Jo-Anne Brown Observations of the Galactic Magnetic Field from the International Galactic Plane Survey

People SGPS CGPS 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 SGPS CGPS 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 SGPS CGPS

Observations

Canadian Galactic Plane Survey Pilot Project (PhD): Magdalen Normandeau

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 105 o 135 o

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 detectable magnetic 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

Calculating the Scale Height

Southern Galactic Plane Survey PhD Thesis: Naomi Mclure-Griffiths

SGPS Region: Pulsars and EGS

Comparing CGPS and SGPS

RM vs Longitude: SGPS

RM Modulation by Spiral Arms

Binsize: 3 o Stepsize: 0.5 o Binned CGPS RMs over Stokes I

Summary  IGPS has yielded much needed EG RMs (so far) in CGPS I,II,III in SGPS (depolarization)  No B-Field reversals in the Outer Galaxy  Rough calculations show magneto-ionic scale height of ~1.2 kpc at l=110 o  RM “oscillations” may correlate with H II or arms