Search arXiv⌕ Search
Home/Archive/arXiv

arXiv · 2609.38299

Not So Heavy Metal I: Low Metallicity Enhances the Rate of high-redshift Superluminous Supernovae

Ben Margalit·Allison L. Strom·Cristina Andrade·Michael W. Coughlin·Adam A. Miller·Steve Schulze·Ved G. Shah
View original source ↗Read source document ↗Export metadata ↓

Abstract

Type-I superluminous supernovae (SLSNe) are extremely luminous stellar explosions originating from the core collapse of massive stars. Unlike normal core-collapse supernovae, however, SLSNe occur almost exclusively in metal-poor environments. As a result, their volumetric rate should not simply trace the cosmic star-formation history, but instead evolve with the metallicity distribution of galaxies across cosmic time. In this work, we introduce a new theoretical framework for modeling the volumetric rate of astrophysical sources as a function of redshift and metallicity. Our formalism combines metallicity scaling relations, stellar-mass distribution functions, and metallicity-dependent production efficiencies. Importantly, it also distinguishes between metallicity measures based on O/H and Fe/H abundances. Applying our new formalism to SLSNe, we predict volumetric rates that are nearly an order of magnitude higher at $z \gtrsim 2$ compared to models in which the rate traces the cosmic star-formation rate alone. This has direct implications on the detection prospects of high-$z$ SLSNe with the Vera C. Rubin Observatory and other time-domain surveys.

Explore related subjects

astro-ph.HEastro-ph.GA

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Ben Margalit, Allison L. Strom, Cristina Andrade, Michael W. Coughlin, Adam A. Miller, Steve Schulze, Ved G. Shah. 2026-09-29. Not So Heavy Metal I: Low Metallicity Enhances the Rate of high-redshift Superluminous Supernovae. https://arxiv.org/abs/2609.38299

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

arXiv2026

Dark matter in neutron stars: two-fluid $f$-mode oscillations in full general relativity

A dark-matter core and a soft nuclear equation of state can produce similar mass--radius signatures, motivating a complementary probe through the $f$-mode spectrum. We compute quadrupolar $f$-mode frequencies and gravitational-wave damping times in full general relativity for cold, nonrotating neutron stars admixed with self-interacting bosonic dark matter (DM). Our two-fluid survey spans 21 nuclear equations of state covering nucleonic, hyperonic, $Δ$-admixed, and combined hyperon--$Δ$ compositions at $F_{\rm DM}=1$--$20\%$. The main sequences use $λ=π$ and boson masses of $500$ and $100\,\mathrm{MeV}$ for the core and halo studies, respectively. Independent normal-matter (NM) and DM displacements couple through the metric, yielding NM-led and DM-led $f$-mode branches whose radiative damping is determined by outgoing-wave boundary conditions. At $1.4\,M_\odot$, the core DM-led damping time decreases from order $10^3\,\mathrm{s}$ at $F_{\rm DM}=1\%$ to order $1\,\mathrm{s}$ at $20\%$, approximately following an empirical $F_{\rm DM}^{-2}$ dependence, while NM-led damping times remain within $0.12$--$0.33\,\mathrm{s}$. Halo DM-led damping instead increases with dark fraction: at the same stellar mass and $F_{\rm DM}=20\%$, dark radii approach $88\,\mathrm{km}$, frequencies fall to $0.14\,\mathrm{kHz}$, and damping times reach approximately $450\,\mathrm{s}$. Selected high-mass core sequences exhibit strong DM-led damping-time upturns not reproduced by the leading mass-quadrupole diagnostic. Representative core calculations show greater DM-led sensitivity to the bosonic self-coupling and retain both branches at $\ell=3$. Under the adopted nonrotating, circular-binary prescriptions, no evaluated configuration satisfies all geometric and perturbative conditions for a controlled linear tidal resonance.

astro-ph.HE↗
arXiv2026

The fading superorbital clock of Hercules X-1 in its 2025--2026 extended low state

We present two decades of X-ray monitoring of the eclipsing accreting pulsar Hercules X-1 with \textit{Fermi}/GBM, \textit{Swift}/BAT and \textit{MAXI}/GSC, centred on the extended low state (ELS) that began in 2025 May (the first such event in 22 years) and is still ongoing at the time of writing, $\sim$480~d after its onset. The 35-d superorbital clock does not simply stop in the ELS; it fades. The surviving modulation stays phase-locked to the pre-ELS clock until the flux of the main high state (the bright phase of the 35-d cycle) has decayed to a few per cent of its normal level. The in-phase coherence is then lost, around 2026 January--March. We classify the pre-ELS pulse-frequency history into three torque states: spin-up, spin-down and flat. The spin derivative correlates positively with the main-high hard X-ray flux (Pearson $r\simeq0.7$), and the ELS hosts the longest sustained spin-down of the record, $\dotν\approx-4.7\times10^{-13}$~Hz~s$^{-1}$ over the $\gtrsim$380~d of \fer/GBM coverage. The 8--50 keV pulse-profile morphology is statistically indistinguishable across the torque states at fixed superorbital phase, and the shape parameters show no secular drift over the 18-yr record. These results show that the precessing warped accretion disc keeps its rhythm while the pulsar fades from direct view: the clock keeps its phase, the torque keeps tracking the accretion flux, and the beam keeps its shape. No free precession of the neutron star is required by the current monitoring data.

astro-ph.HE↗
arXiv2026

Fast X-ray Transient EP260321a: Shock Breakout through an Extended Circumstellar Matter

The Einstein Probe (EP) has discovered a fast X-ray transient, EP260321a, whose optical counterpart was subsequently classified as a broad-lined Type Ic supernova. Its observed rise time of about 690 seconds is inconsistent with theoretical predictions for shock breakout (SBO) from a Wolf-Rayet star, which is typically regarded as the progenitor of envelope-stripped supernovae. In this paper, we propose that EP260321a arose from a SBO within extended circumstellar matter (CSM), where breakout photons were initially trapped, then diffused out of the unshocked CSM as the ejecta expanded and the opacity decreased. We modeled this photon diffusion process using both Monte Carlo simulations and an analytical approach to describe the temperature evolution. Through Markov Chain Monte Carlo sampling, we obtain the best-fit CSM parameters of log10(Mcsm/Msun) = -3.3 for the total CSM mass, Rin = 160 Rsun for the inner CSM radius, and Rout = 612 Rsun for the outer CSM radius. The presence of such a dense CSM indicates that the progenitor of EP260321a underwent episodic mass loss just days before the explosion, providing new observational constraints on the late-stage evolution of massive stars.

astro-ph.HE↗