Black holes, neutron stars, white dwarfs and their local environment

    General
    Description

    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

    Principal investigator
    1. 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.
    2. 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.
    3. 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.
    4. We measured the mass of the neutron star in PSR J2215+5135 and found it is one of the heaviest known to date.
    5. We presented the first detailed study on the ultra-compact system SLX 1737-282.

    Related publications

    • The optical counterpart of the bright X-ray transient Swift J1745-26
      We present a 30-day monitoring campaign of the optical counterpart of the bright X-ray transient Swift J1745-26, starting only 19 min after the discovery of the source. We observe the system peaking at i' ˜ 17.6 on day six (MJD 561 92) to then decay at a rate of ˜0.04 mag d-1. We show that the optical peak occurs at least 3 d later than the hard X
      Muñoz-Darias, T. et al.

      Advertised on:

      6
      2013
      Citations
      19
    • Broad iron line in the fast spinning neutron-star system 4U 1636-53
      We analysed the X-ray spectra of six observations, simultaneously taken with XMM-Newton and Rossi X-ray Timing Explorer (RXTE), of the neutron-star low-mass X-ray binary 4U 1636-53. The observations cover several states of the source, and therefore a large range of inferred mass accretion rate. These six observations show a broad emission line in
      Sanna, Andrea et al.

      Advertised on:

      6
      2013
      Citations
      38
    • A 2 h periodic variation in the low-mass X-ray binary Ser X-1
      Spectroscopy of the low-mass X-ray binary Ser X-1 using the Gran Telescopio Canarias have revealed a ≃2 h periodic variability that is present in the three strongest emission lines. We tentatively interpret this variability as due to orbital motion, making it the first indication of the orbital period of Ser X-1. Together with the fact that the
      Cornelisse, R. et al.

      Advertised on:

      6
      2013
      Citations
      13
    • An Evolving Compact Jet in the Black Hole X-Ray Binary MAXI J1836–194
      We report striking changes in the broadband spectrum of the compact jet of the black hole transient MAXI J1836–194 over state transitions during its discovery outburst in 2011. A fading of the optical-infrared (IR) flux occurred as the source entered the hard-intermediate state, followed by a brightening as it returned to the hard state. The
      Russell, D. M. et al.

      Advertised on:

      5
      2013
      Citations
      68
    • Observational constraints on the powering mechanism of transient relativistic jets
      We revisit the paradigm of the dependence of jet power on black hole (BH) spin in accreting BH systems. In a previous paper, we showed that the luminosity of compact jets continuously launched due to accretion on to BHs in X-ray binaries (analogous to those that dominate the kinetic feedback from active galactic nuclei) does not appear to correlate
      Fender, R. P. et al.

      Advertised on:

      5
      2013
      Citations
      88
    • A Black Hole Nova Obscured by an Inner Disk Torus.
      Stellar-mass black holes (BHs) are mostly found in X-ray transients, a subclass of X-ray binaries that exhibit violent outbursts. None of the 50 Galactic BHs known show eclipses, which is surprising for a random distribution of inclinations. Swift J1357.2-0933 is a very faint X-ray transient detected in 2011. On the basis of spectroscopic evidence
      Corral-Santana, J. M. et al.

      Advertised on:

      3
      2013
      Citations
      87
    • Multiwavelength spectral evolution during the 2011 outburst of the very faint X-ray transient Swift J1357.2-0933
      We report our multiwavelength study of the 2011 outburst evolution of the newly discovered black hole candidate X-ray binary Swift J1357.2-0933. We analysed the Swift X-ray Telescope and Ultraviolet/Optical Telescope (UVOT) data taken during the ˜7 months duration of the outburst. It displayed a 2-10 keV X-ray peak luminosity of ˜1035(D/1.5 kpc)2
      Wijnands, R. et al.

      Advertised on:

      2
      2013
      Citations
      59
    • Jet spectral breaks in black hole X-ray binaries
      In X-ray binaries, compact jets are known to commonly radiate at radio to infrared frequencies, whereas at optical to γ-ray energies, the contribution of the jet is debated. The total luminosity, and hence power of the jet, is critically dependent on the position of the break in its spectrum, between optically thick (self-absorbed) and optically
      Gandhi, P. et al.

      Advertised on:

      2
      2013
      Citations
      107
    • A complex state transition from the black hole candidate Swift J1753.5-0127
      We present our monitoring campaign of the outburst of the black hole candidate Swift J1753.5-0127, observed with the Rossi X-ray Timing Explorer and the Swift satellites. After ˜4.5 yr since its discovery, the source had a transition to the hard intermediate state. We performed spectral and timing studies of the transition showing that, unlike the
      van der Klis, M. et al.

      Advertised on:

      2
      2013
      Citations
      41
    • Quiescent X-ray/optical counterparts of the black hole transient H 1705-250
      We report the result of a new Chandra observation of the black hole X-ray transient H 1705-250 in quiescence. H 1705-250 was barely detected in the new ˜50 ks Chandra observation. With five detected counts, we estimate the source quiescent luminosity to be LX ˜ 9.1 × 1030 erg s-1 in the 0.5-10 keV band (adopting a distance of 8.6 kpc). This value
      Wijnands, R. et al.

