Discovery of ∼2200 new supernova remnants in 19 nearby star-forming galaxies with MUSE spectroscopy
arxiv(2024)
Abstract
We present the largest extragalactic survey of supernova remnant (SNR)
candidates in nearby star-forming galaxies using exquisite spectroscopic maps
from MUSE. Supernova remnants exhibit distinctive emission-line ratios and
kinematic signatures, which are apparent in optical spectroscopy. Using optical
integral field spectra from the PHANGS-MUSE project, we identify SNRs in 19
nearby galaxies at 100 pc scales. We use five different optical diagnostics:
(1) line ratio maps of [SII]/Hα; (2) line ratio maps of [OI]/Hα;
(3) velocity dispersion map of the gas; (4) and (5) two line ratio diagnostic
diagrams from BPT diagrams to identify and distinguish SNRs from other nebulae.
Given that our SNRs are seen in projection against HII regions and diffuse
ionized gas, in our line ratio maps we use a novel technique to search for
objects with [SII]/Hα or [OI]/Hα in excess of what is expected at
fixed Hα surface brightness within photoionized gas. In total, we
identify 2,233 objects using at least one of our diagnostics, and define a
subsample of 1,166 high-confidence SNRs that have been detected with at least
two diagnostics. The line ratios of these SNRs agree well with the MAPPINGS
shock models, and we validate our technique using the well-studied nearby
galaxy M83, where all SNRs we found are also identified in literature catalogs
and we recover 51
are detected with only one diagnostic and we classify them as SNR candidates.
We find that 35
regions from literature catalogs, highlighting the importance of using
indicators beyond line intensity morphology to select SNRs. [OI]/Hα line
ratio is responsible for selecting the most objects (1,368; 61
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