scholarly journals Optical counterpart to Swift J0243.6+6124

2020 ◽  
Vol 640 ◽  
pp. A35
Author(s):  
P. Reig ◽  
J. Fabregat ◽  
J. Alfonso-Garzón
Keyword(s):  
Rotational Velocity ◽  
High Mass ◽  
Circumstellar Disk ◽  
Optical Counterpart ◽  
Optical Extinction ◽  
X Ray ◽  
Unique System ◽  
Unique Source ◽  
Photometric Monitoring

Context. Swift J0243.6+6124 is a unique system. It is the first and only ultra-luminous X-ray source in our Galaxy. It is the first and only high-mass Be X-ray pulsar showing radio jet emission. It was discovered during a giant X-ray outburst in October 2017. While there are numerous studies in the X-ray band, very little is known about the optical counterpart. Aims. Our aim is to characterize the variability timescales in the optical and infrared bands in order to understand the nature of this intriguing system. Methods. We performed optical spectroscopic observations to determine the spectral type. Long-term photometric light curves together with the equivalent width of the Hα line were used to monitor the state of the circumstellar disk. We used BVRI photometry to estimate the interstellar absorption and distance to the source. Continuous photometric monitoring in the B and V bands allowed us to search for intra-night variability. Results. The optical counterpart to Swift J0243.6+6124 is a V = 12.9, O9.5Ve star, located at a distance of ∼5 kpc. The optical extinction in the direction of the source is AV = 3.6 mag. The rotational velocity of the O-type star is 210 km s−1. The long-term optical variability agrees with the growth and subsequent dissipation of the Be circumstellar disk after the giant X-ray outburst. The optical and X-ray luminosity are strongly correlated during the outburst, suggesting a common origin. We did not detect short-term periodic variability that could be associated with nonradial pulsations from the Be star photosphere. Conclusions. The long-term optical and infrared pattern of variability of Swift J0243.6+6124 is typical of Be/X-ray binaries. However, the absence of nonradial pulsations is unusual and adds another peculiar trait to this unique source.

Long term multiwavelength monitoring of high mass x-ray binaries

1994 ◽  
Author(s):  
Paul Roche ◽  
Malcolm Coe ◽  
Chris Everall ◽  
Juan Fabregat ◽  
Victor Reglero ◽  
...  
Keyword(s):  
High Mass ◽  
X Ray ◽  
X Ray Binaries

LMC X–4: Different Types of Long-Term Variability

2017 ◽  
Vol 14 (S339) ◽  
pp. 146-146
Author(s):  
S. Molkov
Keyword(s):  
Binary Systems ◽  
Noise Model ◽  
High Mass ◽  
Time Interval ◽  
Spin Torque ◽  
X Ray ◽  
Spin Period ◽  
Different Types ◽  
First Time

AbstractThis talk presented a summary of our study of different types of long-term variability in the high-mass X-ray binary LMC X-4, by taking advantage of more than 43 years of measurements in the X-ray domain. In particular, we investigated the 30-day cycle of modulation of the X-ray emission from the source (super-orbital or precessional variability), and refined the orbital period and its first derivative. We showed that the precession period in the time-interval 1991–2015 is near its equilibrium value of Psup = 30.370 days, while the observed historical changes in the phase of this variability can be interpreted in terms of the ‘red noise’ model. We obtained an analytical law from which the precession phase can be determined to within 5% throughout the entire time-interval under consideration. Our analysis revealed for the first time that the source is displaying near-periodic variations of its spin period, on a time-scale of roughly 6.8 years, thus making LMC X-4 one of the (few) known binary systems that show remarkable long-term spin–torque reversals.

scholarly journals The superslow pulsation X-ray pulsars in high mass X-ray binaries

2012 ◽  
Vol 8 (S291) ◽  
pp. 203-206 ◽  
Author(s):  
Wei Wang
Keyword(s):  
Neutron Star ◽  
Binary Systems ◽  
High Mass ◽  
X Ray ◽  
Origin And Evolution ◽  
Surface Magnetic Field ◽  
Spin Period ◽  
Binary Evolution ◽  
X Ray Binaries

