A Survey About Nothing: Monitoring a Million Supergiants for Failed Supernovae

Abstract

Extragalactic transient searches have historically been limited to looking for the appearance of new sources such as supernovae. It is now possible to carry out a new kind of survey that will do the opposite, that is, search for the disappearance of massive stars. This will entail the systematic observation of galaxies within a distance of 10 Mpc in order to watch ∼ 10 6 supergiants. Reaching this critical number ensures that something will occur yearly, since these massive stars must end their lives with a core collapse within ∼ 10 6 years. Using deep imaging and image subtraction it is possible to determine the fates of these stars whether they end with a bang (supernova) or a whimper (fall out of sight). Such a survey would place completely new limits on the total rate of all core collapses, which is critical for determining the validity of supernova models. It would also determine the properties of supernova progenitors, better characterize poorly understood optical transients, such as η Carina-like mass ejections, find and characterize large numbers of Cepheids, luminous blue variables and eclipsing binaries, and allow the discovery of any new phenomena that inhabit this relatively unexplored parameter space.

Galactic constraints on supernova progenitor models

“…We will show that the mean masses of oxygen and iron ejected per A&A 557, A107 (2013) CC SNe event and iron per SNeIa-P appear to be significantly lower than usually assumed. A lower mean ejected mass of oxygen per CC event supports the inferences of Heger et al (2003), Kochanek et al (2008), Smartt et al (2009), Moriya et al (2011), and others, who suggest that extremely massive stars do not explode as CC SNe (and therefore do not pollute the surrounding ISM with heavy elements), in order to avoid an overproduction problem for oxygen within the Galaxy. However, if that is the case, we are faced with a conundrum, in that present observations certainly demonstrate the existence of very massive stars up to ∼100 M (e.g.…”

“…Can we state with certainty that these very massive stars will not end their lives as CC SNe? In this sense, and being counter to conventional wisdom governing CC SNe searches, a strategy for searching events associated with a massive star disappearing quietly, rather than in a spectacular explosion, appears an interesting approach (Kochanek et al 2008).…”

“…Kochanek et al 2008;Smartt et al 2009). The latest developments in the field have unfortunately not clarified the situation.…”

The next-generation liquid-scintillator neutrino observatory LENA

“…The most interesting possibility is prompt black hole formation, as this is expected to have a nonzero rate even in standard scenarios [172,173], and present constraints allow even larger rates [112,150,151,156,174]. Even though the neutrino emission can be cut off, it is expected to be enhanced before that, such that the time-integrated total and average neutrino energies can be larger than usual [92,[152][153][154].…”

On the progenitors of core-collapse supernovae

“…Quiescent collapse to a BH for massive RSG remains an intriguing possibility. As pointed out by Kochanek et al (2008), at this point the optical signatures of direct BH formation are virtually unconstrained by either theory or observation. Could this "RSG problem" (as dubbed by Smartt 2009) be the first indication of a mass cutoff between stars that successfully eject their envelopes after core collapse (i.e., those below ∼ 16.5 M ⊙ ) and stars that do not (i.e., those above ∼ 16.5 M ⊙ )?…”