In:
Monthly Notices of the Royal Astronomical Society, Oxford University Press (OUP), Vol. 531, No. 3 ( 2024-06-05), p. 3279-3286
Abstract:
Binary neutron star mergers are expected to produce fast dynamical ejecta, with mildly relativistic velocities extending to β = v/c & gt; 0.6. In a preceding paper, we derived an analytic description of the time-dependent radio to X-ray synchrotron flux produced by collision-less shocks driven by such fast ejecta into the interstellar medium, for spherical ejecta with broken power-law mass (or energy) distributions, M( & gt; γβ)∝(γβ)−s with s = sKN at γβ & lt; γ0β0 and s = sft at γβ & gt; γ0β0 (where γ is the Lorentz factor). Here, we extend our analysis and provide analytic expressions for the self-absorption frequency, the cooling frequency, and the observed angular size of the emitting region (which appears as a ring in the sky). For parameter values characteristic of merger calculation results – a ‘shallow’ mass distribution, 1 & lt; sKN & lt; 3, for the bulk of the ejecta (at γβ ≈ 0.2), and a steep, sft & gt; 5, ‘fast tail’ mass distribution – the analytic results reproduce well (to tens of per cent accuracy) the results of detailed numeric calculations, a significant improvement over earlier order-of-magnitude estimates (based on extrapolations of results valid for γβ ≪ 1).
Type of Medium:
Online Resource
ISSN:
0035-8711
,
1365-2966
DOI:
10.1093/mnras/stae1286
Language:
English
Publisher:
Oxford University Press (OUP)
Publication Date:
2024
detail.hit.zdb_id:
207232-4
detail.hit.zdb_id:
2016084-7
SSG:
16,12
