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Old 25-11-2017, 09:50 AM
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gary is offline
Join Date: Apr 2005
Location: Mt. Kuring-Gai
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VLT Multi Unit Spectroscopic Explorer (MUSE) images enormous nebula around quasar

Using the remarkable Multi Unit Spectroscopic Explorer (MUSE) instrument
on ESO’s Very Large Telescope (VLT) at the Paranal Observatory in Chile,
astronomers have discovered and imaged an Enormous Lyman-Alpha
nebula (ELAN) around the quasar 4C.10.29 ( aka SDSS J102009.99+104002.7)
at a redshift of z = 3.164.

That large a redshift implies the object is now being seen about 2 billion
years after the big bang.

Image and press release by ESO here :-

Originally Posted by ESO
The cloud of gas (or nebula) surrounding the quasar is known to astronomers as an Enormous Lyman-Alpha Nebula (ELAN). These types of nebula are massive structures of gas which formed in the early Universe, and they can help astronomers to learn how angular momentum — which explains the observed rotation of more recent galaxies — was created in the Universe. Thanks to the revolutionary MUSE instrument, it is now possible to observe these rare giant nebulae in greater detail than ever before.

This particular ELAN has a diameter of about a million light-years, and MUSE’s spectral imaging capabilities have allowed astronomers to measure the signature of inspiraling motions within the nebula — for the first time ever.
A paper has been submitted by Fabrizio Arrigoni Battaia entitled
"Inspiraling Halo Accretion Mapped in Lyman-α Emission around a z∼3 Quasar" .

Originally Posted by Fabrizio Arrigoni Battaia


In an effort to search for Lyα emission from circum- and intergalactic gas on scales of hundreds of kpc around z∼3 quasars, and thus characterise the physical properties of the gas in emission, we have initiated an extensive fast-survey with the Multi Unit Spectroscopic Explorer (MUSE): Quasar Snapshot Observations with MUse: Search for Extended Ultraviolet eMission (QSO MUSEUM).

In this work, we report the discovery of an enormous Lyα nebula (ELAN) around the quasar SDSS~J102009.99+104002.7 at z=3.164 , which we followed-up with deeper MUSE observations.

This ELAN spans ∼297 projected kpc, has an average Lyα surface brightness SB Lyα ∼6.0410 −18 erg s −1 cm −2 arcsec −2 (within the 2σ isophote), and is associated with an additional four, previously unknown embedded sources: two Lyα emitters and two faint active galactic nuclei (one Type-1 and one Type-2 quasar). By mapping at high significance the line-of-sight velocity in the entirety of the observed structure, we unveiled a large-scale coherent rotation-like pattern spanning ∼300 km s −1 with a velocity dispersion of <270 km s −1 , which we interpret as a signature of the inspiraling accretion of substructures within the quasar's host halo. Future multiwavelength data will complement our MUSE observations, and are definitely needed to fully characterise such a complex system.

None the less, our observations reveal the potential of new sensitive integral-field spectrographs to characterise the dynamical state of diffuse gas on large scales in the young Universe, and thereby witness the assembly of galaxies.
The paper is available for download from here :-

MUSE - the Multi Unit Spectroscopic Explorer - is one of the most sophisticated
instruments ever attached to a telescope. An image of it appears below (copyright ESO).

A link to a 33 minute documentary on the creation of MUSE can be found in the IceInspace Astronomy Books and Media forum here :-
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Last edited by gary; 25-11-2017 at 10:14 AM.
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