ARE SUPERLUMINOUS SUPERNOVAE AND LONG GRBs THE PRODUCTS OF DYNAMICAL PROCESSES IN YOUNG DENSE STAR CLUSTERS?

Abstract

Super Luminous supernovae (SLSN) occur almost exclusively in small galaxies (SMC/LMC-like or smaller), and the few SLSN observed in larger star-forming galaxies always occur close to the nuclei of their hosts. Another type of peculiar and highly energetic supernovae are the broad-line type Ic SNe (SN Ic-BL) that are associated with long-duration gamma-ray bursts (LGRBs). Also these have a strong preference for occurring in small (SMC/LMC-like or smaller) star-forming galaxies, and in these galaxies LGRBs always occur in the brightest spots. Studies of nearby star-forming galaxies that are similar to the hosts of LGRBs show that these brightest spots are giant HII regions produced by massive dense young star clusters with many hundreds of O-and Wolf-Rayet-type stars. Such dense young clusters are also found in abundance within a few hundred parsecs from the nucleus of larger galaxies like our own. We argue that the SLSN and the SN Ic-BL/LGRBs are exclusive products of two types of dynamical interactions in dense young star clusters. In our model the high angular momentum of the collapsing stellar cores required for the engines of a SN Ic-BL results from the post-main sequence mergers of dynamically produced cluster binaries with almost equal-mass components. The merger produces a critically rotating single helium star with sufficent angular momentum to produce a LGRB; the observed "metal aversion" of LGRBs is a natural consequence of the model. We argue that, on the other hand, SLSN could be the products of runaway multiple collisions in dense clusters, and we present (and quantize) plausible scenarios of how the different types of SLSNs can be produced.

A Superluminous Supernova in High Surface Density Molecular Gas within the Bar of a Metal-rich Galaxy

“…This picture is consistent with the occurrence of SLSNe in the central regions of metal-rich galaxies as gas flows, driven by galaxy interactions or bars, can create dense concentrations of molecular gas in the central regions of galaxies (Sheth et al 2005;Gallagher et al 2018). It is also compatible with progenitor models in which massive stars in dense and young star cluster merge into a star with sufficient mass for forming a SLSN (Portegies Zwart & van den Heuvel 2007;Pan et al 2012;van den Heuvel & Portegies Zwart 2013). SLSN PTF10tpz (type II SLSN) at z = 0.03994 is one of the SLSNe which occurred close to the nucleus of a massive and metal-rich galaxy.…”

“…All these, together with the high molecular gas surface densities and short depletion time we report, suggest that massive clusters have formed near the intersection regions of the gas lanes and the inner structure that we have identified in the host galaxy of SLSN PTF10tpz. Such clusters are the birth-place of massive stars, potential progenitors of SLSNe, either directly and/or through a runaway process in their core (Portegies Zwart & van den Heuvel 2007;Pan et al 2012;van den Heuvel & Portegies Zwart 2013). These clusters would then continue their motion along the ring (clockwise in Fig.…”

Massive stars formed in atomic hydrogen reservoirs: H I observations of gamma-ray burst host galaxies

“…Due to a similar shape of all standard extinction and attenuation curves between 0.275 μm and V-band, our A V estimate would only be ∼10% higher if we used the LMC or the Milky Way extinction curves (Gordon et al 2003), and ∼20% higher with the Calzetti et al (2000) attenuation curve. Up to date 89 long-GRB hosts have been targeted in the radio continuum (Berger et al 2001Vreeswijk et al 2001;Fox et al 2003;Frail et al 2003;van der Horst et al 2005;Wiersema et al 2008;Michałowski et al 2009Michałowski et al , 2012bStanway et al 2010Stanway et al , 2014Watson et al 2011;Perley et al 2015b), and only 15 (∼17%) were detected: the hosts of GRB 980425 (Michałowski et al 2009), 980703 (Berger et al 2001), 000418, 010222, , 021211 (Michałowski et al 2012b), 031203 (Stanway et al 2010;Watson et al 2011;Michałowski et al 2012b), 051022, 080207, and 090404 ; 051006, 060814, 061121, 070306, (Perley et al 2015b), 080517 (Stanway et al 2015a), 100621A (Stanway et al 2014); with the addition of the hosts of short (duration <2 s) GRBs 071227 (Nicuesa Guelbenzu et al 2014), and 120804A (Berger et al 2013). The map for the GRB 111005A host is not shown, as we use archival data with poor spatial resolution (Sect.…”

“…Second, this high-metallicity problem is alleviated by some models, which predict the GRB preference for low metallicity, A78, page 10 of 14 but do not exclude metal-rich examples, for example the model in which a GRB progenitor is a rapidly rotating Helium star created by a merger of post-main sequence stars (van den Heuvel & Portegies Zwart 2013). In both collapsar and binary scenarios the low metallicity preference (even if it is not strict) is consistent with our interpretation that GRB hosts have recently started a star formation episode.…”

Host Galaxies of Type Ic and Broad-lined Type Ic Supernovae from the Palomar Transient Factory: Implications for Jet Production

“…Wang & Dai (2011) show that variations in the stellar initial mass function (IMF), such as those proposed by Davé (2008) could lead to higher rates of closebinary systems or more massive stars in galaxies, both of which are associated with the occurrence of GRBs. If GRBs were products of dynamical processes in young dense star clusters as suggested by van den Heuvel & Portegies Zwart (2013), GRBs would clearly prefer host galaxies with the highest star formation rates (SFR). Although multiple studies have shown that GRBs prefer low metallicity environments, it is still somewhat debated whether low metallicity causes GRB progenitors to form, or whether it is a side-effect of high sSFR, since there is a galaxy relationship in which high sSFR galaxies are also metal-poor (e.g.…”