An Optical and X‐Ray Examination of Two Radio Supernova Remnant Candidates in 30 Doradus

Abstract

The giant H II region 30 Doradus is known for its violent internalmotions and bright diffuse X-ray emission, suggesting the existence ofsupernova remnants (SNRs), but no nonthermal radio emission has beendetected. Recently, Lazendic et al. compared the H{α}/H{β} andradio/H{α} ratios and suggested two small radio sources to benonthermal and thus SNR candidates; however, no optical or X-raycounterparts were detected. We have used high-resolution optical imagesand high-dispersion spectra to examine the morphological, spectral, andkinematic properties of these two SNR candidates and still find nooptical evidence supporting their identification as SNRs. We have alsodetermined the X-ray luminosities of these SNR candidates and find them1-3 orders of magnitude lower than those commonly seen in young SNRs.High extinction can obscure optical and X-ray signatures of an SNR, butwould prohibit the use of a high radio/H{α} ratio to identifynonthermal radio emission. We suggest that the SNR candidate MCRXJ053831.8-690620 is associated with a young star-forming region; whilethe radio emission originates from the obscured star-forming region, theobserved optical emission is dominated by the foreground. We suggestthat the SNR candidate MCRX J053838.8-690730 is associated with adust/molecular cloud, which obscures some optical emission but not theradio emission.