Browsing by Author "Rest, A."

Now showing 1 - 20 of 28
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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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    A large and homogeneous sample of SX Phe stars in the Fornax dwarf spheroidal galaxy .
    (2006) Poretti, E.; Dell'Arciprete, L.; Clementini, G.; Held, E. V.; Greco, C.; Gullieuszik, M.; Maio, M.; Rizzi, L.; Catelan , Marcio; Smith, H. A.; Pritzl, B.; De Lee, N.; Rest, A.
    We report on the detection of sixty-one SX Phe stars in the Fornax dwarf spheroidal galaxy using the Wide-Field Imager at the 2.2m ESO-MPI telescope. In spite of their extreme faintness (22.0...
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    A search for a surviving companion in SN 1006
    (2018) Kerzendorf, W. E.; Strampelli, G.; Shen, K. J.; Schwab, J.; Pakmor, R.; Do, T.; Buchner, J.; Rest, A.
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    AT 2022aedm and a New Class of Luminous, Fast-cooling Transients in Elliptical Galaxies
    (2023) Nicholl, M.; Srivastav, S.; Fulton, M. D.; Gomez, S.; Huber, M. E.; Oates, S. R.; Ramsden, P.; Rhodes, L.; Smartt, S. J.; Smith, K. W.; Aamer, A.; Anderson, J. P.; Bauer, F. E.; Berger, E.; de Boer, T.; Chambers, K. C.; Charalampopoulos, P.; Chen, T. -w.; Fender, R. P.; Fraser, M.; Gao, H.; Green, D. A.; Galbany, L.; Gompertz, B. P.; Gromadzki, M.; Gutierrez, C. P.; Howell, D. A.; Inserra, C.; Jonker, P. G.; Kopsacheili, M.; Lowe, T. B.; Magnier, E. A.; Mccully, C.; Mcgee, S. L.; Moore, T.; Mueller-Bravo, T. E.; Newsome, M.; Gonzalez, E. Padilla; Pellegrino, C.; Pessi, T.; Pursiainen, M.; Rest, A.; Ridley, E. J.; Shappee, B. J.; Sheng, X.; Smith, G. P.; Terreran, G.; Tucker, M. A.; Vinko, J.; Wainscoat, R. J.; Wiseman, P.; Young, D. R.
    We present the discovery and extensive follow-up of a remarkable fast-evolving optical transient, AT 2022aedm, detected by the Asteroid Terrestrial impact Last Alert Survey (ATLAS). In the ATLAS o band, AT 2022aedm exhibited a rise time of 9 & PLUSMN; 1 days, reaching a luminous peak with M g & AP; -22 mag. It faded by 2 mag in the g band during the next 15 days. These timescales are consistent with other rapidly evolving transients, though the luminosity is extreme. Most surprisingly, the host galaxy is a massive elliptical with negligible current star formation. Radio and X-ray observations rule out a relativistic AT 2018cow-like explosion. A spectrum in the first few days after explosion showed short-lived He ii emission resembling young core-collapse supernovae, but obvious broad supernova features never developed; later spectra showed only a fast-cooling continuum and narrow, blueshifted absorption lines, possibly arising in a wind with v & AP; 2700 km s-1. We identify two further transients in the literature (Dougie in particular, as well as AT 2020bot) that share similarities in their luminosities, timescales, color evolution, and largely featureless spectra and propose that these may constitute a new class of transients: luminous fast coolers. All three events occurred in passive galaxies at offsets of & SIM;4-10 kpc from the nucleus, posing a challenge for progenitor models involving massive stars or black holes. The light curves and spectra appear to be consistent with shock breakout emission, though this mechanism is usually associated with core-collapse supernovae. The encounter of a star with a stellar-mass black hole may provide a promising alternative explanation.
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    ATClean: a novel method for detecting low-luminosity transients and application to pre-explosion counterparts from SN 2023ixf
    (2024) Rest, S.; Rest, A.; Kilpatrick, C. D.; Jencson, J. E.; Coelln, S. von; Strolger, L.; Smartt, S.; Anderson, J. P.; Clocchiatti García, Alejandro; Coulter, D. A.; Denneau, L.; Gómez, S.; Heinze, A.; Ridden-Harper, R.; Smith, K. W.; Stalder, B.; Tonry, J. l.; Wang, Q.; Zenati, Y.
