J/MNRAS/391/1384 Deep MERLIN 5GHz radio sources in M82 (Fenech+, 2008)
Deep MERLIN 5GHz radio imaging of supernova remnants in the M82 starburst.
Fenech D.M., Muxlow T.W.B., Beswick R.J., Pedlar A., Argo M.K.
<Mon. Not. R. Astron. Soc., 391, 1384-1402 (2008)>
=2008MNRAS.391.1384F 2008MNRAS.391.1384F (SIMBAD/NED BibCode)
ADC_Keywords: Supernova remnants ; H II regions ; Radio sources ; Morphology
Keywords: H II regions - supernova remnants - galaxies: individual: M82 -
galaxies: ISM - galaxies: starburst
Abstract:
The results of an extremely deep, 8-d long observation of the central
kpc of the nearby starburst galaxy M82 using Multi-Element Radio
Linked Interferometer Network (MERLIN) at 5GHz are presented. The
17µJy/beam rms noise level in the naturally weighted image makes it
the most sensitive high-resolution radio image of M82 made to date.
Over 50 discrete sources are detected, the majority of which are
supernova remnants, but with 13 identified as H ii regions. Sizes,
flux densities and radio brightnesses are given for all of the
detected sources, which are all well resolved with a majority showing
shell or partial shell structures. Those sources within the sample
which are supernova remnants have diameters ranging from 0.3 to 6.7pc,
with a mean size of 2.9pc.
Description:
The 2002 deep integration was obtained using six of the MERLIN
antennas, including the Cambridge telescope. The observing strategy
and correlator configuration replicated those used in the 1992 5-GHz
observations presented by Muxlow et al. (1994MNRAS.266..455M 1994MNRAS.266..455M). The
2002 observations were undertaken between the April 1 and 28 at a
frequency of 4.994GHz using both left-left (LL) and right-right (RR)
polarizations and with a bandwidth of 15MHz divided into 15 channels.
The total on source integration time was over 175h.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 117 55 Flux densities and deconvolved sizes of the
sources detected in the 2002 5-GHz MERLIN data set
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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- 2 I2 --- Seq Sequential number
4- 13 A10 --- [FMB2008] Name (offsets from 09:51:00.0+69:54:00 B1950)
15- 16 I2 h RAh Right ascension (J2000)
18- 19 I2 min RAm Right ascension (J2000)
21- 25 F5.2 s RAs Right ascension (J2000)
27 A1 --- DE- Declination sign (J2000)
28- 29 I2 deg DEd Declination (J2000)
31- 32 I2 arcmin DEm Declination (J2000)
34- 38 F5.2 arcsec DEs Declination (J2000)
40- 45 F6.3 mJy Speak Peak flux density at 5GHz (in mJy/beam)
47- 51 F5.3 mJy e_Speak rms uncertainty on Speak
53- 58 F6.3 mJy Sint Integrated flux density at 5GHz
60- 64 F5.3 mJy e_Sint rms uncertainty on Sint
66- 70 F5.1 mas Siz1 Deconvolved size, in mas
72- 76 F5.2 mas e_Siz1 ? rms uncertainty on Siz1
77 A1 --- --- [x]
78- 82 F5.1 mas Siz2 ? Deconvolved size, in mas
84- 88 F5.2 mas e_Siz2 ? rms uncertainty on Siz2
90- 92 A3 --- n_Siz2 [LAS] LAS = Largest Angular Size given
(for sources weaker than 0.1mJy/beam)
94- 97 F4.1 pc lin1 Deconvolved size, in pc
98 A1 --- --- [x]
99-101 F3.1 pc lin2 ? Deconvolved size, in pc
103-115 A13 --- Type Type (1)
117 A1 --- n_Type [ab] Unknown source type (2)
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Note (1): those sources previously identified in the literature as SNRs or
HII regions have been labelled as SNR or HII. These identifications
are taken from Muxlow et al. (1994MNRAS.266..455M 1994MNRAS.266..455M), Wills et al.
(1997MNRAS.291..517W 1997MNRAS.291..517W), Allen (1999, PhD thesis, Univ. Toronto
(Canada)) and McDonald et al. (2002MNRAS.334..912M 2002MNRAS.334..912M).
Note (2): Note as follows:
a = Sources labelled as unknown have had no prior identification as
either SNR or HII region, as there is little or no spectral
index information available. These sources will be discussed
individually in Section 5.
b = The true nature of the source 41.95+57.5 is unknown and will be
discussed further in Section 3.2.
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 12-Jun-2009