Please use this identifier to cite or link to this item:
http://hdl.handle.net/20.500.12386/32047
Title: | Polarized kilonovae from black hole-neutron star mergers | Authors: | Bulla, M. Kyutoku, K. Tanaka, M. COVINO, Stefano Bruten, J. R. Matsumoto, T. Maund, J. R. TESTA, Vincenzo Wiersema, K. |
Issue Date: | 2021 | Journal: | MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY | Number: | 501 | Issue: | 2 | First Page: | 1891 | Abstract: | We predict linear polarization for a radioactively-powered kilonova following the merger of a black hole and a neutron star. Specifically, we perform 3-D Monte Carlo radiative transfer simulations for two different models, both featuring a lanthanide-rich dynamical ejecta component from numerical-relativity simulations while only one including an additional lanthanide-free disk wind component. We calculate polarization spectra for nine different orientations at 1.5, 2.5 and 3.5 d after the merger and in the $0.1-2\,\mu$m wavelength range. We find that both models are polarized at a detectable level 1.5 d after the merger while show negligible levels thereafter. The polarization spectra of the two models are significantly different. The model lacking a disk wind shows no polarization in the optical, while a signal increasing at longer wavelengths and reaching $\sim1\%-6\%$ at $2\,\mu$m depending on the orientation. The model with a disk-wind component, instead, features a characteristic "double-peak" polarization spectrum with one peak in the optical and the other in the infrared. Polarimetric observations of future events will shed light on the debated neutron richness of the disk-wind component. The detection of optical polarization would unambiguously reveal the presence of a lanthanide-free disk-wind component, while polarization increasing from zero in the optical to a peak in the infrared would suggest a lanthanide-rich composition for the whole ejecta. Future polarimetric campaigns should prioritize observations in the first $\sim48$ hours and in the $0.5-2\,\mu$m range, where polarization is strongest, but also explore shorter wavelengths/later times where no signal is expected from the kilonova and the interstellar polarization can be safely estimated. | URI: | http://hdl.handle.net/20.500.12386/32047 | URL: | http://arxiv.org/abs/2009.07279v2 https://academic.oup.com/mnras/article/501/2/1891/6030051?login=true |
ISSN: | 0035-8711 | DOI: | 10.1093/mnras/staa3796 | Bibcode ADS: | 2021MNRAS.501.1891B | Fulltext: | open |
Appears in Collections: | 1.01 Articoli in rivista |
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staa3796.pdf | Pdf editoriale | 1.84 MB | Adobe PDF | View/Open |
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