J/ApJ/903/132 Radio & optical observations of supernova SN2020oi (Horesh+, 2020)
A Non-equipartition Shock Wave Traveling in a Dense Circumstellar Environment
around SN 2020oi.
Horesh A., Sfaradi I., Ergon M., Barbarino C., Sollerman J., Moldon
J., Dobie D., Schulze S., Perez-Torres M., Williams D.R.A., Fremling C.,
Gal-Yam A., Kulkarni S.R., O'Brien A., Lundqvist P., Murphy T., Fender R.,
Anand S., Belicki J., Bellm E.C., Coughlin M.W., De K., Golkhou V.Z., Graham
M.J., Green D.A., Hankins M., Kasliwal M., Kupfer T., Laher R.R., Masci
F.J., Miller A.A., Neill J.D., Ofek E.O., Perrott Y., Porter M., Reiley
D.J., Rigault M., Rodriguez H., Rusholme B., Shupe D.L., Titterington D.
<Astrophys. J., 903, 132 (2020)>
=2020ApJ...903..132H 2020ApJ...903..132H
ADC_Keywords: Supernovae; Spectra, millimetric/submm; Spectra, optical;
X-ray sources
Keywords: Supernovae ; Type Ic supernovae ; Core-collapse supernovae ;
Radio transient sources ; Radio observatories ; Optical
observation ; X-ray transient sources ; Transient sources
Abstract:
We report the discovery and panchromatic follow-up observations of the
young Type Ic supernova (SNIc) SN2020oi in M100, a grand-design spiral
galaxy at a mere distance of 14Mpc. We followed up with observations
at radio, X-ray, and optical wavelengths from only a few days to
several months after explosion. The optical behavior of the supernova
is similar to those of other normal SNeIc. The event was not detected
in the X-ray band but our radio observations revealed a bright mJy
source (Lν∼1.2x1027erg/s/Hz). Given the relatively small number
of stripped envelope SNe for which radio emission is detectable, we
used this opportunity to perform a detailed analysis of the
comprehensive radio data set we obtained. The radio-emitting electrons
initially experience a phase of inverse Compton cooling, which leads
to steepening of the spectral index of the radio emission. Our
analysis of the cooling frequency points to a large deviation from
equipartition at the level of εe/εB≳200, similar
to a few other cases of stripped envelope SNe. Our modeling of the
radio data suggests that the shock wave driven by the SN ejecta into
the circumstellar matter (CSM) is moving at ∼3x104km/s. Assuming a
constant mass loss from the stellar progenitor, we find that the
mass-loss rate is M∼1.4x10-4M☉/yr for an assumed wind velocity
of 1000km/s. The temporal evolution of the radio emission suggests a
radial CSM density structure steeper than the standard r-2.
Description:
Supernova SN2020oi in M100 was discovered in r-band images obtained by
the Zwicky Transient Facility (ZTF) on 2020 January 7.
Upon discovery, we triggered photometric observations with the Las
Cumbres Observatory (LCO) telescope network. In addition to
photometric observations, we carried out 16 spectroscopic observations
of SN2020oi over the first three months after discovery using multiple
telescopes: the P60 telescope, the Nordic Optical Telescope (NOT), the
Palomar 200inch telescope (P200) and the Keck Telescope (KECK).
Radio observations of SN2020oi were rapidly initiated using several
facilities, including the Karl G. Jansky Very Large Array (VLA), the
Arcminute Microkelvin Imager-Large Array (AMI-LA), The Australian
Telescope Compact Array (ATCA), and the e-MERLIN Telescope.
Swift observed SN 2020oi with its onboard X-ray telescope (XRT) in the
energy range from 0.3 to 10keV between 2020 January 8 and February 28.
Objects:
------------------------------------------------
RA (2000) DE Designation(s)
------------------------------------------------
12 22 54.93 +15 49 25.0 SN 2020oi = SN 2020oi
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table4.dat 84 6 SN2020oi radio spectral fits and the derived
equipartition shockwave parameters
table5.dat 23 165 SN 2020oi VLA sub-band observations
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See also:
VIII/65 : 1.4GHz NRAO VLA Sky Survey (NVSS) (Condon+ 1998)
J/MNRAS/397/1177 : Swift-XRT observations of GRBs (Evans+, 2009)
J/other/Nat/463.513 : Radio observations of SN 2009bb (Soderberg+, 2010)
J/ApJ/760/L33 : Photometry of the Ic supernova PTF12gzk (Ben-Ami+, 2012)
J/MNRAS/429/3330 : AMI Galactic Plane Survey at 16GHz. I. (Perrott+, 2013)
J/A+A/562/A17 : SN 2011dh - The first 100 days (Ergon+, 2014)
J/A+A/593/A68 : PTF12os & iPTF13bvn spectra and light curves (Fremling+, 2016)
J/A+A/618/A37 : Spectral log of (i)PTF stripped-envelope SN (Fremling+, 2018)
J/ApJ/895/32 : Zwicky Transient Facility BTS. I. (Fremling+, 2020)
Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 F4.1 d Time [5/20.4] Time of the peak (1)
6- 9 F4.2 d e_Time [1/2] Error in Time
11- 14 F4.2 mJy/beam Peak [2.21/5.24] Peak flux
16- 19 F4.2 mJy/beam e_Peak [0.3/0.9] Error in Peak
21- 25 F5.2 GHz Freq [5.1/31.4] Frequency of the peak
27- 30 F4.2 GHz e_Freq [0.3/2]? Error in Freq
32- 36 F5.2 --- Sp+Ind [-1.31/-0.53]? Spectral slope
38- 41 F4.2 --- e_Sp+Ind [0.1/0.4]? Error in Sp+Index
43- 46 F4.2 --- chi [0.02/0.69] Reduced chi square
48 I1 --- dof [1/9] Degrees of freedom
50- 53 F4.2 10+15cm Rad [0.59/4.66] Radius of the emitting shell (2)
55- 58 F4.2 10+15cm e_Rad [0.16/0.83] Error in Rad
60- 63 F4.2 10^-4T B [1.08/3.9] Magnetic field strength (2)
65- 68 F4.2 10^-4T e_B [0.2/1] Error in B
70- 72 F3.1 10+4km/s Vel [3.9/4.1] Shock velocity (2)
74- 76 F3.1 10^4km/s e_Vel [0.9/1.3] Error in Vel
78- 80 F3.1 10-5Msun/yr Mdot [0.8/1.4] Mass-loss rate (2)
82- 84 F3.1 10-5Msun/yr e_Mdot [0.4/1] Error in Mdot
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Note (1): The last row shows a summary of the radio peak fit for the 5.1GHz
light curve measured by e-MERLIN (see Section 5.2)
Note (2): Using Chevalier, 1998ApJ...651..381C 1998ApJ...651..381C and assuming equipartition.
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 5 F5.2 d Time [5.15/93.8] Days since the explosion
7- 8 I2 GHz Freq [5/47] Observed central frequency
10- 13 F4.2 mJy/beam Flux [0/5.25] Peak flux density (1)
15- 18 F4.2 mJy/beam e_Flux [0/0.54] Error in Flux (1)
20- 23 F4.2 mJy RMS [0.01/0.57] Image RMS
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Note (1): A zero indicates an observation in which a source was not detected.
The upper limit in such cases is 3 sigma rms.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Coralie Fix [CDS], 10-Feb-2022