Gas Kinematic within Lyman Alpha Blobs

Monday, 14 September 2015 9 a.m. — 10 a.m. MST

AURA Lecture Hall

NOIRLab South Colloquia
YUJIN YANG (Korea Astronomy and Space Science Institute, South Korea (KASI) and Gemini South Visiting Astronomer)

High-redshift Lyman alpha nebulae (Ly-alpha "blobs", LABs) are the site of massive galaxy formation and their early interaction with the IGM. Research in the past decade has struggled to make progress on the question of what powers these huge Ly-alpha halos and whether the Ly-alpha-emitting gas is outflowing or infalling.  First, I will present our optical/NIR spectroscopic observations to investigate gas kinematics of Lya-emitting gas.  Using three measures --- the velocity offset between the Lyalpha line and the nonresonant [O III] or Halpha line, the offset of stacked interstellar metal absorption lines, and the spectrally resolved [OIII] line profile --- we study the kinematics of gas along the line of sight to galaxies within each blob center.  All these measures show that there are only weak outflows, therefore exclude gas inflow and extreme hyper/superwinds as a source of the extended Ly-alpha emission.  I will also present the first detection of molecular gas from a Ly-alpha blob and our on-going effort to characterize the physical conditions of its ISM.