Browsing by Author "Casares, J."

Now showing 1 - 5 of 5
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    A DESGW Search for the Electromagnetic Counterpart to the LIGO/Virgo Gravitational-wave Binary Neutron Star Merger Candidate S190510g
    (2020) Garcia, A.; Morgan, R.; Herner, K.; Palmese, A.; Soares Santos, M.; Annis, J.; Brout, D.; Vivas, A. K.; Drlica Wagner, A.; Quirola Vásquez, Jonathan Alexander; Santana Silva, L.; Tucker, D. L.; Allam, S.; Wiesner, M.; Garcia Bellido, J.; Gill, M. S. S.; Sako, M.; Kessler, R.; Davis, T. M.; Scolnic, D.; Casares, J.; Chen, H.; Conselice, C.; Cooke, J.; Doctor, Z.; Foley, R. J.; Horvath, J.; Howell, D. A.; Kilpatrick, C. D.; Lidman, C.; Olivares, E. F.; Paz Chinchon, F.; Pineda G., J.; Rest, A.; Sherman, N.; Abbott, T. M. C.; Aguena, M.; Avila, S.; Bertin, E.; Bhargava, S.; Brooks, D.; Burke, D. L.; Rosell, A. C.; Kind, M. C.; Carretero, J.; Costanzi, M.; da Costa, L. N.; Desai, S.; Diehl, H. T.; Dietrich, J. P.
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    BlackCAT : a catalogue of stellar-mass black holes in X-ray transients
    (2016) Corral Santana, J. M.; Casares, J.; Muñoz DariasT.; Bauer, Franz Erik; Martínez Pais, I. G.; Russel, D. M.
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    Discovery of optical outflows and inflows in the black hole candidate GRS 1716−249
    (2020) Cúneo, V. A.; Muñoz-Darias, T.; Sánchez-Sierras, J.; Jiménez-Ibarra, F.; Armas Padilla, M.; Buckle, D. A. H.; Casares, J.; Charles, P.; Corral-Santana, J. M.; Fender, R.; Fernández-Ontiveros, J. A.; Mata Sánchez, D.; Panizo-Espinar, G.; Ponti, G.; Torr, M. A. P.
    We present optical spectroscopy obtained with the GTC, VLT, and SALT telescopes during the decline of the 2016–2017 outburst of the black hole candidate GRS 1716−249 (Nova Oph 1993). Our 18-epoch data set spans 6 months and reveals that the observational properties of the main emission lines are very variable, even on time-scales of a few hours. Several epochs are characterized by P-Cyg (as well as flat-top and asymmetric) profiles in the  Hα,  Hβ, and He  ii (λ4686) emission lines, implying the presence of an accretion disc wind, which is likely hot and dense. The wind's terminal velocity (∼2000 km s−1) is similar to that observed in other black hole X-ray transients. These lines also show transient and sharp red-shifted absorptions, taking the form of inverted P-Cyg profiles. We argue that these profiles can be explained by the presence of infalling material at ∼1300 km s−1. We propose a failed wind scenario to explain this inflow and discuss other alternatives, such as obscuration produced by an accretion-related structure (e.g. the gas stream) in a high inclination system.
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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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