Browsing by Author "Torres, M. A. P."

Now showing 1 - 6 of 6
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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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    Observational constraints on the optical and near-infrared emission from the neutron star-black hole binary merger candidate S190814bv
    (2020) Ackley, K.; Amati, L.; Barbieri, C.; Bauer, F. E.; Benetti, S.; Bernardini, M. G.; Bhirombhakdi, K.; Botticella, M. T.; Branchesi, M.; Brocato, E.; Bruun, S. H.; Bulla, M.; Campana, S.; Cappellaro, E.; Castro-Tirado, A. J.; Chambers, K. C.; Chaty, S.; Chen, T-W; Ciolfi, R.; Coleiro, A.; Copperwheat, C. M.; Covino, S.; Cutter, R.; D'Ammando, F.; D'Avanzo, P.; De Cesare, G.; D'Elia, V; Della Valle, M.; Denneau, L.; De Pasquale, M.; Dhillon, V. S.; Dyer, M. J.; Elias-Rosa, N.; Evans, P. A.; Eyles-Ferris, R. A. J.; Fiore, A.; Fraser, M.; Fruchter, A. S.; Fynbo, J. P. U.; Galbany, L.; Gall, C.; Galloway, D. K.; Getman, F., I; Ghirlanda, G.; Gillanders, J. H.; Gomboc, A.; Gompertz, B. P.; Gonzalez-Fernandez, C.; Gonzalez-Gaitan, S.; Grado, A.; Greco, G.; Gromadzki, M.; Groot, P. J.; Gutierrez, C. P.; Heikkila, T.; Heintz, K. E.; Hjorth, J.; Hu, Y-D; Huber, M. E.; Inserra, C.; Izzo, L.; Japelj, J.; Jerkstrand, A.; Jin, Z. P.; Jonker, P. G.; Kankare, E.; Kann, D. A.; Kennedy, M.; Kim, S.; Klose, S.; Kool, E. C.; Kotak, R.; Kuncarayakti, H.; Lamb, G. P.; Leloudas, G.; Levan, A. J.; Longo, F.; Lowe, T. B.; Lyman, J. D.; Magnier, E.; Maguire, K.; Maiorano, E.; Mandel, I; Mapelli, M.; Mattila, S.; McBrien, O. R.; Melandri, A.; Michalowski, M. J.; Milvang-Jensen, B.; Moran, S.; Nicastro, L.; Nicholl, M.; Guelbenzu, A. Nicuesa; Nuttal, L.; Oates, S. R.; O'Brien, P. T.; Onori, F.; Palazzi, E.; Patricelli, B.; Perego, A.; Torres, M. A. P.; Perley, D. A.; Pian, E.; Pignata, G.; Piranomonte, S.; Poshyachinda, S.; Possenti, A.; Pumo, M. L.; Quirola-Vasquez, J.; Ragosta, F.; Ramsay, G.; Rau, A.; Rest, A.; Reynolds, T. M.; Rosetti, S. S.; Rossi, A.; Rosswog, S.; Sabha, N. B.; Carracedo, A. Sagues; Salafia, O. S.; Salmon, L.; Salvaterra, R.; Savaglio, S.; Sbordone, L.; Schady, P.; Schipani, P.; Schultz, A. S. B.; Schweyer, T.; Smartt, S. J.; Smith, K. W.; Smith, M.; Sollerman, J.; Srivastav, S.; Stanway, E. R.; Starling, R. L. C.; Steeghs, D.; Stratta, G.; Stubbs, C. W.; Tanvir, N. R.; Testa, V; Thrane, E.; Tonry, J. L.; Turatto, M.; Ulaczyk, K.; van der Horst, A. J.; Vergani, S. D.; Walton, N. A.; Watson, D.; Wiersema, K.; Wiik, K.; Wyrzykowski, L.; Yang, S.; Yi, S-X; Young, D. R.