    In an effort to search for faint sources of emission over arbitrary timescales, we present a novel method for analyzing forced photometry light curves in difference imaging from optical surveys. Our method “ATLAS Clean” or ATClean, utilizes the reported fluxes, uncertainties, and fits to the point-spread function from difference images to quantify the statistical significance of individual measurements. We apply this method to control light curves across the image to determine whether any source of flux is present in the data for a range of specific timescales. From ATLAS o-band imaging at the site of the Type II supernova (SN) 2023ixf in M101 from 2015–2023, we show that this method accurately reproduces the 3σ flux limits produced from other, more computationally expensive methods. We derive limits for emission on timescales of 5 days and 80-300 days at the site of SN 2023ixf, which are 19.8 and 21.3 mag, respectively. The latter limits rule out variability for inextinguished red supergiants (RSG) with initial masses >22 M⊙, comparable to the most luminous predictions for the SN 2023ixf progenitor system. We also compare our limits to short timescale outbursts, similar to those expected for Type IIn SN progenitor stars or the Type II SN 2020tlf, and rule out outburst ejecta masses of >0.021 M⊙, much lower than the inferred mass of circumstellar matter around SN 2023ixf in the literature. In the future, these methods can be applied to any forced point-spread function photometry on difference imaging from other surveys, such as Rubin optical imaging.
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    Cluster Cosmology Constraints from the 2500 deg2 SPT-SZ Survey: Inclusion of Weak Gravitational Lensing Data from Magellan and the Hubble Space Telescope
    (2019) Bocquet, S.; Dietrich, J. P.; Schrabback, T.; Bleem, L. E.; Klein, M.; Allen, S. W.; Applegate, D. E.; Ashby, M. L. N.; Bautz, M.; Bayliss, M.; Benson, B. A.; Brodwin, M.; Bulbul, E.; Canning, R. E. A.; Capasso, R.; Carlstrom, J. E.; Chang, C. L.; Chiu, I; Cho, H-M; Clocchiatti, A.; Crawford, T. M.; Crites, A. T.; de Haan, T.; Desai, S.; Dobbs, M. A.; Foley, R. J.; Forman, W. R.; Garmire, G. P.; George, E. M.; Gladders, M. D.; Gonzalez, A. H.; Grandis, S.; Gupta, N.; Halverson, N. W.; Hlavacek-Larrondo, J.; Hoekstra, H.; Holder, G. P.; Holzapfel, W. L.; Hou, Z.; Hrubes, J. D.; Huang, N.; Jones, C.; Khullar, G.; Knox, L.; Kraft, R.; Lee, A. T.; von der Linden, A.; Luong-Van, D.; Mantz, A.; Marrone, D. P.; McDonald, M.; McMahon, J. J.; Meyer, S. S.; Mocanu, L. M.; Mohr, J. J.; Morris, R. G.; Padin, S.; Patil, S.; Pryke, C.; Rapetti, D.; Reichardt, C. L.; Rest, A.; Ruhl, J. E.; Saliwanchik, B. R.; Saro, A.; Sayre, J. T.; Schaffer, K. K.; Shirokoff, E.; Stalder, B.; Stanford, S. A.; Staniszewski, Z.; Stark, A. A.; Story, K. T.; Strazzullo, V; Stubbs, C. W.; Vanderlinde, K.; Vieira, J. D.; Vikhlinin, A.; Williamson, R.; Zenteno, A.
