A. Clocchiatti
A5067881179- Gamma-ray bursts and supernovae
- Astronomy and Astrophysical Research
- Astrophysics and Cosmic Phenomena
- Stellar, planetary, and galactic studies
- Astrophysical Phenomena and Observations
- Galaxies: Formation, Evolution, Phenomena
- Pulsars and Gravitational Waves Research
- Astro and Planetary Science
- Cosmology and Gravitation Theories
- Astronomical Observations and Instrumentation
- Neutrino Physics Research
- Astrophysics and Star Formation Studies
- Geophysics and Gravity Measurements
- Solar and Space Plasma Dynamics
- Superconducting Materials and Applications
- Adaptive optics and wavefront sensing
- Particle Accelerators and Free-Electron Lasers
- Engineering and Information Technology
- Calibration and Measurement Techniques
- History and Developments in Astronomy
- Radio Astronomy Observations and Technology
- SAS software applications and methods
- Geological and Geophysical Studies
- Spacecraft and Cryogenic Technologies
- Spectroscopy and Chemometric Analyses
Pontificia Universidad Católica de Chile
2015-2024
Millennium Institute of Astrophysics
2015-2024
Millennium Science Initiative
2011-2020
Universidad Nacional de La Plata
1986-2008
Cerro Tololo Inter-American Observatory
1996-2006
Association of Universities For Research In Astronomy
1998-2006
U.S. National Science Foundation
1998-2006
California Public Utilities Commission
2002
The University of Texas at Austin
1992-1996
We present spectral and photometric observations of 10 Type Ia supernovae (SNe Ia) in the redshift range 0.16 ≤ z 0.62. The luminosity distances these objects are determined by methods that employ relations between SN light curve shape. Combined with previous data from our High-z Supernova Search Team recent results Riess et al., this expanded set 16 high-redshift a 34 nearby used to place constraints on following cosmological parameters: Hubble constant (H0), mass density (ΩM), (i.e.,...
The High-z Supernova Search Team has discovered and observed 8 new supernovae in the redshift interval z=0.3-1.2. These independent observations, confirm result of Riess et al. (1998a) Perlmutter (1999) that supernova luminosity distances imply an accelerating universe. More importantly, they extend range consistently SN Ia to z~1, where signature cosmological effects opposite sign some plausible systematic effects. Consequently, these measurements not only provide another quantitative...
The High-Z Supernova Search is an international collaboration to discover and monitor Type Ia supernovae (SNe Ia) at z > 0.2 with the aim of measuring cosmic deceleration global curvature. Our has pursued a basic understanding in nearby universe, discovering observing large sample objects developing methods measure accurate distances SNe Ia. This paper describes extension this program ≥ 0.2, outlining our search techniques follow-up program. We have devised high-throughput filters that...
We present constraints on the dark energy equation-of-state parameter, w=P/(rho c^2), using 60 Type Ia supernovae (SNe Ia) from ESSENCE supernova survey. derive a set of nature assuming flat Universe. By including (Omega_M, w) baryon acoustic oscillations, we obtain value for static parameter w=-1.05^{+0.13}_{-0.12} (stat; 1 sigma) +- 0.11 (sys) and Omega_M=0.274^{+0.033}_{-0.020} with best-fit chi^2/DoF 0.96. These results are consistent those reported by SuperNova Legacy Survey in similar...
We use Type Ia supernovae studied by the High-z Supernova Search Team to constrain properties of an energy component that may have contributed accelerating cosmic expansion. find for a flat geometry equation-of-state parameter unknown component, αx = Px/ρx, must be less than -0.55 (95% confidence) any value Ωm, and it is further limited < -0.60 if Ωm assumed greater 0.1. These values are inconsistent with being topological defects such as domain walls, strings, or textures. The supernova...
We have coordinated Hubble Space Telescope (HST) photometry with ground-based discovery for three supernovae: Type Ia supernovae near z ≈ 0.5 (SN 1997ce, SN 1997cj) and a third event at = 0.97 1997ck). The superb spatial resolution of HST separates each supernova from its host galaxy leads to good precision in the light curves. use these curves relations between luminosity, light-curve shape, color calibrated low-z samples derive relative luminosity distances that are accurate 10% 20% 1....
