Shock Breakout in Type Ii Plateau Supernovae: Prospects for High-Redshift Supernova Surveys

Abstract

Shock breakout is the brightest radiative phenomenon in a supernova (SN) but is difficult to be observed owing to the short duration and X-ray/ultraviolet (UV)-peaked spectra. After the first observation from the rising phase reported in 2008, its observability at high redshift is attracting enormous attention. We perform multigroup radiation hydrodynamics calculations of explosions for evolutionary presupernova models with various main-sequence masses M MS , metallicities Z, and explosion energies E. We present multicolor light curves of shock breakout in Type II plateau SNe, being the most frequent core-collapse SNe, and predict apparent multicolor light curves of shock breakout at various redshifts z. We derive the observable SN rate and reachable redshift as functions of filter x and limiting magnitude m x,lim by taking into account an initial mass function, cosmic star formation history, intergalactic absorption, and host galaxy extinction. We propose a realistic survey strategy optimized for shock breakout. For example, the g ′ -band observable SN rate for m g ′ ,lim = 27.5 mag is 3.3 SNe degree −2 day −1 and a half of them locates at z ≥ 1.2. It is clear that the shock breakout is a beneficial clue to probe high-z core-collapse SNe. We also establish ways to identify shock breakout and constrain SN properties from the observations of shock breakout, brightness, time scale, and color. We emphasize that the multicolor observations in blue optical bands with ∼ hour intervals, preferably over ≥ 2 continuous nights, are essential to efficiently detect, identify, and interpret shock breakout.

Finding the First Cosmic Explosions. Ii. Core-Collapse Supernovae

“…Our simulations assume that the ions and electrons are strongly coupled, leading to only mild deviations between the matter and radiation temperatures. As such, we do not expect, and our simulations do not produce, a strong spike in the matter temperature at the front of the shock, in agreement with many recent results (Tominaga et al 2011;Moriya et al 2013;Tolstov et al 2013). Since Ensman & Burrows (1992) also assume electron/ion coupling, one would not expect a spike in temperature in their simulations either.…”

“…We show the evolution of the z40G and u40G spectra in Figure 6 (compare to Figure 2 in Tominaga et al 2011). Unlike with much more energetic Pop III PI SNe, the outer regions of the ejecta and the envelope are never fully ionized so bound-bound and bound-free transitions absorb most of the flux at the short wavelength limit of the spectrum.…”

Low-energy Population III supernovae and the origin of extremely metal-poor stars

“…But these rough estimates suggest that the plateau phase for Z12 and Z60 would not be visible at z 5. The shock breakout transient is much brighter but is primarily composed of X-rays and hard UV that would mostly be absorbed by the neutral IGM at z 6 (Tominaga et al 2011). …”

The discovery and classification of 16 supernovae at high redshifts in ELAIS-S1

“…Future pencil beam surveys targeting high-redshift SNe should thus be aimed at regions with good spectral and multiwavelength coverage. We found the cadence of the search to be more or less optimal, given the constraint on total observational time, but with more frequent observations it should be possible to detect the UV breakout phase of core collapse SNe as well (e.g., Tominaga et al 2011). Observations in more than one filter is mandatory to be able to do photometric typing, but we also found it to be quite important for rejecting spurious objects in the detection step.…”