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تسجيل مستخدم جديدPhysical parameters of the high-mass X-ray binary 4U1700-37
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J. S. Clark
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We present the results of a detailed non-LTE analysis of the UV and optical spectrum of the O6.5Iaf+ star HD153919 - the mass donor in the high-mass X-ray binary 4U1700-37. Given the eclipsing nature of the system these results allow us to determine the most likely masses of both components of the binary via Monte Carlo simulations. These suggest a mass for HD153919 of 58+/-11M_sun - implying the initial mass of the companion was rather high (>60 M_sun). The most likely mass for the compact companion is found to be 2.44+/-0.27M_sun, with only 3.5 per cent of the trials resulting in a mass less than 2.0M_sun and none less than 1.65M_sun. Our observational data is inconsistent with the canonical neutron star mass and the lowest black hole mass observed (>4.4M_sun; Nova Vel). Significantly changing observational parameters can force the compact object mass into either of these regimes but this results in the O-star mass changing by factors of greater than 2, well beyond the limits determined from its evolutionary state and surface gravity. The low mass of the compact object implies that it is difficult to form high mass black holes through both the Case A & B mass transfer channels and, if the compact object is a neutron star, would significantly constrain the high density nuclear EoS
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Based on its Hipparcos proper motion, we propose that the high-mass X-ray binary HD153919/4U1700-37 originates in the OB association Sco OB1. At a distance of 1.9 kpc the space velocity of 4U1700-37 with respect to Sco OB1 is 75 km/s. This runaway ve
locity indicates that the progenitor of the compact X-ray source lost about 7 Msun during the (assumed symmetric) supernova explosion. The systems kinematical age is about 2 +/- 0.5 million years which marks the date of the supernova explosion forming the compact object. The present age of Sco OB1 is <8 Myr; its suggested core, NGC 6231, seems to be somewhat younger (~5 Myr). If HD153919/4U1700-37 was born as a member of Sco OB1, this implies that the initially most massive star in the system terminated its evolution within <6 million years, corresponding to an initial mass >30 Msun. With these parameters the evolution of the binary system can be constrained.
We present results of a monitoring campaign of the high-mass X-ray binary system 4U 1700-37/HD 153919, carried out with XMM-Newton in February 2001. The system was observed at four orbital phase intervals, covering 37% of one 3.41-day orbit. The ligh
tcurve includes strong flares, commonly observed in this source. We focus on three epochs in which the data are not affected by photon pile up: the eclipse, the eclipse egress and a low-flux interval in the lightcurve around orbital phase phi ~0.25. The high-energy part of the continuum is modelled as a direct plus a scattered component, each represented by a power law with identical photon index (alpha ~1.4), but with different absorption columns. We show that during the low-flux interval the continuum is strongly reduced, probably due to a reduction of the accretion rate onto the compact object. A soft excess is detected in all spectra, consistent with either another continuum component originating in the outskirts of the system or a blend of emission lines. Many fluorescence emission lines from near-neutral species and discrete recombination lines from He- and H-like species are detected during eclipse and egress. The detection of recombination lines during eclipse indicates the presence of an extended ionised region surrounding the compact object. The observed increase in strength of some emission lines corresponding to higher values of the ionisation parameter xi further substantiates this conclusion.
We present an analysis of the first observation of the iconic High Mass X-ray Binary so with the chandra High Energy Transmission Gratings during an X-ray eclipse. The goal of the observation was to study the structure/physical conditions in the clum
py stellar wind through high resolution spectroscopy. We find that: a) emission line brightness from K shell transitions, corresponding to near neutral species, directly correlates with continuum illumination. However, these lines do not greatly diminish during eclipse. This is readily explained if fluorescence K$alpha$ emission comes from the bulk of the wind. b) The highly ionised Fexxv and Fexxvi Ly$alpha$ diminish during eclipse. Thus, they must be produced in the vicinity of the compact object where $log xi >3$. c) to describe the emission line spectrum, the sum of two self consistent photo ionisation models with low ionisation ($log xisim -1$) and high ionisation ($log xisim 2.4$) is required. From their emission measures, the clump-to-interclump density ratio can be estimated to be $n_c/n_isim 300$. To fit the complex He-like ion{Si}{xiii}{} profile, the plasma requires a broadening with $v_{rm bulk}sim 840$ km s$^{-1}$. Reproducing the observed $rapprox f$ line fluxes requires the addition of a third collisionally ionised plasma. d) Emission lines widths appear unresolved at the textsc{hetg} gratings resolution with exception of Silicon. There is no clear radial segregation between (quasi)neutral and ionised species, consistent with cold wind clumps interspersed in a hot rarefied interclump medium.
We present new radial velocities of the high-mass X-ray binary star 4U 2206+54 based on optical spectra obtained with the Coude spectrograph at the 2m RCC telescope at the Rozhen National Astronomical Observatory, Bulgaria in the period November 2011
-- July 2013. The radial velocity curve of the HeI $lambda$6678 AA line is modeled with an orbital period P$_{orb}$ = 9.568~d and an eccentricity of $e$ = 0.3. These new measurements of the radial velocity resolve the disagreements of the orbital period discussions.
We present an X-ray spectral analysis of the high-mass binary 4U~1700-37 during its hard-soft state evolution. We use the BeppoSAX, Suzaku and RXTE (Rossi X-ray Timing Explorer), Suzaku and BeppoSAX observations for this investigation. We argue that
the X-ray broad-band spectra during all spectral states can be adequately reproduced by a model, consisting of a low-temperature Blackbody component, two Comptonized components both due to the presence of a Compton cloud (CC) that up-scatters seed photons of $T_{s1}$~< 1.4 keV, and $T_{s2}<$1 keV, and an iron-line component. We find using this model that the photon power-law index is almost constant, $Gamma_{1}sim 2$ for all spectral states. However, $Gamma_{2}$ shows a behavior depending on the spectral state. Namely, $Gamma_{2}$ is quasi-constant at the level of $Gamma_{2}sim 2$ while the CC plasma temperature $kT^{(2)}_e$ is less than 40 keV; on the other hand, $Gamma_{2}$ is in the range of $1.3<Gamma_{2}<2$, when $kT^{(2)}_e$ is greater than 40 keV. We explain this quasi-stability of $Gamma$ during most of hard-soft transitions of 4U~1700-37 in a framework of the model in which the resulting spectrum is described by two Comptonized components. We find that these Comptonized spectral components of the HMXB 4U~1700-37 are similar to those previously found in NS sources. This index dependence versus both mass accretion rate and $kT_e$ revealed in 4U~1700-37 is a universal observational evidence for the presence of a NS in 4U 1700-37.
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