    We derive cosmological constraints using a galaxy cluster sample selected from the 2500 deg(2) SPT-SZ survey. The sample spans the redshift range 0.25 < z < 1.75 and contains 343 clusters with SZ detection significance xi > 5. The sample is supplemented with optical weak gravitational lensing measurements of 32 clusters with 0.29 < z < 1.13 (from Magellan and Hubble Space Telescope) and X-ray measurements of 89 clusters with 0.25 < z < 1.75 (from Chandra). We rely on minimal modeling assumptions: (i) weak lensing provides an accurate means of measuring halo masses, (ii) the mean SZ and X-ray observables are related to the true halo mass through power-law relations in mass and dimensionless Hubble parameter E(z) with a priori unknown parameters, and (iii) there is (correlated, lognormal) intrinsic scatter and measurement noise relating these observables to their mean relations. We simultaneously fit for these astrophysical modeling parameters and for cosmology. Assuming a flat nu Lambda CDM model, in which the sum of neutrino masses is a free parameter, we measure Omega(m) = 0.276 +/- 0.047, sigma(8) = 0.781 +/- 0.037, and sigma(8)(Omega(m)/0.3)(0.2) = 0.766 +/- 0.025. The redshift evolutions of the X-ray Y-X-mass and M-gas-mass relations are both consistent with self-similar evolution to within 1 sigma. The mass slope of the Y-X-mass relation shows a 2.3 sigma deviation from self-similarity. Similarly, the mass slope of the M-gas-mass relation is steeper than self-similarity at the 2.5 sigma level. In a nu omega CDM cosmology, we measure the dark energy equation-of-state parameter w = -1.55 +/- 0.41 from the cluster data. We perform a measurement of the growth of structure since redshift z similar to 1.7 and find no evidence for tension with the prediction from general relativity. This is the first analysis of the SPT cluster sample that uses direct weak-lensing mass calibration and is a step toward using the much larger weak-lensing data set from DES. We provide updated redshift and mass estimates for the SPT sample.
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    COSMOLOGICAL CONSTRAINTS FROM SUNYAEV-ZEL'DOVICH-SELECTED CLUSTERS WITH X-RAY OBSERVATIONS IN THE FIRST 178 deg2 OF THE SOUTH POLE TELESCOPE SURVEY
    (2013) Benson, B. A.; de Haan, T.; Dudley, J. P.; Reichardt, C. L.; Aird, K. A.; Andersson, K.; Armstrong, R.; Ashby, M. L. N.; Bautz, M.; Bayliss, M.; Bazin, G.; Bleem, L. E.; Brodwin, M.; Carlstrom, J. E.; Chang, C. L.; Cho, H. M.; Clocchiatti, A.; Crawford, T. M.; Crites, A. T.; Desai, S.; Dobbs, M. A.; Foley, R. J.; Forman, W. R.; George, E. M.; Gladders, M. D.; Gonzalez, A. H.; Halverson, N. W.; Harrington, N.; High, F. W.; Holder, G. P.; Holzapfel, W. L.; Hoover, S.; Hrubes, J. D.; Jones, C.; Joy, M.; Keisler, R.; Knox, L.; Lee, A. T.; Leitch, E. M.; Liu, J.; Lueker, M.; Luong-Van, D.; Mantz, A.; Marrone, D. P.; McDonald, M.; McMahon, J. J.; Mehl, J.; Meyer, S. S.; Mocanu, L.; Mohr, J. J.; Montroy, T. E.; Murray, S. S.; Natoli, T.; Padin, S.; Plagge, T.; Pryke, C.; Rest, A.; Ruel, J.; Ruhl, J. E.; Saliwanchik, B. R.; Saro, A.; Sayre, J. T.; Schaffer, K. K.; Shaw, L.; Shirokoff, E.; Song, J.; Spieler, H. G.; Stalder, B.; Staniszewski, Z.; Stark, A. A.; Story, K.; Stubbs, C. W.; Suhada, R.; van Engelen, A.; Vanderlinde, K.; Vieira, J. D.; Vikhlinin, A.; Williamson, R.; Zahn, O.; Zenteno, A.
