Grants related:
General
Accreting black-holes and neutron stars in X-ray binaries provide an ideal laboratory for exploring the physics of compact objects, yielding not only confirmation of the existence of stellar mass black holes via dynamical mass measurements, but also the best opportunity for probing high-gravity environments and the physics of accretion; the most efficient form of energy production known. The latter is an essential physical process to understand the universe, playing a crucial role in galactic and extra-galactic astronomy.
This project has the following scientific goals:
- X-ray binaries offer the opportunity to study accretion as its best, since their relevant changes occur on convenient time-scales for human beings. This project focuses on the universal relation between black-hole accretion and ejection processes in the form of collimated jets and wide-angle winds. We will focus on the general properties and astrophysical impact of the cold optical accretion disc wind that our group has discovered. We want to understand how frequent these winds are, which is their impact in the black-hole accretion process, and what is their relation with jets and hot X-ray winds. Likewise, we carry out very detailed X-ray spectral studies on the different accretion states and geometries and their evolution with luminosity.
- We want to define the mass distribution of black-holes and neutron stars. Thus, we continue our contribution to one of the fundamental experiments in modern astrophysics by measuring dynamical masses in X-ray binaries. We expect to significantly improve the observed mass distribution of compact objects. This will allow testing models of supernovae explosions and close binary evolution as well as setting constraints on the equation of state of nuclear matter. We will measure masses in newly discovered or known transient X-ray binaries. In addition, we will also search for the large number of dormant X-ray binaries expected in the Galaxy and suitable for dynamical studies.
- To study the structure of accretion discs in different energy bands (optical-X rays). The high energy spectral distribution and time variability during outburst is important to constrain the eruption models and accretion disc properties (e.g. radius of advective disc) as well as to constrain the contribution of the jet to the optical and infrared emission of the system.
see group web page: https://research.iac.es/proyecto/compactos/pages/en/introduction.php
Members
Results
- Our team has led the multi-wavelength study of the two 2015 outbursts of the Black-hole transient V404 Cyg. In 2018, we published a global paper which include all the spectroscopy taken during the 1989 and 2015 campaigns.
- We have presented solid evidence for the presence of very similar wind to that found in V404 Cyg in another black hole transient, V4641 Sgr.
- We published the final paper as well as a pilot study on a novel method developed by the group. It aims at discovering and measuring masses of black hole transient in quiescence. This method has the potential of increasing the known population of these systems by a factor of three.
- We measured the mass of the neutron star in PSR J2215+5135 and found it is one of the heaviest known to date.
- We presented the first detailed study on the ultra-compact system SLX 1737-282.
Scientific activity
Related publications
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On the binary nature of the γ-ray sources AGL J2241+4454 (= MWC 656) and HESS J0632+057 (= MWC 148)We present optical spectroscopy of MWC 656 and MWC 148, the proposed optical counterparts of the γ-ray sources AGL J2241+4454 and HESS J0632+057, respectively. The main parameters of the Hα emission line [equivalent width (EW), full width at half-maximum and centroid velocity] in these stars are modulated on the proposed orbital periods of 60.37Casares, J. et al.
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42012 -
Observations of the quiescent X-ray transients GRS 1124-684 (=GUMus) and Cen X-4 (=V822Cen) taken with ULTRACAM on the VLTWe present high time-resolution multicolour optical observations of the quiescent X-ray transients GRS 1124-684 (=GUMus) and Cen X-4 (=V822Cen) obtained with ULTRACAM. Superimposed on the secondary stars' ellipsoidal modulation in both objects are large flares on time-scales of 30-60min as well as several distinct rapid flares on time-scales of aShahbaz, T. et al.
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42010 -
Observations of the 599 Hz Accreting X-Ray Pulsar IGR J00291+5934 during the 2004 Outburst and in QuiescenceWe report on optical and near-infrared observations obtained during and after the 2004 December discovery outburst of the X-ray transient and accretion-powered millisecond pulsar IGR J00291+5934. Our observations monitored the evolution of the brightness and the spectral properties of IGR J00291+5934 during the outburst decay toward quiescence. WeTorres, M. A. P. et al.
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12008 -
High time resolution optical/X-ray cross-correlations for X-ray binaries: anticorrelations and rapid variabilityUsing simultaneous observations in X-rays and optical, we have performed a homogeneous analysis of the cross-correlation behaviours of four X-ray binaries: SWIFT J1753.5-0127, GX 339-4, Sco X-1 and Cyg X-2. With high-time-resolution observations using ULTRACAM and RXTE, we concentrate on the short time-scale, δt 20 s, variability in these sourcesDurant, M. et al.
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22011 -
Evidence for a black hole in the X-ray transient XTE J1859+226We present the results of time-resolved optical photometry and spectroscopy of the X-ray transient XTE J1859+226 (V406 Vul). Photometric observations taken during 2000 and 2008 reveal the presence of the secondary star's ellipsoidal modulation. Further photometry obtained in 2010 shows the system ≃1 mag brighter than its quiescence level and theCorral-Santana, J. M. et al.
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52011 -
Dynamical constraints on the neutron star mass in EXO 0748-676We present Very Large Telescope (VLT) intermediate resolution spectroscopy of UY Vol, the optical counterpart of the low mass X-ray binary (LMXB) X-ray burster EXO 0748-676. By using Doppler tomography we detect narrow components within the broad HeII λ4542, λ4686 and λ5412 emission lines. The phase, velocity and narrowness of these lines areMuñoz-Darias, T. et al.
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32009 -
Doppler tomography of the black hole binary A0620-00 and the origin of chromospheric emission in quiescent X-ray binariesContext. Doppler tomography of emission line profiles in low-mass X-ray binaries allows us to disentangle the different emission sites and study the structure and variability of accretion disks. Aims: We present UVES high-resolution spectroscopic observations of the black hole binary A0620-00 at quiescence. Methods: These spectroscopic dataGonzález Hernández, J. I. et al.
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62010 -
Chemical Abundances of the Secondary Star in the Black Hole X-Ray Binary V404 CygniWe present a chemical abundance analysis of the secondary star in the black hole binary V404 Cygni, using Keck I/High Resolution Spectrometer. We adopt a χ2-minimization procedure to derive the stellar parameters, taking into account any possible veiling from the accretion disk. With these parameters we determine the atmospheric abundances of O, NaGonzález-Hernández, J. I. et al.
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92011 -
A first catalogue of automatically selected ultraviolet-excess sources from the UVEX surveyWe present the first catalogue of point-source ultraviolet (UV)-excess sources selected from the UV-Excess Survey of the Northern Galactic Plane (UVEX). UVEX images the Northern Galactic Plane in the U, g, r and ? bands in the Galactic latitude range -5° b +5°. Through an automated algorithm, which works on a field-to-field basis, we select blueVerbeek, Kars et al.
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22012
