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Revisiting the Gas Kinematics in SSA22 Lyman-α Blob 1 with Radiative Transfer Modeling in a Multiphase, Clumpy Medium

Li, Zhihui and Steidel, Charles C. and Gronke, Max and Chen, Yuguang (2020) Revisiting the Gas Kinematics in SSA22 Lyman-α Blob 1 with Radiative Transfer Modeling in a Multiphase, Clumpy Medium. . (Unpublished)

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We present new observations of Lyman-α (Lyα) 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 Lyα image and identified several prominent features. By comparing the spatial distributions and intensities of Lyα and Hβ, we find that recombination of photo-ionized HI gas followed by resonant scattering is sufficient to explain all the observed Lyα/Hβ ratios. We further decode the spatially-resolved Lyα profiles using both moment maps and Monte-Carlo radiative transfer (MCRT) modeling. By fitting a set of multiphase, 'clumpy' models to the observed Lyα 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 Lyα morphologies at different locations, and the main results are: (1) The observed Lyα 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 Lyα line center.

Item Type:Report or Paper (Discussion Paper)
Related URLs:
URLURL TypeDescription Paper
Li, Zhihui0000-0001-5113-7558
Steidel, Charles C.0000-0002-4834-7260
Gronke, Max0000-0003-2491-060X
Chen, Yuguang0000-0003-4520-5395
Additional Information:ZL acknowledges Michael Zhang, for his professional guidance and kind company during the excruciating debugging process. The data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. We are also grateful to the dedicated staff of the W.M. Keck Observatory who keep the instruments and telescopes running effectively. MG was supported by NASA through the NASA Hubble Fellowship grant HST-HF2-51409 awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS5-26555. Numerical calculations were run on the Caltech compute cluster “Wheeler,” allocations from XSEDE TG-AST130039 and PRAC NSF.1713353 supported by the NSF, and NASA HEC SMD-16-7592. This research made use of Montage. It is funded by the National Science Foundation under Grant Number ACI-1440620, and was previously funded by the National Aeronautics and Space Administration’s Earth Science Technology Office, Computation Technologies Project, under Cooperative Agreement Number NCC5-626 between NASA and the California Institute of Technology.
Group:Astronomy Department
Funding AgencyGrant Number
W. M. Keck FoundationUNSPECIFIED
NASA Hubble FellowshipHST-HF2-51409
Subject Keywords:galaxies: kinematics and dynamics; intergalactic medium; galaxies: high-redshift; galaxies: evolution
Record Number:CaltechAUTHORS:20200908-075612693
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:105263
Deposited By: Tony Diaz
Deposited On:08 Sep 2020 16:51
Last Modified:08 Sep 2020 16:51

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