AbstractThere exists a special class of X-ray pulsars that exhibit very slow pulsation of Pspin > 1000 s in the high mass X-ray binaries (HMXBs). We have studied the temporal and spectral properties of these superslow pulsation neutron star binaries in hard X-ray bands with INTEGRAL observations. Long-term monitoring observations find spin period evolution of two sources: spin-down trend for 4U 2206+54 (Pspin ~ 5560 s with Ṗspin ~ 4.9 × 10−7 s s−1) and long-term spin-up trend for 2S 0114+65 (Pspin ~ 9600 s with Ṗspin ~ −1 × 10−6 s s−1) in the last 20 years. A Be X-ray transient, SXP 1062 (Pspin ~ 1062 s), also showed a fast spin-down rate of Ṗspin ~ 3 × 10−6 s s−1 during an outburst. These superslow pulsation neutron stars cannot be produced in the standard X-ray binary evolution model unless the neutron star has a much stronger surface magnetic field (B > 1014 G). The physical origin of the superslow spin period is still unclear. The possible origin and evolution channels of the superslow pulsation X-ray pulsars are discussed. Superslow pulsation X-ray pulsars could be younger X-ray binary systems, still in the fast evolution phase preceding the final equilibrium state. Alternatively, they could be a new class of neutron star system – accreting magnetars.

scholarly journals Diverse Long-term Variability of Five Candidate High-mass X-Ray Binaries fromSwiftBurst Alert Telescope Observations

2017 ◽  
Vol 846 (2) ◽  
pp. 161 ◽  
Author(s):  
Robin H. D. Corbet ◽  
Joel B. Coley ◽  
Hans A. Krimm
Keyword(s):  
High Mass ◽  
X Ray ◽  
X Ray Binaries

scholarly journals Tidal tearing of circumstellar disks in Be/X-ray and gamma-ray binaries

2016 ◽  
Vol 12 (S329) ◽  
pp. 432-432
Author(s):  
Atsuo T. Okazaki
Keyword(s):  
Gamma Ray ◽  
Compact Object ◽  
High Energy ◽  
High Mass ◽  
List Type ◽  
X Ray ◽  
Short Period ◽  
Be Star ◽  
X Ray Binaries

AbstractAbout one half of high-mass X-ray binaries host a Be star [an OB star with a viscous decretion (slowly outflowing) disk]. These Be/X-ray binaries exhibit two types of X-ray outbursts (Stella et al. 1986), normal X-ray outbursts (LX~1036−37 erg s−1) and occasional giant X-ray outbursts (LX > 1037 erg s−1). The origin of giant X-ray outbursts is unknown. On the other hand, a half of gamma-ray binaries have a Be star as the optical counterpart. One of these systems [LS I +61 303 (Porb = 26.5 d)] shows the superorbital (1,667 d) modulation in radio through X-ray bands. No consensus has been obtained for its origin. In this paper, we study a possibility that both phenomena are caused by a long-term, cyclic evolution of a highly misaligned Be disk under the influence of a compact object, by performing 3D hydrodynamic simulations. We find that the Be disk cyclically evolves in mildly eccentric, short-period systems. Each cycle consists of the following stages: 1)As the Be disk grows with time, the initially circular disk becomes eccentric by the Kozai-Lidov mechanism.2)At some point, the disk is tidally torn off near the base and starts precession.3)Due to precession, a gap opens between the disk base and mass ejection region, which allows the formation of a new disk in the stellar equatorial plane (see Figure 1).4)The newly formed disk finally replaces the precessing old disk. Such a cyclic disk evolution has interesting implications for the long-term behavior of high energy emission in Be/X-ray and gamma-ray binaries.

scholarly journals Observations of GRO J1744–28 in quiescence with XMM-Newton

2020 ◽  
Vol 643 ◽  
pp. A62
Author(s):  
V. Doroshenko ◽  
V. Suleimanov ◽  
S. Tsygankov ◽  
J. Mönkkönen ◽  
L. Ji ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Neutron Star ◽  
Binary System ◽  
Galactic Center ◽  
Optical Counterpart ◽  
X Ray ◽  
Upper Limit ◽  
Dipole Term ◽  
The Magnetic Field

We report on the deep observations of the “bursting pulsar” GRO J1744–28, which were performed with XMM-Newton and aimed to clarify the origin of its X-ray emission in quiescence. We detect the source at a luminosity level of ∼1034 erg s−1 with an X-ray spectrum that is consistent with the power law, blackbody, or accretion-heated neutron star atmosphere models. The improved X-ray localization of the source allowed us to confirm the previously identified candidate optical counterpart as a relatively massive G/K III star at 8 kpc close to the Galactic center, implying an almost face-on view of the binary system. Although we could only find a nonrestricting upper limit on the pulsed fraction of ∼20%, the observed hard X-ray spectrum and strong long-term variability of the X-ray flux suggest that the source is also still accreting when not in outburst. The luminosity corresponding to the onset of centrifugal inhibition of accretion is thus estimated to be at least two orders of magnitude lower than previously reported. We discuss this finding in the context of previous studies and argue that the results indicate a multipole structure in the magnetic field with the first dipole term of ∼1010 G, which is much lower than previously assumed.

