# THE PAIR BEAM PRODUCTION SPECTRUM FROM PHOTON-PHOTON ANNIHILATION IN COSMIC VOIDS

## Abstract

Highly beamed relativistic e {sup {+-}}-pair energy distributions result in double photon collisions of the beamed gamma rays from TeV blazars at cosmological distances with the isotropically distributed extragalactic background light (EBL) in the intergalactic medium. The typical energies k {sub 0} {approx_equal} 10{sup -7} in units of m{sub e}c {sup 2} of the EBL are more than 10 orders of magnitude smaller than the observed gamma-ray energies k {sub 1} {>=} 10{sup 7}. Using the limit k {sub 0} << k {sub 1}, we demonstrate that the angular distribution of the generated pairs in the lab frame is highly beamed in the direction of the initial gamma-ray photons. For the astrophysically important case of power-law distributions of the emitted gamma-ray beam up to the maximum energy M interacting with Wien-type N(k {sub 0}){proportional_to}k{sup q} {sub 0}exp (- k {sub 0}/{Theta}) soft photon distributions with total number density N {sub 0}, we calculate analytical approximations for the electron production spectrum. For distant objects with luminosity distances d{sub L} >> r {sub 0} = ({sigma} {sub T} N {sub 0}){sup -1} = 0.49N {sup -1} {sub 0} Mpc (with Thomson cross section {sigma} {sub T}), the implied large values of themore »

- Authors:

- Institut fuer Theoretische Physik, Lehrstuhl IV: Weltraum- und Astrophysik, Ruhr-Universitaet Bochum, D-44780 Bochum (Germany)
- Institut d'Astrophysique et de Geophysique, Universite de Liege, B-4000 Liege (Belgium)
- Physics Department, Wolfgang-Pauli-Strasse 27, ETH-Zuerich, CH-8093 Zuerich (Switzerland)

- Publication Date:

- OSTI Identifier:
- 22086512

- Resource Type:
- Journal Article

- Journal Name:
- Astrophysical Journal

- Additional Journal Information:
- Journal Volume: 758; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0004-637X

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ANGULAR DISTRIBUTION; ANNIHILATION; APPROXIMATIONS; ASTROPHYSICS; BEAM PRODUCTION; COSMIC ELECTRONS; COSMIC PHOTONS; COSMOLOGY; CROSS SECTIONS; DENSITY; ENERGY SPECTRA; GAMMA RADIATION; LUMINOSITY; PHOTON COLLISIONS; QUASARS; RELATIVISTIC RANGE; TEV RANGE; VISIBLE RADIATION

### Citation Formats

```
Schlickeiser, R., Ibscher, D., Elyiv, A., and Miniati, F., E-mail: rsch@tp4.rub.de, E-mail: ibscher@tp4.rub.de, E-mail: elyiv@astro.ulg.ac.be, E-mail: fm@phys.ethz.ch.
```*THE PAIR BEAM PRODUCTION SPECTRUM FROM PHOTON-PHOTON ANNIHILATION IN COSMIC VOIDS*. United States: N. p., 2012.
Web. doi:10.1088/0004-637X/758/2/101.

```
Schlickeiser, R., Ibscher, D., Elyiv, A., & Miniati, F., E-mail: rsch@tp4.rub.de, E-mail: ibscher@tp4.rub.de, E-mail: elyiv@astro.ulg.ac.be, E-mail: fm@phys.ethz.ch.
```*THE PAIR BEAM PRODUCTION SPECTRUM FROM PHOTON-PHOTON ANNIHILATION IN COSMIC VOIDS*. United States. doi:10.1088/0004-637X/758/2/101.

```
Schlickeiser, R., Ibscher, D., Elyiv, A., and Miniati, F., E-mail: rsch@tp4.rub.de, E-mail: ibscher@tp4.rub.de, E-mail: elyiv@astro.ulg.ac.be, E-mail: fm@phys.ethz.ch. Sat .
"THE PAIR BEAM PRODUCTION SPECTRUM FROM PHOTON-PHOTON ANNIHILATION IN COSMIC VOIDS". United States. doi:10.1088/0004-637X/758/2/101.
```

```
@article{osti_22086512,
```

title = {THE PAIR BEAM PRODUCTION SPECTRUM FROM PHOTON-PHOTON ANNIHILATION IN COSMIC VOIDS},

author = {Schlickeiser, R. and Ibscher, D. and Elyiv, A. and Miniati, F., E-mail: rsch@tp4.rub.de, E-mail: ibscher@tp4.rub.de, E-mail: elyiv@astro.ulg.ac.be, E-mail: fm@phys.ethz.ch},

abstractNote = {Highly beamed relativistic e {sup {+-}}-pair energy distributions result in double photon collisions of the beamed gamma rays from TeV blazars at cosmological distances with the isotropically distributed extragalactic background light (EBL) in the intergalactic medium. The typical energies k {sub 0} {approx_equal} 10{sup -7} in units of m{sub e}c {sup 2} of the EBL are more than 10 orders of magnitude smaller than the observed gamma-ray energies k {sub 1} {>=} 10{sup 7}. Using the limit k {sub 0} << k {sub 1}, we demonstrate that the angular distribution of the generated pairs in the lab frame is highly beamed in the direction of the initial gamma-ray photons. For the astrophysically important case of power-law distributions of the emitted gamma-ray beam up to the maximum energy M interacting with Wien-type N(k {sub 0}){proportional_to}k{sup q} {sub 0}exp (- k {sub 0}/{Theta}) soft photon distributions with total number density N {sub 0}, we calculate analytical approximations for the electron production spectrum. For distant objects with luminosity distances d{sub L} >> r {sub 0} = ({sigma} {sub T} N {sub 0}){sup -1} = 0.49N {sup -1} {sub 0} Mpc (with Thomson cross section {sigma} {sub T}), the implied large values of the optical depth {tau}{sub 0} = d{sub L} /r {sub 0} indicate that the electron production spectra differ at energies inside and outside the interval [({Theta}ln {tau}{sub 0}){sup -1}, {tau}{sub 0}/{Theta}], given the maximum gamma-ray energy M >> {Theta}{sup -1}. In the case M >> {Theta}{sup -1}, the production spectrum is strongly peaked near E {approx_equal} {Theta}{sup -1}, being exponentially reduced at small energies and decreasing with the steep power law {proportional_to}E {sup -1-p} up to the maximum energy E = M - (1/2).},

doi = {10.1088/0004-637X/758/2/101},

journal = {Astrophysical Journal},

issn = {0004-637X},

number = 2,

volume = 758,

place = {United States},

year = {2012},

month = {10}

}