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A global view on star formation: The GLOSTAR Galactic plane survey: II. Supernova remnants in the first quadrant of the Milky Way

Dokara, R and Brunthaler, A and Menten, KM and Dzib, SA and Reich, W and Cotton, WD and Anderson, LD and Chen, C-HR and Gong, Y and Medina, S-NX and Ortiz-León, GN and Rugel, M and Urquhart, JS and Wyrowski, F and Yang, AY and Beuther, H and Billington, SJ and Csengeri, T and Carrasco-González, C and Roy, N (2021) A global view on star formation: The GLOSTAR Galactic plane survey: II. Supernova remnants in the first quadrant of the Milky Way. In: Astronomy and Astrophysics, 651 .

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Official URL: https://doi.org/10.1051/0004-6361/202039873


Context. The properties of the population of Galactic supernova remnants (SNRs) are essential to our understanding of the dynamics of the interstellar medium (ISM) in the Milky Way. However, the completeness of the catalog of Galactic SNRs is expected to be only �30, with on order 700 SNRs yet to be detected. Deep interferometric radio continuum surveys of the Galactic plane help in rectifying this apparent deficiency by identifying low surface brightness SNRs and compact SNRs that have not been detected in previous surveys. However, SNRs are routinely confused with H II regions, which can have similar radio morphologies. Radio spectral index, polarization, and emission at mid-infrared (MIR) wavelengths can help distinguish between SNRs and H II regions. Aims. We aim to identify SNR candidates using continuum images from the Karl G. Jansky Very Large Array GLObal view of the STAR formation in the Milky Way (GLOSTAR) survey. Methods. GLOSTAR is a C-band (4-8 GHz) radio wavelength survey of the Galactic plane covering 358° l � 60° |b| �1°. The continuum images from this survey, which resulted from observations with the most compact configuration of the array, have an angular resolution of 1800. We searched for SNRs in these images to identify known SNRs, previously identified SNR candidates, and new SNR candidates.We study these objects in MIR surveys and the GLOSTAR polarization data to classify their emission as thermal or nonthermal. Results. We identify 157 SNR candidates, of which 80 are new. Polarization measurements provide evidence of nonthermal emission from nine of these candidates. We find that two previously identified candidates are filaments. We also detect emission from 91 of the 94 known SNRs in the survey region. Four of these are reclassified as H II regions following detection in MIR surveys. Conclusions. The better sensitivity and resolution of the GLOSTAR data have led to the identification of 157 SNR candidates, along with the reclassification of several misidentified objects. We show that the polarization measurements can identify nonthermal emission, despite the diffuse Galactic synchrotron emission. These results underscore the importance of higher resolution and higher sensitivity radio continuum data in identifying and confirming SNRs. © 2021 American Society of Civil Engineers (ASCE). All rights reserved.

Item Type: Journal Article
Publication: Astronomy and Astrophysics
Publisher: EDP Sciences
Additional Information: The copyright for this article belongs to Authors
Keywords: Galaxies; Polarization; Supernovae, Galactic plane surveys; Galactic supernova; Interstellar mediums; Nonthermal emission; Polarization measurements; Radio spectral index; Surface brightness; Synchrotron emission, Surveys
Department/Centre: Division of Physical & Mathematical Sciences > Physics
Date Deposited: 20 Nov 2021 11:33
Last Modified: 20 Nov 2021 11:33
URI: http://eprints.iisc.ac.in/id/eprint/69886

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