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FACULTY OF MATHEMATICS
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Radio Surveys of the Galactic Plane
Melvin Hoare, Cormac Purcell, Bill Cotton, Mark Wieringa, Ed
Churchwell, James Urquhart, Katharine Johnston, Ivayla Kalcheva,
Tonye Sokari, Harry Steggles and the CORNISH Survey teams
Outline
• 
The CORNISH-North Survey
• 
Ultra-Compact H II regions
• 
Planetary Nebulae
• 
The CORNISH-South Survey
• 
The MAGPIS Survey
• 
• 
The THOR Survey
• 
• 
Evolved H II regions and SNRs
RRLs, OH and H I
Summary
Radio surveys of the Galactic plane
•  Most previous surveys at either at low frequency (≤ 1.4
GHz) or low spatial resolution (single-dish)
•  Not useful for the study of compact, thermal sources such
as dense photo-ionized gas or stellar wind sources
UCHII (Avalos et al. 2009)
MYSO (Gibb & Hoare 2007)
CORNISH-North
•  The Co-Ordinated Radio ‘N’ Infrared Survey for Highmass star formation
•  5 GHz, 1.5ʺ″ resolution VLA survey of the Galactic Plane
•  10o<l<65o, |b|<1o Spitzer northern GLIMPSE I region
•  400 hours in total
•  0.4 mJy rms noise level
•  Data reduction and source catalogue complete:
•  Purcell et al. (2013)
•  cornish.leeds.ac.uk
Example Sources
•  Cometary ultra-compact H II regions
•  Similar morphology in radio and PAH emission
Deeply embedded H II regions
•  Potentially some UCHII regions hidden behind dense dust
clouds that are missed in IR surveys
Planetary Nebulae
•  Similar radio and IR morphology, but isolated and not in
molecular cloud
New PN
•  Newly discovered PN
UKIDSS 2µm image
New Radio Stars
Radio Galaxies
•  Double-lobed sources with no IR counterpart
Object Types
1800
1600
1400
1200
1000
800
600
400
200
0
HII
PN
Radio Stars
Radio Galaxy
IR Quiet
PN Sample
Sokari (PhD, Leeds)
UCHII Region Sample
Kalcheva (PhD, Leeds)
UCHII Region Sample
terion for massive star formation determined by Kauffmann et al.
(2010b, i.e., where m(r) ! 580 M⊙ (Reff /pc)1.33 ; yellow shaded region).4 The LH threshold was determined from studies of nearby
molecular clouds and is therefore not specific to massive star formation. The Kauffmann et al. (2010b) criterion was determined
from an investigation of the mass-radius relationship of nearby
molecular clouds (<500 pc, i.e., Ophiuchus, Perseus, Taurus and
the Pipe Nebula; Kauffmann et al. 2010a,b) and known samples of
high-mass star formation such as those of Beuther et al. (2002),
Hill et al. (2005), Motte et al. (2007) and Mueller et al. (2002),
Kauffmann et al. (2010b). However, as stated in Paper I the lower
bound of 0.05 g cm−2 is approximately twice the LH-threshold and
provides a better constraint than Kauffmann et al. for the high-mass
end of the distribution (i.e., Reff " 0.5 pc or Mclump "500 M⊙ ).
So while the LH threshold can be considered a reasonable criterion for “efficient” star formation the value of 0.05 g cm−2 , found
to fit the lower envelope of the mass-radius relationship for both
methanol maser and H ii region associated clumps, can be considered the threshold required for “efficient” high mass star formation.
The area highlighted in green in the upper portion of Fig. 20
shows the region of parameter space where massive proto-cluster
(MPC) candidates are expected to be located (Bressert et al. 2012;
see Paper I for details). Six of our sources are located in this region. Three are associated with W49A (AGAL043.148+00.014,
AGAL043.164−00.029 and AGAL043.166+00.011) and have a
combined mass ∼ 4 × 105 M⊙ . One clump is associated with each
of the W31 and W51 star-forming regions (AGAL010.472+00.027
and AGAL049.489−00.369, respectively). The remaining source
is AGAL019.609−00.234. All six have masses above 104 M⊙
and are therefore possible progenitors of future young massive
clusters (YMCs) such as the Arches and Quintuplet clusters
(Portegies Zwart et al. 2010). The MPC candidates in W31, W49A
and W51 were previously identified by Ginsburg et al. (2012) from
an analysis of 1.1 mm continuum data from the BGPS and so
AGAL019.609−00.234 is the only new potential MPC identified
by this work.5
In Paper I we identified 7 MPC candidates, six of which were
new, and together with those identified by Longmore et al. (2012)
and Ginsburg et al. (2012) we estimated the total population of
MPC candidates is likely to be # 20 ± 6. However, comparing
this estimate with the number of known YMCs we found that
ATLASGAL-CORNISH UC H ii regions
21
Urquhart et al. (2013)
CORNISH-ATLASGAL cross-matches
Figure 21. Galactic distribution of the ATLASGAL-CORNISH associations with known distances and masses above the completeness limit
(1,000 M⊙ ). The Galactic positions of our sample derived from the maser
4
R. Cesaroni et al.: The infrared emission of young HII regions: A Herschel/Hi-GAL study
Table 1. Steps of the source selection process.
