A mismatch in the ultraviolet spectra between low-redshift and intermediate-redshift type Ia supernovae as a possible systematic uncertainty for supernova cosmology

Ryan J. Foley, Alexei V. Filippenko, Richard Kessler, Bruce Bassett, Joshua A. Frieman, Peter M. Garnavich, Saurabh Jha, Kohki Konishi, Hubert Lampeitl, Adam G. Riess, Masao Sako, Donald P. Schneider, Jesper Sollerman, Mathew Smith

Research output: Contribution to journalArticle

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Abstract

We present Keck high-quality rest-frame ultraviolet (UV) through optical spectra of 21 Type Ia supernovae (SNeIa) in the redshift range 0.11 ≤ z ≤ 0.37 and a mean redshift of 0.22 that were discovered during the Sloan Digital Sky Survey-II (SDSS-II) SN Survey. Using the broadband photometry of the SDSS survey, we are able to reconstruct the SN host-galaxy spectral energy distributions (SEDs), allowing for a correction for the host-galaxy contamination in the SN Ia spectra. Comparison of composite spectra constructed from a subsample of 17 high-quality spectra to those created from a low-redshift sample with otherwise similar properties shows that the Keck/SDSS SNeIa have, on average, extremely similar rest-frame optical spectra but show a UV flux excess. This observation is confirmed by comparing synthesized broadband colors of the individual spectra, showing a difference in mean colors at the 2.4σ-4.4σ level for various UV colors. We further see a slight difference in the UV spectral shape between SNe with low-mass and high-mass host galaxies. Additionally, we detect a relationship between the flux ratio at 2770 and 2900 Å and peak luminosity that differs from that observed at low redshift. We find that changing the UV SED of an SN Ia within the observed dispersion can change the inferred distance moduli by 0.1mag. This effect only occurs when the data probe the rest-frame UV. We suggest that this discrepancy could be due to differences in the host-galaxy population of the two SN samples or to small-sample statistics.

Original languageEnglish (US)
Article number113
JournalAstronomical Journal
Volume143
Issue number5
DOIs
StatePublished - May 1 2012

Fingerprint

ultraviolet spectra
cosmology
supernovae
galaxies
spectral energy distribution
color
optical spectrum
broadband
photometry
contamination
luminosity
statistics
composite materials
energy
probes
probe

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Keywords

  • cosmology: observations
  • distance scale
  • supernovae: general

Cite this

Foley, Ryan J. ; Filippenko, Alexei V. ; Kessler, Richard ; Bassett, Bruce ; Frieman, Joshua A. ; Garnavich, Peter M. ; Jha, Saurabh ; Konishi, Kohki ; Lampeitl, Hubert ; Riess, Adam G. ; Sako, Masao ; Schneider, Donald P. ; Sollerman, Jesper ; Smith, Mathew. / A mismatch in the ultraviolet spectra between low-redshift and intermediate-redshift type Ia supernovae as a possible systematic uncertainty for supernova cosmology. In: Astronomical Journal. 2012 ; Vol. 143, No. 5.
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abstract = "We present Keck high-quality rest-frame ultraviolet (UV) through optical spectra of 21 Type Ia supernovae (SNeIa) in the redshift range 0.11 ≤ z ≤ 0.37 and a mean redshift of 0.22 that were discovered during the Sloan Digital Sky Survey-II (SDSS-II) SN Survey. Using the broadband photometry of the SDSS survey, we are able to reconstruct the SN host-galaxy spectral energy distributions (SEDs), allowing for a correction for the host-galaxy contamination in the SN Ia spectra. Comparison of composite spectra constructed from a subsample of 17 high-quality spectra to those created from a low-redshift sample with otherwise similar properties shows that the Keck/SDSS SNeIa have, on average, extremely similar rest-frame optical spectra but show a UV flux excess. This observation is confirmed by comparing synthesized broadband colors of the individual spectra, showing a difference in mean colors at the 2.4σ-4.4σ level for various UV colors. We further see a slight difference in the UV spectral shape between SNe with low-mass and high-mass host galaxies. Additionally, we detect a relationship between the flux ratio at 2770 and 2900 {\AA} and peak luminosity that differs from that observed at low redshift. We find that changing the UV SED of an SN Ia within the observed dispersion can change the inferred distance moduli by 0.1mag. This effect only occurs when the data probe the rest-frame UV. We suggest that this discrepancy could be due to differences in the host-galaxy population of the two SN samples or to small-sample statistics.",
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Foley, RJ, Filippenko, AV, Kessler, R, Bassett, B, Frieman, JA, Garnavich, PM, Jha, S, Konishi, K, Lampeitl, H, Riess, AG, Sako, M, Schneider, DP, Sollerman, J & Smith, M 2012, 'A mismatch in the ultraviolet spectra between low-redshift and intermediate-redshift type Ia supernovae as a possible systematic uncertainty for supernova cosmology', Astronomical Journal, vol. 143, no. 5, 113. https://doi.org/10.1088/0004-6256/143/5/113

