J/A+A/679/A22 SNR Kes 17 and ISM from radio and gamma rays (Supan+, 2023)
The interaction of SNR Kes 17 with the interstellar medium:
Fresh view from radio and gamma-rays.
Supan L., Castelletti G., Lemiere A.
<Astron. Astrophys. 679, A22 (2023)>
=2023A&A...679A..22S 2023A&A...679A..22S (SIMBAD/NED BibCode)
ADC_Keywords: Supernova remnants ; Interstellar medium ; Radio continuum ;
Gamma rays
Keywords: ISM: supernova remnants -
ISM: individual objects: Kes 17 (G304.6+0.1) -
radio continuum: general - gamma rays: ISM
Abstract:
This paper presents a comprehensive analysis of the Galactic supernova
remnant (SNR) Kes 17 (G304.6+0.1). The focus is on its radio
synchrotron emission, its surroundings, and the factors contributing
to the observed gamma rays. The fitting to the first obtained
integrated radio continuum spectrum spanning from 88 to 8800MHz yields
an index alpha=-0.488±0.023 (Snu propto nualpha), which is
indicative of a linear particle acceleration process at the shock
front of the remnant. Accounting for the SNR radio shell size, the
distribution of atomic hydrogen (nH ∼10cm-3), and assuming that
the SNR is in the Sedov-Taylor stage of its evolution, we estimate
that the remnant age is roughly 11 kyr. This result falls at the lower
end of the wide range (∼2-64kyr) derived from previous analyses of the
diffuse X-ray emission interior to the remnant. Furthermore, we used
12CO and 13CO (J=1-0) emission line data as a proxy for molecular
hydrogen and provide the first evidence that the eastern shell of Kes
17 is engulfing a molecular enhancement in the surrounding gas, with
an average mass 4.2x104M☉ and density n∼300cm-3 . Towards
the western boundary of Kes 17, no signatures of carbon monoxide
emissions are detected above 3 sigma, despite previously reported
infrared observations that revealed shocked molecular gas at this
location. This suggests the existence of a CO-dark interacting
molecular gas, a phenomenon also recorded in other Galactic SNRs (e.g.
CTB 37A and RX J1713.7-3946) that reveals itself both in the infrared
and gamma-ray domains. Additionally, by analysing ∼14.5yr of
continuously collected data from the Large Area Telescope on board the
satellite Fermi, we determined that the best-fit power-law photon
index for the 0.3-300GeV gamma-ray emission from the Kes 17 region is
Gamma=2.39±0.04+0.063-0.114(±stat±syst), in agreement with
prior studies. The energy flux is (2.98±0.14)x10-11erg/cm2/s,
implying a luminosity (2.22±0.45)x1035erg/s at ∼8kpc. Finally,
we successfully modelled the multiwavelength spectral energy
distribution by incorporating the radio-synchrotron spectrum and the
new measurements of GeV gamma-rays. Our analysis indicates that the
observed gamma-ray flux most likely originates from the interaction of
Kes 17 with a western dark CO zone with a proton density
np∼400cm-3.
Description:
Integrated flux densities over the full extent of Kes 17 that we
used to construct the radio continuum spectrum of the remnant.
Objects:
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RA (2000) DE Designation(s)
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13 05 58.99 -62 42 00.0 Kes 17 = SNR G304.6+00.1
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 13 14 Flux densities with errors
list.dat 258 10 List of fits images
fits/* . 10 Individual fits images
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 4 I4 MHz Freq Frequency
6- 9 F4.1 Jy S Flux density (1)
11- 13 F3.1 Jy e_S Flux density error (1)
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Note (1): Some values where not corrected to bring them to the
Perley & Bultler (2017ApJS..230....7P 2017ApJS..230....7P, Cat. J/ApJS/230/7) absolute flux
scale. See paper for details.
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Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
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1- 9 F9.5 deg RAdeg Right Ascension of center (J2000)
10- 18 F9.5 deg DEdeg Declination of center (J2000)
20- 22 I3 --- Nx Number of pixels along X-axis
24- 26 I3 --- Ny Number of pixels along Y-axis
28- 31 I4 Kibyte size Size of FITS file
33- 86 A54 --- FileName Name of FITS file, in subdirectory fits
88-259 A172 --- Title Title of the FITS file
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Acknowledgements:
Leonardo Supan, lsupan -at- iafe.uba.ar,
Instituto de Astronomia y Fisica del Espacio
(End) Patricia Vannier [CDS] 20-Oct-2023