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# Type Ia SNe Along Redshift: The R(Si II) Ratio and the Expansion Velocities in Intermediate-z Supernovae

Altavilla, G. and Ruiz-Lapuente, P. and Balastegui, A. and Méndez, J. and Irwin, M. and España-Bonet, C. and Ellis, R. S. and Folatelli, G. and Goobar, A. and Hillebrandt, W. and McMahon, R. M. and Nobili, S. and Stanishev, V. and Walton, N. A. (2009) Type Ia SNe Along Redshift: The R(Si II) Ratio and the Expansion Velocities in Intermediate-z Supernovae. Astrophysical Journal, 695 (1). pp. 135-148. ISSN 0004-637X. https://resolver.caltech.edu/CaltechAUTHORS:20090709-100009622

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## Abstract

We present a study of intermediate-z Type Ia supernovae (SNe Ia) using empirical physical diagrams which permit the investigation of those SNe explosions. This information can be very useful to reduce systematic uncertainties of the Hubble diagram of SNe Ia up to high z. The study of the expansion velocities and the measurement of the ratio R(Si II) allow subtyping of SNe Ia as done in nearby samples. The evolution of this ratio as seen in the diagram R(Si II)-(t) together with F(Si II)_max versus (B – V)_0 indicates consistency of the properties at intermediate-z compared with the nearby SNe Ia. At intermediate-z, expansion velocities of Ca II and Si II are found similar to those of the nearby sample. This is found in a sample of six SNe Ia in the range 0.033 ≤ z ≤ 0.329 discovered within the International Time Programme of SNe Ia for Cosmology and Physics in the spring run of 2002. The program run under Omega and Lambda from Supernovae and the Physics of Supernova Explosions within the International Time Programme at the telescopes of the European Northern Observatory (ENO) at La Palma (Canary Islands, Spain). Two SNe Ia at intermediate-z were of the cool FAINT type, one being an SN1986G-like object highly reddened. The R(Si II) ratio as well as subclassification of the SNe Ia beyond templates help to place SNe Ia in their sequence of brightness and to distinguish between reddened and intrinsically red supernovae. This test can be done with very high z SNe Ia and it will help to reduce systematic uncertainties due to extinction by dust. It should allow to map the high-z sample into the nearby one.

Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1088/0004-637X/695/1/135DOIUNSPECIFIED
http://www.iop.org/EJ/abstract/0004-637X/695/1/135/PublisherUNSPECIFIED
ORCID:
AuthorORCID
Ellis, R. S.0000-0001-7782-7071
Goobar, A.0000-0002-4163-4996
Additional Information:© 2009 American Astronomical Society. Print publication: Issue 1 (2009 April 10); received 2006 October 4; accepted for publication 2009; January 12; published 2009 March 27. This research was carried through the International Time Programme Omega and Lambda from Supernovae and the Physics of Supernova Explosions at the ENO Observatory and it is based on observations made with the 4.2 m William Herschel Telescope, operated on the island of La Palma by the Isaac Newton Group in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias. Thanks are given to the scientific staff of the Observatory in Padova, and specially to Stefano Benetti. This work is supported in part by the European Community’s Human Potential Programme under contract HPRN-CT-2002-00303, The Physics of Type Ia Supernovae.
Funders:
Funding AgencyGrant Number
European Community's Human Potential ProgrammeHPRN-CT-2002-00303
Subject Keywords:cosmology: observations; supernovae: general; supernovae: individual (2002li, 2002lj, 2002lk, 2002ln, 2002lo, 2002lp, 2002lq, 2002lr)
Issue or Number:1
Record Number:CaltechAUTHORS:20090709-100009622
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20090709-100009622
Official Citation:Type Ia SNe Along Redshift: The $\mathcal {R}$(Si II) Ratio and the Expansion Velocities in Intermediate-z Supernovae G. Altavilla, P. Ruiz-Lapuente, A. Balastegui, J. Méndez, M. Irwin, C. España-Bonet, R. S. Ellis, G. Folatelli, A. Goobar, W. Hillebrandt, R. M. McMahon, S. Nobili, V. Stanishev, and N. A. Walton 2009 ApJ 695 135-148 doi: 10.1088/0004-637X/695/1/135
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:14539
Collection:CaltechAUTHORS
Deposited By: Jason Perez
Deposited On:01 Sep 2009 18:17