J/ApJ/855/140 MMT spectra of SNRs and SNR candidates in M33 (Long+, 2018)
MMT spectroscopy of supernova remnant candidates in M33.
Long K.S., Blair W.P., Milisavljevic D., Raymond J.C., Winkler P.F.
<Astrophys. J., 855, 140 (2018)>
=2018ApJ...855..140L 2018ApJ...855..140L
ADC_Keywords: Supernova remnants; Spectra, optical; X-ray sources;
Cross identifications
Keywords: galaxies: individual (M33) ; ISM: supernova remnants
Abstract:
To date, over 220 emission nebulae in M33 have been identified as
supernova remnants (SNRs) or SNR candidates, principally through
[SII]:Hα line ratios that are elevated compared to those in HII
regions. In many cases, the determination of a high [SII]:Hα
line ratio was made using narrow-band interference filter images and
has not been confirmed spectroscopically. Here, we present MMT 6.5m
optical spectra that we use to measure [SII]:Hα and other line
ratios in an attempt to determine the nature of these suggested
candidates. Of the 197 objects in our sample, 120 have no previously
published spectroscopic observations. We confirm that the majority of
candidate SNRs have emission line ratios characteristic of SNRs. While
no candidates show Doppler-broadened lines expected from young,
ejecta-dominated SNRs (≳1000km/s), a substantial number do exhibit
lines that are broader than HII regions. We argue that the majority of
the objects with high [SII]:Hα line ratios (>0.4) are indeed
SNRs, but the distinction between HII regions and SNRs becomes less
obvious at low surface brightness, and additional criteria, such as
X-ray detection, are needed. We discuss the properties of the sample
as a whole and compare it with similar samples in other nearby
galaxies.
Description:
We have obtained spectra of 197 SNRs and SNR candidates in M33, using
the Hectospec fiber-fed spectrograph at the 6.5m MMT Observatory at
Mt. Hopkins (total spectral coverage of 3600-9100Å). The
observations took place over eight nights in 2016 October and
November, under good conditions.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 82 217 SNR Candidates in M33
table2.dat 64 197 Emission line fluxes of SNR candidates
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See also:
J/A+AS/114/215 : New SNR candidates in M31 (Magnier+, 1995)
J/ApJS/120/247 : Supernova remnants in M33 (Gordon+, 1999)
J/AJ/131/2478 : M31 and M33 UBVRI photometry (Massey+, 2006)
J/AJ/134/2474 : Hα em. stars in 7 dwarfs galaxies (Massey+, 2007)
J/ApJ/675/1213 : Abundances in M33 HII regions (Rosolowsky+, 2008)
J/ApJS/187/495 : SNRs in M33 from optical and X-ray (Long+, 2010)
J/A+A/512/A63 : Abundances of M33 HII regions (Magrini+, 2010)
J/ApJS/193/31 : M33 Chandra ACIS survey: final catalog (Tullmann+, 2011)
J/ApJS/203/8 : Optical SNR candidates in M83 (Blair+, 2012)
J/ApJ/758/133 : HII regions & PNe metallicity profiles (Sanders+, 2012)
J/MNRAS/429/189 : SNRs in six nearby galaxies (Leonidaki+, 2013)
J/ApJ/788/55 : HST/WFC3 SNR discoveries in M83 (NGC5236) (Blair+, 2014)
J/ApJ/786/130 : Catalog of M31 SNR candidates (Lee+, 2014)
J/ApJ/793/134 : M33 SNR candidates properties (Lee+, 2014)
J/ApJS/212/21 : A deep Chandra ACIS survey of M83 (Long+, 2014)
J/ApJS/218/9 : Deep XMM-Newton survey of M33 (Williams+, 2015)
J/MNRAS/460/1739 : Giant HII regions BOND abundances (Vale Asari+, 2016)
J/MNRAS/472/308 : SNRs in M33: X-ray properties (Garofali+, 2017)
J/ApJ/842/97 : Spectroscopic obs. of 413 HII regions in M33 (Lin+, 2017)
J/ApJ/839/83 : GMOS spectroscopy of SNR candidates in M83 (Winkler+, 2017)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 8 A8 --- ID Source identifier used in this paper
10- 11 I2 h RAh [1] Hour of Right Ascension (J2000)
13- 14 I2 min RAm [32/35] Minute of Right Ascension (J2000)
16- 20 F5.2 s RAs Second of Right Ascension (J2000)
22 A1 --- DE- [+] Sign of Declination (J2000)
23- 24 I2 deg DEd [30/31] Degree of Declination (J2000)
26- 27 I2 arcmin DEm Arcminute of Declination (J2000)
29- 32 F4.1 arcsec DEs Arcsecond of Declination (J2000)
34- 36 I3 pc Diam [11/183] Apparent diameter
38- 40 F3.1 kpc rho [0.2/8.1] Galactocentric distance
42- 45 A4 --- --- [L10- ]
46- 48 I03 --- [LBW2010] ? Long+ 2010, J/ApJS/187/495 identifier
50- 54 A5 --- --- [LL14- ]
55- 57 I3 --- [LL2014b] ? Lee & Lee 2014, J/ApJ/793/134 identifier
59- 65 A7 --- [GWP2017] XMM identifier
from Garofali+, 2017, J/MNRAS/472/308
67- 69 A3 --- X-ray X-ray detected? (1)
71- 74 A4 --- Prev Literature code of a previous spectrum (2)
76- 78 A3 --- New New spectrum from MMT observations?
