Revisiting the Gas Kinematics in SSA22 Lyman-$\alpha$ Blob 1 with
  Radiative Transfer Modeling in a Multiphase, Clumpy Medium
  We present new observations of Lyman-$\alpha$ (Ly$\alpha$) Blob 1 (LAB1) in
the SSA22 protocluster region ($z$ = 3.09) using the Keck Cosmic Web Imager
(KCWI) and the Keck Multi-object Spectrometer for Infrared Exploration
(MOSFIRE). By applying matched filtering to the KCWI datacube, we have created
a narrow-band Ly$\alpha$ image and identified several prominent features. By
comparing the spatial distributions and intensities of Ly$\alpha$ and H$\beta$,
we find that recombination of photo-ionized HI gas followed by resonant
scattering is sufficient to explain all the observed Ly$\alpha$/H$\beta$
ratios. We further decode the spatially-resolved Ly$\alpha$ profiles using both
moment maps and Monte-Carlo radiative transfer (MCRT) modeling. By fitting a
set of multiphase, 'clumpy' models to the observed Ly$\alpha$ profiles, we are
able to reasonably constrain many parameters, namely the HI number density in
the inter-clump medium (ICM), the cloud volume filling factor, the random
velocity and outflow velocity of the clumps, the HI outflow velocity of the ICM
and the local systemic redshift. Our model has successfully reproduced the
diverse Ly$\alpha$ morphologies at different locations, and the main results
are: (1) The observed Ly$\alpha$ spectra require relatively few clumps per
line-of-sight as they have significant fluxes at the line center; (2) The
velocity dispersion of the clumps yields a significant broadening of the
spectra as observed; (3) The clump bulk outflow can also cause additional
broadening if the HI in the ICM is optically thick; (4) The HI in the ICM is
responsible for the absorption feature close to the Ly$\alpha$ line center.
