scholarly journals Swift unveils the orbital period of IGR J18214-1318

2020 ◽  
Vol 498 (2) ◽  
pp. 2750-2756
Author(s):  
G Cusumano ◽  
A D’Aì ◽  
A Segreto ◽  
V La Parola ◽  
M Del Santo
Keyword(s):  
Orbital Period ◽  
Timing Analysis ◽  
Broad Band ◽  
Physical Models ◽  
High Mass ◽  
Periodic Signal ◽  
Deep Minimum ◽  
Companion Star ◽  
Bulk Motion ◽  
Using Data

ABSTRACT We analysed 13 yr of the Neil Gehrels Swift Observatory survey data collected on the high-mass X-ray binary IGR J18214-1318. Performing the timing analysis, we detected a periodic signal of 5.42 d. From the companion star characteristics, we derived an average orbital separation of $\sim 41 \rm R_{\odot }\simeq 2 R_{\star }$. The spectral type of the companion star (O9) and the tight orbital separation suggest that IGR J18214-1318 is a wind-accreting source with eccentricity lower than 0.17. The intensity profile folded at the orbital period shows a deep minimum compatible with an eclipse of the source by the companion star. In addition, we report on the broad-band 0.6–100 keV spectrum using data from XMM–Newton, NuSTAR, and Swift, applying self-consistent physical models. We find that the spectrum is well fitted either by a pure thermal Comptonization component, or, assuming that the source is a neutron star accreting above the critical regime, by a combined thermal and bulk motion Comptonization model. In both cases, the presence of a local neutral absorption (possibly related to the thick wind of the companion star) is required.

Superhump period of SDSS J214354.59+124457.8: First Z Cam star with superhumps in the standstill

2019 ◽  
Vol 489 (1) ◽  
pp. 1451-1462
Author(s):  
Metin Altan ◽  
Taichi Kato ◽  
Ryoko Ishioka ◽  
Linda Schmidtobreick ◽  
Tolga Güver ◽  
...  
Keyword(s):  
Light Curve ◽  
Orbital Period ◽  
Timing Analysis ◽  
Periodic Signal ◽  
Mass Ratio ◽  
Short Intervals ◽  
Upper Limit ◽  
Term Variation ◽  
Two Phases

Abstract The cataclysmic variable SDSS J214354.59+124457.8 (hereafter SDSS J214354) was observed photometrically on sixty one nights between 2012 July 28 and 2019 May 26. The long term variation of this object shows changes between two phases; a dwarf nova type and a novalike. This implies that the object belongs to the group of Z Cam type stars. The timing analysis of the light curve reveals a periodic signal at 0.13902(5) d, which we identify as the superhump period. However, the fractional superhump excess of 10 per cent longer than the orbital period is exceptionally large. We obtained a mass ratio of ∼0.4, which is above the accepted upper limit of q = 0.33 for the formation of superhumps. We suggest that the object contains a secondary with an evolved core. With an orbital period of 0.126 d, SDSS J214354 is situated at the upper border of the period gap. The long term light curve of SDSS J214354 is similar to those of Z Cam type stars which are characterized by recurring standstills, followed by short intervals with DN type outbursts. Therefore, we conclude that SDSS J214354 is a new member of the Z Cam type stars.

scholarly journals Revisiting the spectral and timing properties of 4U 1909+07 with NuSTAR and Astrosat

2020 ◽  
Vol 498 (4) ◽  
pp. 4830-4838 ◽  
Author(s):  
Gaurava K Jaisawal ◽  
Sachindra Naik ◽  
Wynn C G Ho ◽  
Neeraj Kumari ◽  
Prahlad Epili ◽  
...  
Keyword(s):  
Broad Band ◽  
High Energy ◽  
High Mass ◽  
X Rays ◽  
Pulse Profile ◽  
X Ray ◽  
Beam Geometry ◽  
Cyclotron Absorption ◽  
Using Data ◽  
Wind Distribution