80- 82 A3 --- Conf A [SII]/Hα≥0.4 confirmation? (3)
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Note (1): We have listed an object as X-ray detected if the significance of the
detection was 3σ with Chandra by Long+ (2010, J/ApJS/187/495) or with
XMM-Newton by Garofali+ (2017, J/MNRAS/472/308).
Note (2): Code as follows:
L10 = Long et al. (2010, J/ApJS/187/495);
LL14 = Lee & Lee (2014, J/ApJ/793/134);
G98 = Gordon et al. (1998ApJS..117...89G 1998ApJS..117...89G);
S93 = Smith et al. (1993ApJ...407..564S 1993ApJ...407..564S);
BK85 = Blair & Kirshner (1985ApJ...289..582B 1985ApJ...289..582B).
Note (3): We record an object as [SII]:Hα confirmed if we find an
[SII]:Hα ratio greater than or equal to 0.4, or if it was not
observed by us but previous observers have reported a similarly high
ratio. Objects with no entry in this column are objects without (to
the best of our knowledge) any previous spectroscopic follow-up.
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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- 8 A8 --- ID Source identifier used in this paper
10- 13 I4 10-20W/m2 FHa [2/2485] Hα flux (1)
15- 15 A1 --- u_Hb [~] Approximation flag on Hb
16- 19 I4 --- Hb [19/126]? Hβ emission line
strength (2)
21- 21 A1 --- u_[OIII] [~] Approximation flag on [OIII]
22- 25 I4 --- [OIII] [13/693]? The [OIII]5007Å emission
line strength (2)
27- 27 A1 --- u_[OI] [~] Approximation flag on [OI]
28- 31 I4 --- [OI] [8/151]? The [OI]6300Å emission line
strength (2)
33- 35 I3 --- Ha [300] Halpha emission line strength (2)
37- 37 A1 --- u_[NII] [~] Approximation flag on [NII]
38- 41 I4 --- [NII] [-8/190]? The [NII]6584A emission line
strength (2)
43- 43 A1 --- u_[SII]6717 [~] Approximation flag on [SII]6717
44- 47 I4 --- [SII]6717 [28/253]? The [SII]6717A emission line
strength (2)
49- 49 A1 --- u_[SII]6731 [~] Approximation flag on [SII]6731
50- 53 I4 --- [SII]6731 [19/195]? The [SII]6731Å emission line
strength (2)
55- 55 A1 --- u_[SII]/Ha [~] Approximation flag on [SII]/Ha
56- 60 F5.2 --- [SII]/Ha [0.1/1.5]? Ratio of [SII] to Halpha lines
62- 64 F3.1 0.1nm FWHM [4.2/9.1] Full-Width at Half-Maximum of
Hα line in Angstroms
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Note (1): This is the flux sampled by a 1.5 arcsec diameter fiber, not the
total flux from the entire object. Since all the objects are larger
than the fibers that sampled them, this flux is best interpreted
as a surface brightness. In units of 1e-17erg/s/cm2.
Note (2): We follow the convention where the Hα flux is taken to be 300,
except for the ratio of the two [S II] lines where we give the
simple ratio between those two lines. We have not quoted errors for
the various values contained in the table, as it is unclear how to
do this in a robust manner. Based on a comparison of the flux ratios
in spectra of the same object observed on multiple nights, the ratio
errors for bright, well-observed lines are typically less than 15%.
Lines where the accuracy of the line ratio is clearly worse than
this have entries preceded by a ∼ symbol.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 23-Jan-2019