Evidence for an intrinsic luminosity–decay correlation in GRB radio afterglows
ABSTRACT We present the discovery of a correlation, in a sample of 16 gamma-ray burst 8.5 GHz radio afterglows, between the intrinsic luminosity measured at 10 d in the rest frame, $L_{\mathrm{Radio,10\,d}}$, and the average rate of decay past this time, $\alpha _{{>}10\,\mathrm{ d}}$. The correlation has a Spearman’s rank coefficient of $-0.70 \pm 0.13$ at a significance of ${>}3\sigma$ and a linear regression fit of $\alpha _{>10\,\mathrm{ d}} = -0.29^{+0.19}_{-0.28} \log \left(L_{\mathrm{Radio,10\,d}} \right) + 8.12^{+ 8.86}_{-5.88}$. This finding suggests that more luminous radio afterglows have higher average rates of decay than less luminous ones. We use a Monte Carlo simulation to show the correlation is not produced by chance or selection effects at a confidence level of ${>}3\sigma$. Previous studies found this relation in optical/UV, X-ray, and GeV afterglow light curves, and we have now extended it to radio light curves. The Spearman’s rank coefficients and the linear regression slopes for the correlation in each waveband are all consistent within $1\sigma$. We discuss how these new results in the radio band support the effects of observer viewing geometry, and time-varying microphysical parameters, as possible causes of the correlation as suggested in previous works.
Authors
- Lauren Rhodes (ORCID: https://orcid.org/0000-0003-2705-4941)
- Д. А. Канн (ORCID: https://orcid.org/0000-0003-2902-3583)
- M. R. Smith (ORCID: https://orcid.org/0000-0002-3321-1432)
- S. R. Oates (ORCID: https://orcid.org/0000-0001-9309-7873)
- Maria Debora De Pasquale (ORCID: https://orcid.org/0000-0003-1082-6810)
- Benjamin P. Gompertz (ORCID: https://orcid.org/0000-0002-5826-0548)
- K-Ryan Hinds (ORCID: https://orcid.org/0000-0002-0129-806X)
- Kim L. Page (ORCID: https://orcid.org/0000-0001-5624-2613)
- J. Racusin
- Rahul Gupta (ORCID: https://orcid.org/0000-0003-4905-7801)
- A. A. Breeveld (ORCID: https://orcid.org/0000-0002-0001-7270)
- M. Nicholl (ORCID: https://orcid.org/0000-0002-2555-3192)
- Samuel P. R. Shilling (ORCID: https://orcid.org/0009-0009-4622-7749)
- Jyoti C. Patel (ORCID: https://orcid.org/0000-0003-0295-6180)
- B. Cenko
Institutions
- University of Messina (IT)
- Goethe University Frankfurt (DE)
- Queen's University Belfast (GB)
- Goddard Space Flight Center (US)
- Department of Space (IN)
- University of Oxford (GB)
- Queens University (BD)
- National Postdoctoral Association (US)
- Institute of Astronomy (RU)
- Astronomy and Space (AU)
- Instituto de Astrofísica de Andalucía (ES)
- Azienda Ospedaliera Ospedali Riuniti Papardo Piemonte (IT)
- University College London (GB)
- Liverpool John Moores University (GB)
- Lancaster University (GB)
- University of Birmingham (GB)
Publication Details
- Journal
- Monthly Notices of the Royal Astronomical Society
- Published
- 2025-08-10
- DOI
- https://doi.org/10.1093/mnras/staf1303
- Citations
- 1
- Primary Topic
- Gamma-ray bursts and supernovae
- Type
- article
- Field-Weighted Citation Impact
- 1.15
Funders
- National Aeronautics and Space Administration
- Oak Ridge Associated Universities
- European Commission
- Goddard Space Flight Center
- Science and Technology Facilities Council