ABSTRACT We present the results obtained from the analysis of high-mass X-ray binary pulsar 4U 1909+07 using NuSTAR and Astrosat observations in July 2015 and 2017, respectively. X-ray pulsations at ≈604 s are clearly detected in our study. Based on the long-term spin-frequency evolution, the source is found to spun-up in the last 17 yr. We observed a strongly energy-dependent pulse profile that evolved from a complex broad structure in soft X-rays into a profile with a narrow emission peak followed by a plateau in energy ranges above 20 keV. This behaviour ensured a positive correlation between the energy and pulse fraction. The pulse profile morphology and its energy evolution are almost similar during both the observations, suggesting a persistent emission geometry of the pulsar over time. The broad-band energy spectrum of the pulsar is approximated by an absorbed high-energy exponential cut-off power-law model with iron emission lines. In contrast to the previous report, we found no statistical evidence for the presence of cyclotron absorption features in the X-ray spectra. We performed phase-resolved spectroscopy using data from the NuSTAR observation. Our results showed a clear signature of absorbing material at certain pulse phases of the pulsar. These findings are discussed in terms of stellar wind distribution and its effect on the beam geometry of this wind-fed accreting neutron star. We also reviewed the subsonic quasi-spherical accretion theory and its implication on the magnetic field of 4U 1909+07 depending on the global spin-up rate.

scholarly journals AstroSat and MAXI view of the black hole binary 4U 1630−472 during 2016 and 2018 outbursts

2020 ◽  
Vol 497 (1) ◽  
pp. 1197-1211
Author(s):  
Blessy E Baby ◽  
V K Agrawal ◽  
M C Ramadevi ◽  
Tilak Katoch ◽  
H M Antia ◽  
...  
Keyword(s):  
Black Hole ◽  
Timing Analysis ◽  
Broad Band ◽  
Physical Models ◽  
Bolometric Luminosity ◽  
Extensive Coverage ◽  
State Evolution ◽  
Dominant State ◽  
Photon Index ◽  
Black Hole Binary

ABSTRACT We present an in-depth spectral and timing analysis of the black hole binary 4U 1630−472 during 2016 and 2018 outbursts as observed by AstroSat and MAXI. The extensive coverage of the outbursts with MAXI is used to obtain the hardness intensity diagram (HID). The source follows a ‘c’-shaped profile in agreement with earlier findings. Based on the HIDs of previous outbursts, we attempt to track the evolution of the source during a ‘super’-outburst and ‘mini’-outbursts. We model the broad-band energy spectra (0.7–20.0 keV) of AstroSat observations of both outbursts using phenomenological and physical models. No Keplerian disc signature is observed at the beginning of 2016 outburst. However, the disc appears within a few hours after which it remains prominent with temperature (Tin) ∼ 1.3 keV and increase in photon index (Γ) from 1.8 to 2.0, whereas the source was at a disc dominant state throughout the AstroSat campaign of 2018 outburst. Based on the HIDs and spectral properties, we classify the outbursts into three different states – the ‘canonical’ hard and soft states along with an intermediate state. Evolution of rms along different states is seen although no quasi-periodic oscillations are detected. We fit the observed spectra using a dynamical accretion model and estimate the accretion parameters. Mass of the black hole is estimated using inner disc radius, bolometric luminosity, and two-component flow model to be 3–9 M⊙. Finally, we discuss the possible implications of our findings.

scholarly journals X-ray variability of the HMXB Cen X-3: evidence for inhomogeneous accretion flows.

2020 ◽  
Author(s):  
G Sanjurjo-Ferrín ◽  
J M Torrejón ◽  
K Postnov ◽  
L Oskinova ◽  
J J Rodes-Roca ◽  
...  
Keyword(s):  
Equivalent Width ◽  
Compact Star ◽  
Timing Analysis ◽  
Roche Lobe ◽  
The Other ◽  
Emission Lines ◽  
High Mass ◽  
X Ray ◽  
Accretion Flows ◽  
Inner Radius

Abstract Cen X-3 is a compact high mass X-ray binary likely powered by Roche lobe overflow. We present a phase-resolved X-ray spectral and timing analysis of two pointed XMM-Newton observations. The first one took place during a normal state of the source, when it has a luminosity LX ∼ 1036 erg s−1. This observation covered orbital phases φ = 0.00 − 0.37, i.e. the egress from the eclipse. The egress lightcurve is highly structured, showing distinctive intervals. We argue that different intervals correspond to the emergence of different emitting structures. The lightcurve analysis enables us to estimate the size of such structures around the compact star, the most conspicuous of which has a size ∼0.3R*, of the order of the Roche lobe radius. During the egress, the equivalent width of Fe emission lines, from highly ionized species, decreases as the X-ray continuum grows. On the other hand, the equivalent width of the Fe Kα line, from near neutral Fe, strengthens. This line is likely formed due to the X-ray illumination of the accretion stream. The second observation was taken when the source was 10 times X-ray brighter and covered the orbital phases φ = 0.36 − 0.80. The X-ray lightcurve in the high state shows dips. These dips are not caused by absorption but can be due to instabilities in the accretion stream. The typical dip duration, of about 1000 s, is much longer than the timescale attributed to the accretion of the clumpy stellar wind of the massive donor star, but is similar to the viscous timescale at the inner radius of the accretion disk.

