2. High-redshift supernova rates measured with the gravitational telescope A 1689Tanja Petrushevska, R. Amanullah, Ariel Goobar, S. Fabbro, Joel Johansson, Tor Kjellsson, Chris Lidman, K. Paech, Johan Richard, H. Dahle, Raphael Ferretti, J.P. Kneib, M. Limousin, Jakob Nordin, V. Stanishev, 2016, izvirni znanstveni članek Opis: Aims. We present a ground-based, near-infrared search for lensed supernovae behind the massive cluster Abell 1689 at z = 0.18, which is one of the most powerful gravitational telescopes that nature provides.
Methods. Our survey was based on multi-epoch J-band observations with the HAWK-I instrument on VLT, with supporting optical data from the Nordic Optical Telescope.
Results. Our search resulted in the discovery of five photometrically classified, core-collapse supernovae with high redshifts of 0.671 < z < 1.703 and magnifications in the range ∆m = −0.31 to −1.58 mag, as calculated from lensing models in the literature.
Owing to the power of the lensing cluster, the survey had the sensitivity to detect supernovae up to very high redshifts, z ∼ 3, albeit for a limited region of space. We present a study of the core-collapse supernova rates for 0.4 ≤ z < 2.9, and find good agreement with previous estimates and predictions from star formation history. During our survey, we also discovered two Type Ia supernovae in A 1689 cluster members, which allowed us to determine the cluster Ia rate to be 0.14+0.19 −0.09 ± 0.01 SNuB h 2 (SNuB ≡ 10−12 SNe L −1 ,B yr−1), where the error bars indicate 1σ confidence intervals, statistical and systematic, respectively. The cluster rate normalized by the stellar mass is 0.10+0.13 −0.06 ± 0.02 in SNuM h 2 (SNuM ≡ 10−12 SNe M−1 yr−1). Furthermore, we explore the optimal future survey for improving the core-collapse supernova rate measurements at z & 2 using gravitational telescopes, and for detections
with multiply lensed images, and we find that the planned WFIRST space mission has excellent prospects.
Conclusions. Massive clusters can be used as gravitational telescopes to significantly expand the survey range of supernova searches, with important implications for the study of the high-z transient Universe. Ključne besede: supernovae: general – gravitational lensing: strong – galaxies: star formation – galaxies: clusters: individual: A 1689 –
techniques: photometric Objavljeno v RUNG: 23.01.2018; Ogledov: 4599; Prenosov: 0 Gradivo ima več datotek! Več... |
3. THE PECULIAR EXTINCTION LAW OF SN 2014J MEASURED WITH THE HUBBLE SPACE TELESCOPERahman Amanullah, Ariel Goobar, Joel Johansson, D.P.K. Banerjee, V. Venkataraman, V. Joshi, N.M. Ashok, Yi Cao, Mansi Kasliwal, S.R. Kulkarni, P.E. Nugent, Tanja Petrushevska, V. Stanishev, 2014, izvirni znanstveni članek Opis: The wavelength dependence of the extinction of Type Ia SN 2014J in the nearby galaxy M82 has been measured
using UV to near-IR photometry obtained with the Hubble Space Telescope, the Nordic Optical Telescope, and
the Mount Abu Infrared Telescope. This is the first time that the reddening of an SN Ia is characterized over the
full wavelength range of 0.2–2μm. A total-to-selective extinction, RV 3.1, is ruled out with high significance.
The best fit at maximum using a Galactic type extinction law yields RV = 1.4 ± 0.1. The observed reddening of
SN 2014J is also compatible with a power-law extinction, Aλ/AV = (λ/λV )
p as expected from multiple scattering
of light, with p = −2.1 ± 0.1. After correcting for differences in reddening, SN 2014J appears to be very similar
to SN 2011fe over the 14 broadband filter light curves used in our study. Ključne besede: dust, extinction – galaxies: individual (Messier 82) – supernovae: individual SN2014J Objavljeno v RUNG: 22.01.2018; Ogledov: 4123; Prenosov: 0 Gradivo ima več datotek! Več... |