Near-infrared [Fe II] emission in starburst galaxies

Date

2018-11-16

Authors

Labrie, Kathleen

Journal Title

Journal ISSN

Volume Title

Publisher

Abstract

We used the near-infrared [Fe II] emission line signature to detect supernova remnants (SNRs) in the nearby starburst galaxies NGC 1569, NGC 3738 and NGC 5253. The near-infrared narrow-band imaging program has led to the detection of 10 SNR candidates in NGC 1569, 7 in NGC 5253, and none in NGC 3738. A spatially extended component to the [Fe II] line emission is observed in NGC 1569 and NGC 5253. This component dominates the integrated [Fe II] luminosity in both galaxies, the compact sources accounting for 14% and 7% of the total [Fe II] luminosity of NGC 1569 and NGC 5253, respectively. Despite the starburst environment, the [Fe II] luminosity of the individual SNRs is two orders of magnitude lower than the luminosities observed for SNRs in M82. We find that the density and the structure of the interstellar medium is a more important factor than the starburst nature of a galaxy in determining the average [Fe II] luminosity of a SNR. We caution against the blind usage of supernova rate vs. [Fe II] luminosity relations, which are most often calibrated with the average luminosity of the remnants in M82. We suggest that a significant fraction of the ISM in NGC 1569 and NGC 5253 is under the influence of SNRs. This does not appear to be the case in M82, where the impact of the SNRs is limited to high density knots. Also, we find evidence for an [Fe II]-emitting lifetime as long as 105 yrs, which contrasts with the 104 yrs derived from SNRs in M82-like galaxies. We find that the [Fe II] morphology, and the integrated luminosity observed in our sample galaxies, can be reproduced from a [Fe II]-emitting SNR population, as long as the pre-shock density is kept as low as 1 cm −3. Higher pre-shock density models are strongly rejected. We find a supernova rate of 0.006 SN/yr for NGC 1569 and 0.005 SN/yr for NGC 5253.

Description

Keywords

Starbursts, Supernova remnants, Luminosity, Galaxies

Citation