scholarly journals A tale of two periods: determination of the orbital ephemeris of the super-Eddington pulsar NGC 7793 P13

2018 ◽  
Vol 616 ◽  
pp. A186 ◽  
Author(s):  
F. Fürst ◽  
D. J. Walton ◽  
M. Heida ◽  
F. A. Harrison ◽  
D. Barret ◽  
...  
Keyword(s):  
Accretion Disk ◽  
Orbital Period ◽  
Timing Analysis ◽  
X Ray ◽  
System Parameters ◽  
Orbital Resonance ◽  
Photometric Period ◽  
Orbital Periods ◽  
Analyze Data

We present a timing analysis of multiple XMM-Newton and NuSTAR observations of the ultra-luminous pulsar NGC 7793 P13 spread over its 65 d variability period. We use the measured pulse periods to determine the orbital ephemeris, confirm a long orbital period with Porb = 63.9+0.5−0.6 d, and find an eccentricity of e ≤ 0.15. The orbital signature is imprinted on top of a secular spin-up, which seems to get faster as the source becomes brighter. We also analyze data from dense monitoring of the source with Swift and find an optical photometric period of 63.9 ± 0.5 d and an X-ray flux period of 66.8 ± 0.4 d. The optical period is consistent with the orbital period, while the X-ray flux period is significantly longer. We discuss possible reasons for this discrepancy, which could be due to a super-orbital period caused by a precessing accretion disk or an orbital resonance. We put the orbital period of P13 into context with the orbital periods implied for two other ultra-luminous pulsars, M82 X-2 and NGC 5907 ULX, and discuss possible implications for the system parameters.

scholarly journals The Relation between Spin and Orbital Periods in HMXBs

2003 ◽  
Vol 214 ◽  
pp. 215-217
Author(s):  
Q. Z. Liu ◽  
X. D. Li ◽  
D. M. Wei
Keyword(s):  
Magnetic Fields ◽  
Orbital Period ◽  
Critical Line ◽  
High Mass ◽  
Orbital Eccentricity ◽  
X Ray ◽  
Spin Period ◽  
Orbital Periods ◽  
X Ray Binaries

The relation between the spin period (Ps) and the orbital period (Po) in high-mass X-ray binaries (HMXBs) is investigated. In order for Be/X-ray binaries to locate above the critical line of observable X-ray emission due to accretion, it is necessary for an intermediate orbital eccentricity to be introduced. We suggest that some peculiar systems in the Po − Ps diagram are caused by their peculiar magnetic fields.

scholarly journals An environmental dependence of the physical and structural properties in the Hydra cluster galaxies

2020 ◽  
Vol 500 (1) ◽  
pp. 1323-1339
Author(s):  
Ciria Lima-Dias ◽  
Antonela Monachesi ◽  
Sergio Torres-Flores ◽  
Arianna Cortesi ◽  
Daniel Hernández-Lang ◽  
...  
Keyword(s):  
Structural Properties ◽  
Clustering Algorithm ◽  
Spatial Clustering ◽  
Broad Band ◽  
Visible Region ◽  
Early Type ◽  
Cluster Galaxies ◽  
Using Data ◽  
Stellar Masses ◽  
Environmental Dependence

ABSTRACT The nearby Hydra cluster (∼50 Mpc) is an ideal laboratory to understand, in detail, the influence of the environment on the morphology and quenching of galaxies in dense environments. We study the Hydra cluster galaxies in the inner regions (1R200) of the cluster using data from the Southern Photometric Local Universe Survey, which uses 12 narrow and broad-band filters in the visible region of the spectrum. We analyse structural (Sérsic index, effective radius) and physical (colours, stellar masses, and star formation rates) properties. Based on this analysis, we find that ∼88 per cent of the Hydra cluster galaxies are quenched. Using the Dressler–Schectman test approach, we also find that the cluster shows possible substructures. Our analysis of the phase-space diagram together with density-based spatial clustering algorithm indicates that Hydra shows an additional substructure that appears to be in front of the cluster centre, which is still falling into it. Our results, thus, suggest that the Hydra cluster might not be relaxed. We analyse the median Sérsic index as a function of wavelength and find that for red [(u − r) ≥2.3] and early-type galaxies it displays a slight increase towards redder filters (13 and 18 per cent, for red and early type, respectively), whereas for blue + green [(u − r)<2.3] galaxies it remains constant. Late-type galaxies show a small decrease of the median Sérsic index towards redder filters. Also, the Sérsic index of galaxies, and thus their structural properties, do not significantly vary as a function of clustercentric distance and density within the cluster; and this is the case regardless of the filter.

