cornish a 5 ghz vla survey of the northern galactic plane · the university of manchester jbca the...

The University of Manchester

JBCAThe Galactic Plane In depth and across the spectrum

CORNISH A 5 GHz VLA survey of the

northern Galactic PlaneCormac Purcell, Melvin Hoare, Bill Cotton, Phil Diamond and the CORNISH team


JBCA

Universifty of Barcelona: Josep Paredes.

CORNISH consortium members

University of Leeds:Melvin Hoare, Stuart Lumsden, Rene Oudmaijer, James Urquhart.

University of Manchester: Phil Diamond, Cormac Purcell, Simon Garrington, Tom Muxlow, Steve Smethurst, Alastair Gunn, Ralph Spencer, Albert Zijlstra, Anita RichardsGarry Fuller

NRAO: Bill Cotton, Claire Chandler, Debra Shepherd.

University of Wisconsin: Ed Churchwell.

UNAM: Stan Kurtz.

University of Maryland: Lee Mundy.

Cornell University: Paul Goldsmith, Jagadeep Pandian.

Boston University: Jim Jackson, Ronak Shah.

Liverpool JMU: Toby Moore.DRAO:

Sean Doherty.

University of Hertfordshire:Tim Gledhill.

University of Southampton: Rob Fender

University of Jaen: Josep Marti.


JBCAMotivation: massive star formation

∘ Thermal IR and sub-mm bands well covered at present or in near future

UK

IDS

S

GLI

MP

SE

HE

RS

CH

EL

SC

UB

A2

MIP

SG

AL

Figure: Melvin Hoare

MYSO

UCHII




∘ No equivalent radio survey for compact ionised gas

UK

IDS

S

GLI

MP

SE

HE

RS

CH

EL

SC

UB

A2

MIP

SG

AL


MYSO

UCHII





∘ Essential to distinguish more evolved UCHII regions from their precursors - massive young stellar objects (MYSOs)U

KID

SS

GLI

MP

SE

HE

RS

CH

EL

SC

UB

A2

MIP

SG

AL


MYSO

UCHII





∘ Essential to distinguish more evolved UCHII regions from their precursors - massive young stellar objects (MYSOs)U

KID

SS

GLI

MP

SE

HE

RS

CH

EL

SC

UB

A2

MIP

SG

AL

CO

RN

ISH


MYSO

UCHII



∘ Co-Ordinated Radio 'N' Infrared Survey for High-mass star formation

- A uniform and high resolution 5 GHz radio counterpart to the IR GLIMPSE I survey

- Also comparable with UKIDSS, IPHAS, GRS, MMB ...



∘ Co-Ordinated Radio 'N' Infrared Survey for High-mass star formation

- A uniform and high resolution 5 GHz radio counterpart to the IR GLIMPSE I survey

- Also comparable with UKIDSS, IPHAS, GRS, MMB ...

∘ Multi-λ colour-colour diagrams will allow identification of:

- UCHII regions (red, radio-loud, 8μm PAHs emission)

- MYSOs (red, radio-quiet)

- PNs and PPNs (red, distinct IR morphologies )

- Active stars (blue)

- Extragalactic radio-galaxies, AGN and Quasars


JBCASurvey design

∘ Northern GLIMPSE I region

∘ 10o < l < 65o |b| < 1o

Galactic longitude

Gal

actic

long

itude

MSX 8µm

VLA array configurations B & BnA


JBCASurvey design


∘ 10o < l < 65o |b| < 1o

∘ 1.5'' resolution on the VLA

Galactic longitude

Gal

actic

long

itude

MSX 8µm



JBCASurvey design


∘ 10o < l < 65o |b| < 1o

∘ 1.5'' resolution on the VLA

∘ < 4 mJy/bm RMS noise

- Sufficient to detect a BO star across the Galaxy

Galactic longitude

Gal

actic

long

itude

MSX 8µm



JBCASurvey design

∘ 110 square degree area divided into 42 blocks

∘ 1 block = 8 hours

BnA Array

B Array


JBCASurvey design

∘ Scan in RA, & phase- calibrate at end of each row

∘ 20 pointings x 11 rows

∘ Uniform dwell times |b| <1.0

BnA Array

B Array


JBCASurvey design

∘ Hexagonal pointing pattern

∘ Separation between pointings is 7.4' compared with a primary beam of 8.5'

∘ Sensitivity uniform to 10%





JBCASurvey design

∘ 2 x 40s snapshot images

∘ Separated by 4 hours HA

∘ 2.5'' x 1.5'',

∘ Θmaj / Θmin = 1.6





JBCAObservations

∘ July – September '06

- 21 blocks complete

- 21o < l < 45o

- VLA antennas only

2006


JBCAObservations

∘ July – September '06


- 21o < l < 45o

- VLA antennas only

∘ September '07– Feb '08


- Remainder + cleanup

- VLA + EVLA antennas

∘ 9327 fields observed

∘ 20485 snapshot pointings

20062007


JBCAObservations

∘ Actual dwell times 77 – 80 seconds for most fields


JBCAData processing pipeline

∘ Custom pipeline built using 'industry standard' AIPS & experimental Obit software by Bill Cotton

∘ Scripted in python

AIPS Tasks Obit Tasks

ObitTalk / Python

Control Scripts

Raw Data (stored as FITS files)

