Details

Autor(en) / Beteiligte

• Koch Ocker, Stella
• Cordes, James M.
• Chatterjee, Shami
• Niu, Chen-Hui
• Li, Di
• McKee, James W.
• Law, Casey J.
• Tsai, Chao-Wei
• Anna-Thomas, Reshma
• Yao, Ju-Mei
• Cruces, Marilyn

Titel

The Large Dispersion and Scattering of FRB 20190520B Are Dominated by the Host Galaxy

Ist Teil von

• The Astrophysical journal, 2022-06, Vol.931 (2), p.87

Ort / Verlag

Philadelphia: The American Astronomical Society

Erscheinungsjahr

2022

Quelle

EZB Electronic Journals Library

Beschreibungen/Notizen

• Abstract The repeating fast radio burst FRB 20190520B is localized to a galaxy at z = 0.241, much closer than expected given its dispersion measure DM = 1205 ± 4 pc cm −3 . Here we assess implications of the large DM and scattering observed from FRB 20190520B for the host galaxy’s plasma properties. A sample of 75 bursts detected with the Five-hundred-meter Aperture Spherical radio Telescope shows scattering on two scales: a mean temporal delay τ (1.41 GHz) = 10.9 ± 1.5 ms, which is attributed to the host galaxy, and a mean scintillation bandwidth Δ ν d (1.41 GHz) = 0.21 ± 0.01 MHz, which is attributed to the Milky Way. Balmer line measurements for the host imply an H α emission measure (galaxy frame) EM s = 620 pc cm −6 × ( T /10 4 K) 0.9 , implying DM H α of order the value inferred from the FRB DM budget, DM h = 1121 − 138 + 89 pc cm −3 for plasma temperatures greater than the typical value 10 4 K. Combining τ and DM h yields a nominal constraint on the scattering amplification from the host galaxy F ˜ G = 1.5 − 0.3 + 0.8 ( pc 2 km ) − 1 / 3 , where F ˜ describes turbulent density fluctuations and G represents the geometric leverage to scattering that depends on the location of the scattering material. For a two-screen scattering geometry where τ arises from the host galaxy and Δ ν d from the Milky Way, the implied distance between the FRB source and dominant scattering material is ≲100 pc. The host galaxy scattering and DM contributions support a novel technique for estimating FRB redshifts using the τ –DM relation, and are consistent with previous findings that scattering of localized FRBs is largely dominated by plasma within host galaxies and the Milky Way.