The spherical ejecta of AT2017gfo


Sneppen, A. (2023). The spherical ejecta of AT2017gfo. Perimeter Institute. https://pirsa.org/23040084


Sneppen, Albert. The spherical ejecta of AT2017gfo. Perimeter Institute, Apr. 06, 2023, https://pirsa.org/23040084


          @misc{ pirsa_23040084,
            doi = {10.48660/23040084},
            url = {https://pirsa.org/23040084},
            author = {Sneppen, Albert},
            keywords = {Strong Gravity},
            language = {en},
            title = {The spherical ejecta of AT2017gfo},
            publisher = {Perimeter Institute},
            year = {2023},
            month = {apr},
            note = {PIRSA:23040084 see, \url{https://pirsa.org}}

Albert Sneppen Niels Bohr Institute

Talk Type Scientific Series


The geometry of kilonovae is a key diagnostic of the physics of merging neutron stars with current hydrodynamical merger models typically showing aspherical ejecta. Previously, Sr II was identified in the spectrum of the only well-studied kilonova AT2017gfo, associated with the gravitational wave event GW170817. In this talk, we show that combining the strong Sr II P Cygni absorption-emission spectral feature and the blackbody nature of the kilonova spectrum, to determine that the kilonova is highly spherical at early epochs. Line shape analysis combined with the known inclination angle of the source also shows the same sphericity independently. The near-spherical geometry suggests early spectra of kilonovae may provide excellent precision cosmic distance measurements using the Expanding Photosphere Method.

Zoom link:  https://pitp.zoom.us/j/97287055430?pwd=bFVyeTRuZHVLcGlDdnhlK1d0OWE1Zz09