The host galaxies of 2003fg-like type Ia supernovae
Year: 2026
Type: article
Abstract: SN 2003fg-like events are a peculiar type Ia supernova (SN Ia) subtype characterized by broader light curves, higher near-infrared luminosities, and stronger carbon absorptions at early times. Here we present observations of the largest compilation of 2003fg-like SN Ia host galaxies to date, obtained with integral field spectroscopy (IFS). For 20 objects, we study both the global host-galaxy properties and, for the first time for a sizeable sample, the local environment at the SN position. Globally, 2003fg-like SNe Ia occur in galaxies with a lower stellar mass, lower oxygen abundance, and marginally higher specific star formation rate (sSFR) than those of normal SNe Ia, although their hosts are neither as extreme in such properties as superluminous SNe nor representative of metal-poor dwarf-galaxy samples. Locally, the SN positions show a lower star formation rate, stellar-mass surface densities, and sSFR than normal SN Ia environments, consistent with a significant preference for the outskirts of their hosts, while their stellar age indicators are typical. The most distinctive local property is metallicity, with 2003fg-like SNe Ia occupying the most metal-poor environments among SNe Ia. We also find a tentative positive correlation between the light-curve width and the oxygen abundance for 2003fg-like events. Our results imply that 2003fg-like SNe Ia arise from the merger of two white dwarfs (WDs) or the core-degenerate scenario, but disfavor the single, rapidly rotating super-M_ch C-O WD progenitor, as this channel requires a young stellar population that we do not observe at the SN positions. The preference of 2003fg-like SNe Ia for low-metallicity environments suggests that they may have been more common in the early Universe. Since they are overluminous after light-curve standardization (negative Hubble residuals), they will inevitably enter distant SN Ia samples used for cosmology, introducing potential systematic uncertainties in future dark energy experiments. A better understanding of these peculiar SNe Ia is therefore crucial, not only to decipher their progenitors and explosion mechanism, but also to reduce systematic errors in cosmological parameters.
Source: Astronomy and Astrophysics
Authors: Lluís Galbany, Chris Ashall, Jing Lu, Jason T. Hinkle, Willem B. Hoogendam, Benjamin J. Shappee, Alaa Alburai, Ramon Sanfeliu, Joseph P. Anderson, Eddie Baron, Chris Burns, Georgios Dimitriadis, Inma Domínguez, Peter Hoeflich, Eric Y. Hsiao, Hanindyo Kuncarayakti, Joseph D. Lyman, Nidia Morrell, Mark M. Phillips, Sebastián F. Sánchez, Maximilian D. Stritzinger, Nicholas B. Suntzeff
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $1,865
Awards: G1092424111, G1175115578, G1204847676, G1672945522, G2030784793, G2262748287, G2547019181, G2835226076, G300979063, G31735808, G3480869486, G425668148, Hawaii Supernova Flows, G433322167, G464105488, Graduate Research Fellowship Program (GRFP), G5080475149, Collaborative Research: Unravelling Stripped Supernovae - Synergy between Observations and Modeling, G58316358, G5888866032, G6080697404, G617610489, G6273510985, MRI: Development of a Robotic University of Hawaii 88" Telescope (Robo88): A new tool for large surveys, rapid transient classification, and multimessenger astronomy, G6802002986, G7001747737, G7061629469, Graduate Research Fellowship Program (GRFP), G855041801
OpenAlex ID: W7204527909
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