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

    • Near-infrared emission lines trace the state-independent accretion disc wind of the black hole transient MAXI J1820+070
      The black hole transient MAXI J1820+070 displayed optical P Cyg profiles and other wind-related emission line features during the hard state of its discovery outburst. We present near-infrared (NIR) spectroscopy covering the different accretion states of the system during this event. Our eight-epoch data set (VLT/X-shooter) reveals strong
      Sánchez-Sierras, J. et al.

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      8
      2020
      Citations
      36
    • A New Class of Roche Lobe-filling Hot Subdwarf Binaries
      We present the discovery of the second binary with a Roche lobe-filling hot subdwarf transferring mass to a white dwarf (WD) companion. This 56 minute binary was discovered using data from the Zwicky Transient Facility. Spectroscopic observations reveal an He-sdOB star with an effective temperature of T eff = 33,700 ± 1000 K and a surface gravity
      Kupfer, Thomas et al.

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      7
      2020
      Citations
      41
    • A pulsating white dwarf in an eclipsing binary
      White dwarfs are the burnt-out cores of Sun-like stars and are the fate of 97 per cent of the stars in our Galaxy. The internal structure and composition of white dwarfs are hidden by their high gravities, which causes all elements apart from the lightest ones to settle out of their atmospheres. The most direct method of probing the inner structure
      Parsons, Steven G. et al.

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      3
      2020
      Citations
      23
    • The variable radio counterpart of Swift J1858.6-0814
      Swift J1858.6-0814 is a transient neutron star X-ray binary discovered in 2018 October. Multiwavelength follow-up observations across the electromagnetic spectrum revealed many interesting properties, such as erratic flaring on minute time-scales and evidence for wind outflows at both X-ray and optical wavelengths, strong and variable local
      van den Eijnden, J. et al.

      Advertised on:

      6
      2020
      Citations
      16
    • A NICER look at the state transitions of the black hole candidate MAXI J1535-571 during its reflares
      The black hole candidate and X-ray binary MAXI J1535-571 was discovered in 2017 September. During the decay of its discovery outburst, and before returning to quiescence, the source underwent at least four reflaring events, with peak luminosities of ∼10 35-36 erg s -1 (d/4.1 kpc) 2. To investigate the nature of these flares, we analysed a sample of
      Cúneo, V. A. et al.

      Advertised on:

      6
      2020
      Citations
      27
    • IGAPS: the merged IPHAS and UVEX optical surveys of the northern Galactic plane
      The INT Galactic Plane Survey (IGAPS) is the merger of the optical photometric surveys, IPHAS and UVEX, based on data from the Isaac Newton Telescope (INT) obtained between 2003 and 2018. Here, we present the IGAPS point source catalogue. It contains 295.4 million rows providing photometry in the filters, i, r, narrow-band Hα, g, and U RGO. The
      Monguió, M. et al.

      Advertised on:

      6
      2020
      Citations
      28
    • Optical, X-ray, and γ-ray observations of the candidate transitional millisecond pulsar 4FGL J0427.8-6704
      We present an optical, X-ray, and γ-ray study of 1SXPS J042749.2-670434, an eclipsing X-ray binary that has an associated γ-ray counterpart, 4FGL J0427.8-6704. This association has led to the source being classified as a transitional millisecond pulsar (tMSP) in an accreting state. We analyse 10.5 yr of Fermi LAT data and detect a γ-ray eclipse at
      Kennedy, M. R. et al.

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      4
      2020
      Citations
      17
    • First measurement of the total gravitational quadrupole moment of a black widow companion
      We present the first measurement of the gravitational quadrupole moment of the companion star of a spider pulsar, namely the black widow PSR J2051-0827. To this end, we have re-analysed radio timing data using a new model that is able to account for periastron precession caused by tidal and centrifugal deformations of the star as well as by general
      Voisin, Guillaume et al.

      Advertised on:

      4
      2020
      Citations
      2
    • EX draconis: using eclipses to separate outside-in and inside-out outbursts
      We present a study of the eclipses in the accreting white dwarf EX draconis (EX Dra) during TESS Cycles 14 and 15. During both of the two outbursts present in this data set, the eclipses undergo a hysteretic loop in eclipse-depth/out-of-eclipse-flux space. In each case, the direction in which the loops are executed strongly suggests an outburst
      Court, J. M. C. et al.

      Advertised on:

      4
      2020
      Citations
      8
    • LOFAR 144-MHz follow-up observations of GW170817
      We present low-radio-frequency follow-up observations of AT 2017gfo, the electromagnetic counterpart of GW170817, which was the first binary neutron star merger to be detected by Advanced LIGO-Virgo. These data, with a central frequency of 144 MHz, were obtained with LOFAR, the Low-Frequency Array. The maximum elevation of the target is just 13 ${_
      Broderick, J. W. et al.

