Hard spectra of X-ray pulsars from INTEGRAL data

Filippova, E.V.; Tsygankov, Sergey S.; Lutovinov, A.; Sunyaev, R.

doi:10.1134/1.2123288

Cited by 86 publications

(100 citation statements)

References 88 publications

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“…The absence of eclipse constrains the inclination angle in the range (44 • − 78 • ). A deep and variable 60 R. Walter et al cyclotron resonance feature is observed at hard X-rays Filippova et al, 2005;Fürst et al, 2011b). Spin up episodes have been observed and explained by the formation of transient accretion disks .…”

Section: Discussionmentioning

confidence: 99%

“…Long-term observations of 4U 1145-619 with the Ariel V observatory revealed outbursts from the source, which occurred at regular intervals of ≃ 187.5 days and which were interpreted as a motion of a neutron star in a highly eccentric e > 0.6 orbit with the corresponding period (Watson et al, 1981). Further observations of the source performed by different observatories allowed to trace its pulse period history (see, e.g., Lutovinov et al, 1994;Bildsten et al, 1997, and references therein), to measure for the first time the source spectrum up to 100 keV (Filippova et al, 2005), etc. It is necessary to note, that distance estimations from spectroscopic observations d = 3.1 ± 0.5 kpc (Stevens et al, 1997) is several times larger than that from the parallax measurements d = 0.51 ± 0.24 kpc (Clark and Dolan, 1999).…”

Section: Discussionmentioning

confidence: 99%

“…It was interpreted as an indication that AX J1820.5-1434 is a high-mass X-ray binary system, but a clear optical identification and determination of the spectral class of the optical star are still problematic (Negueruela and Schurch, 2007). A detection of the hard X-ray emission from from AX J1820.5-1434 with the INTEGRAL observatory allowed to reconstruct the source spectrum up to ∼ 70 keV and to show that it is typical for X-ray pulsars in HMXB (Filippova et al, 2005). This source is also tentatively associated with the SFXT class due to the detection of fast flaring activity with INTEGRAL (Walter and Zurita Heras, 2007b).…”

Section: Discussionmentioning

confidence: 99%

“…In such systems, the plasma approaching the neutron star is stopped by the pressure of the dipolar magnetic field and forced to move along the field lines toward the magnetic poles, where the captured matter releases its gravitational energy in the form of X-rays. The X-ray continuum of accreting pulsars is characterized by a powerlaw of photon index 0.3-2 with a high-energy exponential cutoff (7-30 keV, White et al, 1983;Filippova et al, 2005), sometimes modified by absorption and emission lines in the soft X-rays and by Cyclotron Resonance Scattering Features (CRSF) at higher energies (Coburn et al, 2002;Filippova et al, 2005;Caballero and Wilms, 2012). The plasma falls in the accretion column at almost the speed of light and heats to 10 8 K close to the neutron star surface (see, e.g.…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

High-mass X-ray binaries in the Milky Way

Walter

Lutovinov

Bozzo

et al. 2015

Astron Astrophys Rev

230

234

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“…Audley et al 2006, and references therein). The object has been studied since its discovery in the 1970s by a fair number of authors with several X-ray observatories up to about 160 keV, recently also with INTEGRAL (Filippova et al 2005;Barnstedt et al 2008). In the range from 3 to 160 keV they find consistently an absorbed, exceptionally hard spectrum with index Γ ≈ 1.0 which then softens with an exponential cutoff at energies around 25 keV.…”

Section: Oao 1657-415mentioning

confidence: 99%

Soft gamma-ray sources detected by INTEGRAL

Petry

Beckmann

Halloin

et al. 2009

A&A

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Aims. We aim to exploit the available INTEGRAL/SPI data to provide time-averaged spectra of the brightest soft gamma-ray sources. Methods. Employing a maximum-likelihood fit technique for our SPI data analysis, we take as input to our source model the source catalog derived by Bouchet et al. (2008) from a SPI all-sky study. We use the first four years of public SPI data and extract spectra between 25 keV and 1 MeV for the 20 catalog sources detected by Bouchet et al. at 200−600 keV with ≥2.5σ. In order to verify our analysis, we also extract spectra for the same sources from the corresponding INTEGRAL/ISGRI data. We fit adequate spectral models to the energy range 25−1000 keV for SPI and 25−600 keV for ISGRI. We use our spectra from the Crab (which is among the 20 sources studied here) and an empty location in a crowded field to derive an estimation of the systematic errors. Results. The agreement between our SPI and ISGRI measurements is good if we normalise them on the Crab spectrum. Our SPI flux measurements also agree well with those by Bouchet et al. (2008). All 20 sources in our sample are detected independently in the bands 25−100 keV and 100−200 keV. At 200−600 keV we detect eight sources, at 600−1000 keV we detect two sources. Our spectra agree well with the results from previous publications where available. For six of the 14 XRBs in our sample we find evidence for a hard powerlaw-component which becomes dominant above the cutoff energy of the thermal Comptonization component. In two of these cases, our study provides the first indication of such emission. For the others, our results confirm previous studies. Our spectrum of the Crab, integrated over 1.3 Ms, shows a significant flux in all points and is well described by a powerlaw with a break near 100 keV and spectral indices 2.11 and 2.20.

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Magnetic Fields of Neutron Stars in X-Ray Binaries

Revnivtsev

Mereghetti

2016

Space Sciences Series of ISSI

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A substantial fraction of the known neutron stars resides in X-ray binaries -systems in which one compact object accretes matter from a companion star. Neutron stars in X-ray binaries have magnetic fields among the highest found in the Universe, spanning at least the range from ∼ 10 8 to several 10 13 G. The magnetospheres around these neutron stars have a strong influence on the accretion process, which powers most of their emission. The magnetic field intensity and geometry, are among the main factors responsible for the large variety of spectral and timing properties observed in the X-ray energy range, making these objects unique laboratories to study the matter behavior and the radiation processes in magnetic fields unaccessible on Earth. In this paper we review the main observational aspects related to the presence of magnetic fields in neutron star X-ray binaries and some methods that are used to estimate their strength.

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Hard spectra of X-ray pulsars from INTEGRAL data

Cited by 86 publications

References 88 publications

High-mass X-ray binaries in the Milky Way

High-mass X-ray binaries in the Milky Way

Soft gamma-ray sources detected by INTEGRAL

Magnetic Fields of Neutron Stars in X-Ray Binaries

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