Browsing by Author "Casares, J."

Now showing 1 - 9 of 9
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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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    An infrared FWHM-K2 correlation to uncover highly reddened quiescent black holes
    (2023) Cuneo, V. A.; Casares, J.; Padilla, M. Armas; Sanchez-Sierras, J.; Corral-Santana, J. M.; Maccarone, T. J.; Sanchez, D. Mata; Munoz-Darias, T.; Torres, M. A. P.; Vincentelli, F.
    Among the sample of Galactic transient X-ray binaries (SXTs) discovered to date, about 70 have been proposed as likely candidates to host a black hole. Yet, only 19 have been dynamically confirmed. Such a reliable confirmation requires phase-resolved spectroscopy of their companion stars, which is generally feasible when the system is in a quiescent state. However, since most of the SXT population lies in the galactic plane, which is strongly affected by interstellar extinction, their optical brightness during quiescence usually falls beyond the capabilities of the current instrumentation (R greater than or similar to 22). To overcome these limitations and thereby increase the number of confirmed Galactic black holes, a correlation between the full-width at half maximum (FWHM) of the H alpha line and the semi-amplitude of the donor's radial velocity curve (K-2) was presented in the past. Here, we extend the FWHM-K-2 correlation to the near-infrared (NIR), exploiting disc lines such as He I lambda 10830, Pa gamma, and Br gamma, in a sample of dynamically confirmed black-hole SXTs. We obtain K-2 = 0.22(3) FWHM, in good agreement with the optical correlation derived using H alpha. The similarity of the two correlations seems to imply that the widths of H alpha and the NIR lines are consistent in quiescence. When combined with information on orbital periods, the NIR correlation allows us to constrain the mass of the compact object of systems in quiescence by using single-epoch spectroscopy. We anticipate that this new correlation will give access to highly reddened black hole SXTs, which cannot be otherwise studied at optical wavelengths.
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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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    SOAR/Goodman Spectroscopic Assessment of Candidate Counterparts of the LIGO/Virgo Event GW190814*
    (2022) Tucker, D. L.; Wiesner, M. P.; Allam, S. S.; Soares-Santos, M.; Bom, C. R.; Butner, M.; Garcia, A.; Morgan, R.; Olivares E, F.; Palmese, A.; Santana-Silva, L.; Shrivastava, A.; Annis, J.; Garcia-Bellido, J.; Gill, M. S. S.; Herner, K.; Kilpatrick, C. D.; Makler, M.; Sherman, N.; Amara, A.; Lin, H.; Smith, M.; Swann, E.; Arcavi, I; Bachmann, T. G.; Bechtol, K.; Berlfein, F.; Briceno, C.; Brout, D.; Butler, R. E.; Cartier, R.; Casares, J.; Chen, H-Y; Conselice, C.; Contreras, C.; Cook, E.; Cooke, J.; Dage, K.; D'Andrea, C.; Davis, T. M.; de Carvalho, R.; Diehl, H. T.; Dietrich, J. P.; Doctor, Z.; Drlica-Wagner, A.; Drout, M.; Farr, B.; Finley, D. A.; Fishbach, M.; Foley, R. J.; Forster-Buron, F.; Fosalba, P.; Friedel, D.; Frieman, J.; Frohmaier, C.; Gruendl, R. A.; Hartley, W. G.; Hiramatsu, D.; Holz, D. E.; Howell, D. A.; Kawash, A.; Kessler, R.; Kuropatkin, N.; Lahav, O.; Lundgren, A.; Lundquist, M.; Malik, U.; Mann, A. W.; Marriner, J.; Marshall, J. L.; Martinez-Vazquez, C. E.; McCully, C.; Menanteau, F.; Meza, N.; Narayan, G.; Neilsen, E.; Nicolaou, C.; Nichol, R.; Paz-Chinchon, F.; Pereira, M. E. S.; Pineda, J.; Points, S.; Quirola-Vasquez, J.; Rembold, S.; Rest, A.; Rodriguez, O.; Romer, A. K.; Sako, M.; Salim, S.; Scolnic, D.; Smith, J. A.; Strader, J.; Sullivan, M.; Swanson, M. E. C.; Thomas, D.; Valenti, S.; Varga, T. N.; Walker, A. R.; Weller, J.; Wood, M. L.; Yanny, B.; Zenteno, A.; Aguena, M.; Andrade-Oliveira, F.; Bertin, E.; Brooks, D.; Burke, D. L.; Rosell, A. Carnero; Kind, M. Carrasco; Carretero, J.; Costanzi, M.; da Costa, L. N.; De Vicente, J.; Desai, S.; Everett, S.; Ferrero, I; Flaugher, B.; Gaztanaga, E.; Gerdes, D. W.; Gruen, D.; Gschwend, J.; Gutierrez, G.; Hinton, S. R.; Hollowood, D. L.; Honscheid, K.; James, D. J.; Kuehn, K.; Lima, M.; Maia, M. A. G.; Miquel, R.; Ogando, R. L. C.; Pieres, A.; Malagon, A. A. Plazas; Rodriguez-Monroy, M.; Sanchez, E.; Scarpine, V; Schubnell, M.; Serrano, S.; Sevilla-Noarbe, I; Suchyta, E.; Tarle, G.; To, C.; Zhang, Y.
    On 2019 August 14 at 21:10:39 UTC, the LIGO/Virgo Collaboration (LVC) detected a possible neutron star-black hole merger (NSBH), the first ever identified. An extensive search for an optical counterpart of this event, designated GW190814, was undertaken using the Dark Energy Camera on the 4 m Victor M. Blanco Telescope at the Cerro Tololo Inter-American Observatory. Target of Opportunity interrupts were issued on eight separate nights to observe 11 candidates using the 4.1 m Southern Astrophysical Research (SOAR) telescope's Goodman High Throughput Spectrograph in order to assess whether any of these transients was likely to be an optical counterpart of the possible NSBH merger. Here, we describe the process of observing with SOAR, the analysis of our spectra, our spectroscopic typing methodology, and our resultant conclusion that none of the candidates corresponded to the gravitational wave merger event but were all instead other transients. Finally, we describe the lessons learned from this effort. Application of these lessons will be critical for a successful community spectroscopic follow-up program for LVC observing run 4 (O4) and beyond.
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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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    The isotopic 6Li/7Li ratio in Centaurus X-4 and the origin of Li in X-ray binaries
    (2007) Casares, J.; Bonifacio, P.; Gonzalez Hernandez, J. I.; Molaro, P.; Zoccali, M.
    Context. Cool stars, companions to compact objects, are known to show Li abundances which are high compared to field stars of the same spectral type, which are heavily Li depleted. This may be due either to Li production or Li preservation in these systems.
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    The Necklace: equatorial and polar outflows from the binary central star of the new planetary nebula IPHASX J194359.5+170901
    (2011) Corradi, R. L. M.; Sabin, L.; Miszalski, B.; Rodriguez-Gil, P.; Santander-Garcia, M.; Jones, D.; Drew, J. E.; Mampaso, A.; Barlow, M. J.; Rubio-Diez, M. M.; Casares, J.; Viironen, K.; Frew, D. J.; Giammanco, C.; Greimel, R.; Sale, S. E.
    IPHASX J194359.5+170901 is a new high-excitation planetary nebula with remarkable characteristics. It consists of a knotty ring expanding at a speed of 28 km s-1, and a fast collimated outflow in the form of faint lobes and caps along the direction perpendicular to the ring. The expansion speed of the polar caps is similar to 100 km s-1, and their kinematical age is twice as large as the age of the ring.