摘要:We present spatially resolved ALMA [CII] observations of the bright (flux density
S350 =
400 mJy at 350 μm), gravitationally lensed, starburst galaxy PLCK
G045.1+61.1 at
z = 3.427,
the “Garnet”. This source is part of our set of “Planck’s Dusty GEMS”,
discovered with the Planck’s all-sky survey. Two emission-line clouds
with a relative velocity offset of ~600 km s-1 extend towards north-east and south-west, respectively,
of a small, intensely star-forming clump with a star-formation intensity of
220 M⊙ yr-1 kpc-2, akin to maximal starbursts.
[CII] is also seen in absorption, with a redshift of +350 km s-1 relative to the brightest CO
component. [CII] absorption has previously only been found in the Milky Way along
sightlines toward bright high-mass star-forming regions, and this is the first detection
in another galaxy. Similar to Galactic environments, the [CII] absorption feature is
associated with [CI] emission, implying that this is diffuse gas shielded from the UV
radiation of the clump, and likely at large distances from the clump. Since absorption can
only be seen in front of a continuum source, the gas in this structure can definitely be
attributed to gas flowing towards the clump. The absorber could be part of a cosmic
filament or merger debris being accreted onto the galaxy. We discuss our results also in
light of the on-going debate of the origin of the [CII] deficit in dusty star-forming
galaxies.
关键词:galaxies: high-redshift;Galaxy: formation;galaxies: ISM;galaxies: starburst;galaxies: kinematics and dynamics;infrared: galaxies