Unravelling

the mysteries of stellar winds with polarimetric

observations of

millisecond pulsars

Xiaopeng

YOU

Outline•

Pulsar wind from J1748-2446A

•

Solar wind effect by J1730-2304

Basic properties of J1748-2446A•

Discovered in 1990, Parkes

telescope, 20-cm

(Lyne

et al., 1990)•

Locating in the globular cluster Terzan

5

•

Period : 11.56 ms•

Dispersion Measure: 242.0

•

Circular orbital period: 1.8 hours•

Projected semi-major axis: 0.119 light second

•

Companion: White drawf, 0.089 Mʘ•

Eclipsing time: variable, depending on frequency, greater than Roche lobe, 0.2 Rʘ

•

Sometimes disappearing

•

3 observations at 20cm•

2 observations at 10/50 cm.

•

Almost all observations cover whole orbital phase.

Observations

Eclipsing : 20 cm

Eclipsing : 50 cm

Eclipsing : 10 cm

Depolarization Phenomenon•

3-min sub-integration

•

Searching for RM and showing polarization profiles.

•

RM: 173.6 rad

m-2

•

found PSR-WD system with depolarization phenomenon

Polarization profiles•

10 cm: no linear polarization, because of weak signal and low linear polarization

Polarization properties VS orbital phase

Turbulence of Pulsar wind

2 4RM 1s l >

2 2 40 RM( ) exp( 2 )P Pl s l= -

Orbital Phase [0.7,0.8] < 4

[0.55, 0.7] [0.8,0.9]others

•

Depolarization due to turbulence of Faraday Rotation (Burn 1996)

•

Lower frequency, easier depolarized

•

Assume significant depolarization when

2RM (rad m )s -

RM4 25s< <

RM25 100s< <

Conclusions •

Obtain polarization profiles for 3 bands for the eclipsing pulsar PSR J1748-2446A

•

Found no eclipse at 10 cm•

Found PSR-WD system with depolarization phenomenon

•

Duration of both total eclipse and depolarization depend on frequency

•

Depolarization because of turbulence of Faraday rotation of pulsar wind

•

Help understanding the eclipse mechanism

Some research of solar wind by J1730-2304

•

Using a millisecond pulsars PSR J1730- 2304 (be

=0.19o) •

Obtain both RM and DM from the solar wind

•

Model fitting our measurement to obtain magnetic field of solar wind (more work to do)

Obtain RM from the Sun•

Adjust RM to optimize the linearly polarized intensity, depolarization

•

Separate the each observation into two halves •

Calculating PA difference close and far from the Sun

•

Subtracting the contribution from ionosphere (IRI model)

141216:22:33 R0=6.4 Rs

PA=135.4o, RMs=49.2 rad

m-2

Obtain DM from the Sun•

Fitting timing model

•

Obtain extra timing residual from the Sun

Obtain DM from the Sun•

Fitting timing model

•

Obtain extra timing residual from the Sun

141216:22:33

R0=6.4 Rs

t=15.4μs, DMs=7.0X10-3

cm-3pc

Observational results