2021ApJ...922..173C

We present a high-resolution analysis of the host galaxy of fast radio burst (FRB) 190608, an SB(r)c galaxy at z = 0.11778 (hereafter HG 190608), to dissect its local environment and its contributions to the FRB properties. Our Hubble Space Telescope Wide Field Camera 3 ultraviolet and visible light image reveals that the subarcsecond localization of FRB 190608 is coincident with a knot of star formation (Σ_SFR = 1.5 x 10^–2 M_☉ yr^–1 kpc^–2) in the northwest spiral arm of HG 190608. Using Hβ emission present in our Keck Cosmic Web Imager integral field spectrum of the galaxy with a surface brightness of µ_Hβ=(3.36±0.21)×10^–17ergs^–1cm^–2arcsec^–2, we infer an extinction-corrected Hα surface brightness and compute a dispersion measure (DM) from the interstellar medium of HG 190608 of DM_Host,ISM = 94 ± 38 pc cm^–3. The galaxy rotates with a circular velocity v_circ = 141 ± 8 km s^–1 at an inclination i_gas = 37° ± 3°, giving a dynamical mass M_halo^dyn~10^11.96±0.08^M_☉. This implies a halo contribution to the DM of DM_Host,Halo = 55 ± 25 pc cm^–3 subject to assumptions on the density profile and fraction of baryons retained. From the galaxy rotation curve, we infer a bar-induced pattern speed of Ω_p = 34 ± 6 km s^–1 kpc^–1 using linear resonance theory. We then calculate the maximum time since star formation for a progenitor using the furthest distance to the arm's leading edge within the localization, and find t_enc=21_–6⁺²⁵ Myr. Unlike previous high-resolution studies of FRB environments, we find no evidence of disturbed morphology, emission, or kinematics for FRB 190608.