http://arxiv.org/abs/2005.13158
We present a high-resolution analysis of the host galaxy of fast radio burst FRB 190608, an SBc galaxy at $z=0.11778$ (hereafter HG 190608), to dissect its local environment and its contributions to the FRB properties. Our Hubble Space Telescope WFC3/UVIS image reveals that the sub-arcsecond localization of FRB 190608 is coincident with a knot of star-formation ($\Sigma_{SFR} = 1.2 \times 10^{-2}~ M_{\odot} \, kpc^{-2}$) in one of the prominent spiral arms of HG 190608. This is confirmed by H$\beta$ emission present in our Keck/KCWI integral field spectrum of the galaxy with a surface brightness of $\mu_{H\beta} = (3.35\pm0.18)\times10^{-17}\;erg\;s^{-1}\;cm^{-2}\;arcsec^{-2}$. We infer an extinction-corrected H$\alpha$ surface brightness and compute a dispersion measure from the interstellar medium of HG 190608 of ${DM}{Host,ISM} = 82 \pm 35~ pc \, cm^{-3}$. The galaxy rotates with a circular velocity $v{circ} = 141 \pm 8~ km \, s^{-1}$ at an inclination $i_{gas} = 37 \pm 3^\circ$, giving a dynamical mass $M_{halo}^{dyn} \approx 10^{11.96 \pm 0.08}~ M_{\odot}$. A surface photometric analysis of the galaxy using FORS2 imaging suggests a stellar disk inclination of $i_{stellar} = 26 \pm 3^\circ$. The dynamical mass estimate implies a halo contribution to the dispersion measure of ${DM}_{Host,Halo} = 55 \pm 25\; pc \, cm^{-3}$ subject to assumptions on the density profile and fraction of baryons retained. The relatively high temporal broadening ($\tau = 3.3 \pm 0.2 \; ms$ at 1.28 GHz) and rotation measure ($ RM = 353 \pm 2\; rad \; m^{-2}$) (Day et al. 2020) of FRB 190608 may be attributable to both turbulent gas within the spiral arm and gas local to the FRB progenitor. In contrast to previous high-resolution studies of FRB progenitor environments, we find no evidence for disturbed morphology, emission, nor kinematics for FRB 190608.
J. Chittidi, S. Simha, A. Mannings, et. al.
Thu, 28 May 20
5/55
Comments: 16 pages, 8 figure files, 7 figures in paper, 3 tables. Submitted to ApJ
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