    We usemeasurements from the South Pole Telescope (SPT) Sunyaev-Zel'dovich (SZ) cluster survey in combination with X-ray measurements to constrain cosmological parameters. We present a statistical method that fits for the scaling relations of the SZ and X-ray cluster observables with mass while jointly fitting for cosmology. The method is generalizable to multiple cluster observables, and self-consistently accounts for the effects of the cluster selection and uncertainties in cluster mass calibration on the derived cosmological constraints. We apply this method to a data set consisting of an SZ-selected catalog of 18 galaxy clusters at z > 0.3 from the first 178 deg(2) of the 2500 deg(2) SPT-SZ survey, with 14 clusters having X-ray observations from either Chandra or XMM-Newton. Assuming a spatially flat Lambda CDM cosmological model, we find the SPT cluster sample constrains sigma(8)(Omega(m)/0.25)(0.30) = 0.785 +/- 0.037. In combination with measurements of the cosmic microwave background (CMB) power spectrum from the SPT and the seven-year Wilkinson Microwave Anisotropy Probe data, the SPT cluster sample constrains sigma(8) = 0.795 +/- 0.016 and Omega(m) = 0.255 +/- 0.016, a factor of 1.5 improvement on each parameter over the CMB data alone. We consider several extensions beyond the Lambda CDM model by including the following as free parameters: the dark energy equation of state (w), the sum of the neutrino masses (Sigma m(nu)), the effective number of relativistic species (N-eff), and a primordial non-Gaussianity (f(NL)). We find that adding the SPT cluster data significantly improves the constraints on w and Sigma m(nu) beyond those found when using measurements of the CMB, supernovae, baryon acoustic oscillations, and the Hubble constant. Considering each extension independently, we best constrain w = -0.973 +/- 0.063 and the sum of neutrino masses Sigma m(nu) < 0.28 eV at 95% confidence, a factor of 1.25 and 1.4 improvement, respectively, over the constraints without clusters. Assuming a Lambda CDM model with a free N-eff and Sigma m(nu), we measure N-eff = 3.91 +/- 0.42 and constrain Sigma m(nu) < 0.63 eV at 95% confidence. We also use the SPT cluster sample to constrain f(NL) = -220 +/- 317, consistent with zero primordial non-Gaussianity. Finally, we discuss the current systematic limitations due to the cluster mass calibration, and future improvements for the recently completed 2500 deg(2) SPT-SZ survey. The survey has detected similar to 500 clusters with a median redshift of similar to 0.5 and a median mass of similar to 2.3 x 10(14) M-circle dot h(-1) and, when combined with an improved cluster mass calibration and existing external cosmological data sets will significantly improve constraints on w.
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    DISCOVERY AND COSMOLOGICAL IMPLICATIONS OF SPT-CL J2106-5844, THE MOST MASSIVE KNOWN CLUSTER AT z > 1
    (2011) Foley, R. J.; Andersson, K.; Bazin, G.; de Haan, T.; Ruel, J.; Ade, P. A. R.; Aird, K. A.; Armstrong, R.; Ashby, M. L. N.; Bautz, M.; Benson, B. A.; Bleem, L. E.; Bonamente, M.; Brodwin, M.; Carlstrom, J. E.; Chang, C. L.; Clocchiatti, A.; Crawford, T. M.; Crites, A. T.; Desai, S.; Dobbs, M. A.; Dudley, J. P.; Fazio, G. G.; Forman, W. R.; Garmire, G.; George, E. M.; Gladders, M. D.; Gonzalez, A. H.; Halverson, N. W.; High, F. W.; Holder, G. P.; Holzapfel, W. L.; Hoover, S.; Hrubes, J. D.; Jones, C.; Joy, M.; Keisler, R.; Knox, L.; Lee, A. T.; Leitch, E. M.; Lueker, M.; Luong-Van, D.; Marrone, D. P.; McMahon, J. J.; Mehl, J.; Meyer, S. S.; Mohr, J. J.; Montroy, T. E.; Murray, S. S.; Padin, S.; Plagge, T.; Pryke, C.; Reichardt, C. L.; Rest, A.; Ruhl, J. E.; Saliwanchik, B. R.; Saro, A.; Schaffer, K. K.; Shaw, L.; Shirokoff, E.; Song, J.; Spieler, H. G.; Stalder, B.; Stanford, S. A.; Staniszewski, Z.; Stark, A. A.; Story, K.; Stubbs, C. W.; Vanderlinde, K.; Vieira, J. D.; Vikhlinin, A.; Williamson, R.; Zenteno, A.