scholarly journals Rotation of the Mass Donors in High-mass X-ray Binaries and Symbiotic Stars

2015 ◽  
Vol 2 (1) ◽  
pp. 286-290
Author(s):  
K. Stoyanov ◽  
R. Zamanov
Keyword(s):  
Rotational Velocity ◽  
High Mass ◽  
Symbiotic Stars ◽  
Orbital Eccentricity ◽  
X Ray ◽  
Tidal Interaction ◽  
Theoretical Predictions ◽  
Orbital Periods ◽  
Red Giant ◽  
X Ray Binaries

Our aim is to investigate the tidal interaction in High-mass X-ray Binaries and Symbiotic stars in order to determine in which objects the rotation of the mass donors is synchronized or pseudosynchronized with the orbital motion of the compact companion. We find that the Be/X-ray binaries are not synchronized and the orbital periods of the systems are greater than the rotational periods of the mass donors. The giant and supergiant High-mass X-ray binaries and symbiotic stars are close to synchronization. We compare the rotation of mass donors in symbiotics with the projected rotational velocities of field giants and find that the M giants in S-type symbiotics rotate on average 1.5 times faster than the field M giants. We find that the projected rotational velocity of the red giant in symbiotic star MWC 560 is <em>v</em> sin <em>i</em>= 8.2±1.5 km.s<sup>−1</sup>, and estimate its rotational period to be <em>P</em><sub>rot&lt;&gt;/sub = 144 - 306 days. Using the theoretical predictions of tidal interaction and pseudosynchronization, we estimate the orbital eccentricity e = 0.68 − 0.82.</sub>

scholarly journals Long-term Monitoring with Small and Medium-sized Telescopes on the Ground and in Space

2011 ◽  
Vol 7 (S285) ◽  
pp. 23-28
Author(s):  
P. A. Charles ◽  
M. M. Kotze ◽  
A. Rajoelimanana
Keyword(s):  
Large Scale ◽  
High Mass ◽  
Time Data ◽  
X Ray ◽  
Wide Range ◽  
Long Time ◽  
Sky Monitor ◽  
Real Time Data Processing ◽  
Large Telescopes

AbstractThe last 20 years have seen revolutionary developments of large-scale synoptic surveys of the sky, both from the ground (e.g., the MACHO and OGLE projects, which were targetted at micro-lensing studies) and in space (e.g., the X-ray All-Sky Monitor onboard RXTE). These utilised small and medium-sized telescopes to search for transient-like events, but they have now built up a huge database of long-term light-curves, thereby enabling archival research on a wide range of objects that has not been possible hitherto. This is illustrated with examples of long time-scale optical and X-ray variability studies from the field of X-ray binary research: the high-mass BeX binaries in the SMC (using MACHO and OGLE), and the bright galactic-bulge X-ray sources (mostly LMXBs, using RXTE/ASM). As such facilities develop greater capabilities in future and at other wavelengths (developments in South Africa will be described), real-time data processing will allow much more rapid follow-up studies with the new generation of queue-scheduled large telescopes such as SALT.

scholarly journals Optical Counterpart of the X-ray Transient RX J0117·6–7330: Spectroscopy and Photometry

1999 ◽  
Vol 16 (2) ◽  
pp. 147-151 ◽  
Author(s):  
Roberto Soria
Keyword(s):  
Rotational Velocity ◽  
Quiescent State ◽  
Spectral Features ◽  
Optical Counterpart ◽  
Primary Star ◽  
X Ray ◽  
Systemic Velocity ◽  
Photometric Observations ◽  
Be Star ◽  
Hα Emission

AbstractWe conducted spectroscopic and photometric observations of the optical companion of the X-ray transient RX J0117·6–7330 in the Small Magellanic Cloud, during a quiescent state. The primary star is identified as a B0·5 IIIe with a mass M* = (18 ± 2)M⨀ and bolometric magnitude Mbol = –7·4 ± 0·2. The main spectral features are strong Hα emission, Hβ and Hγ emission cores with absorption wings, and narrow He I and O II absorption lines. Equivalent widths and full widths at half maximum of the main lines are listed. The average systemic velocity over our observing run is vr = (184 ± 4) km s−1; measurements over a longer period of time are needed to determine the binary period and the K velocity of the primary. We determine a projected rotational velocity v sin i = (145 ± 10) km s−1 for the Be star; if we assume a true rotational velocity at the equator v = (400 ± 50) km s−1, we deduce that the inclination angle of the system is i = (21 ± 3) deg.

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