scholarly journals The Swift-BAT survey reveals the orbital period of three high-mass X-ray binaries

2011 ◽  
Vol 529 ◽  
pp. A30 ◽  
Author(s):  
A. D’Aì ◽  
V. La Parola ◽  
G. Cusumano ◽  
A. Segreto ◽  
P. Romano ◽  
...  
Keyword(s):  
Orbital Period ◽  
High Mass ◽  
X Ray ◽  
X Ray Binaries

scholarly journals Modelling decretion discs in Be/X-ray binaries

2019 ◽  
Author(s):  
R O Brown ◽  
M J Coe ◽  
W C G Ho ◽  
A T Okazaki
Keyword(s):  
Neutron Star ◽  
Orbital Period ◽  
Major Axis ◽  
High Mass ◽  
Model Parameters ◽  
Be Stars ◽  
Semi Major Axis ◽  
X Ray ◽  
Smoothed Particle ◽  
X Ray Binaries

Abstract As the largest population of high mass X-ray binaries, Be/X-ray binaries provide an excellent laboratory to investigate the extreme physics of neutron stars. It is generally accepted that Be stars possess a circumstellar disc, providing an additional source of accretion to the stellar winds present around young hot stars. Interaction between the neutron star and the disc is often the dominant accretion mechanism. A large amount of work has gone into modelling the properties of these circumstellar discs, allowing for the explanation of a number of observable phenomena. In this paper, smoothed particle hydroynamics simulations are performed whilst varying the model parameters (orbital period, eccentricity, the mass ejection rate of the Be star and the viscosity and orientation of the disc). The relationships between the model parameters and the disc’s characteristics (base gas density, the accretion rate of the neutron star and the disc’s size) are presented. The observational evidence for a dependency of the size of the Be star’s circumstellar disc on the orbital period (and semi-major axis) is supported by the simulations.

scholarly journals A broad-band X-ray spectral study of the Seyfert 1 galaxy ESO 141–G055 with XMM–Newton and NuSTAR

2020 ◽  
Vol 497 (4) ◽  
pp. 4213-4221
Author(s):  
Ritesh Ghosh ◽  
Sibasish Laha
Keyword(s):  
Black Hole ◽  
Spectral Study ◽  
Column Density ◽  
Broad Band ◽  
Accretion Disc ◽  
Physical Models ◽  
X Ray ◽  
Reflection Model ◽  
Ionization Parameter

ABSTRACT We have extensively studied the broad--band X-ray spectra of the source ESO 141–G055 using all available XMM–Newton and NuSTAR observations. We detect a prominent soft excess below $2\rm \, \, {\rm keV}$, a narrow Fe line, and a Compton hump ($\gt 10\rm \, \, {\rm keV}$). The origin of the soft excess is still debated. We used two models to describe the soft excess: the blurred reflection from the ionized accretion disc and the intrinsic thermal Comptonization model. We find that both of these models explain the soft excess equally well. We confirm that we do not detect any broad Fe line in the X-ray spectra of this source, although both the physical models prefer a maximally spinning black hole scenario (a > 0.96). This may mean that either the broad Fe line is absent or blurred beyond detection. The Eddington rate of the source is estimated to be $\lambda _{\rm \, Edd}\sim 0.31$. In the reflection model, the Compton hump has a contribution from both ionized and neutral reflection components. The neutral reflector which simultaneously describes the narrow Fe K α and the Compton hump has a column density of $N_{\rm H} \ge 7\times 10^{24} \, \rm cm^{-2}$. In addition, we detect a partially covering ionized absorption with ionization parameter $\log \xi /\rm \, erg\, cm\, s^{-1}$  = $0.1^{+0.1}_{-0.1}$ and column density $N_{\rm H} =20.6^{+1.0}_{-1.0}\times 10^{22} \, \rm cm^{-2}$ with a covering factor of $0.21^{+0.01}_{-0.01}$.

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