J/A+A/686/A129 SN 2019oys radio observations (Sfaradi+, 2024)
The dense and non-homogeneous circumstellar medium revealed in radio
wavelengths around the Type Ib SN 2019oys.
Sfaradi I., Horesh A., Sollerman J., Fender R., Rhodes L., Williams D.R.A.,
Bright J., Green D.A., Schulze S., Gal-Yam A.
<Astron. Astrophys. 686, A129 (2024)>
=2024A&A...686A.129S 2024A&A...686A.129S (SIMBAD/NED BibCode)
ADC_Keywords: Supernovae ; Radio sources
Keywords: circumstellar matter - stars: mass-loss - supernovae: general -
supernovae: individual: SN2019oys - radio continuum: general
Abstract:
Mass loss from massive stars, especially towards the end of their
lives, plays a key role in their evolution. Radio emission from
core-collapse supernovae (SNe) serves as a probe of the interaction of
the SN ejecta with the circumstellar medium (CSM) and can reveal the
mass-loss history of the progenitor.
We aim to present broadband radio observations of the CSM-interacting
SN 2019oys. SN 2019oys was first detected in the optical and was
classified as a Type Ib SN. Then, ∼100 days after discovery, it
showed an optical rebrightening and a spectral transition to a
spectrum dominated by strong narrow emission lines, which suggests
strong interaction with a distant, dense, CSM shell.
We modelled the broadband, multi-epoch radio spectra, covering 2.2 to
36GHz and spanning from 22 to 1425 days after optical discovery, as a
synchrotron emitting source. Using this modelling, we characterised
the shockwave and the mass-loss rate of the progenitor.
Our broadband radio observations show strong synchrotron emission.
This emission, as observed 201 and 221 days after optical discovery,
exhibits signs of free-free absorption from the material in front of
the shock travelling in the CSM. In addition, the steep power law of
the optically thin regime points towards synchrotron cooling of the
radiating electrons. Analysing these spectra in the context of the
SN-CSM interaction model gives a shock velocity of 11000km/s and an
electron number density of 4.1x105cm-3 at a distance of
2.6x1016cm. This translates to a high mass-loss rate from the
progenitor massive star of 10-3M_☉/yr for an assumed wind of
100km/s (assuming a constant mass-loss rate in steady winds). The
late-time radio spectra, 392 and 557 days after optical discovery,
show broad spectral peaks. We show that this can be explained by
introducing a non-homogeneous CSM structure.
Description:
Radio observations of the type Ib SN 2019oys conducted with the Very
Large Array (VLA) and the Arcminute-Microkelvin Imager - Large Array
(AMI-LA). The Time column is for time since optical discovery in days.
The Frequency column is for the observed central frequency in GHz. The
Band column is for the observed band. The flux column is the peak flux
of the fitted point source in mJy (zero means a non-detection). The
Flux Error column is the uncertainty of the flux in mJy (when a
non-detected is made this uncertainty is the 3sigma rms limit). The
Image RMS column is the rms of the image in mJy. The Telescope column
is for the telescope used in the observation, for VLA observation we
specify the configuration after the colon.
Objects:
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RA (2000) DE Designation(s)
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07 07 59.26 +31 39 55.2 SN 2019oys = ZTF19abucwzt
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 38 113 Radio observations of SN2019oys
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Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 4 I4 d Time Time since optical discovery
6- 9 F4.1 GHz Freq Observed central frequency
11- 12 A2 --- Band Observed band
14 A1 --- l_Flux Limit flag for 3sigma rms upper limit for
radio non-detections
15- 19 F5.2 mJy Flux Peak flux density in Band
21- 24 F4.2 mJy e_Flux ? Uncertainty of the peak flux density in Band
26- 29 F4.2 mJy rms RMS of the image
31- 38 A8 --- Tel Telescope used for observation
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Acknowledgements:
Itai Sfaradi, itai.sfaradi(at)mail.huji.ac.il
(End) I. Sfaradi [Hebrew Univ. Jerusalem, Israel], P. Vannier [CDS] 17-May-2024