GASKAP
The Galactic ASKAP Survey
On behalf of the GASKAP team
Dr Andrew Walsh
ASKAP – the Australian SKA Pathfinder
• 36 x 12m antennas
• Frequency range from 700 – 1800 MHz
• 30 square degree field of view
• Maximum baseline ~6km
GASKAP2
ASKAP – the Australian SKA Pathfinder
• First 5 years, about 75% of time for Survey Science Projects (each at least 1500 hours)
GASKAP3
• Evolutionary Map of the Universe (EMU)
• Widefield ASKAP L-Band Legacy All-Sky Blind Survey (WALLABY)
• The First Large Absorption Survey in HI (FLASH)
• An ASKAP Survey for Variables and Slow Transients (VAST)
• Polarization Sky Survey of the Universe's Magnetism (POSSUM)
• The Commensal Real-time ASKAP Fast Transients survey (CRAFT)
• Deep Investigations of Neutral Gas Origins (DINGO)
• The High Resolution Components of ASKAP (VLBI)
• Compact Objects with ASKAP: Surveys and Timing (COAST)
GASKAP –The Galactic ASKAP Survey
GASKAP – The Galactic ASKAP Survey
GASKAP4
• HI emission at 1420 MHz
• OH emission 1612, 1665 and 1667 MHz
• Galactic Plane: |b|<10°, 167° < l < 360° and 0° < l < 79° (all declinations south of δ=+40°)
• Entire area of Magellanic Stream and Clouds
• Sensitivity typically 1K at 30” resolution and 1 km/s
GASKAP – The Galactic ASKAP Survey
GASKAP5
• HI emission at 1420 MHz
• OH emission 1612, 1665 and 1667 MHz
• Galactic Plane: |b|<10°, 167° < l < 360° and 0° < l < 79° (all declinations south of δ=+40°)
• Entire area of Magellanic Stream and Clouds
• Sensitivity typically 1K at 30” resolution and 1 km/s
GASKAP – The Galactic ASKAP Survey
GASKAP6
• HI emission at 1420 MHz
• OH emission 1612, 1665 and 1667 MHz
• Galactic Plane: |b|<10°, 167° < l < 360° and 0° < l < 79° (all declinations south of δ=+40°)
• Entire area of Magellanic Stream and Clouds
• Sensitivity typically 1K at 30” resolution and 1 km/s
Maser science with GASKAP
GASKAP7
• Evolved stars
• Star formation
• Galactic kinematics/structure
• Magnetic fields
• Variability
• Milky Way – Magellanic Clouds comparison
Maser science with GASKAP
GASKAP8
Evolved stars
• Flux limited survey of evolved stars in the Milky Way
• Expect to detect thousands of OH masers
• Identify rare masers associated very young (<100yr) planetary nebulae
Maser science with GASKAP
GASKAP9
Star formation
• Flux limited survey of star formation masers in the Milky Way
• Expect to detect ~103 OH masers
• Maser timelines
• Star formation structure – disks/outflows0 104 2×104 3×104 4×104 5×104
Time (years)
UCHII
Class II CH3OH maser
Class I CH3OH maser OH maser
H2O maser
Breen et al. (2010) maser timeline:
Maser science with GASKAP
GASKAP10
Galactic Structure/Kinematics
• Both evolved star and star formation masers used to trace structure and kinematics of the Milky Way and MCs
• Star formation masers will be tightly linked to spiral arms – compare with Class II methanol masers from MMB
• Structure of the Galactic Centre
(courtesy John Bally)(courtesy John Bally)
Galactic Centre Structure(Artist’s impression byJohn Bally – private communication)
Maser science with GASKAP
GASKAP11
Magnetic Fields
• OH, as paramagnetic molecule, is ideal polarisation tool
• Demonstrates Zeeman splitting (large splitting factor, milliGauss fields)
• Can be used to measure magnetic fields:larger scale with star forming OH maserssmall, local fields with evolved star masers
• Sensitivity to probe polarisation of weak maser features
Maser science with GASKAP
GASKAP12
Variability
• OH masers are typically slowly varying over years
• GASKAP will involve multi-epoch observations of bright masers over 5 years
• Closely track variability in a large number of masers over these timescales
Maser science with GASKAP
GASKAP13
Milky Way – Magellanic Clouds comparison
• GASKAP MC observations will increase number of known masers by two orders of magnitude
• Compare the occurrence of OH masers under normal- (Galactic) and low-metallicity (MCs) circumstances
Summary
GASKAP14
• GASKAP will be coming in a few years
• Observe the Galactic Plane, MCs and Magellanic Stream
• Includes 1612, 1665 and 1667 MHz OH transitions
• Discover thousands of new masers
• Learn about: Evolved stars, Star formation, Galactic kinematics/structure, Magnetic fields, OH maser Variability, Milky Way – MCs comparison
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