2005) and MJD 54 005 (Caballero-Garcia et al 2016) with Hα equivalent widths of −10 Å and −6.2 Å, respectively. These two points have been depicted in Fig.…”

Section: Circumstellar Disk and X-ray Variabilitymentioning

confidence: 99%

Long-term optical variability of high-mass X-ray binaries

Reig

Nersesian

Zezas

et al. 2016

A&A

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Context. High-mass X-ray binaries are bright X-ray sources. The high-energy emission is caused by the accretion of matter from the massive companion onto a neutron star. The accreting material comes from either the strong stellar wind in binaries with supergiant companions or the cirscumstellar disk in Be/X-ray binaries. In either case, the Hα line stands out as the main source of information about the state of the accreting material. Aims. We present the results of our monitoring program to study the long-term variability of the Hα line in high-mass X-ray binaries. Our aim is to characterise the optical variability timescales and study the interaction between the neutron star and the accreting material. Methods. We fitted the Hα line with Gaussian profiles and obtained the line parameters and equivalent width. The peak separation in split profiles was used to determine the disk velocity law and estimate the disk radius. The relative intensity of the two peaks (V/R ratio) allowed us to investigate the distribution of gas particles in the disk. The equivalent width was used to characterise the degree of variability of the systems. We also studied the variability of the Hα line in correlation with the X-ray activity. Results. Our results can be summarised as follows: i) we find that Be/X-ray binaries with narrow orbits are more variable than systems with long orbital periods; ii) we show that a Keplerian distribution of gas particles provides a good description of the disks in Be/X-ray binaries, as it does in classical Be stars; iii) a decrease in the Hα equivalent width is generally observed after major X-ray outbursts; iv) we confirm that the Hα equivalent width correlates with disk radius; v) while systems with supergiant companions display multistructured profiles, most of the Be/X-ray binaries show, at some epoch, double-peak asymmetric profiles, which indicates that density inhomogeneities is a common property in the disk of Be/X-ray binaries; vi) the profile variability (V/R ratio) timescales are shorter and the Hα equivalent widths are smaller in Be/X-ray binaries than in isolated Be stars; and vii) we provide new evidence that the disk in Be/X-ray binaries is, on average, denser than in classical Be stars. Conclusions. We carried out the most complete optical spectroscopic study of the global properties of high-mass X-ray binaries with the analysis of more than 1100 spectra from 20 sources. Our results provide further evidence for the truncation of the disk in Be/X-ray binaries. We conclude that the interaction between the compact object and the Be-type star works in two directions: the massive companion provides the source of matter for accretion, affecting the surroundings of the compact object, and the continuous revolution of the neutron star around the optical counterpart also produces the truncation of the Be star's equatorial disk.

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“…Note also that the high-luminosity pulsars mentioned above contain supergiant companions, while the low-luminosity systems harbour main-sequence stars. In between these extreme cases one finds the wind-fed supergiant systems (filled triangles), such as Vela X-1, with kT bb = 0.2 keV and R bb = 70 km (Hickox et al 2004) and 2S 0114+650, with kT bb = 0.3 keV and R bb = 200 km (Masetti et al 2006a). In these systems the thermal component responsible for the soft excess is likely to be a cloud of diffuse plasma around the neutron star (Hickox et al 2004).…”

Section: Soft Componentmentioning

confidence: 99%

Discovery of slow X-ray pulsations in the high-mass X-ray binary 4U 2206+54

Reig

Torrejón

Negueruela

et al. 2008

A&A

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Context. The source 4U 2206+54 is one of the most enigmatic high-mass X-ray binaries. In spite of intensive searches, X-ray pulsations have not been detected in the time range 10 −3 -10 3 s. A cyclotron line at ∼30 keV has been suggested by various authors but never detected with significance. The stellar wind of the optical companion is abnormally slow. The orbital period, initially reported to be 9.6 days, disappeared and a new periodicity of 19.25 days emerged. Aims. The main objective of our RXTE monitoring of 4U 2206+54 is to study the X-ray orbital variability of the spectral and timing parameters. The new long and uninterrupted RXTE observations allow us to search for long (∼1 h) pulsations for the first time. Methods. We divided the ∼7-day observation into five intervals and obtained time-averaged energy spectra and power spectral density for each observation interval. We also searched for pulsations using various algorithms. Results. We have discovered 5560-s pulsations in the light curve of 4U 2206+54. Initially detected in RXTE data, these pulsations are also present in INTEGRAL and EXOSAT observations. The average X-ray luminosity in the energy range 2-10 keV is 1.5 × 10 35 erg s −1 with a ratio F max /F min ≈ 5. This ratio implies an eccentricity of ∼0.4, somewhat higher than previously suggested. The power spectrum is dominated by red noise that can be fitted with a single power law whose index and strength decrease with X-ray flux. The source also shows a soft excess at low energies. If the soft excess is modelled with a blackbody component, then the size and temperature of the emitting region agrees with its interpretation in terms of a hot spot on the neutron star surface. Conclusions. The discovery of X-ray pulsations in 4U 2206+54 confirms the neutron star nature of the compact companion and definitively rules out the presence of a black hole. The source displays variability on time scales of days, presumably due to changes in the mass accretion rate as the neutron star moves around the optical companion in a moderately eccentric orbit. If current models for the spin evolution in X-ray pulsars are correct, then the magnetic field of 4U 2206+54 at birth must have been B 10 14 G.

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TheBeppoSAXview of the galactic high-mass X-ray binary 4U 0114+65

Cited by 23 publications

References 38 publications

INTEGRALobservation of V 0332+53 in outburst

INTEGRALobservation of V 0332+53 in outburst

Long-term optical variability of high-mass X-ray binaries

Discovery of slow X-ray pulsations in the high-mass X-ray binary 4U 2206+54

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