# A NOVEL EMISSION SPECTRUM FROM A RELATIVISTIC ELECTRON MOVING IN A RANDOM MAGNETIC FIELD

## Abstract

We numerically calculate the radiation spectrum from relativistic electrons moving in small-scale turbulent magnetic fields expected in high-energy astrophysical sources. Such a radiation spectrum is characterized by the strength parameter a = {lambda}{sub B} e|B|/mc {sup 2}, where {lambda}{sub B} is the length scale of the turbulent field. When a is much larger than the Lorentz factor of a radiating electron {gamma}, synchrotron radiation is realized, while a << 1 corresponds to the so-called jitter radiation regime. Because for 1 < a < {gamma} we cannot use either approximations, we should have recourse to the Lienard-Wiechert potential to evaluate the radiation spectrum, which is performed in this Letter. We generate random magnetic fields assuming Kolmogorov turbulence, inject monoenergetic electrons, solve the equation of motion, and calculate the radiation spectrum. We perform numerical calculations for several values of a with {gamma} = 10. We obtain various types of spectra ranging between jitter radiation and synchrotron radiation. For a {approx} 7, the spectrum takes a novel shape which had not been noticed up to now. It is like a synchrotron spectrum in the middle energy region, but in the low frequency region it is a broken power law and in the highmore »

- Authors:

- Department of Earth and Space Science, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka 560-0043 (Japan)

- Publication Date:

- OSTI Identifier:
- 21562548

- Resource Type:
- Journal Article

- Journal Name:
- Astrophysical Journal Letters

- Additional Journal Information:
- Journal Volume: 735; Journal Issue: 2; Other Information: DOI: 10.1088/2041-8205/735/2/L44; Journal ID: ISSN 2041-8205

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; COSMIC GAMMA BURSTS; ELECTRONS; EMISSION SPECTRA; EQUATIONS OF MOTION; MAGNETIC FIELDS; SYNCHROTRON RADIATION; TURBULENCE; BREMSSTRAHLUNG; COSMIC RADIATION; DIFFERENTIAL EQUATIONS; ELECTROMAGNETIC RADIATION; ELEMENTARY PARTICLES; EQUATIONS; FERMIONS; IONIZING RADIATIONS; LEPTONS; PARTIAL DIFFERENTIAL EQUATIONS; PRIMARY COSMIC RADIATION; RADIATIONS; SPECTRA

### Citation Formats

```
Teraki, Yuto, and Takahara, Fumio, E-mail: teraki@vega.ess.sci.osaka-u.ac.jp.
```*A NOVEL EMISSION SPECTRUM FROM A RELATIVISTIC ELECTRON MOVING IN A RANDOM MAGNETIC FIELD*. United States: N. p., 2011.
Web. doi:10.1088/2041-8205/735/2/L44.

```
Teraki, Yuto, & Takahara, Fumio, E-mail: teraki@vega.ess.sci.osaka-u.ac.jp.
```*A NOVEL EMISSION SPECTRUM FROM A RELATIVISTIC ELECTRON MOVING IN A RANDOM MAGNETIC FIELD*. United States. doi:10.1088/2041-8205/735/2/L44.

```
Teraki, Yuto, and Takahara, Fumio, E-mail: teraki@vega.ess.sci.osaka-u.ac.jp. Sun .
"A NOVEL EMISSION SPECTRUM FROM A RELATIVISTIC ELECTRON MOVING IN A RANDOM MAGNETIC FIELD". United States. doi:10.1088/2041-8205/735/2/L44.
```

```
@article{osti_21562548,
```

title = {A NOVEL EMISSION SPECTRUM FROM A RELATIVISTIC ELECTRON MOVING IN A RANDOM MAGNETIC FIELD},

author = {Teraki, Yuto and Takahara, Fumio, E-mail: teraki@vega.ess.sci.osaka-u.ac.jp},

abstractNote = {We numerically calculate the radiation spectrum from relativistic electrons moving in small-scale turbulent magnetic fields expected in high-energy astrophysical sources. Such a radiation spectrum is characterized by the strength parameter a = {lambda}{sub B} e|B|/mc {sup 2}, where {lambda}{sub B} is the length scale of the turbulent field. When a is much larger than the Lorentz factor of a radiating electron {gamma}, synchrotron radiation is realized, while a << 1 corresponds to the so-called jitter radiation regime. Because for 1 < a < {gamma} we cannot use either approximations, we should have recourse to the Lienard-Wiechert potential to evaluate the radiation spectrum, which is performed in this Letter. We generate random magnetic fields assuming Kolmogorov turbulence, inject monoenergetic electrons, solve the equation of motion, and calculate the radiation spectrum. We perform numerical calculations for several values of a with {gamma} = 10. We obtain various types of spectra ranging between jitter radiation and synchrotron radiation. For a {approx} 7, the spectrum takes a novel shape which had not been noticed up to now. It is like a synchrotron spectrum in the middle energy region, but in the low frequency region it is a broken power law and in the high frequency region an extra power-law component appears beyond the synchrotron cutoff. We give a physical explanation of these features.},

doi = {10.1088/2041-8205/735/2/L44},

journal = {Astrophysical Journal Letters},

issn = {2041-8205},

number = 2,

volume = 735,

place = {United States},

year = {2011},

month = {7}

}