jo-anne brown observations of the galactic magnetic field from the international galactic plane...
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Jo-Anne Brown
Observations of the
Galactic Magnetic Fieldfrom the
International Galactic Plane Survey
People
SGPSCGPS
• Russ Taylor• Tom Landecker• Andrew Gray• Rob Reid• Roland Kothes• Dave Delrizzo• Bulent Uyaniker• Marta Peracaula
• Marijke Haverkorn • Bryan Gaensler• Natalya Bizunok• Naomi McClure-Griffiths• John Dickey• Anne Green
People
SGPSCGPS
• Russ Taylor• Tom Landecker• Andrew Gray• Rob Reid• Roland Kothes• Dave Delrizzo• Bulent Uyaniker• Marta Peracaula
• Marijke Haverkorn • Bryan Gaensler• Natalya Bizunok• Naomi McClure-Griffiths• John Dickey• Anne Green
Outline
Introduction Observations: CGPS Observations: SGPS Summary
The Galactic Magnetic Field
• field is concentrated in disk• follows the spiral arms• local field is cw• Sagittarius field is ccw• additional reversals unclear• Determining the location of reversals may help understand the evolution of the field.
Faraday Rotation
Probes of the Field
Pulsars
EGS
Compact Polarised Sources
Pulsars: 529
Compact Polarised Sources
Pulsars: 529
EGS: 887
First Large Catalog of EGS (555 sources): Simard-Normandin, M, P. P. Kronberg, Button, S (1981) ApJS, 45, 91
Low-latitude Polarised Sources
Pulsars: 375
EGS: 121
Low-latitude Polarised Sources
EGS: 121
Pulsars: 375
SGPSCGPS
Observations
Canadian Galactic Plane Survey
Pilot Project (PhD): Magdalen Normandeau
CGPS Region: Pulsars and EGS
CGPS Region: Pulsars and EGS
Science with the CGPS
• Field Alignment with the spiral arms • Reversals in the outer Galaxy• Small-scale field correlation with the large-scale field.
• Latitude Dependence
Science with the CGPS
• Field Alignment with the spiral arms • Reversals in the outer Galaxy• Small-scale field correlation with the large-scale field.
• Latitude Dependence
Appropriate Longitude Range
105o
135o
Previous Studies
Data ranges: Lyne & Smith (1989):105 < l < 135, |b| < 30
Han et al. (1999): 104 < l < 119, |b| < 30
Path Length Comparison
CGPS for 105 < l < 135
Combining Pulsars with CGPS EGS:
No detectablemagnetic field reversal in the outer Galaxy.
Published: ApJ, 592:L29-L32, July 2003
Science with the CGPS
• Field Alignment with the spiral arms • Reversals in the outer Galaxy• Small-scale field correlation with the large-scale field.
• Latitude Dependence
CGPS Region: Pulsars and EGS
RM vs Latitude
RM vs Latitude
Calculating the Scale Height
Calculating the Scale Height
Southern Galactic Plane Survey
PhD Thesis: Naomi Mclure-Griffiths
SGPS Region: Pulsars and EGS
SGPS Region: Pulsars and EGS
Comparing CGPS and SGPS
RM vs Longitude: SGPS
RM Modulation by Spiral Arms
Binsize: 3o Stepsize: 0.5o
Binned CGPS RMs over Stokes I
Summary
IGPS has yielded much needed EG RMs- 1078 (so far) in CGPS I,II,III
- 149 in SGPS (depolarization) No B-Field reversals in the Outer Galaxy Rough calculations show magneto-ionic scale
height of ~1.2 kpc at l=110o
RM “oscillations” may correlate with HII or arms
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