J/MNRAS/448/2344 MALT-45, a 7mm survey of the southern Galaxy (Jordan+, 2015)
MALT-45: a 7 mm survey of the southern Galaxy.
I. Techniques and spectral line data.
Jordan C.H., Walsh A.J., Lowe V., Voronkov M.A., Ellingsen S.P.,
Breen S.L., Purcell C.R., Barnes P.J., Burton M.G., Cunningham M.R.,
Hill T., Jackson J.M., Longmore S.N., Peretto N., Urquhart J.S.
<Mon. Not. R. Astron. Soc., 448, 2344-2361 (2015)>
=2015MNRAS.448.2344J 2015MNRAS.448.2344J (SIMBAD/NED BibCode)
ADC_Keywords: Surveys ; Milky Way ; Masers
Keywords: masers - surveys - stars: formation - ISM: molecules -
Galaxy: structure - radio lines: ISM
Abstract:
We present the first results from the MALT-45 (Millimetre Astronomer's
Legacy Team-45GHz) Galactic Plane survey. We have observed 5 square
degrees (l=330°-335°, b=±0.5°) for spectral lines in the
7mm band (42-44 and 48-49GHz), including CS (1-0), class I CH3OH
masers in the 7(0,7)-6(1,6) A+ transition and SiO (1-0) v=0,1,2,3.
MALT-45 is the first unbiased, large-scale, sensitive spectral line
survey in this frequency range. In this paper, we present data from
the survey as well as a few intriguing results; rigorous analyses of
these science cases are reserved for future publications. Across the
survey region, we detected 77 class I CH3OH masers, of which 58 are
new detections, along with many sites of thermal and maser SiO
emission and thermal CS. We found that 35 class I CH3OH masers were
associated with the published locations of class II CH3OH, H2O and
OH masers but 42 have no known masers within 60 arcsec. We compared
the MALT-45 CS with NH3 (1,1) to reveal regions of CS depletion and
high opacity, as well as evolved star-forming regions with a high
ratio of CS to NH3. All SiO masers are new detections, and appear to
be associated with evolved stars from the Spitzer Galactic Legacy
Infrared Mid-Plane Survey Extraordinaire (GLIMPSE). Generally, within
SiO regions of multiple vibrational modes, the intensity decreases as
v=1, 2, 3, but there are a few exceptions where v=2 is stronger
than v=1.
Description:
MALT-45 is an untargeted Galactic plane survey for spectral lines
which are commonly bright in star-forming regions at 45GHz (7mm
waveband). We have so far observed 5 square degrees within the region
bounded by 330°≤l≤335°, b=±0.5°. MALT-45 observations
were conducted on the Australia Telescope Compact Array (ATCA), which
provides 2x2048MHz broad-band continuum windows for observing.
Section 1.1 discusses the primary lines surveyed, and their rest
frequencies dictate the positions of the broad-band windows for
MALT-45. Within the frequency ranges of the broad-band windows, we
survey for 12 spectral lines.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 112 77 Properties of detected MALT-45 class I CH3OH
maser emission (each maser was detected within
a 64MHz zoom window)
table3.dat 133 47 *Properties of detected MALT-45 SiO (1-0) maser
emission (each maser was detected within a
64MHz zoom window)
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Note on table3.dat: If data are not available in one of the lines for a source,
it was not detected by MALT-45.
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See also:
VIII/96 : 6-GHz methanol multibeam maser catalogue (Caswell+, 2010-12)
J/A+AS/124/509 : ATCA/VLA OH 1612 MHz survey. II. (Sevenster+ 1997)
J/MNRAS/359/1498 : Class I and class II methanol masers (Ellingsen+, 2005)
J/AJ/136/2391 : GLIMPSE Extended Green Objects catalog (Cyganowski+, 2008)
J/ApJS/196/9 : 95GHz methanol maser survey toward GLIMPSE EGOs (Chen+ 2011)
J/MNRAS/442/2240 : Accurate water maser positions from HOPS (Walsh+, 2014)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 12 A12 --- Name Source name (GLLL.ll+B.bb), derived from
Galactic coordinates of the brightest peak
14- 15 I2 h RAh Maser right ascension (J2000)
17- 18 I2 min RAm Maser right ascension (J2000)
20- 23 F4.1 s RAs Maser right ascension (J2000)
25 A1 --- DE- Maser declination sign (J2000)
26- 27 I2 deg DEd Maser declination (J2000)
29- 30 I2 arcmin DEm Maser declination (J2000)
32- 35 F4.1 arcsec DEs Maser declination (J2000)
37- 41 F5.1 Jy Speak Source peak flux density in 7mm band
43- 47 F5.1 --- RMS RMS noise level of the peak
50- 55 F6.1 km/s Vmin Velocity range of maser emission,
within a 1.5σ cutoff
58- 63 F6.1 km/s Vmax Velocity range of maser emission,
within a 1.5σ cutoff
65- 70 F6.1 km/s Vpeak Velocity at the peak
72- 76 F5.2 kpc Dist Kinematic distance calculated, based on
position and peak velocity (1)
78- 81 F4.2 kpc E_Dist Upper error for the kinematic distance
84- 87 F4.2 kpc e_Dist Lower error for the kinematic distance
89- 93 F5.2 K.km/s ICS ? Integrated intensity of CS (1-0) at the
brightest peak
95- 98 F4.2 K.km/s ISiO ? Integrated intensity of SiO (1-0) v=0 at the
brightest peak
100-105 A6 --- Rem Additional remarks (2)
107-112 A6 --- Omasers Associations with other masers and EGOs (3)
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Note (1): Kinematic distances are derived using the kinematic distance model
of Reid et al. (2009ApJ...700..137R 2009ApJ...700..137R).