We present a catalog of galaxy clusters selected via their Sunyaev-Zel'dovich (SZ) effect signature from 2500 deg$^2$ South Pole Telescope (SPT) data. This work represents the complete sample detected at high significance in 2500-square-degree SPT-SZ survey, which was completed 2011. A total 677 (409) cluster candidates are identified above signal-to-noise threshold $\xi$ =4.5 (5.0). Ground- and space-based optical near-infrared (NIR) imaging confirms overdensities similarly colored galaxies...
The first cosmological results from the ESSENCE supernova survey (Wood-Vasey and coworkers) are extended to a wider range of models including dynamical dark energy nonstandard models. We fold in greater number external data sets such as recent Higher-z release high-redshift supernovae (Riess coworkers), well several complementary probes. Model comparison statistics Bayesian Akaike information criteria applied gauge worth These favor that give good fit with fewer parameters. Based on this...
We present photometric and spectroscopic observations of 23 high-redshift supernovae (SNe) spanning a range z = 0.34-1.03, nine which are unambiguously classified as Type Ia. These SNe were discovered during the IfA Deep Survey, began in 2001 September observed total 2.5 deg2 to depth approximately m ≈ 25-26 RIZ over 9-17 visits, typically every 1-3 weeks for nearly 5 months, with additional continuing until 2002 April. give brief description survey motivations, observational strategy,...
(abridged) We present cosmological constraints obtained from galaxy clusters identified by their Sunyaev-Zel'dovich effect signature in the 2500 square degree South Pole Telescope Sunyaev Zel'dovich survey. consider 377 cluster candidates at z>0.25 with a detection significance greater than five, corresponding to 95% purity threshold for compute on models using measured abundance as function of mass and redshift. include additional multi-wavelength observations, including Chandra X-ray data...
We present a catalog of galaxy cluster candidates, selected through their Sunyaev–Zel'dovich (SZ) effect signature in the first 720 deg2 South Pole Telescope (SPT) survey. This area was mapped with SPT 2008 and 2009 austral winters to depth ∼18 μKCMB-arcmin at 150 GHz; 550 it also ∼44 95 GHz. Based on optical imaging all 224 candidates near-infrared majority we have found and/or infrared counterparts for 158, which then classify as confirmed clusters. Of these 158 clusters, 135 were...
We use measurements from the South Pole Telescope (SPT) Sunyaev Zel'dovich (SZ) cluster survey in combination with X-ray to constrain cosmological parameters. present a statistical method that fits for scaling relations of SZ and observables mass while jointly fitting cosmology. The is generalizable multiple observables, self-consistently accounts effects selection uncertainties calibration on derived constraints. apply this data set consisting an SZ-selected catalog 18 galaxy clusters at z...
The Public European Southern Observatory Spectroscopic Survey of Transient Objects (PESSTO) began as a public spectroscopic survey in April 2012. We describe the data reduction strategy and products which are publicly available through ESO archive Data Release 1 (SSDR1). PESSTO uses New Technology Telescope with EFOSC2 SOFI to provide optical NIR spectroscopy imaging. target supernovae transients brighter than 20.5mag for classification. Science targets then selected follow-up based on...
We describe the implementation and optimization of ESSENCE supernova survey, which we have undertaken to measure equation state parameter dark energy. present a method for optimizing survey exposure times cadence maximize our sensitivity energy w=P/rho c^2 given fixed amount telescope time. For on CTIO 4m telescope, measuring luminosity distances redshifts supernovae at modest (z~0.5 +- 0.2) is optimal determining w. data analysis pipeline based using reliable robust image subtraction find...
