A COLIBRI Photometric Study of SN 2025bvm: A Normal, Slowly Declining Type Ia Supernova

TL;DR

This study presents detailed multi-band photometry of SN 2025bvm, a normal, slowly declining Type Ia supernova, highlighting its photometric properties and implications for ejecta mass.

Contribution

First detailed multi-band photometric analysis of SN 2025bvm, confirming its classification as a normal, slow-declining Type Ia supernova with insights into its ejecta mass.

Findings

SN 2025bvm has a slow decline rate of Δm15(B)=0.867 mag.

The supernova's peak absolute magnitude is -19.13 mag.

Photometric features suggest a large ejecta mass.

Abstract

We present 121 days of multi-band (\Bband, \gband, \rband, \iband) optical photometry of the Type Ia supernova SN 2025bvm, obtained with the COLIBRI telescope at OAN-SPM. The light curves show a photometric decline of $\Delta m_{15}(B) = 0.867 \pm 0.051$~mag, characteristic of a slow-declining Type Ia supernova. After correcting for host galaxy extinction ($E(B-V)_{host} = 0.308 \pm 0.030$~mag) and adopting a distance of 70~Mpc, we derive a peak absolute magnitude of $M_B = -19.13 \pm 0.40$~mag. This luminosity is fully consistent with its slow decline rate, placing SN 2025bvm within the population of normal Type Ia supernovae. We conclude that SN 2025bvm is a normal Type Ia supernova, whose photometric properties, such as a slow late-time decline and a prominent \iband-band secondary maximum, suggest an explosion that resulted in a particularly massive ejecta.