A Search For Supernova Remnants in The Nearby Spiral Galaxy M74 NGC 628 - Astrophysics > Astrophysics of GalaxiesReportar como inadecuado




A Search For Supernova Remnants in The Nearby Spiral Galaxy M74 NGC 628 - Astrophysics > Astrophysics of Galaxies - Descarga este documento en PDF. Documentación en PDF para descargar gratis. Disponible también para leer online.

Abstract: We have identified nine new SNR candidates in M74 with S II-H$\alpha$$\geq$ 0.4 as the basic criterion. We obtain S II-H$\alpha$ ratio in therange from 0.40 to 0.91 and H$\alpha$ intensities from 2.8 $\times$ $10^{-15}$erg cm$^{-2}$ s$^{-1}$ to 1.7 $\times$ $10^{-14}$ erg cm$^{-2}$ s$^{-1}$. Wealso present spectral follow-up observations of the SNR candidates and canconfirm only three of them SNR2, SNR3, and SNR5. The lack of confirmation forthe rest might be due to the contamination by the nearby H II emission regionsas well as due to the inaccurate positioning of the long slit on these objects.In addition, we search the $Chandra$ Observatory archival data for the X-raycounterparts to the optically identified candidates. We find positionalcoincidence with only three SNR candidates, SNR1, SNR2, and SNR8. The spectrumof SNR2 yields a shock temperature of 10.8 keV with an ionization timescale of1.6 $\times$ 10$^{10}$ s cm$^{-3}$ indicating a relatively young remnant in anearly Sedov phase which is not supported by our optical wavelength analysis.Given the high luminosity of 10$^{39}$ erg s$^{-1}$ and the characteristics ofthe X-ray spectrum, we favor an Ultra Luminous X-ray Source interpretation forthis source associated with an SNR. We calculate an X-ray flux upper limit of9.0 $\times$ $10^{-15}$ erg cm$^{-2}$ s$^{-1}$ for the rest of the SNRsincluding spectroscopically identified SNR3 and SNR5.



Autor: E. Sonbas, A. Akyuz, S. Balman, M. E. Ozel

Fuente: https://arxiv.org/



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