Browsing by Author "Mata Sanchez, D."

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    Probing for the host galaxies of the fast X-ray transients XRT 000519 and XRT 110103
    (2022) Eappachen, D.; Jonker, P. G.; Fraser, M.; Torres, M. A. P.; Dhillon, V. S.; Marsh, T.; Littlefair, S. P.; Quirola-Vasquez, J.; Maguire, K.; Mata Sanchez, D.; Cannizzaro, G.; Kostrzewa-Rutkowska, Z.; Wevers, T.; Onori, F.; Inkenhaag, Anne; Brennan, S. J.
    Over the past few years, similar to 30 extragalactic fast X-ray transients (FXRTs) have been discovered, mainly in Chandra and XMM-Newton data. Their nature remains unclear, with proposed origins, including a double neutron star merger, a tidal disruption event involving an intermediate-mass black hole and a white dwarf, or a supernova shock breakout. A decisive differentiation between these three promising mechanisms for their origin requires an understanding of the FXRT energetics, environments, and/or host properties. We present optical observations obtained with the Very Large Telescope for the FXRTs XRT 000519 and XRT 110103 and Gran Telescopio Canarias observations for XRT 000519 designed to search for host galaxies of these FXRTs. In the g(s), r(s), and R-band images, we detect an extended source on the north-west side of the similar to 1 '' (68 per cent confidence) error circle of the X-ray position of XRT 000519 with a Kron magnitude of g(s) = 26.29 +/- 0.09 (AB magnitude). We discuss the XRT 000519 association with the probable host candidate for various possible distances, and we conclude that if XRT 000519 is associated with the host candidate a supernova shock breakout scenario is likely excluded. No host galaxy is found near XRT 110103 down to a limiting magnitude of R > 25.8.
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    Swift J1357.2-0933: a massive black hole in the Galactic thick disc
    (OXFORD UNIV PRESS, 2015) Mata Sanchez, D.; Munoz Darias, T.; Casares, J.; Corral Santana, J. M.; Shahbaz, T.
    Swift J1357.2-0933 is one of the shortest orbital period black hole X-ray transients. It exhibited deep optical dips together with an extremely broad Ha line during outburst. We present 10.4-m Gran Telescopio Canarias (GTC) time-resolved spectroscopy during quiescence searching for donor star absorption features. The large contribution of the accretion flow to the total luminosity prevents the direct detection of the companion. Nevertheless, we constrain the non-stellar contribution to be larger than similar to 80 per cent of the total optical light, which sets new lower limits to the distance (d > 2.29 kpc) and the height over the Galactic plane (z > 1.75 kpc). This places the system in the Galactic thick disc. We measure a modulation in the centroid of the Ha line with a period of P = 0.11 +/- 0.04 d which, combined with the recently presented full width at half-maximum-K-2 correlation, results in a massive black hole (M-1 > 9.3 M-circle dot) and an similar to M2V companion star (M-2 similar to 0.4 M-circle dot). We also present further evidence supporting a very high orbital inclination (i greater than or similar to 80 degrees).
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    XMM-Newton-discovered Fast X-ray Transients: host galaxies and limits on contemporaneous detections of optical counterparts
    (2024) Eappachen, D.; Jonker, P. G.; Quirola-Vasquez, J.; Mata Sanchez, D.; Inkenhaag, A.; Levan, A. J.; Fraser, M.; Torres, M. A. P.; Bauer, F. E.; Chrimes, A. A.; Stern, D.; Graham, M. J.; Smartt, S. J.; Smith, K. W.; Ravasio, M. E.; Zabludoff, A. I.; Yue, M.; Stoppa, F.; Malesani, D. B.; Stone, N. C.; Wen, S.
    Extragalactic fast X-ray transients (FXTs) are a class of soft (0.3-10 keV) X-ray transients lasting a few hundred seconds to several hours. Several progenitor mechanisms have been suggested to produce FXTs, including supernova shock breakouts, binary neutron star mergers, or tidal disruptions involving an intermediate-mass black hole and a white dwarf. We present detailed host studies, including spectroscopic observations of the host galaxies of seven XMM-Newton-discovered FXTs. The candidate hosts lie at redshifts 0.0928