The He-rich core-collapse supernova 2007Y: Observations from X-ray to Radio Wavelengths

TL;DR

This study presents comprehensive multi-wavelength observations and modeling of supernova 2007Y, revealing its low explosion energy, progenitor characteristics, and ejecta composition, contributing valuable data on Type Ib supernovae.

Contribution

It provides the first detailed multi-wavelength dataset and modeling analysis of supernova 2007Y, highlighting its low energy and specific progenitor properties.

Findings

Nickel-56 mass of 0.06 M_sun confirmed by light curve modeling.

Explosion energy estimated at ~10^50 erg, among the lowest for Type Ib supernovae.

Progenitor likely a 3.3 M_sun He core star from a 10-13 M_sun ZAMS star.

Abstract

A detailed study spanning approximately a year has been conducted on the Type Ib supernova 2007Y. Imaging was obtained from X-ray to radio wavelengths, and a comprehensive set of multi-band (w2m2w1u'g'r'i'UBVYJHKs) light curves and optical spectroscopy is presented. A virtually complete bolometric light curve is derived, from which we infer a (56)Ni-mass of 0.06 M_sun. The early spectrum strongly resembles SN 2005bf and exhibits high-velocity features of CaII and H_alpha; during late epochs the spectrum shows evidence of a ejecta-wind interaction. Nebular emission lines have similar widths and exhibit profiles that indicate a lack of major asymmetry in the ejecta. Late phase spectra are modeled with a non-LTE code, from which we find (56)Ni, O and total-ejecta masses (excluding He) to be 0.06, 0.2 and 0.42 M_sun, respectively, below 4,500 km/s. The (56)Ni mass confirms results obtained from the bolometric light curve. The oxygen abundance suggests the progenitor was most likely a ~3.3 M_sun He core star that evolved from a zero-age-main-sequence mass of 10-13 M_sun. The explosion energy is determined to be ~10^50 erg, and the mass-loss rate of the progenitor is constrained from X-ray and radio observations to be <~10^-6 M_sun/yr. SN 2007Y is among the least energetic normal Type Ib supernovae ever studied.