The South Pole Telescope (SPT) is currently surveying 2500 deg^2 of the southern sky to detect massive galaxy clusters out epoch their formation using Sunyaev-Zel'dovich (SZ) effect. This paper presents a catalog 26 most significant SZ cluster detections in full survey region. includes 14 which have been previously identified and 12 that are new discoveries. These were fields observed two differing noise depths: 1500 at final SPT depth 18 uK-arcmin 150 GHz, 1000 54 uK-arcmin. Clusters...
We present observations of the Type Ia supernovae (SNe) 1999M, 1999N, 1999Q, 1999S, and 1999U, at redshift z ≈ 0.5. They were discovered in early 1999 with 4.0 m Blanco telescope Cerro Tololo Inter-American Observatory by High-z Supernova Search Team (HZT) subsequently followed many ground-based telescopes. SNe 1999Q 1999U also observed Hubble Space Telescope. computed luminosity distances to new using two methods added them high-z diagram that HZT has been constructing since 1995. The...
Characterizing the nature and spatial distribution of lensing objects that produce previously measured microlensing optical depth toward Large Magellanic Cloud (LMC) remains an open problem. We present appraisal ability SuperMACHO Project, a next-generation survey directed LMC, to discriminate between various proposed populations. consider two scenarios: by uniform foreground screen self-lensing LMC stars. have carried out extensive simulations, based upon data obtained during first year...
We present first results on the cooling properties derived from Chandra X-ray observations of 83 high-redshift (0.3 < z 1.2) massive galaxy clusters selected by their Sunyaev–Zel'dovich signature in South Pole Telescope data. measure each cluster's central time, entropy, and mass deposition rate, compare these to those for local cluster samples. find no significant evolution ∼ 0 1 distribution properties, suggesting that cores is stable over long periods time. also average cool core entropy...
We present a velocity dispersion-based mass calibration of the South Pole Telescope Sunyaev-Zel'dovich effect survey (SPT-SZ) galaxy cluster sample. Using homogeneously selected sample 100 candidates from 720 deg2 along with 63 dispersion ($\sigma_v$) and 16 X-ray Yx measurements clusters, we simultaneously calibrate mass-observable relation constrain cosmological parameters. The calibrations using $\sigma_v$ are consistent at $0.6\sigma$ level, preferring ~16% higher masses. use full...
Abstract We explore properties of Type Ib and IIb SN progenitors that are produced by stable mass transfer in binary systems using a new grid stellar evolution models from an initial primary the range <?CDATA $10\mbox{--}18\,{M}_{\odot }$?> at solar Large Magellanic Cloud metallicities. find blue yellow supergiant (e.g., 2008ax, 2011dh, 2016gkg) have hydrogen envelope less than about $0.15\,{M}_{\odot , mostly resulting early Case B with relatively low masses and/or metallicity. Red (RSG)...
We present the first cosmological parameter constraints using measurements of type Ia supernovae (SNe Ia) from Dark Energy Survey Supernova Program (DES-SN). The analysis uses a subsample 207 spectroscopically confirmed SNe three years DES-SN, combined with low-redshift sample 122 literature. Our "DES-SN3YR" result these 329 is based on series companion analyses and improvements covering SN discovery, spectroscopic selection, photometry, calibration, distance bias corrections, evaluation...
We derive cosmological constraints using a galaxy cluster sample selected from the 2500~deg$^2$ SPT-SZ survey. The spans redshift range $0.25< z<1.75$ and contains 343 clusters with SZ detection significance $\xi>5$. is supplemented optical weak gravitational lensing measurements of 32 $0.29<z<1.13$ (from Magellan HST) X-ray 89 $0.25<z<1.75$ Chandra). rely on minimal modeling assumptions: i) provides an accurate means measuring halo masses, ii) mean observables are related to true mass...
The shape of the light curve peak radioactive--powered core--collapse "stripped--envelope" supernovae constrains ejecta mass, nickel and kinetic energy by brightness diffusion time for a given opacity observed expansion velocity. Late--time curves give constraints on mass energy, gamma--ray opacity. Previous work has shown that principal peaks SN~IIb with small amounts hydrogen hydrogen/helium--deficient SN~Ib/c are often rather similar near maximum light, suggesting masses energies, but...