      Advertised on:

      12
      2012
      Citations
      10
    • Spectroscopic follow-up of ultraviolet-excess objects selected from the UVEX survey
      We present the results of the first spectroscopic follow-up of 132 optically blue ultraviolet (UV)-excess sources selected from the UV-Excess Survey of the Northern Galactic Plane (UVEX). The UV-excess spectra are classified into different populations and grids of model spectra are fitted to determine spectral types, temperatures, surface gravities
      Verbeek, Kars et al.

      Advertised on:

      10
      2012
      Citations
      17
    • A Search for the Optical Counterpart to the Magnetar CXOU J010043.1-721134
      After our tentative detection of an optical counterpart to CXOU J010043.1-721134 from archival Hubble Space Telescope (HST) imaging, we have followed up with further images in four bands. Unfortunately, the source originally identified is not confirmed. We provide deep photometric limits in four bands and accurate photometry of field stars around
      Durant, M. et al.

      Advertised on:

      6
      2008
      Citations
      8
    • Optical pulsations from the anomalous X-ray pulsar 1E1048.1-5937
      We present high-speed optical photometry of the anomalous X-ray pulsar 1E1048.1-5937 obtained with ULTRACAM on the 8.2-m Very Large Telescope in 2007 June. We detect 1E1048.1-5937 at a magnitude of i' = 25.3 +/- 0.2, consistent with the values found by Wang et al. and hence confirming their conclusion that the source was approximately 1mag brighter
      Dhillon, V. S. et al.

      Advertised on:

      3
      2009
      Citations
      27
    • Optical/infrared observations of the X-ray burster KS1731-260 in quiescence
      Aims: We performed an optical/infrared study of the counterpart of the low-mass X-ray binary KS 1731-260 to test its identification and obtain information about the donor. Methods: Optical and infrared images of the counterpart of KS 1731-260 were taken in two different epochs (2001 and 2007) after the source returned to quiescence in X-rays. We
      Zurita, C. et al.

      Advertised on:

      3
      2010
      Citations
      6
    • On the nature of HD 207331: a new δ Scuti variable
      While testing a Strömgren spectrophotometer attached to the 1.5 m telescope at the San Pedro Mártir observatory, Mexico, a number of A-type stars were observed, one of which, HD 207331, presented clear indications of photometric variability. CCD photometric data acquired soon after, confirmed its variability. In order to determine its pulsation
      Fox Machado, L. et al.

      Advertised on:

      11
      2008
      Citations
      3
    • Disentangling jet and disc emission from the 2005 outburst of XTE J1118+480
      The black hole X-ray transient, XTE J1118+480, has now twice been observed in outbursts - 2000 and 2005 - and on both occasions remained in the low/hard X-ray spectral state. Here we present radio, infrared, optical, soft X-ray and hard X-ray observations of the more recent outburst. We find that the light curves have very different morphologies
      Brocksopp, C. et al.

      Advertised on:

      5
      2010
      Citations
      25
    • Time-Resolved Optical Photometry of the Ultracompact Binary 4U 0614+091
      We present a detailed optical study of the ultracompact X-ray binary 4U 0614+091. We have used 63 hr of time-resolved optical photometry taken with three different telescopes (IAC80, NOT, and SPM) to search for optical modulations. The power spectra of each data set reveals sinusoidal modulations with different periods, which are not always present
      Shahbaz, T. et al.

      Advertised on:

      8
      2008
      Citations
      34
    • The First Polarimetric Signatures of Infrared Jets in X-Ray Binaries
      We present near-infrared linear spectropolarimetry of a sample of persistent X-ray binaries, Sco X-1, Cyg X-2, and GRS 1915+105. The slopes of the spectra are shallower than what is expected from a standard steady state accretion disk, and can be explained if the near-infrared flux contains a contribution from an optically thin jet. For the neutron
      Shahbaz, T. et al.

      Advertised on:

      1
      2008
      Citations
      36
    • SWIFT J1753.5-0127: A Surprising Optical/X-Ray Cross-Correlation Function
      We have conducted simultaneous optical and X-ray observations of SWIFT J1753.5-0127 with RXTE and ULTRACAM, while the system persisted in its relatively bright low/hard state. In the cross-correlation function, we find that the optical emission, with a broad negative peak, leads the X-ray emission by a few seconds and has a smaller positive peak at
      Durant, Martin et al.

      Advertised on:

      7
      2008
      Citations
      60
    • Rapid optical and X-ray timing observations of GX339-4: multicomponent optical variability in the low/hard state
      A rapid timing analysis of Very Large Telescope (VLT)/ULTRACAM (optical) and RXTE (X-ray) observations of the Galactic black hole binary GX339-4 in the low/hard, post-outburst state of 2007 June is presented. The optical light curves in the r',g' and u' filters show slow (~20s) quasi-periodic variability. Upon this is superposed fast flaring
      Gandhi, P. et al.

      Advertised on:

      10
      2010
      Citations
      116

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