    Using the South Pole Telescope (SPT), we have discovered the most massive known galaxy cluster at z > 1, SPT-CL J2106-5844. In addition to producing a strong Sunyaev-Zel'dovich (SZ) effect signal, this system is a luminous X-ray source and its numerous constituent galaxies display spatial and color clustering, all indicating the presence of a massive galaxy cluster. Very Large Telescope and Magellan spectroscopy of 18 member galaxies shows that the cluster is at z = 1.132(-0.003)(+0.002). Chandra observations obtained through a combined HRC-ACIS GTO program reveal an X-ray spectrum with an Fe K line redshifted by z = 1.18 +/- 0.03. These redshifts are consistent with the galaxy colors found in optical, near-infrared, and mid-infrared imaging. SPT-CL J2106-5844 displays extreme X-ray properties for a cluster having a core-excluded temperature of T-X = 11.0(-1.9)(+2.6) keV and a luminosity (within r(500)) of L-X(0.5-2.0 keV) = (13.9 +/- 1.0) x 10(44) erg s(-1). The combined mass estimate from measurements of the SZ effect and X-ray data is M-200 = (1.27 +/- 0.21) x 10(15) h(70)(-1) M-circle dot. The discovery of such amassive gravitationally collapsed system at high redshift provides an interesting laboratory for galaxy formation and evolution, and is a probe of extreme perturbations of the primordial matter density field. We discuss the latter, determining that, under the assumption of Lambda CDM cosmology with only Gaussian perturbations, there is only a 7% chance of finding a galaxy cluster similar to SPT-CL J2106-5844 in the 2500 deg(2) SPT survey region and that only one such galaxy cluster is expected in the entire sky.
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    Double “acct”: A Distinct Double-peaked Supernova Matching Pulsational Pair Instability Models
    (2024) Angus, C.R.; Woosley, S.E.; Foley, R.J.; Nicholl, M.; Villar, V.A.; Taggart, K.; Pursiainen, M.; Ramsden, P.; Srivastav, S.; Stevance, H.F.; Moore, T.; Auchettl, K.; Hoogendam, W.B.; Khetan, N.; Yadavalli, S.K.; Dimitriadis, G.; Gagliano, A.; Siebert, M.R.; Aamer, A.; Boer, T.D.; Chambers, K.C.; Clocchiatti García, Alejandro; Coulter, D.A.; Drout, M.R.; Farias, D.; Fulton, M.D.; Gall, C.; Gao, H.; Izzo, L.; Jones, D.O.; Lin, C.-C.; Magnier, E.A.; Narayan, G.; Ramirez-Ruiz, E.; Ransome, C.L.; Rest, A.; Smartt, S.J.; Smith, K.W.
    We present multiwavelength data of SN 2020acct, a double-peaked stripped-envelope supernova (SN) in NGC 2981 at ∼150 Mpc. The two peaks are temporally distinct, with maxima separated by 58 rest-frame days and a factor of 20 reduction in flux between. The first is luminous (Mr = −18.00 ± 0.02 mag) and blue (g − r = 0.27 ± 0.03 mag) and displays spectroscopic signatures of interaction with hydrogen-free circumstellar material. The second peak is fainter (Mr = −17.29 ± 0.03 mag) and has some spectroscopic similarities to an evolved stripped-envelope SN, with strong forbidden [Ca ii] and [O ii] features. No other known double-peaked SN exhibits a light curve similar to that of SN 2020acct. We find the likelihood of two individual SNe occurring in the same star-forming region within that time to be highly improbable, while an implausibly fine-tuned configuration would be required to produce two SNe from a single binary system. We find that the peculiar properties of SN 2020acct match models of pulsational pair instability (PPI), in which the initial peak is produced by collisions of shells of ejected material, shortly followed by core collapse. Pulsations from a star with a 72 M⊙ helium core provide an excellent match to the double-peaked light curve. The local galactic environment has a metallicity of 0.4 Z⊙, a level where massive single stars are not expected to retain enough mass to encounter the PPI. However, late binary mergers or a low-metallicity pocket may allow the required core mass. We measure the rate of SN 2020acct-like events to be <3.3 × 10−8 Mpc−3 yr−1 at z = 0.07, or <0.1% of the total core-collapse SN rate.
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    Final Moments. II. Observational Properties and Physical Modeling of Circumstellar-material-interacting Type II Supernovae
    (2024) Jacobson-Galan, W. V.; Dessart, L.; Davis, K. W.; Kilpatrick, C. D.; Margutti, R.; Foley, R. J.; Chornock, R.; Terreran, G.; Hiramatsu, D.; Newsome, M.; Padilla Gonzalez, E.; Pellegrino, C.; Howell, D. A.; Filippenko, A. V.; Anderson, J. P.; Angus, C. R.; Auchettl, K.; Bostroem, K. A.; Brink, T. G.; Cartier, R.; Coulter, D. A.; de Boer, T.; Drout, M. R.; Earl, N.; Ertini, K.; Farah, J. R.; Farias, D.; Gall, C.; Gao, H.; Gerlach, M. A.; Guo, F.; Haynie, A.; Hosseinzadeh, G.; Ibik, A. L.; Jha, S. W.; Jones, D. O.; Langeroodi, D.; Lebaron, N.; Magnier, E. A.; Piro, A. L.; Raimundo, S. I.; Rest, A.; Rest, S.; Rich, R. Michael; Rojas-Bravo, C.; Sears, H.; Taggart, K.; Villar, V. A.; Wainscoat, R. J.; Wang, X-f.; Wasserman, A. R.; Yan, S.; Yang, Y.; Zhang, J.; Zheng, W.