    Context. Gravitational wave (GW) astronomy has rapidly reached maturity, becoming a fundamental observing window for modern astrophysics. The coalescences of a few tens of black hole (BH) binaries have been detected, while the number of events possibly including a neutron star (NS) is still limited to a few. On 2019 August 14, the LIGO and Virgo interferometers detected a high-significance event labelled S190814bv. A preliminary analysis of the GW data suggests that the event was likely due to the merger of a compact binary system formed by a BH and a NS.Aims. In this paper, we present our extensive search campaign aimed at uncovering the potential optical and near infrared electromagnetic counterpart of S190814bv. We found no convincing electromagnetic counterpart in our data. We therefore use our non-detection to place limits on the properties of the putative outflows that could have been produced by the binary during and after the merger.Methods. Thanks to the three-detector observation of S190814bv, and given the characteristics of the signal, the LIGO and Virgo Collaborations delivered a relatively narrow localisation in low latency - a 50% (90%) credible area of 5 deg(2) (23 deg(2)) - despite the relatively large distance of 26752 Mpc. ElectromagNetic counterparts of GRAvitational wave sources at the VEry Large Telescope collaboration members carried out an intensive multi-epoch, multi-instrument observational campaign to identify the possible optical and near infrared counterpart of the event. In addition, the ATLAS, GOTO, GRAWITA-VST, Pan-STARRS, and VINROUGE projects also carried out a search on this event. In this paper, we describe the combined observational campaign of these groups.Results. Our observations allow us to place limits on the presence of any counterpart and discuss the implications for the kilonova (KN), which was possibly generated by this NS-BH merger, and for the strategy of future searches. The typical depth of our wide-field observations, which cover most of the projected sky localisation probability (up to 99.8%, depending on the night and filter considered), is r similar to 22 (resp. K similar to 21) in the optical (resp. near infrared). We reach deeper limits in a subset of our galaxy-targeted observations, which cover a total similar to 50% of the galaxy-mass-weighted localisation probability. Altogether, our observations allow us to exclude a KN with large ejecta mass M greater than or similar to 0.1 M-circle dot to a high (> 90%) confidence, and we can exclude much smaller masses in a sub-sample of our observations. This disfavours the tidal disruption of the neutron star during the merger.Conclusions. Despite the sensitive instruments involved in the campaign, given the distance of S190814bv, we could not reach sufficiently deep limits to constrain a KN comparable in luminosity to AT 2017gfo on a large fraction of the localisation probability. This suggests that future (likely common) events at a few hundred megaparsecs will be detected only by large facilities with both a high sensitivity and large field of view. Galaxy-targeted observations can reach the needed depth over a relevant portion of the localisation probability with a smaller investment of resources, but the number of galaxies to be targeted in order to get a fairly complete coverage is large, even in the case of a localisation as good as that of this event.
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    Panning for gold, but finding helium: Discovery of the ultra-stripped supernova SN 2019wxt from gravitational-wave follow-up observations
    (2023) Agudo, I.; Amati, L.; An, T.; Bauer, F. E.; Benetti, S.; Bernardini, M. G.; Beswick, R.; Bhirombhakdi, K.; de Boer, T.; Branchesi, M.; Brennan, S. J.; Brocato, E.; Caballero-Garcia, M. D.; Cappellaro, E.; Castro Rodriguez, N.; Castro-Tirado, A. J.; Chambers, K. C.; Chassande-Mottin, E.; Chaty, S.; Chen, T. -W.; Coleiro, A.; Covino, S.; D'Ammando, F.; D'Avanzo, P.; D'Elia, V.; Fiore, A.; Floers, A.; Fraser, M.; Frey, S.; Frohmaier, C.; Fulton, M.; Galbany, L.; Gall, C.; Gao, H.; Garcia-Rojas, J.; Ghirlanda, G.; Giarratana, S.; Gillanders, J. H.; Giroletti, M.; Gompertz, B. P.; Gromadzki, M.; Heintz, K. E.; Hjorth, J.; Hu, Y. -D.; Huber, M. E.; Inkenhaag, A.; Izzo, L.; Jin, Z. P.; Jonker, P. G.; Kann, D. A.; Kool, E. C.; Kotak, R.; Leloudas, G.; Levan, A. J.; Lin, C. -C.; Lyman, J. D.; Magnier, E. A.; Maguire, K.; Mandel, I.; Marcote, B.; Sanchez, D. Mata; Mattila, S.; Melandri, A.; Michalowski, M. J.; Moldon, J.; Nicholl, M.; Guelbenzu, A. Nicuesa; Oates, S. R.; Onori, F.; Orienti, M.; Paladino, R.; Paragi, Z.; Perez-Torres, M.; Pian, E.; Pignata, G.; Piranomonte, S.; Quirola-Vasquez, J.; Ragosta, F.; Rau, A.; Ronchini, S.; Rossi, A.; Sanchez-Ramirez, R.; Salafia, O. S.; Schulze, S.; Smartt, S. J.; Smith, K. W.; Sollerman, J.; Srivastav, S.; Starling, R. L. C.; Steeghs, D.; Stevance, H. F.; Tanvir, N. R.; Testa, V.; Torres, M. A. P.; Valeev, A.; Vergani, S. D.; Vescovi, D.; Wainscost, R.; Watson, D.; Wiersema, K.; Wyrzykowski, L.; Yang, J.; Yang, S.; Young, D. R.
