GRB 241105A : A test case for GRB classification and rapid r-process nucleosynthesis channels

Dimple and Gompertz, B P and Levan, A J and Malesani, D B and Laskar, T and Bala, S and Chrimes, A A and Heintz, K and Izzo, L and Lamb, G P and O’Neill, D and Palmerio, J T and Saccardi, A and Anderson, G E and De Barra, C and Huang, Y and Kumar, A and Li, H and McBreen, S and Mukherjee, O and Oates, S R and Pathak, U and Qiu, Y and Roberts, O J and Sonawane, R and Veres, P and Ackley, K and Han, X and Julakanti, Y and Wang, J and D’Avanzo, P and Martin-Carrillo, A and Ravasio, M E and Rossi, A and Tanvir, N R and Anderson, J P and Arabsalmani, M and Belkin, S and Breton, R P and Brivio, R and Burns, E and Casares, J and Campana, S and Chastain, S I and D’Elia, V and Dhillon, V S and Dyer, M J and Fynbo, J P U and Galloway, D K and Gulati, A and Godson, B and Goodwin, A J and Gromadzki, M and Hartmann, D H and Jakobsson, P and Killestein, T L and Kotak, R and Leung, J K and Lyman, J D and Melandri, A and Mattila, S and McGee, S and Morley, C and Mukherjee, T and Müller-Bravo, T E and Noysena, K and Nuttall, L K and O’Brien, P and De Pasquale, M and Pignata, G and Pollacco, D and Pugliese, G and Ramsay, G and Sahu, A and Salvaterra, R and Schady, P and Schneider, B and Steeghs, D and Starling, R L C and Tsalapatas, K and Ulaczyk, K and van der Horst, A J and Wang, C and Wiersema, K and Worssam, I and Wortley, M E and Xiong, S and Zafar, T (2025) GRB 241105A : A test case for GRB classification and rapid r-process nucleosynthesis channels. Monthly Notices of the Royal Astronomical Society. ISSN 0035-8711

Abstract

Gamma-ray bursts (GRBs) offer a powerful window to probe the progenitor systems responsible for the formation of heavy elements through the rapid neutron capture (r-) process, thanks to their exceptional luminosity, which allows them to be observed across vast cosmic distances. GRB 241105A, observed at a redshift of z = 2.681, features a short initial spike (∼1.5 s) and a prolonged weak emission lasting about 64 s, positioning it as a candidate for a compact binary merger and potentially marking it as the most distant merger-driven GRB observed to date. However, the emerging ambiguity in GRB classification necessitates further investigation into the burst’s true nature. Prompt emission analyses, such as hardness ratio, spectral lag, and minimum variability timescales, yield mixed classifications, while machine learning-based clustering places GRB 241105A near both long-duration mergers and collapsar GRBs. We conducted observations using the James Webb Space Telescope (JWST) to search for a potential supernova counterpart. Although no conclusive evidence was found for a supernova, the host galaxy’s properties derived from the JWST observations suggest active star formation with low metallicity, and a sub-kpc offset of the afterglow from the host, which appears broadly consistent with a collapsar origin. Nevertheless, a compact binary merger origin cannot be ruled out, as the burst may plausibly arise from a fast progenitor channel. This would have important implications for heavy element enrichment in the early Universe.