All distances are assumed to be kinematically 'near', unless labelled
otherwise.
Note (2): Additional remarks as follows:
S = 44GHz detection from Slysh et al. (1994MNRAS.268..464S 1994MNRAS.268..464S)
V = 95GHz detection from Val'tts et al. (2000MNRAS.317..315V 2000MNRAS.317..315V)
E = 95GHz detection from Ellingsen (2005, Cat. J/MNRAS/359/1498)
C = 95GHz detection from Chen et al. (2011, Cat. J/ApJS/196/9)
P = indicates a blended spectrum of emission.
P1 = contains a strong peak of emission at a spatially distinct position, with
a different velocity to nearby strong masers (but not as strong as the
neighbour)
P2 = strong neighbour
P3 = next strongest neighbour
F = this maser has been labelled as being kinematically 'far', due to a
class II CH3OH maser being labelled as such by
Green & McClure-Griffiths (2011MNRAS.417.2500G 2011MNRAS.417.2500G)
Note that a source without an S, V, E or C remark is a new detection.
Note (3): Association is credited for any presence within 60 arcsec of the
class I CH3OH maser peak position. All velocities are specified to 0.1km/s,
and all flux densities are specified to two significant figures.
Associations flags as follows:
M = presence of a 6.7GHz class II methanol maser (Caswell et al.,
2011MNRAS.417.1964C 2011MNRAS.417.1964C, Cat. VIII/96)
W = presence of a 22GHz H2O maser (Breen et al. 2010MNRAS.406.1487B 2010MNRAS.406.1487B;
Walsh et al. 2011, Cat. J/MNRAS/416/1764; 2014, Cat. J/MNRAS/442/2240)
G = presence of an EGO classified by Cyganowski et al. (2008,
Cat. J/AJ/136/2391)
S = presence of a 1612 OH maser (Sevenster et al., 1997, Cat. J/A+AS/124/509)
C = presence of a 1665 or 1667MHz OH maser (Caswell, 1998MNRAS.297..215C 1998MNRAS.297..215C)
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 12 A12 --- Name Source name (GLLL.ll+B.bb), derived from
Galactic coordinates of the brightest peak
14- 15 I2 h RAh Maser right ascension (J2000)
17- 18 I2 min RAm Maser right ascension (J2000)
20- 23 F4.1 s RAs Maser right ascension (J2000)
25 A1 --- DE- Maser declination sign (J2000)
26- 27 I2 deg DEd Maser declination (J2000)
29- 30 I2 arcmin DEm Maser declination (J2000)
32- 35 F4.1 arcsec DEs Maser declination (J2000)
37- 40 F4.1 Jy Speak1 ? Source peak flux density, SiO v=1 (1)
42- 47 F6.1 km/s Vmini1 ? Velocity range of maser emission, SiO v=1,
within a 1.5σ cutoff (2)
49- 54 F6.1 km/s Vmax1 ? Velocity range of maser emission, SiO v=1,
within a 1.5σ cutoff (2)
56- 61 F6.1 km/s Vpeak1 ? Velocity at the peak, SiO v=1 (2)
63- 66 F4.1 Jy Speak2 ? Source peak flux density, SiO v=2 (1)
68- 73 F6.1 km/s Vmini2 ? Velocity range of maser emission, SiO v=2,
within a 1.5σ cutoff (2)
75- 80 F6.1 km/s Vmax2 ? Velocity range of maser emission, SiO v=2,
within a 1.5σ cutoff (2)
82- 87 F6.1 km/s Vpeak2 ? Velocity at the peak, SiO v=2 (2)
89- 91 F3.1 Jy Speak3 ? Source peak flux density, SiO v=3 (1)
93- 97 F5.1 km/s Vmini3 ? Velocity range of maser emission, SiO v=3,
within a 1.5σ cutoff (2)
99-103 F5.1 km/s Vmax3 ? Velocity range of maser emission, SiO v=3,
within a 1.5σ cutoff (2)
105-109 F5.1 km/s Vpeak3 ? Velocity at the peak, SiO v=3 (2)
111-114 F4.1 --- RMS RMS noise level, which indicates the most
statistically significant maser peak detected
among the three modes
116-119 F4.2 kpc Dist Kinematic distance calculated, based on
position and peak velocity (3)
121-124 F4.2 kpc E_Dist Upper error for the kinematic distance
127-130 F4.2 kpc e_Dist Lower error for the kinematic distance
132-133 A2 --- Omasers Additional remarks (4)
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Note (1): All flux densities are specified to two significant figures.
Note (2): All velocities are specified to 0.1km/s.
Note (3): Kinematic distances are derived using the kinematic distance model of
Reid et al. (2009ApJ...700..137R 2009ApJ...700..137R). All distances are assumed to be
kinematically 'near', except for G330.14-0.39, G331.08+0.17, G332.40-0.33 and
G334.20+0.22; when assumed to be near, unphysical distances and errors are
generated.
Note (4): Association is credited if the source position is within 30 arcsec of
the peak SiO maser position.
Associations flags as follows:
C = presence of a 1665 MHz OH maser from Caswell (1998MNRAS.297..215C 1998MNRAS.297..215C)
S = presence of a 1612 MHz OH maser from Sevenster et al. (1997,
Cat. J/A+AS/124/509)
W = presence of an H2O maser from Walsh et al. (2011, Cat. J/MNRAS/416/1764;
2014, Cat. J/MNRAS/442/2240)
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 12-Mar-2018