    We present the results from multi-wavelength observations of a transient discovered during an intensive follow-up campaign of S191213g, a gravitational wave (GW) event reported by the LIGO-Virgo Collaboration as a possible binary neutron star merger in a low latency search. This search yielded SN 2019wxt, a young transient in a galaxy whose sky position (in the 80% GW contour) and distance (similar to SIM;150 Mpc) were plausibly compatible with the localisation uncertainty of the GW event. Initially, the transient's tightly constrained age, its relatively faint peak magnitude (M-i similar to -16.7 mag), and the r-band decline rate of similar to 1 mag per 5 days appeared suggestive of a compact binary merger. However, SN 2019wxt spectroscopically resembled a type Ib supernova, and analysis of the optical-near-infrared evolution rapidly led to the conclusion that while it could not be associated with S191213g, it nevertheless represented an extreme outcome of stellar evolution. By modelling the light curve, we estimated an ejecta mass of only similar to 0.1 M circle dot, with Ni-56 comprising similar to 20% of this. We were broadly able to reproduce its spectral evolution with a composition dominated by helium and oxygen, with trace amounts of calcium. We considered various progenitor channels that could give rise to the observed properties of SN 2019wxt and concluded that an ultra-stripped origin in a binary system is the most likely explanation. Disentangling genuine electromagnetic counterparts to GW events from transients such as SN 2019wxt soon after discovery is challenging: in a bid to characterise this level of contamination, we estimated the rate of events with a volumetric rate density comparable to that of SN 2019wxt and found that around one such event per week can occur within the typical GW localisation area of O4 alerts out to a luminosity distance of 500 Mpc, beyond which it would become fainter than the typical depth of current electromagnetic follow-up campaigns.
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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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    The Fast X-Ray Transient XRT 210423 and Its Host Galaxy
    (2023) Eappachen, D.; Jonker, P. G.; Levan, A. J.; Quirola-Vasquez, J.; Torres, M. A. P.; Bauer, F. E.; Dhillon, V. S.; Marsh, T.; Littlefair, S. P.; Ravasio, M. E.; Fraser, M.
    Fast X-ray Transients (FXTs) are X-ray flares with durations ranging from a few hundred seconds to a few hours. Possible origins include the tidal disruption of a white dwarf by an intermediate-mass black hole, a supernova shock breakout, or a binary neutron star merger. We present the X-ray light curve and spectrum as well as deep optical imaging of the FXT XRT 210423, which has been suggested to be powered by a magnetar produced in a binary neutron star merger. Our Very Large Telescope and Gran Telescopio Canarias (GTC) observations began on 2021 May 6, thirteen days after the onset of the flare. No transient optical counterpart is found in the 1 (3s) X-ray uncertainty region of the source to a depth g(s) = 27.0 AB mag. (We use the word "counterpart" for any transient light in a wave band other than the original X-ray detection wave band, whereas the word "host" refers to the host galaxy.) A candidate host lies within the 1 X-ray uncertainty region with a magnitude of 25.9 +/- 0.1 in the GTC/ HiPERCAM g(s) filter. Due to its faintness, it was not detected in other bands, precluding a photometric redshift determination. We detect two additional candidate host galaxies: one with zspec = 1.5082 +/- 0.0001 and an offset of 4 2 +/- 1 (37 +/- 9 kpc) from the FXT, and another one with = z 1.04+ (+0.22)(-0.14) and an offset of 3."6 +/- 1." (30 +/- 8 kpc). Based on the properties of all the prospective hosts, we favor a binary neutron star merger, as previously suggested in the literature, as the explanation for XRT 210423.
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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