Explosions in the Empty: A Survey of Transients in Local Void Galaxies

TL;DR

The paper investigates how cosmic voids influence transient production in the nearby universe by matching SNe, GRBs, and FRBs to void and non-void host galaxies within a defined local volume. It finds a robust CCSN excess and Ia suppression in void hosts, consistent with younger, lower-metallicity, higher-sSFR populations in underdense regions. A short GRB is observed in a void host while no FRBs are identified in voids, highlighting environmental dependence but limited statistics for some classes. These results imply that large-scale structure shapes stellar population evolution and explosive endpoints, with significant implications for understanding star formation, chemical enrichment, and the demographics of transient channels in low-density environments.

Abstract

We present a systematic analysis of transient astrophysical events -- including supernovae (SNe), gamma-ray bursts (GRBs), and fast radio bursts (FRBs) -- in void and non-void galaxies within the local universe ($0.005 < z < 0.05$). Cosmic voids, defined by low galaxy densities and characterized by minimal environmental interactions, offer a natural laboratory for isolating the impact of large-scale underdensities on stellar evolution and transient production. Using multi-wavelength data from the Sloan Digital Sky Survey, the Sternberg Astronomical Institute Supernova Catalogue, and high-energy space observatories, we compare transient occurrence rates and host galaxy properties across environments. We find that core-collapse supernovae (CCSNe) are significantly more common in void galaxies, indicating that massive star formation remains active in underdense regions. In contrast, Type Ia supernovae are less frequent in voids, consistent with a scarcity of older stellar populations. Notably, we identify a short-duration GRB hosted by a void galaxy, demonstrating that compact object mergers can occur in isolated environments. Additionally, we find no FRBs associated with void galaxies. Taken together, these results show that cosmic voids exert a measurable influence on the star formation history of galaxies and hence on the production of transients.

Figures (4)

• Figure 1: Projected comoving maps for the declination slice within our VoidFinder volume: $40^\circ$–$41^\circ$ which is chosen to include the only one GRB event in our sample. Black points denote non-void galaxies; red points denote void galaxies; blue stars mark SNe in voids; cyan plus signs mark SNe in non-void regions. Yellow stars indicate GRBs: GRB 080121. Axes $(X,Y)$ are projected comoving coordinates in the plane of each slice (see §\ref{['section 2']}); the numerical scale is set by the redshift distribution within each declination bin.
• Figure 2: Projected comoving maps in three declination slices showing the distributions of void/non-void galaxies and transients. Panels (top to bottom) correspond to ${\rm DEC}=13.5^\circ$–$14.5^\circ$, $21^\circ$–$22^\circ$, and $27^\circ$–$28^\circ$ which are chosen to include the three FRB events in our sample. Symbols: black points—non-void galaxies; red points—void galaxies; blue stars—SNe in voids; cyan plus signs—SNe in non-void regions; yellow stars—FRBs located outside voids (FRB 20240201A, FRB 20190425A, and FRB 20181223C). Axes $(X,Y)$ are projected comoving coordinates in the plane of each slice (see §\ref{['section 2']}). No FRBs are identified within voids in our volume.
• Figure 3: Fractions of supernova subtypes inside and outside cosmic voids. Yellow hatched bars mark SNe in voids; blue bars mark SNe in non-void regions. Categories are Type Ia, core–collapse (labeled “Collapse”; Types II/Ib/Ic), and Unclassified. Values are the percentage of all SNe in each environment (void: Ia 33.49%, CCSNe 57.21%, Unclassified 9.30%; non-void: Ia 47.08%, CCSNe 40.06%, Unclassified 12.86%), computed from Table \ref{['tab:number']}.
• Figure 4: Distribution of morphological types for supernova (SN) host galaxies located inside (orange) and outside (blue) cosmic voids. The x-axis follows the standard galaxy classification sequence: elliptical (E), lenticular (S0), spiral (Sa–Sd), barred spiral (SBa–SBm), irregular (I), and undefined. Spiral subclasses (a–m) indicate the degree of spiral arm winding, from tightly wound ('a') to loosely wound or irregular ('m'). Void SN hosts are skewed toward late-type spirals (e.g., Sc, Scd), while non-void SN hosts show a broader morphological mix, including more early-type systems.