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