    We present ultraviolet/optical/near-infrared observations and modeling of Type II supernovae (SNe II) whose early time (delta(t) < 2 days) spectra show transient, narrow emission lines from shock ionization of confined (r < 10(15) cm) circumstellar material (CSM). The observed electron-scattering broadened line profiles (i.e., IIn-like) of H i, He i/ii, C iv, and N iii/iv/v from the CSM persist on a characteristic timescale (t(IIn)) that marks a transition to a lower-density CSM and the emergence of Doppler-broadened features from the fast-moving SN ejecta. Our sample, the largest to date, consists of 39 SNe with early time IIn-like features in addition to 35 "comparison" SNe with no evidence of early time IIn-like features, all with ultraviolet observations. The total sample includes 50 unpublished objects with a total of 474 previously unpublished spectra and 50 multiband light curves, collected primarily through the Young Supernova Experiment and Global Supernova Project collaborations. For all sample objects, we find a significant correlation between peak ultraviolet brightness and both t(II)n and the rise time, as well as evidence for enhanced peak luminosities in SNe II with IIn-like features. We quantify mass-loss rates and CSM density for the sample through the matching of peak multiband absolute magnitudes, rise times, t(IIn), and optical SN spectra with a grid of radiation hydrodynamics and non-local thermodynamic equilibrium radiative-transfer simulations. For our grid of models, all with the same underlying explosion, there is a trend between the duration of the electron-scattering broadened line profiles and inferred mass-loss rate: t(IIn) approximate to 3.8[M/ (0.01 M-circle dot yr(-1))] days.
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    GALAXY CLUSTERS DISCOVERED VIA THE SUNYAEV-ZEL'DOVICH EFFECT IN THE FIRST 720 SQUARE DEGREES OF THE SOUTH POLE TELESCOPE SURVEY
    (2013) Reichardt, C. L.; Stalder, B.; Bleem, L. E.; Montroy, T. E.; Aird, K. A.; Andersson, K.; Armstrong, R.; Ashby, M. L. N.; Bautz, M.; Bayliss, M.; Bazin, G.; Benson, B. A.; Brodwin, M.; Carlstrom, J. E.; Chang, C. L.; Cho, H. M.; Clocchiatti, A.; Crawford, T. M.; Crites, A. T.; de Haan, T.; Desai, S.; Dobbs, M. A.; Dudley, J. P.; Foley, R. J.; Forman, W. R.; George, E. M.; Gladders, M. D.; Gonzalez, A. H.; Halverson, N. W.; Harrington, N. L.; High, F. W.; Holder, G. P.; Holzapfel, W. L.; Hoover, S.; Hrubes, J. D.; Jones, C.; Joy, M.; Keisler, R.; Knox, L.; Lee, A. T.; Leitch, E. M.; Liu, J.; Lueker, M.; Luong-Van, D.; Mantz, A.; Marrone, D. P.; McDonald, M.; McMahon, J. J.; Mehl, J.; Meyer, S. S.; Mocanu, L.; Mohr, J. J.; Murray, S. S.; Natoli, T.; Padin, S.; Plagge, T.; Pryke, C.; Rest, A.; Ruel, J.; Ruhl, J. E.; Saliwanchik, B. R.; Saro, A.; Sayre, J. T.; Schaffer, K. K.; Shaw, L.; Shirokoff, E.; Song, J.; Spieler, H. G.; Staniszewski, Z.; Stark, A. A.; Story, K.; Stubbs, C. W.; Suhada, R.; van Engelen, A.; Vanderlinde, K.; Vieira, J. D.; Vikhlinin, A.; Williamson, R.; Zahn, O.; Zenteno, A.
