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تسجيل مستخدم جديدDissecting the Local Environment of FRB 190608 in the Spiral Arm of its Host Galaxy
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Jay S. Chittidi
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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 $mu_{Hbeta} = (3.35pm0.18)times10^{-17};erg;s^{-1};cm^{-2};arcsec^{-2}$. 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.
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