UCHII Luminosities
HIIs separation
with Hi-GAL
CORNISH
HIIs
281
′′
→
<11. 5
244
→
counterparts
230
→
Hi-GAL counterparts
with ≥3 fluxes
217
→
CORNISH-HiGAL
<11.′′ 5
204
R. Cesaroni et al.: The infrared emission of young HII regions: A Herschel/Hi-GAL study
→
with distance
estimate
200
5
Fig. 3. Comparison between our and URQ13 estimates of the clump
Fig. 2. Distribution of the luminosities of CORNISH HII regions. The masses associated with CORNISH HII regions. The straight line correFig. sponds
5. Lyman
continuum
solid and dotted histograms are obtained by choosing, respectively, the
to M
= Mgas .of the selected sample of CORNISH HII reDistribution of the clump mass associated with CORNISH HII gions versus theUrqcorresponding
luminosity, obtained from
far and near distances for the 11 targetsCesaroni
for which the KDA
could
not be CORNISH-Hi-GALbolometric
et al.
(2015)
cross-matches
. solved.
The solid
and
dotted
histograms
are
obtained
by
choosing,
rethe Hi-GAL data. The colour of the symbols indicates the choice of the
For the sake of comparison, the distribution of the HII regions
Cometary UCHII regions
•  Preponderance of cometary
UCHII regions implies an
ordered but non-uniform
density environment
•  Massive stars born off-centre
in a density gradient
•  Implies external triggering of
massive star formation
•  Test UCHII region dynamical
and evolutionary models
G014.3313-00.6397
8 µm 3'
Active Contours
•  Developed by Duane
Carey (School of
Computing) as part of
the VIALACTEA
project
Cometary H II Region Simulations
Steggles (PhD, Leeds)
Low Res/Low Frequency Surveys
•  MGPS
•  MOST
•  843 MHz
•  45 arcsec resolution
•  245o<l<365o, |b|<10o
•  MAGPIS
•  VLA B+C+D configurations
•  1.4 GHz
•  6 arcsec resolution
•  5o<l<48.5o, |b|<0.8o
843 MHz (blue), 8µm (green), 24µm (red)
(Buemi, Bufano, Umana)
Evolved H II Regions
MAGPIS 1.4 GHz (blue), Herschel 70µm (red)
CORNISH-South
•  450 hours project on ATCA
•  Southern Spitzer GLIMPSE area 295o<l<350o, |b|<1o
•  Resolution ~3"
•  First Galactic plane survey to use broad band systems
and on-the-fly interferometry
•  4.5-6.5 GHz and 8-10 GHz
•  noise level of 0.2 mJy
•  Simultaneous RRL survey (H98α, H112α)
THOR
•  VLA C+D configurations + GBT
•  1-2 GHz continuum
•  15-20 arcsec resolution
•  15o<l<65o, |b|<1.25o
•  HI 21cm line
•  19 Recombination Lines
•  4 OH lines
•  www.mpia.de/thor
Conclusions
•  CORNISH surveys are delivering an unbiased census of
UCHII regions to test dynamics and feedback in massive star
formation
•  Large legacy of Galactic plane radio sources including
evolved stellar populations and extra-galactic sources
•  Lower frequency radio surveys enabling studies of evolved
H II regions, wind-blown bubbles and SNRs
Plane Surveys Relevant for MSF
Survey
I/VPHAS+
UKIDSS GPS
GLIMPSE
MSX
MIPSGAL
Herschel
SCUBA2
GRS
MMB
IGPS
CORNISH
MAGPIS
λ
Hα
J,H,K
4-8 µm
8-21 µm
24µm
70-500 µm
850 µm
13
CO 1-0
CH3OH
H I 21 cm
5 GHz
1.4 GHz
Beam
0.7"
0.7"
2"
20"
6"
5-34"
14"
46"
0.1"
60"
1"
5"
Sens.
Probe
Nebulae, Em *
0.02mJy Stars & Nebulae
1
Hot Dust
100
Warm Dust
20
Cool Dust
10
Molecular Gas
Masers
Atomic Gas
2
Compact Ionized Gas
5
Diffuse Ionized Gas