    We present a catalog of galaxy cluster candidates, selected through their Sunyaev-Zel'dovich (SZ) effect signature in the first 720 deg(2) of the South Pole Telescope (SPT) survey. This area was mapped with the SPT in the 2008 and 2009 austral winters to a depth of similar to 18 mu K-CMB-arcmin at 150 GHz; 550 deg(2) of it was also mapped to similar to 44 mu K-CMB-arcmin at 95 GHz. Based on optical imaging of all 224 candidates and near-infrared imaging of the majority of candidates, we have found optical and/or infrared counterparts for 158, which we then classify as confirmed galaxy clusters. Of these 158 clusters, 135 were first identified as clusters in SPT data, including 117 new discoveries reported in this work. This catalog triples the number of confirmed galaxy clusters discovered through the SZ effect. We report photometrically derived (and in some cases spectroscopic) redshifts for confirmed clusters and redshift lower limits for the remaining candidates. The catalog extends to high redshift with a median redshift of z = 0.55 and maximum confirmed redshift of z = 1.37. Forty-five of the clusters have counterparts in the ROSAT bright or faint source catalogs from which we estimate X-ray fluxes. Based on simulations, we expect the catalog to be nearly 100% complete above M-500 approximate to 5 x 10(14) M-circle dot h(70)(-1) at z greater than or similar to 0.6. There are 121 candidates detected at signal-to-noise ratio greater than five, at which the catalog purity is measured to be 95%. From this high-purity subsample, we exclude the z < 0.3 clusters and use the remaining 100 candidates to improve cosmological constraints following the method presented by Benson et al. Adding the cluster data to CMB + BAO + H-0 data leads to a preference for non-zero neutrino masses while only slightly reducing the upper limit on the sum of neutrino masses to Sigma m(nu) < 0.38 eV (95% CL). For a spatially flat wCDM cosmological model, the addition of this catalog to the CMB + BAO + H-0 + SNe results yields sigma(8) = 0.807 +/- 0.027 and w = -1.010 +/- 0.058, improving the constraints on these parameters by a factor of 1.4 and 1.3, respectively. The larger cluster catalog presented in this work leads to slight improvements in cosmological constraints from those presented by Benson et al. These cosmological constraints are currently limited by uncertainty in the cluster mass calibration, not the size or quality of the cluster catalog. A multi-wavelength observation program to improve the cluster mass calibration will make it possible to realize the full potential of the final 2500 deg(2) SPT cluster catalog to constrain cosmology.
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    HIGH-AMPLITUDE δ-SCUTIS IN THE LARGE MAGELLANIC CLOUD
    (2010) Garg, A.; Cook, K. H.; Nikolaev, S.; Huber, M. E.; Rest, A.; Becker, A. C.; Challis, P.; Clocchiatti, A.; Miknaitis, G.; Minniti, D.; Morelli, L.; Olsen, K.; Prieto, J. L.; Suntzeff, N. B.; Welch, D. L.; Wood-Vasey, W. M.
    We present 2323 high-amplitude delta-Scuti (HADS) candidates discovered in the Large Magellanic Cloud by the SuperMACHO survey (Rest et al.). Frequency analyses of these candidates reveal that several are multimode pulsators, including 119 whose largest amplitude of pulsation is in the fundamental (F) mode and 19 whose largest amplitude of pulsation is in the first overtone (FO) mode. Using Fourier decomposition of the HADS light curves, we find that the period-luminosity (PL) relation defined by the FO pulsators does not show a clear separation from the PL relation defined by the F pulsators. This differs from other instability strip pulsators such as type c RR Lyrae. We also present evidence for a larger amplitude, subluminous population of HADS similar to that observed in Fornax.
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    Light echoes reveal an unexpectedly cool η Carinae during its nineteenth-century Great Eruption
    (2012) Rest, A.; Prieto, J. L.; Walborn, N. R.; Smith, N.; Bianco, F. B.; Chornock, R.; Welch, D. L.; Howell, D. A.; Huber, M. E.; Foley, R. J.; Fong, W.; Sinnott, B.; Bond, H. E.; Smith, R. C.; Toledo, I.; Minniti, D.; Mandel, K.