AIPS Catalogue

MySQLDatabase

User



∘ Custom pipeline built using 'industry standard' AIPS & experimental Obit software by Bill Cotton

∘ Scripted in python

∘ Key Obit technologies:

- Automatic flagging

- Automatic clean boxes

- Automatic re-centering of sources on a pixel

AIPS Tasks Obit Tasks

ObitTalk / Python

Control Scripts

Raw Data (stored as FITS files)

AIPS Catalogue

MySQLDatabase

User



∘ Primary data product is a mosaiced image 'tile'



∘ Primary data product is a mosaiced image 'tile'

∘ Approximately 25 fields contribute to each tile

∘ Each field is imaged to the 10% primary beam power (r=8')

20'

Weight image


JBCAData quality

RMS noise map

∘ Twin peaked RMS noise distribution

- Peaks at 0.25 & 0.35 mJy/bm

- Median RMS = 0.32 mJy/bm

∘ 96 % fields below target 0.4 mJy/bm


JBCAData quality

RMS noise map

∘ 2006 data: 0.35 mJy/bm peak

- VLA antennas – less sensitive

- Thunderstorm season - stripes caused by weather

20o < l < 49o


JBCAData quality

RMS noise map

∘ 2007 / 2008 data: 0.25 mJy/bm

- Combined EVLA + VLA antennas

- EVLA antennas more sensitive

10o < b < 20o & 49o < b < 65o


JBCAData quality


JBCAData quality

∘ Extended emission > 15'' not well CLEANed

- Will be processed as a secondary data product


JBCAData quality


JBCAData quality

=

=

=

=

=

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JBCAThe CORNISH catalogue

∘ 4322 objects detected above 7 sigma




∘ Majority are compact objects

- Median Θ = 1.7''

- ~¼ are unresolved




∘ Majority are compact objects

- Median Θ = 1.7''

- ~¼ are unresolved

∘ Median flux density = 5.7 mJy




∘ Galactic latitude distribution





∘ Centrally peaked for extended sources (Θ > 2'')





∘ Centrally peaked for extended sources (Θ > 2'')

∘ Flat for unresolved sources



∘ Estimated completeness by finding artificial sources injected into the uv-data for a 'blank' tile



90 % complete at ~4.0 mJy level

50 % complete at ~2.7 mJy level

∘ Estimated completeness by finding artificial sources injected into the uv-data for a 'blank' tile

- 90 % complete at the 4.0 mJy level

- 50 % complete at the 2.7 mJy level



∘ Estimated number of spurious sources by running the source finder on an inverted tile



∘ Estimated number of spurious sources by running the source finder on an inverted tile

∘ Best case: No spurious sources above 5.5 sigma

∘ Typical case: No spurious sources above 6.5 sigma


JBCACounterparts to the CORNISH sources

∘ Currently finalising the catalogue before finding counterparts

- Merging over-resolved sources

- Weeding out sidelobe artefacts






∘ Plan to cross-match with UKIDSS (IR-JHK), IPHAS (H-α), GPS-20cm (spectral index), MMB (masers), IRDC catalogues






∘ Plan to cross-match with UKIDSS (IR-JHK), IPHAS (H-α), GPS-20cm (spectral index), MMB (masers), IRDC catalogues

∘ Currently focused on GLIMPSE: cross-matched within 2''


JBCACounterparts: GLIMPSE & 2MASS

∘ Find 314 CORNISH sources with GLIMPSE data in all bands

- Matching compact sources only



∘ We can calculate the reliability of each match based on the source density above the magnitude of the IR source

Sutherland & Saunders 1992



∘ We can calculate the reliability of each match based on the source density above the magnitude of the IR source

Sutherland & Saunders 1992

8.0μm reliability 4.5μm reliability 3.6μm reliability



Unfiltered:



Filtered: R > 0.999



=+

Filtered: R > 0.999

Known UCHIIs


JBCAFuture work: Identifying sources

G25.716+0.049

G26.598-0.024

GLIMPSECORNISH 5 GHz

∘ Compact UCHII regions – halo of PAHs emission at 8μm

Red=8.0µm, Green=4.5µm, Blue=3.6µm



G21.874+0.008

G26.544+0.414


∘ Cometary UCHII regions



G22..154-0.154


∘ Active stars: blue infrared colours



G23.371-1.034

G26.238-0.79

∘ Radio lobes from external galaxies


JBCASummary

∘ 1st uniform, deep, broad, high-resolution survey targeting UCHII regions at 5 GHz.

∘ 10o < l < 65o, |b| < 1o Beam=1.5' Sens = 2-4 mJy/bm


JBCASummary



∘ Version 1.0 data reduction finally complete

- Initial pipeline reduced tiles released April 2009 (V0.9)

- Official catalogue release to follow – next few months

- Followed by image & calibrated uv-data server


JBCASummary



∘ Version 1.0 data reduction finally complete

- Initial pipeline reduced tiles released April 2009 (V0.9)

- Official catalogue release to follow – next few months

- Followed by image & calibrated uv-data server

∘ Priority now on cross-matching with complementary surveys

- Identifying UCHIIs, MYSOs, (P)PN, Active stars ...

For more information see the CORNISH survey homepage:

http://www.ast.leeds.ac.uk/Cornish/

cornish a 5 ghz vla survey of the northern galactic plane · the university of manchester jbca the...

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