      Advertised on:

      4
      2020
      Citations
      7
    • The Binary Mass Ratio in the Black Hole Transient MAXI J1820+070
      We present intermediate-resolution spectroscopy of the optical counterpart to the black hole X-ray transient MAXI J1820+070 (=ASASSN-18ey) obtained with the OSIRIS spectrograph on the 10.4 m Gran Telescopio Canarias. The observations were performed with the source close to the quiescent state and before the onset of renewed activity in 2019 August
      Torres, M. A. P. et al.

      Advertised on:

      4
      2020
      Citations
      89
    • The Changing-look Optical Wind of the Flaring X-Ray Transient Swift J1858.6-0814
      We present the discovery of an optical accretion disk wind in the X-ray transient Swift J1858.6-0814. Our 90-spectrum data set, taken with the 10.4 m Gran Telescopio Canarias telescope over eight different epochs and across five months, reveals the presence of conspicuous P-Cyg profiles in He i at 5876 &angst and Hα. These features are detected
      Muñoz-Darias, T. et al.

      Advertised on:

      4
      2020
      Citations
      22
    • The First Ultracompact Roche Lobe-Filling Hot Subdwarf Binary
      We report the discovery of the first short-period binary in which a hot subdwarf star (sdOB) filled its Roche lobe and started mass transfer to its companion. The object was discovered as part of a dedicated high-cadence survey of the Galactic plane named the Zwicky Transient Facility and exhibits a period of P = 39.3401(1) minutes, making it the
      Kupfer, Thomas et al.

      Advertised on:

      3
      2020
      Citations
      54
    • The Formation of a 70 M<SUB>☉</SUB> Black Hole at High Metallicity
      A 70 ${M}_{\odot }$ black hole (BH) was discovered in the Milky Way disk in a long-period detached binary system (LB-1) with a high-metallicity 8 ${M}_{\odot }$ B star companion. Current consensus on the formation of BHs from high-metallicity stars limits the BH mass to be below 20 ${M}_{\odot }$ due to strong mass loss in stellar winds. Using
      Belczynski, K. et al.

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      2
      2020
      Citations
      60
    • Fast quasi-periodic oscillations in the eclipsing polar VV Puppis from VLT and XMM-Newton observations
      We present high time resolution optical photometric data of the polar VV Puppis obtained simultaneously in three filters (u', HeII λ4686, r') with the ULTRACAM camera mounted at the ESO-VLT telescope. An analysis of a long 50 ks XMM-Newton observation of the source, retrieved from the database, is also provided. Quasi-periodic oscillations (QPOs)
      Bonnet-Bidaud, J. M. et al.

      Advertised on:

      1
      2020
      Citations
      1
    • Full orbital solution for the binary system in the northern Galactic disc microlensing event Gaia16aye
      Gaia16aye was a binary microlensing event discovered in the direction towards the northern Galactic disc and was one of the first microlensing events detected and alerted to by the Gaia space mission. Its light curve exhibited five distinct brightening episodes, reaching up to I = 12 mag, and it was covered in great detail with almost 25 000 data
      Wyrzykowski, Ł. et al.

      Advertised on:

      1
      2020
      Citations
      36
    • A black hole X-ray binary at ̃100 Hz: multiwavelength timing of MAXI J1820+070 with HiPERCAM and NICER
      We report on simultaneous sub-second optical and X-ray timing observations of the low-mass X-ray binary black hole candidate MAXI J1820+070. The bright 2018 outburst rise allowed simultaneous photometry in five optical bands (ugriz s) with HiPERCAM/GTC (Optical) at frame rates over 100 Hz, together with NICER/ISS observations (X-rays). Intense
      Paice, J. A. et al.

      Advertised on:

      11
      2019
      Citations
      31
    • Discovery and analysis of a ULX nebula in NGC 3521
      We present Very Large Telescope/X-shooter and Chandra X-ray observatory/ACIS observations of the ULX [SST2011] J110545.62 + 000016.2 in the galaxy NGC 3521. The source identified as a candidate near-infrared counterpart to the ULX in our previous study shows an emission line spectrum of numerous recombination and forbidden lines in the visible and
      López, K. M. et al.

      Advertised on:

      10
      2019
      Citations
      7
    • Detection and Timing of Gamma-Ray Pulsations from the 707 Hz Pulsar J0952-0607
      The Low-Frequency Array radio telescope discovered the 707 Hz binary millisecond pulsar (MSP) J0952-0607 in a targeted radio pulsation search of an unidentified Fermi gamma-ray source. This source shows a weak energy flux of F γ = 2.6 × 10 -12 erg cm -2 s -1 in the energy range between 100 MeV and 100 GeV. Here we report the detection of pulsed
      Nieder, L. et al.

      Advertised on:

      9
      2019
      Citations
      25
    • A wide star-black-hole binary system from radial-velocity measurements
      All stellar-mass black holes have hitherto been identified by X-rays emitted from gas that is accreting onto the black hole from a companion star. These systems are all binaries with a black-hole mass that is less than 30 times that of the Sun 1-4. Theory predicts, however, that X-ray-emitting systems form a minority of the total population of star
      Liu, Jifeng et al.

      Advertised on:

      11
      2019
      Citations
      171

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