    eta Carinae is one of the most massive binary stars in the Milky Way(1,2). It became the second-brightest star in our sky during its mid-nineteenth-century 'Great Eruption', but then faded from view (with only naked-eye estimates of brightness(3,4)). Its eruption is unique in that it exceeded the Eddington luminosity limit for ten years. Because it is only 2.3 kiloparsecs away, spatially resolved studies of the nebula have constrained the ejected mass and velocity, indicating that during its nineteenth-century eruption, eta Car ejected more than ten solar masses in an event that released ten per cent of the energy of a typical core-collapse supernova(5,6), without destroying the star. Here we report observations of light echoes of eta Carinae from the 1838-1858 Great Eruption. Spectra of these light echoes show only absorption lines, which are blueshifted by -210 km s(-1), in good agreement with predicted expansion speeds(6). The light-echo spectra correlate best with those of G2-to-G5 supergiants, which have effective temperatures of around 5,000 kelvin. In contrast to the class of extragalactic outbursts assumed to be analogues of the Great Eruption of eta Carinae(7-12), the effective temperature of its outburst is significantly lower than that allowed by standard opaque wind models(13). This indicates that other physical mechanisms such as an energetic blast wave may have triggered and influenced the eruption.
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    LIGHT. CURVES. OF. 213 TYPE. Ia SUPERNOVAE. FROM. THE. ESSENCE. SURVEY
    (2016) Narayan, G.; Rest, A.; Tucker, B.; Foley, R.; Wood, W.; Challis, P.; Stubbs, C.; Kirshner, R.; Aguilera, C.; Clocchiatti, Alejandro; Becker, A.; Blondin, S.; Covarrubias, R.; Damke, G.; Davis, T.; Filippenko, A.
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    Looking for building blocks of the Galactic halo: variable stars in the Fornax, Bootes I, Canes Venatici II dwarfs and in NGC 2419
    (2010) Greco, Claudia; Clementini, Gisella; Held, E. V.; Poretti, E.; Catelan, Márcio; Federici, L.; Maio, M.; Gullieuszik, M.; Ripepi, V.; Dall'Ora, M.; Di Fabrizio, L.; Kinemuchi, K.; Di Crescienzo, M.; Marconi, M.; Musella, I.; Pritzl, B.; Rest, A.; De Lee, N.; Smith, H.
    Λ cold-dark-matter hierarchical models of galaxy formation suggest that the halo of the Milky Way (MW) has been assembled, at least in part, through accretion of protogalactic fragments partially resembling the present-day dwarf spheroidal (dSph) satellites of the MW. Investigation of the stellar populations of the MW's globular clusters (GCs) and dSph companions can thus provide excellent tests to infer the dominant Galaxy-formation scenario, whether merger/accretion or cloud collapse. Pulsating variable stars offer a very powerful tool in this context, since variables of different types allow tracing the different stellar generations in a galaxy and to reconstruct the galaxy's star-formation history and assembly back to the first epochs of galaxy formation. In particular, the RR Lyrae stars, belonging to the old population (t > 10 Gyr), witnessed the epoch of halo formation, and thus hold a crucial role to identify the MW satellites that may have contributed to build up the Galactic halo. In the MW, most GCs with an RR Lyrae population sharply divide into two distinct groups (Oosterhoff types I and II) based on the mean periods and relative proportion of fundamental-mode (RRab) and first-overtone (RRc) RR Lyrae stars. On the other hand, the Galactic-halo field RR Lyrae stars show a dominance of Oosterhoff I properties. Here, we investigate the Oosterhoff properties of a number of different stellar systems, starting from relatively undisturbed dwarf galaxies (the Fornax dSph and its globular clusters), through distorted and tidally disrupting ones (the Bootes and Canes Venatici II dSphs), to possible final relics of the disruption process (the Galactic globular cluster NGC 2419). We are addressing the crucial question of whether the RR Lyrae pulsation properties in these systems conform to the Oosterhoff dichotomy characterizing the MW variables. If they do not, the Galaxy's halo cannot have been assembled by dSph-like protogalactic fragments resembling the present-day dSph companions of the MW. We have reduced and combined long time series from different telescopes, both ground- and space-based. Variable stars have been detected with image-subtraction techniques using the package isis2.1. Periods, amplitudes and Oosterhoff type for all variable stars, as well as color-magnitude diagrams of the stellar populations are discussed for each stellar cluster analyzed....
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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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    Rest et al. reply
    (2012) Rest, A.; Minniti, D.