An optical search for supernova remnants in the nearby spiral galaxy NGC 2903

TL;DR

This study conducted the first optical survey to identify supernova remnants in NGC 2903, using imaging and spectral analysis to find five candidates based on emission line ratios, revealing characteristics of an old, oxygen-deficient remnant.

Contribution

First optical identification of supernova remnants in NGC 2903 using emission line ratios and spectral data.

Findings

Identified five SNR candidates with specific emission line ratios.

Spectral analysis indicates an old, oxygen-deficient remnant.

First optical survey of SNRs in NGC 2903.

Abstract

We present the results of an optical search for supernova remnants (SNRs) in the nearby spiral galaxy NGC 2903. Interference filter images and spectral data were taken in March 2005 with the f/7.7 1.5 m Russian Turkish Telescope (RTT150) at TUBITAK National Observatory (TUG). Spectral data were obtained with the 6 m BTA (Bolshoi Azimuthal Telescope, Russia). We used the SNR identification criterion that consists of constructing the continuum-subtracted H$\alpha$ and continuum-subtracted [SII]$\lambda$$\lambda$6716,6731 images and their ratios. Five SNR candidates were identified in NGC 2903 with [SII]/H$\alpha$ ratios ranging from 0.41 - 0.74 and H$\alpha$ intensities ranging from 9.4$\times10^{-15}$ to 1.7$\times10^{-14}$ ergs cm$^{-2}$ s$^{-1}$. This work represents the first identification of SNRs by an optical survey in NGC 2903. We present the spectrum of one of the bright candidates and derive an [SII]/H$\alpha$ emission line ratio of 0.42 for this source. In addition, the weak [OIII]$\lambda$5007/H$\beta$ emission line ratio in the spectrum of this SNR indicates an old oxygen-deficient remnant with a low propagation velocity.