A mismatch in the ultraviolet spectra between low-redshift and intermediate-redshift type Ia supernovae as a possible systematic uncertainty for supernova cosmology. / Foley, Ryan J.; Filippenko, Alexei V.; Kessler, Richard; Bassett, Bruce; Frieman, Joshua A.; Garnavich, Peter M.; Jha, Saurabh; Konishi, Kohki; Lampeitl, Hubert; Riess, Adam G.; Sako, Masao; Schneider, Donald P.; Sollerman, Jesper; Smith, Mathew.

In: Astronomical Journal, Vol. 143, No. 5, 113, 01.05.2012.

Research output: Contribution to journalArticle

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T1 - A mismatch in the ultraviolet spectra between low-redshift and intermediate-redshift type Ia supernovae as a possible systematic uncertainty for supernova cosmology

AU - Foley, Ryan J.

AU - Filippenko, Alexei V.

AU - Kessler, Richard

AU - Bassett, Bruce

AU - Frieman, Joshua A.

AU - Garnavich, Peter M.

AU - Jha, Saurabh

AU - Konishi, Kohki

AU - Lampeitl, Hubert

AU - Riess, Adam G.

AU - Sako, Masao

AU - Schneider, Donald P.

AU - Sollerman, Jesper

AU - Smith, Mathew

PY - 2012/5/1

Y1 - 2012/5/1

N2 - We present Keck high-quality rest-frame ultraviolet (UV) through optical spectra of 21 Type Ia supernovae (SNeIa) in the redshift range 0.11 ≤ z ≤ 0.37 and a mean redshift of 0.22 that were discovered during the Sloan Digital Sky Survey-II (SDSS-II) SN Survey. Using the broadband photometry of the SDSS survey, we are able to reconstruct the SN host-galaxy spectral energy distributions (SEDs), allowing for a correction for the host-galaxy contamination in the SN Ia spectra. Comparison of composite spectra constructed from a subsample of 17 high-quality spectra to those created from a low-redshift sample with otherwise similar properties shows that the Keck/SDSS SNeIa have, on average, extremely similar rest-frame optical spectra but show a UV flux excess. This observation is confirmed by comparing synthesized broadband colors of the individual spectra, showing a difference in mean colors at the 2.4σ-4.4σ level for various UV colors. We further see a slight difference in the UV spectral shape between SNe with low-mass and high-mass host galaxies. Additionally, we detect a relationship between the flux ratio at 2770 and 2900 Å and peak luminosity that differs from that observed at low redshift. We find that changing the UV SED of an SN Ia within the observed dispersion can change the inferred distance moduli by 0.1mag. This effect only occurs when the data probe the rest-frame UV. We suggest that this discrepancy could be due to differences in the host-galaxy population of the two SN samples or to small-sample statistics.

AB - We present Keck high-quality rest-frame ultraviolet (UV) through optical spectra of 21 Type Ia supernovae (SNeIa) in the redshift range 0.11 ≤ z ≤ 0.37 and a mean redshift of 0.22 that were discovered during the Sloan Digital Sky Survey-II (SDSS-II) SN Survey. Using the broadband photometry of the SDSS survey, we are able to reconstruct the SN host-galaxy spectral energy distributions (SEDs), allowing for a correction for the host-galaxy contamination in the SN Ia spectra. Comparison of composite spectra constructed from a subsample of 17 high-quality spectra to those created from a low-redshift sample with otherwise similar properties shows that the Keck/SDSS SNeIa have, on average, extremely similar rest-frame optical spectra but show a UV flux excess. This observation is confirmed by comparing synthesized broadband colors of the individual spectra, showing a difference in mean colors at the 2.4σ-4.4σ level for various UV colors. We further see a slight difference in the UV spectral shape between SNe with low-mass and high-mass host galaxies. Additionally, we detect a relationship between the flux ratio at 2770 and 2900 Å and peak luminosity that differs from that observed at low redshift. We find that changing the UV SED of an SN Ia within the observed dispersion can change the inferred distance moduli by 0.1mag. This effect only occurs when the data probe the rest-frame UV. We suggest that this discrepancy could be due to differences in the host-galaxy population of the two SN samples or to small-sample statistics.

KW - cosmology: observations

KW - distance scale

KW - supernovae: general

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