supernovae

First author: Radosław Wojtak The currently used standardisation of type Ia supernovae results in Hubble residuals whose physical origin is unaccounted for. This poses a limitation to the accuracy and precision of distances that can be derived from supernova observations. Here, we present a complete physical interpretation of the Hubble residuals based on a novel Bayesian hierarchical model of type Ia supernovae in which latent variables describing intrinsic and extrinsic (dust related) supernova properties originate from two populations.

First author: Masamitsu Mori We use an asteroseismology method to calculate the frequencies of gravitational waves in a long-term core-collapse supernova simulation, with a mass of 9.6 $M_\odot$. The simulation, which includes neutrino transport in general relativity is performed from core-collapse, bounce, explosion and cooling of protoneutron stars (PNSs) up to 20 s after the bounce self-consistently. Based on the hydrodynamics background, we calculate eigenmodes of the PNS oscillation through a perturbation analysis on fluid and metric.

First author: Keiya Hirashima Small integration timesteps for a small fraction of short-timescale regions are bottlenecks for high-resolution galaxy simulations using massively parallel computing. This is an urgent issue that needs to be resolved for future higher-resolution galaxy simulations. One possible solution is to use an (approximate) Hamiltonian splitting method, in which only regions requiring small timesteps are integrated with small timesteps, separated from the entire galaxy. In particular, gas affected by supernova (SN) explosions often requires the smallest timestep in such a simulation.

First author: Noel D. Richardson Ultra-stripped supernovae are different from other terminal explosions of massive stars, as they show little or no ejecta from the actual supernova event. They are thought to occur in massive binary systems after the exploding star has lost its surface through interactions with its companion. Such supernovae produce little to no kick, leading to the formation of a neutron star without loss of the binary companion, which itself may also evolve into another neutron star.

First author: Agnibha De Sarkar We present a simple phenomenological model of hadronic interaction between protons accelerated in an old supernova remnant (SNR) and cold protons situated within the associated molecular clouds (MCs). The accelerated protons from the old SNR escaped the SNR shock front, and got injected into the MCs at an earlier time, producing ultra high energy gamma-rays and neutrinos through inelastic proton-proton interaction. We also take into account the acceleration and subsequent escape of electrons from the SNR shock front.

First author: Mohammad Malekjani Given a \textit{model building} assumption on the (effective) equation of state (EoS) of the Universe, the Hubble constant $H_0$ arises as an integration constant when one solves the Friedmann equations. Therefore, while $H_0$ is \textit{mathematically} a constant, it need not be a constant \textit{observationally}, unless the EoS or model accurately describes the Universe. Building on earlier results, we show that redshift evolution of flat $\Lambda$CDM cosmological parameters $(H_0, \Omega_{m})$ persists in the most up-to-date Pantheon+ sample.

First author: Melissa Shahbandeh Supernova (SN) explosions have been sought for decades as a possible source of dust in the Universe, providing the seeds of galaxies, stars, and planetary systems. SN 1987A offers one of the most promising examples of significant SN dust formation, but until the James Webb Space Telescope (JWST), instruments have traditionally lacked the sensitivity at both late times (>1 yr post-explosion) and longer wavelengths (i.e., >10 um) to detect analogous dust reservoirs.

First author: Daichi Tsuna Early-time light curves/spectra of some hydrogen-rich supernovae (SNe) give firm evidence on the existence of confined, dense circumstellar matter (CSM) surrounding dying massive stars. We numerically and analytically study radiative acceleration of CSM in such systems, where the radiation is mainly powered by the interaction between the SN ejecta and the CSM. We find that the acceleration of the ambient CSM is larger for massive and compact CSM, with velocities reaching up to $\sim 10^3\ {\rm km\ s^{-1}}$ for a CSM of order $0.

First author: Hiroki Nagakura One of the greatest uncertainties in any modeling of inner engine of core-collapse supernova (CCSN) is neutrino flavor conversions driven by neutrino self-interactions. We carry out large-scale numerical simulations of multi-energy, multi-angle, three-flavor framework, and general relativistic quantum kinetic neutrino transport in spherical symmetry with an essential set of neutrino-matter interactions under a realistic fluid profile of CCSN. Our result suggests that the neutrino heating in the gain region is reduced by $\sim 50%$ due to fast neutrino-flavor conversion (FFC).

First author: M. D. Fulton We present extensive optical photometry of the afterglow of GRB 221009A. Our data cover $0.9 - 59.9$ days from the time of Swift and Fermi GRB detections. Photometry in $rizy$-band filters was collected primarily with Pan-STARRS and supplemented by multiple 1- to 4-meter imaging facilities. We analyzed the Swift X-ray data of the afterglow and found a single decline rate power-law $f(t) \propto t^{-1.556\pm0.002}$ best describes the light curve.