Wang, Xiaofeng and Van Dyk, Schuyler D. (2012) Evidence for Type Ia Supernova Diversity from Ultraviolet Observations with the Hubble Space Telescope. Astrophysical Journal, 749 (2). p. 126. ISSN 0004-637X http://resolver.caltech.edu/CaltechAUTHORS:20120516-091904189
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We present ultraviolet (UV) spectroscopy and photometry of four Type Ia supernovae (SNe 2004dt, 2004ef, 2005M, and 2005cf) obtained with the UV prism of the Advanced Camera for Surveys on the Hubble Space Telescope. This data set provides unique spectral time series down to 2000 Å. Significant diversity is seen in the near-maximum-light spectra (~2000-3500 Å) for this small sample. The corresponding photometric data, together with archival data from Swift Ultraviolet/Optical Telescope observations, provide further evidence of increased dispersion in the UV emission with respect to the optical. The peak luminosities measured in the uvw1/F250W filter are found to correlate with the B-band light-curve shape parameter Δm 15(B), but with much larger scatter relative to the correlation in the broadband B band (e.g., ~0.4 mag versus ~0.2 mag for those with 0.8 mag < Δm_15(B) < 1.7 mag). SN 2004dt is found as an outlier of this correlation (at > 3σ), being brighter than normal SNe Ia such as SN 2005cf by ~0.9 mag and ~2.0 mag in the uvw1/F250W and uvm2/F220W filters, respectively. We show that different progenitor metallicity or line-expansion velocities alone cannot explain such a large discrepancy. Viewing-angle effects, such as due to an asymmetric explosion, may have a significant influence on the flux emitted in the UV region. Detailed modeling is needed to disentangle and quantify the above effects.
|Additional Information:||© 2012 American Astronomical Society. Received 2011 October 26; accepted 2012 February 6; published 2012 March 30. We thank Mark Sullivan and Andy Howell for their suggestions. Financial support for this work has been provided by the National Science Foundation of China (NSFC grants 11178003, 11073013, and 10173003) and the National Key Basic Research Science Foundation (NKBRSF TG199075402). A.V.F.’s group at U.C. Berkeley is grateful for the support of NSF grants AST-0607485 and AST-0908886, the TABASGO Foundation, and US Department of Energy grants DE-FC02-06ER41453 (SciDAC) and DE-FG02-08ER41563. Substantial financial support for this work was also provided by NASA through grants GO-10182, AR-12126, and AR-12623 from the Space Telescope Science Institute, which is operated by Associated Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. The work of L.W. is supported by NSF grant AST-0708873. J.C.W. is supported by NSF grant AST-0707769. K.N. is supported by WPI Initiative, MEXT, Japan. M.T., S.B., and E.C. are supported by grant ASI-INAF I/009/10/0. P.A.M. is supported by NASA ADP NNX06AH85G. The work of M.H. is supported by ICM grant P10-064-F and CONICYT grants 150100003 and PFB-06, Chile.|
|Subject Keywords:||cosmology: observations; distance scale; dust, extinction; supernovae: general; ultraviolet: general|
|Official Citation:||Evidence for Type Ia Supernova Diversity from Ultraviolet Observations with the Hubble Space Telescope Xiaofeng Wang et al. 2012 ApJ 749 126|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Jason Perez|
|Deposited On:||17 May 2012 18:01|
|Last Modified:||26 Dec 2012 15:13|
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