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See Change: VLT spectroscopy of a sample of high-redshift Type Ia supernova host galaxies. (arXiv:2005.07112v1 [astro-ph.GA])

[Submitted on 14 May 2020]

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Abstract: The Supernova Cosmology Project has conducted the `See Change’ programme,
aimed at discovering and observing high-redshift (1.13 $leq$ z $leq$ 1.75)
Type Ia supernovae (SNe Ia). We used multi-filter Hubble Space Telescope (HST)
observations of massive galaxy clusters with sufficient cadence to make the
observed SN Ia light curves suitable for a cosmological probe of dark energy at
z > 0.5. As part of the See Change programme, we obtained ground-based
spectroscopy of each discovered transient and/or its host galaxy. Here we
present Very Large Telescope (VLT) spectra of See Change transient host
galaxies, deriving their redshifts, and host parameters such as stellar mass
and star formation rate. Of the 39 See Change transients/hosts that were
observed with the VLT, we successfully determined the redshift for 26,
including 15 SNe Ia at z > 0.97. This new sample of SNe Ia with multi-colour
light curves is the largest to date at these redshifts. We show that even in
passive environments, it is possible to recover secure redshifts for the
majority of SN hosts out to z = 1.5. We find that with typical exposure times
of 3 – 4 hrs on an 8m-class telescope we can recover ~75% of SN Ia redshifts in
the range of 0.97 < z < 1.5. Furthermore, we show that the combination of HST photometry and VLT spectroscopy is able to provide estimates of host galaxy stellar mass that are sufficiently accurate for use in a mass-step correction in the cosmological analysis.

Submission history

From: Steven Williams [view email]

[v1]
Thu, 14 May 2020 16:28:01 UTC (4,305 KB)

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