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Old 24-11-2017, 10:24 AM
gary
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The Cosmic Snake - Hubble investigates clumps in this gravitational lensed galaxy

The Hubble Space Telescope team have released an image of the
highly-gravitationally lensed galaxy which has been nicknamed "The Cosmic Snake".

The Cosmic Snake is lensed by a galaxy cluster designated MACSJ1206.2-0847.

Photo here :-
https://www.spacetelescope.org/images/potw1747a/

Clumpy regions within The Cosmic Snake are the subject of a 27 Nov 2017
paper in Nature by Cava et. al

Quote:
Originally Posted by Cava et.al. Nature
The nature of giant clumps in distant galaxies probed by the anatomy of the cosmic snake

Abstract

Giant stellar clumps are ubiquitous in high-redshift galaxies.

They are thought to play an important role in the build-up of galactic bulges and as diagnostics of star formation feedback in galactic discs.

Hubble Space Telescope (HST) blank field imaging surveys have estimated that these clumps have masses of up to 109.5 M⊙ and linear sizes of ≳1 kpc.

Recently, gravitational lensing has also been used to get higher spatial resolution. However, both recent lensed observations and models suggest that the clumps’ properties may be overestimated by the limited resolution of standard imaging techniques.

A definitive proof of this observational bias is nevertheless still missing.

Here we investigate directly the effect of resolution on clump properties by analysing multiple gravitationally lensed images of the same galaxy at different spatial resolutions, down to 30 pc.

We show that the typical mass and size of giant clumps, generally observed at ~1 kpc resolution in high-redshift galaxies, are systematically overestimated.

The high spatial resolution data, only enabled by strong gravitational lensing using currently available facilities, support smaller scales of clump formation by fragmentation of the galactic gas disk via gravitational instabilities.

Paper here (subscription required)
https://www.nature.com/articles/s41550-017-0295-x

A Press Release appears at the University of Geneva :-
https://www.unige.ch/communication/c...es-lointaines/
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