主要内容:
Pe'er他们就是想说光球辐射可以解释一切。
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文章信息:
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- · arXiv e-print (arXiv:1309.7652)
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| Title: |
| Polarization properties of photospheric emission from relativistic, collimated outflows |
| Authors: |
| Lundman, Christoffer; Pe'er, Asaf; Ryde, Felix |
| Publication: |
| eprint arXiv:1309.7652 |
| Publication Date: |
| 09/2013 |
| Origin: |
| ARXIV |
| Keywords: |
| Astrophysics - High Energy Astrophysical Phenomena |
| Comment: |
| 17 pages, 12 figures, submitted to MNRAS |
| Bibliographic Code: |
| 2013arXiv1309.7652L |
Abstract
We consider the polarization properties of
photospheric emission
originating in
jets consisting of a highly relativistic core of opening
angle theta_j and Lorentz factor Gamma_0, and a surrounding shear layer
where the Lorentz factor is decreasing as a power law of index p with
angle from the jet axis. We find significant degrees of linear
polarization for observers located at viewing angles theta_v \gtrsim
theta_j. In particular, the polarization degree of emission from narrow
jets (theta_j \approx 1/Gamma_0) with steep Lorentz factor gradients (p
\gtrsim 4) reaches \sim 40%. The angle of polarization may shift by pi/2
for time-variable jets. The spectrum below the thermal peak of the
polarized emission appears non-thermal due to
aberration of light,
without the need for additional
radiative processes or energy
dissipation. Furthermore, above the thermal peak a power law of photons
forms due to Comptonization of photons that repeatedly scatter between
regions of different Lorentz factor before escaping. We show that
polarization degrees of a few tens of percent and broken power law
spectra are natural in the context of photospheric emission from
structured jets. Applying the model
to gamma-ray bursts, we discuss
expected correlations between the spectral shape and the polarization
degree of the prompt emission.
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