GASKAP The Galactic ASKAP Survey On behalf of the GASKAP team Dr Andrew Walsh.
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Transcript of GASKAP The Galactic ASKAP Survey On behalf of the GASKAP team Dr Andrew Walsh.
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