Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userHigh resolution X-ray spectroscopy of Supergiant HMXB 4U1700$-$37 during the compact object eclipse
96
0
0.0
(
0
)
Added by
Maria Martinez-Chicharro Ms
Publication date
2020
fields
Physics
and research's language is
English
Ask ChatGPT about the research
No Arabic abstract
We present an analysis of the first observation of the iconic High Mass X-ray Binary so with the chandra High Energy Transmission Gratings during an X-ray eclipse. The goal of the observation was to study the structure/physical conditions in the clumpy stellar wind through high resolution spectroscopy. We find that: a) emission line brightness from K shell transitions, corresponding to near neutral species, directly correlates with continuum illumination. However, these lines do not greatly diminish during eclipse. This is readily explained if fluorescence K$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.
rate research
Read More
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 lightcurve 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 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
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 velocity 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 a $sim$130 ks observation of the prototypical wind-accreting, high-mass X-ray binary Vela X-1 collected with XMM-Newton at orbital phases between 0.12 and 0.28. A strong flare took place during the observation that allows us to investigate the reaction of the clumpy stellar wind to the increased X-ray irradiation. To examine the winds reaction to the flare, we performed both time-averaged and time-resolved analyses of the RGS spectrum and examined potential spectral changes. We focused on the high-resolution XMM-Newton RGS spectra and divided the observation into pre-flare, flare, and post-flare phases. We modeled the time-averaged and time-resolved spectra with phenomenological components and with the self-consistent photoionization models calculated via CLOUDY and XSTAR in the pre-flare phase, where strong emission lines due to resonant transitions of highly ionized ions are seen. In the spectra, we find emission lines corresponding to K-shell transitions in highly charged ions of oxygen, neon, magnesium, and silicon as well as radiative recombination continua (RRC) of oxygen. Additionally, we observe potential absorption lines of magnesium at a lower ionization stage and features identified as iron L lines. The CLOUDY and XSTAR photoionization models provide contradictory results, either pointing towards uncertainties in theory or possibly a more complex multi-phase plasma, or both. We are able to demonstrate the existence of a plethora of variable narrow features, including the firm detection of oxygen lines and RRC that RGS enables to observe in this source for the first time. We show that Vela X-1 is an ideal source for future high-resolution missions, such as XRISM and Athena.
Since the launch of Chandra and XMM-Newton, high-resolution X-ray spectra of cosmic sources of all kinds have become available. These spectra have resulted in major scientific breakthroughs. However, due to the techniques used, in general high-quality spectra can only be obtained for the brightest few sources of each class. Moreover, except for the most compact extended sources, like cool core clusters, grating spectra are limited to point sources. Hitomi made another major step forward, in yielding for the first time a high-quality spectrum of an extended source, and improved spectral sensitivity in the Fe-K band. For point sources with the proposed Arcus mission, and for all sources with the launch of Athena, X-ray spectroscopy will become mature. It allows us to extend the investigations from the few handful of brightest sources of each category to a large number of sources far away in space and time, or to get high time-resolution, high-spectral resolution spectra of bright time variable sources.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
