Evidence for Infalling Gas in a Lyman-$\alpha$ Blob
Abstract
Lyman- blobs (LABs) are spatially extended nebulae of emission in the Ly line of hydrogen, seen at high redshifts, and most commonly found in the dense environment of star-forming galaxies. The origin of Ly emission in the LABs is still unclear and under debate. Proposed powering sources generally fall into two categories: (1) photoionization, galactic super-winds/outflows, resonant scattering of Ly photons from starbursts or active galactic nuclei (AGNs) and (2) cooling radiation from cold streams of gas accreting onto galaxies. Here we analyze the gas kinematics within a LAB providing rare observational evidence for infalling gas. This is consistent with the release of gravitational accretion energy as cold streams radiate Ly photons. It also provides direct evidence for possible cold streams feeding the central galaxies. The infalling gas is not important by mass but hints at more than one mechanism to explain the origin of the extended Ly emission around young galaxies. It is also possible that the infalling gas may represent material falling back to the galaxy from where it originated, forming a galactic fountain.
Keywords
Cite
@article{arxiv.2003.06099,
title = {Evidence for Infalling Gas in a Lyman-$\alpha$ Blob},
author = {Yiping Ao and Zheng Zheng and Christian Henkel and Shiyu Nie and Alexandre Beelen and Renyue Cen and Mark Dijkstra and Paul J. Francis and James E. Geach and Kotaro Kohno and Matthew D. Lehnert and Karl M. Menten and Junzhi Wang and Axel Weiss},
journal= {arXiv preprint arXiv:2003.06099},
year = {2020}
}
Comments
30 pages, 7 figures, submitted to Nature Astronomy. The full-text access to a view-only version of the published paper is available by using the following SharedIt link: https://rdcu.be/b2JkM