Dissecting the Local Environment of FRB 190608 in the Spiral Arm of its Host Galaxy

• Published in: arXiv.org 2021-12
• Main Authors: Chittidi, Jay S, Simha, Sunil, Mannings, Alexandra, Prochaska, J Xavier, Ryder, Stuart D, Rafelski, Marc, Neeleman, Marcel, Macquart, Jean-Pierre, Tejos, Nicolas, Jorgenson, Regina A, Day, Cherie K, Marnoch, Lachlan, Bhandari, Shivani, Deller, Adam T, Qiu, Hao, Bannister, Keith W, Shannon, Ryan M, Heintz, Kasper E
• Format: Article
• Language: English
• Subjects: Dispersion; Emission; Galactic structure; Galaxies; High resolution; Hubble Space Telescope; Inclination; Interstellar matter; Kinematics; Morphology; Radio bursts; Space telescopes; Star formation; Surface brightness
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.2005.13158

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 (\(\Sigma_{\rm SFR} = 1.5 \times 10^{-2}~ M_{\odot} \, \rm \, yr^{-1} \, kpc^{-2}\)) in the northwest spiral arm of HG~190608. Using H\(\beta\) emission present in our Keck Cosmic Web Imager integral field spectrum of the galaxy with a surface brightness of \(\mu_{\rm H\beta}= \mathrm{(3.36\pm0.21)\times10^{-17}\;erg\;s^{-1}\;cm^{-2}\;arcsec^{-2}}\), we infer an extinction-corrected H\(\alpha\) surface brightness and compute a dispersion measure (DM) from the interstellar medium of HG 190608 of \(\rm DM_{\rm Host,ISM} = 94 \pm 38~ \;pc\;cm^{-3}\). The galaxy rotates with a circular velocity \(v_{\rm circ} = \rm 141 \pm 8~ km\;s^{-1}\) at an inclination \(i_{\mathrm{gas}} = 37 \pm 3^\circ\), giving a dynamical mass \(M_{\rm halo}^{\rm dyn} \approx 10^{11.96 \pm 0.08}~M_{\odot}\). This implies a halo contribution to the DM of \(\rm DM_{\rm Host,Halo}= \rm 55\pm25 \;pc\;cm^{-3}\) 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 \(\Omega_p=34\pm 6\;\mathrm{km\;s^{-1}\;kpc^{-1}}\) 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 \(t_{\mathrm{enc}} = 21_{-6}^{+25}\) Myr. Unlike previous high-resolution studies of FRB environments, we find no evidence of disturbed morphology, emission, or kinematics for FRB 190608.