MUSE stares at the Hubble Deep Field South
The Hubble Deep Field South in the constellation of Tucana
Hubble Deep Field South — Multiple Windows on the Universe
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Videos
A video view of MUSE data of the Hubble Deep Field South
The MUSE instrument on ESO’s Very Large
Telescope has given astronomers the best ever three-dimensional view of
the deep Universe. After staring at the Hubble Deep Field South region
for only 27 hours, the new observations reveal the distances, motions
and other properties of far more galaxies than ever before in this tiny
piece of the sky. They also go beyond Hubble and reveal previously
invisible objects.
By taking very long exposure pictures of regions of the sky, astronomers have created many deep fields
that have revealed much about the early Universe. The most famous of
these was the original Hubble Deep Field, taken by the NASA/ESA Hubble
Space Telescope over several days in late 1995. This spectacular and
iconic picture rapidly transformed our understanding of the content of
the Universe when it was young. It was followed two years later by a
similar view in the southern sky — the Hubble Deep Field South.
But these images did not hold all the answers — to find out more
about the galaxies in the deep field images, astronomers had to
carefully look at each one with other instruments, a difficult and
time-consuming job. But now, for the first time, the new MUSE instrument can do both jobs at once — and far more quickly.
One of the first observations using MUSE after it was commissioned on the VLT in 2014 was a long hard look at the Hubble Deep Field South (HDF-S). The results exceeded expectations.
“After just a few hours of observations at the telescope, we had a
quick look at the data and found many galaxies — it was very
encouraging. And when we got back to Europe we started exploring the
data in more detail. It was like fishing in deep water and each new
catch generated a lot of excitement and discussion of the species we
were finding,” explained Roland Bacon (Centre de Recherche Astrophysique de Lyon, France, CNRS) principal investigator of the MUSE instrument and leader of the commissioning team.
For every part of the MUSE view of HDF-S there is not just a pixel in
an image, but also a spectrum revealing the intensity of the light’s
different component colours at that point — about 90 000 spectra in
total [1]. These
can reveal the distance, composition and internal motions of hundreds
of distant galaxies — as well as catching a small number of very faint
stars in the Milky Way.
Even though the total exposure time was much shorter than for the
Hubble images, the HDF-S MUSE data revealed more than twenty very faint
objects in this small patch of the sky that Hubble did not record at all
[2].
“The greatest excitement came when we found very distant galaxies
that were not even visible in the deepest Hubble image. After so many
years of hard work on the instrument, it was a powerful experience for
me to see our dreams becoming reality,” adds Roland Bacon.
By looking carefully at all the spectra in the MUSE observations of
the HDF-S, the team measured the distances to 189 galaxies. They ranged
from some that were relatively close, right out to some that were seen
when the Universe was less than one billion years old. This is more than
ten times the number of measurements of distance than had existed
before for this area of sky.
For the closer galaxies, MUSE can do far more and look at the
different properties of different parts of the same galaxy. This reveals
how the galaxy is rotating and how other properties vary from place to
place. This is a powerful way of understanding how galaxies evolve
through cosmic time.
“Now that we have demonstrated MUSE’s unique capabilities for
exploring the deep Universe, we are going to look at other deep fields,
such as the Hubble Ultra Deep field.
We will be able to study thousands of galaxies and to discover new
extremely faint and distant galaxies. These small infant galaxies, seen
as they were more than 10 billion years in the past, gradually grew up
to become galaxies like the Milky Way that we see today,” concludes Roland Bacon.
Notes
[1] Each spectrum covers a range of wavelengths from the blue part of the spectrum into the near-infrared (475‒930 nanometres).
[2] MUSE is particularly sensitive to
objects that emit most of their energy at a few particular wavelengths
as these show up as bright spots in the data. Galaxies in the early
Universe typically have such spectra, as they contain hydrogen gas
glowing under the ultraviolet radiation from hot young stars.
More information
This research was presented in a paper
entitled “The MUSE 3D view of the Hubble Deep Field South” by R. Bacon
et al., to appear in the journal Astronomy & Astrophysics on 26 February 2015.
The team is composed of R. Bacon (Observatoire de Lyon, CNRS,
Université Lyon, Saint Genis Laval, France [Lyon]), J. Brinchmann
(Leiden Observatory, Leiden University, Leiden, The Netherlands
[Leiden]), J. Richard (Lyon), T. Contini (Institut de Recherche en
Astrophysique et Planétologie, CNRS, Toulouse, France; Université de
Toulouse, France [IRAP]), A. Drake (Lyon), M. Franx (Leiden), S.
Tacchella (ETH Zurich, Institute of Astronomy, Zurich, Switzerland
[ETH]), J. Vernet (ESO, Garching, Germany), L. Wisotzki
(Leibniz-Institut für Astrophysik Potsdam, Potsdam, Germany [AIP]), J.
Blaizot (Lyon), N. Bouché (IRAP), R. Bouwens (Leiden), S. Cantalupo
(ETH), C.M. Carollo (ETH), D. Carton (Leiden), J. Caruana (AIP), B.
Clément (Lyon), S. Dreizler (Institut für Astrophysik, Universität
Göttingen, Göttingen, Germany [AIG]), B. Epinat (IRAP; Aix Marseille
Université, CNRS, Laboratoire d’Astrophysique de Marseille, Marseille,
France), B. Guiderdoni (Lyon), C. Herenz (AIP), T.-O. Husser (AIG), S.
Kamann (AIG), J. Kerutt (AIP), W. Kollatschny (AIG), D. Krajnovic (AIP),
S. Lilly (ETH), T. Martinsson (Leiden), L. Michel-Dansac (Lyon), V.
Patricio (Lyon), J. Schaye (Leiden), M. Shirazi (ETH), K. Soto (ETH), G.
Soucail (IRAP), M. Steinmetz (AIP), T. Urrutia (AIP), P. Weilbacher
(AIP) and T. de Zeeuw (ESO, Garching, Germany; Leiden).
ESO is the foremost intergovernmental astronomy organisation in
Europe and the world’s most productive ground-based astronomical
observatory by far. It is supported by 16 countries: Austria, Belgium,
Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy,
the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the
United Kingdom, along with the host state of Chile. ESO carries out an
ambitious programme focused on the design, construction and operation of
powerful ground-based observing facilities enabling astronomers to make
important scientific discoveries. ESO also plays a leading role in
promoting and organising cooperation in astronomical research. ESO
operates three unique world-class observing sites in Chile: La Silla,
Paranal and Chajnantor. At Paranal, ESO operates the Very Large
Telescope, the world’s most advanced visible-light astronomical
observatory and two survey telescopes. VISTA works in the infrared and
is the world’s largest survey telescope and the VLT Survey Telescope is
the largest telescope designed to exclusively survey the skies in
visible light. ESO is a major partner in ALMA, the largest astronomical
project in existence. And on Cerro Armazones, close to Paranal, ESO is
building the 39-metre European Extremely Large Telescope, the E-ELT,
which will become “the world’s biggest eye on the sky”.
Links
Contacts
Roland Bacon
CRAL - Centre de recherche astrophysique de Lyon
Saint-Genis-Laval, France
Tel: +33 478 86 85 59
Cell: +33 608 09 14 27
Email: roland.bacon@univ-lyon1.fr
Richard Hook
ESO education and Public Outreach Department
Garching bei München, Germany
Tel: +49 89 3200 6655
Cell: +49 151 1537 3591
Email: rhook@eso.org
ESO education and Public Outreach Department
Garching bei München, Germany
Tel: +49 89 3200 6655
Cell: +49 151 1537 3591
Email: rhook@eso.org
Source: ESO
