J/ApJ/902/55 19yrs of radio and X-ray obs. of SN 2001em (Chandra+, 2020)
Supernova interaction with a dense detached shell in SN 2001em.
Chandra P., Chevalier R.A., Chugai N., Milisavljevic D., Fransson C.
<Astrophys. J., 902, 55 (2020)>
=2020ApJ...902...55C 2020ApJ...902...55C
ADC_Keywords: Supernovae; X-ray sources; Radio sources
Keywords: Supernovae ; Circumstellar matter ; Radio observatories ;
X-ray sources ; Non-thermal radiation sources ; Circumstellar shells
Abstract:
We carry out a comprehensive analysis of supernova SN 2001em covering
a period of 19yr since discovery. SN 2001em is the oldest supernova
known to have undergone a metamorphosis from a stripped envelope to an
interacting supernova. An early spectrum indicates it exploded as a
Type Ib supernova. Later, the ejecta caught up with a dense
circumstellar H-shell, ejected a few thousand years before the
explosion, triggering interaction between the supernova ejecta and the
dense shell, producing radio, X-ray, and Hα emission. We use
archival data with the Very Large Array in radio bands and with
Chandra, XMM-Newton, and Swift-XRT in X-ray bands, along with
published Hα measurements. We combine these data with our low
radio frequency observations with the Giant Metrewave Radio Telescope
at two epochs covering three frequencies. While the observations
missed the phase when the shock entered the dense shell, the X-rays
indicate that the shock came out of the dense shell at around 1750d.
The data suggest a forward shock origin of the X-ray emission. Radio
data show a spectral inversion at late epochs (>5000d) at around 3GHz,
which mimics the properties of the central absorbed component seen in
SN 1986J. A possible explanation for this component is that the
progenitor of SN 2001em was a massive binary system that had undergone
a period of common-envelope evolution. The hydrogen envelope from the
SN 2001em progenitor may have been lost as a result of binary
interaction.
Description:
We observed SN 2001em with the Giant Metrewave Radio Telescope (GMRT)
on 2004 February 13 at 1.3GHz. We also observed SN 2001em with the
upgraded GMRT in frequency band 3 (250-500MHz), band 4 (550-900MHz),
and band 5 (1000-1450MHz) in 2019 December.
The VLA observations started in 2003 October and continued until July
2020. The data from the years 2003-2008 were obtained with the old
VLA covering the frequency range 1.4-22.5GHz.
We obtained Chandra archival data on SN 2001em at five epochs between
2004 April and 2016 August. XMM-Newton observed SN 2001em on 2006 June
for an exposure of around 25ks. The XRT on board Swift observed
SN2001em at various epochs during 2008-2016 January.
Objects:
---------------------------------------------------
RA (ICRS) DE Designation(s)
---------------------------------------------------
21 42 23.61 +12 29 50.3 SN 2001em = SN 2001em
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 81 81 Radio observations of SN 2001em
table2.dat 142 17 *X-ray observations of SN 2001em
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Note on table2.dat: We have fixed the temperature to 20keV for all observations
to derive the SN 2001em flux.
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See also:
B/sn : Asiago Supernova Catalogue (Barbon et al., 1999-)
B/swift : Swift Master Catalog (HEASARC, 2004-)
B/xmm : XMM-Newton Obs. Log (XMM-Newton Science Operation Center, 2012)
B/chandra : The Chandra Archive Log (CXC, 1999-2014)
J/AJ/119/32 : Survey of galaxies within nearby voids. II (Grogin+, 2000)
J/ApJ/781/42 : Optical photometry of SN 2010jl (Ofek+, 2014)
J/ApJ/832/108 : Spectral properties of Type Ic & Ic-bl SNe (Modjaz+, 2016)
J/ApJS/241/38 : A comprehensive analysis of Spitzer supernovae (Szalai+, 2019)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 I4 yr Obs.Y [2003/2020] Year of the observation; UT
6- 8 A3 "month" Obs.M Month of the observation; UT
10- 11 I2 d Obs.D Day of the observation; UT
13- 18 A6 --- Config Telescope array configuration; VLA only
20- 26 A7 --- Prop Proposal identifier
28- 31 I4 d Age [764/6881] Days from date of explosion:
2001 September 13 (UT)
33- 37 F5.2 GHz Freq [0.4/33] Frequency
39- 45 F7.4 arcsec MajAxis [0.0009/42.4] Resolution of major axis
47- 53 F7.4 arcsec MinAxis [0.0008/38] Resolution of minor axis
55 A1 --- f_Flux Limit or approximate flag on Flux
57- 61 F5.3 mJy Flux [0.05/2.17] Flux density at Freq
63- 67 F5.3 mJy e_Flux [0.008/0.4]? Uncertainty in Flux
69- 81 A13 --- Ref Reference (1)
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Note (1): Reference as follows:
Stockdale+04 = Stockdale et al. (2004IAUC.8282....2S 2004IAUC.8282....2S);
Bietenholz+04 = Bietenholz et al. (2004Sci...304.1947B 2004Sci...304.1947B);
Paragi+05 = Paragi et al. (2005MmSAI..76..570P 2005MmSAI..76..570P);
BB+07 = Bietenholz & Bartel (2007ApJ...665L..47B 2007ApJ...665L..47B).
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 11 A11 "Y:M:D" Date Date of observation (UT) or Lower range date
12 A1 --- --- [-]
13- 23 A11 "Y/M/D" Date2 Upper range date of observation if any
25- 34 A10 --- Tel Telescope
36- 46 I011 --- PID1 First observation program identifier
47 A1 --- --- [,]
48- 58 I011 --- PID2 ? Second Swift observation program identifier
59 A1 --- --- [,]
60- 70 I011 --- PID3 ? Third Swift observation program identifier
72- 76 F5.2 ks Exp [0.2/19.7] Exposure time
78- 81 I4 d Age [934/5454] Days from date of explosion:
2024 September 13 (UT)
83 I1 d e_Age [1/7]? Age uncertainty
85 A1 --- l_CR Limit flag on CR
87- 94 E8.3 ct/s CR [0.0008/0.06] X-ray count rate
96- 102 E7.3 ct/s e_CR [0.0006/0.006]? CR uncertainty
104- 111 E8.3 cm-2 NH [1.3e-21/2.7e-21] Column density
113- 120 E8.3 cm-2 e_NH [5.9e-22/1.8e-21]? NH uncertainty
122 A1 --- f_NH Flag on NH
124 A1 --- l_Flux Limit flag on Flux
126- 133 E8.3 mW/m2 Flux [1.4e-14/3.6e-12] Unabosorbed flux
in 0.3-10keV energy range in erg/cm2/s
135- 142 E8.3 mW/m2 e_Flux [8.1e-15/2.3e-14]? Flux uncertainty
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 13-Apr-2022