Measurements of the scatter pulse broadening

of pulsar radio emission and a homogeneity of the turbulent plasma

in the near Galaxy

A.D. Kuzmin & B.Ya. Losovsky

Pushchino Radio Astronomy Observatory, Lebedev Physical Institute, Russia

Low frequency expands a frequency interval of sc dataand provide more precise determination of the frequency dependence

sc (ν) ν-

Large sample of 100 pulsars and uniform measurements and reduction processes

provide more precise determination of a dispersion measure dependence sc (DM) DM

The vast scope of the Galaxy provide a study of distribution of Galactic scattering material

Our Low-frequency study is boundedby dispersion measure of about 100 cm-3 pc,

therefore our scope related to the near Galaxy ( d 3 kpc).

We report the low-frequency measurements of a scatter broadeningof the most complete uniform set of 100 pulsars,

in the vast Galaxy region of Galactic longitude from 6о to 252о

and distances up to 3 kpc

Measurements are performed in 2004 and 2005

The major part of observations were carried out at 111 MHz used the Large Phased Array (BSA) Radio Telescope

at Pushchino Radio Astronomy Observatory

An example of th observed scattered Giant pulses of Crab pulsar at 111 MHz

An additional observations were performed at 40 an 60 MHz with the DKR Radio Telescope

Giant pulse of Crab pulsar as observed at 43 MHz

An example of the scatter pulse broadening determination for the Crab pulsar

The scatter broadening magnitude was determined by matching the observed pulse

with the convolution of the Gaussian template with thin screen scattering function G(t)=exp(-t/sc )

Large sample of 100 pulsars and uniform measurements and reduction processes provide a more precise determination of a dispersion measure

dependence sc (DM) DM

Dispersion measure dependence index is obtained as = 2.20,1, that corresponds to the uniform Kolmogorov spectrum of

turbulence

Frequency interval max /min =55 (402228 МГц) -

Low frequency measurements (110, 60 and 40 MHz) and other data form literature

expand several times the frequency interval of sc dataand provide the more precise determination

of the frequency dependence

For precise determination of the frequency dependence sc (ν) ν

we used 18 pulsars, for which our and reference data span a frequency interval of max /min 10

Table 2. Frequency dependence of the scatter broadening

Mean index of frequency dependence = 4.1 0.3 fit to the normal distribution of irregularities scale

The vast scope of the Galaxy allows to analyze the distribution of the Galactic scattering material

in 100 lines of sight and distances up to 3 kpc.

The measurements of sc was used to estimate the average scattering parameter Cn2

Level of turbulence Cn2 via Galactic longitude

In the range of d 3 kpc one doesn't note a noticible change of Cn2

with the Galaxy longitude

In the range of d 3 kpc one don't note a noticible dependence of Cn2

on the distance from the Earthboth to the Galaxy center and anticenter.

Level of turbulence Cn2 vs. distance from the Earth

In a near Galaxy region up to the distance d 3 kpc

the electron density large scale turbulence is uniformly distributed.

The work under progress

We realized a new way of a remote sensing of the solar corona by measurements of the pulse scatter broadening in occultation state.

Conclusions

1. One performs the uniform low-frequency measurements

of scatter broadening of the most complete set of 100 pulsars

in the vast Galaxy region of Galactic longitude 6о- 252о

and distances up to 3 kpc.

2. Dispersion measure dependence index was determined as = 2.20,1 that corresponds to uniform Kolmogorov spectrum of

turbulence

3. Mean index of frequency dependence was determined as

= 4.1 0.3 that fit to normal distribution of irregularities scale

4. In the near Galaxy region up to the distance d 3 kpc

the large scale electron density turbulence is uniformly distributed.

5. The new ways for a probing solar corona by a pulsar temporal scatter broadening was proposed and realized.

Thank you !

A wide scatter of measured values of index may be arise from a narrow frequency interval 1 / 2 of this measurements.

For instance, Bhat et al. (2005) determinated the index in 1 / 2 = 1.25 !

For 15% sc measurements errorIn the frequency interval of 1 / 2 = 1.25 -value scatter from 2.7 to 5.3In the frequency interval of 1 / 2 = 15 -value scatter from 3.9 to 4.1

One need low- frequency observations.