Evidence for Type Ia Supernova Diversity from Ultraviolet Observations with the Hubble Space Telescope
Creators: name: Wang, Xiaofeng
name: Wang, Lifan
name: Filippenko, Alexei V.
name: Baron, Eddie
name: Kromer, Markus
name: Jack, Dennis
name: Zhang, Tianmeng
name: Aldering, Greg
name: Antilogus, Pierre
name: Arnett, David
name: Baade, Dietrich
name: Barris, Brian J.
name: Benetti, Stefano
name: Bouchet, Patrice
name: Burrows, Adam S.
name: Canal, Ramon
name: Cappellaro, Enrico
name: Carlberg, Raymond
name: di Carlo, Elisa
name: Challis, Peter
name: Crotts, Arlin
name: Danziger, John I.
name: Della Valle, Massimo
name: Fink, Michael
name: Foley, Ryan J.
name: Fransson, Claes
name: Gal-Yam, Avishay
name: Garnavich, Peter
name: Gerardy, Chris L.
name: Goldhaber, Gerson
name: Hamuy, Mario
name: Hillebrandt, Wolfgang
name: Hoeflich, Peter A.
name: Holland, Stephen T.
name: Holz, Daniel E.
name: Hughes, John P.
name: Jeffery, David J.
name: Jha, Saurabh W.
name: Kasen, Dan
name: Khokhlov, Alexei M.
name: Kirshner, Robert P.
name: Knop, Robert
name: Kozma, Cecilia
name: Krisciunas, Kevin
name: Lee, Brian C.
name: Leibundgut, Bruno
name: Lentz, Eric J.
name: Leonard, Douglas C.
name: Lewin, Walter H. G.
name: Li, Weidong
name: Livio, Mario
name: Lundqvist, Peter
name: Maoz, Dan
name: Matheson, Thomas
name: Mazzali, Paolo
name: Meikle, Peter
name: Miknaitis, Gajus
name: Milne, Peter
name: Mochnacki, Stefan
name: Nomoto, Ken'Ichi
name: Nugent, Peter E.
name: Oran, Elaine
name: Panagia, Nino
name: Perlmutter, Saul
name: Phillips, Mark M.
name: Pinto, Philip
name: Poznanski, Dovi
name: Pritchet, Christopher J.
name: Reinecke, Martin
name: Riess, Adam
name: Ruiz-Lapuente, Pilar
name: Scalzo, Richard
name: Schlegel, Eric M.
name: Schmidt, Brian
name: Siegrist, James
name: Soderberg, Alicia M.
name: Sollerman, Jesper
name: Sonneborn, George
name: Spadafora, Anthony
name: Spyromilio, Jason
name: Sramek, Richard A.
name: Starrfield, Sumner G.
name: Strolger, Louis G.
name: Suntzeff, Nicholas B.
name: Thomas, Rollin
name: Tonry, John L.
name: Tornambe, Amedeo
name: Truran, James W.
name: Turatto, Massimo
name: Turner, Michael
name: Van Dyk, Schuyler D.
name: Weiler, Kurt
name: Wheeler, J. Craig
name: Wood-Vasey, Michael
name: Woosley, Stan
name: Yamaoka, Hitoshi
Publisher: name: arXiv
Year: 2011
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences
subject: FOS: Physical sciences

description: 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 dataset provides unique spectral time series down to 2000 Angstrom. Significant diversity is seen in the near maximum-light spectra (~ 2000--3500 Angstrom) 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 uvw1/F250W are found to correlate with the B-band light-curve shape parameter dm15(B), but with much larger scatter relative to the correlation in the broad-band B band (e.g., ~0.4 mag versus ~0.2 mag for those with 0.8 &lt; dm15 &lt; 1.7 mag). SN 2004dt is found as an outlier of this correlation (at &gt; 3 sigma), 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.
description: 17 pages, 13 figures, accepted by ApJ