Browsing by Author "Malik, U."

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    Constraints on the Physical Properties of GW190814 through Simulations Based on DECam Follow-up Observations by the Dark Energy Survey
    (2020) Morgan, R.; Soares Santos, M.; Annis, J.; Herner, K.; Garcia, A.; Palmese, A.; Drlica Wagner, A.; Kessler, R.; Garcia Bellido, J.; Quirola Vásquez, Jonathan Alexander; Bachmann, T. G.; Sherman, N.; Allam, S.; Bechtol, K.; Bom, C. R.; Brout, D.; Butler, R. E.; Butner, M.; Cartier, R.; Chen, H.; Conselice, C.; Cook, E.; Davis, T. M.; Doctor, Z.; Farr, B.; Figueiredo, A. L.; Finley, D. A.; Foley, R. J.; Galarza, J. Y.; Gill, M. S. S.; Gruendl, R. A.; Holz, D. E.; Kuropatkin, N.; Lidman, C.; Lin, H.; Malik, U.; Mann, A. W.; Marriner, J.; Marshall, J. L.; Martinez Vazquez, C. E.; Meza, N.; Neilsen, E.; Nicolaou, C.; Olivares, E. F.; Paz Chinchon, F.; Points, S.; Rodriguez, O.; Sako, M.; Scolnic, D.; Smith, M.; Sobreira, F.; Tucker, D. L.; Vivas, A. K.
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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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    The VST ATLAS quasar survey I: Catalogue of photometrically selected quasar candidates
    (2023) Eltvedt, Alice M.; Shanks, T.; Metcalfe, N.; Ansarinejad, B.; Barrientos, L. F.; Sharp, R.; Malik, U.; Murphy, D. N. A.; Irwin, M.; Wilson, M.; Alexander, D. M.; Kovacs, Andras; Garcia-Bellido, Juan; Ahlen, Steven; Brooks, David; de la Macorra, Axel; Font-Ribera, Andreu; Gontcho, Satya Gontcho a; Honscheid, Klaus; Meisner, Aaron; Miquel, Ramon; Nie, Jundan; Tarle, Gregory; Vargas-Magana, Mariana; Zhou, Zhimin
    We present the VST ATLAS Quasar Survey, consisting of similar to 1229 000 quasar (QSO) candidates with 16 < g < 22.5 over similar to 4700 deg(2). The catalogue is based on VST ATLAS+NEOWISE imaging surveys and aims to reach a QSO sky density of 130 deg-2 for z < 2.2 and similar to 30 deg(-2) for z > 2.2. To guide our selection, we use X-ray/UV/optical/MIR data in the extended William Herschel Deep Field (WHDF) where we find a g < 22.5 broad-line QSO density of 269 +/- 67 deg(-2), roughly consistent with the expected similar to 196 deg(-2). We find that similar to 25 per cent of our QSOs are morphologically classed as optically extended. Overall, we find that in these deep data, MIR, UV, and X-ray selections are similar to 70-90 per cent complete while X-ray suffers less contamination than MIR and UV. MIR is however more sensitive than X-ray or UV to z > 2.2 QSOs at g < 22.5 and the S-X (0.5 - 10 keV) > 1 x10(-14) ergs cm(-2) s(-1) limit of eROSITA. We adjust the selection criteria from our previous 2QDES pilot survey and prioritize VST ATLAS candidates that show both UV and MIR excess, also selecting candidates initially classified as extended. We test our selections using data from DESI (which will be released in DR1) and 2dF to estimate the efficiency and completeness, and we use ANNz2 to determine photometric redshifts. Applying over the similar to 4700 deg(2) ATLAS area gives us similar to 917 000 z < 2.2 QSO candidates of which 472 000 are likely to be z < 2.2 QSOs, implying a sky density of similar to 100 deg(-2), which our WHDF analysis suggests will rise to at least 130 deg(-2) when eROSITA X-ray candidates are included. At z > 2.2, we find similar to 310() 000 candidates, of which 169 000 are likely to be QSOs for a sky density of similar to 36 deg(-2).