Andrew Yee
May 16th 06, 01:59 AM
ESA News
http://www.esa.int
10 May 2006
XMM-Newton reveals the origin of elements in galaxy clusters
Deep observations of two X-ray bright clusters of galaxies with ESA's
XMM-Newton satellite allowed a group of international astronomers to measure
their chemical composition with an unprecedented accuracy. Knowing the
chemical composition of galaxy clusters is of crucial importance to
understanding the origin of chemical elements in the Universe.
Clusters, or conglomerates, of galaxies are the largest objects in the
Universe. By looking at them through optical telescopes it is possible to
see hundreds or even thousands of galaxies occupying a volume a few million
light years across. However, such telescopes only reveal the tip of the
iceberg. In fact most of the atoms in galaxy clusters are in the form of hot
gas emitting X-ray radiation, with the mass of the hot gas five times larger
than the mass in the cluster's galaxies themselves.
Most of the chemical elements produced in the stars of galaxy clusters --
expelled into the surrounding space by supernova explosions and by stellar
winds -- become part of the hot X-ray emitting gas. Astronomers divide
supernovae into two basic types: 'core collapse' and 'Type Ia' supernovae.
The 'core collapse' supernovae originate when a star at the end of its life
collapses into a neutron star or a black hole. These supernovae produce lots
of oxygen, neon and magnesium. The Type Ia supernovae explode when a white
dwarf star consuming matter from a companion star becomes too massive and
completely disintegrates. This type produces lots of iron and nickel.
Respectively in November 2002 and August 2003, and for one and a half day
each time, XMM-Newton's made deep observations of the two galaxy clusters
called 'Sersic 159-03' and '2A 0335+096'. Thanks to these data the
astronomers could determine the abundances of nine chemical elements in the
clusters 'plasma' -- a gas containing charged particles such as ions and
electrons.
These elements include oxygen, iron, neon, magnesium, silicon, argon,
calcium, nickel, and -- detected for the first time ever in a galaxy cluster
-- chromium. "Comparing the abundances of the detected elements to the
yields of supernovae calculated theoretically, we found that about 30
percent of the supernovae in these clusters were exploding white dwarfs
('Type Ia') and the rest were collapsing stars at the end of their lives
('core collapse')," said Norbert Werner, from the SRON Netherlands Institute
for Space Research (Utrecht, Netherlands) and one of the lead authors of
these results.
"This number is in between the value found for our own Galaxy (where Type Ia
supernovae represent about 13 percent of the supernovae 'population') and
the current frequency of supernovae events as determined by the Lick
Observatory Supernova Search project (according to which about 42 percent of
all observed supernovae are Type Ia)," he continued.
The astronomers also found that all supernova models predict much less
calcium than what is observed in clusters and that the observed nickel
abundance cannot be reproduced by these models. These discrepancies indicate
that that the details of supernova enrichment is not yet clearly understood.
Since clusters of galaxies are believed to be fair samples of the Universe,
their X-ray spectroscopy can help to improve the supernova models.
The spatial distribution of elements across a cluster also holds information
about the history of clusters themselves. The distribution of elements in 2A
0335+096 indicates an ongoing merger. The distribution of oxygen and iron
across Sersic 159-03 indicates that while most of the enrichment by the core
collapse supernovae happened long time ago, Type Ia supernovae still
continue to enrich the hot gas by heavy elements especially in the core of
the cluster.
Note to editors
This work is presented in two papers in the Astronomy & Astrophysics
journal. The first one, published in April 2006 and titled 'XMM-Newton
spectroscopy of the cluster of galaxies 2A 035+096' (A&A Volume 449, Page
475), is by N.Werner , J.S.Kaastra and J.A.M.Bleeker (SRON, Utrecht, The
Netherlands), J.de Plaa and J.Vink (SRON and Utrecht University, Utrecht,
The Netherlands), T.Tamura (JAXA, Kanagawa, Japan), J.R.Peterson (Stanford
University, CA, USA), F.Verbunt (Utrecht University, The Netherlands).
The second article, to appear in 2006 and titled 'Chemical evolution in
Sersic 159-03 observed by XMM-Newton' (A&A 2006 and astro-ph/0602582), is by
J.de Plaa, J.Vink and J.A.M.Bleeker (SRON and Utrecht University, Utrecht,
The Netherlands), N.Werner, J.S.Kaastra and M.Mendez (SRON, Utrecht, The
Netherlands), A.M.Bykov (A.F. Ioffe Institute for Physics and Technology,
St.Petersburg, Russia), M.Bonamente (University of Alabama, Hunstville, AL,
USA), J.R. Peterson (Stanford University, CA, USA).
This research is in particular the result of the cooperation between the
SRON Utrecht and the Utrecht University in the Netherlands.
For more information
Norbert Werner
SRON Netherlands Institute for Space Research, Utrecht, the Netherlands
Tel: +31 30 2535 721
Jelle de Plaa
SRON Netherlands Institute for Space Research, Utrecht, the Netherlands
Tel: +31 30 253 5712
Norbert Schartel, ESA XMM-Newton Project Scientist
Norbert.Schartel @ sciops.esa.int
More about ...
* XMM-Newton overview
http://www.esa.int/esaSC/120385_index_0_m.html
Related articles
* XMM-Newton 'spare-time' provides impressive sky survey
http://www.esa.int/esaCP/SEMA7OOFGLE_index_0.html
* XMM-Newton digs into the secrets of fossil galaxy clusters
http://www.esa.int/esaCP/SEMCFFOFGLE_index_0.html
* XMM-Newton reveals a tumbling neutron star
http://www.esa.int/esaCP/SEMSIWNFGLE_index_0.html
* Cannibal stars like their food hot, XMM-Newton reveals
http://www.esa.int/esaCP/SEM7T6OVGJE_index_0.html
* 'Deep impact' of pulsar around companion star
http://www.esa.int/esaCP/SEMK6HMVGJE_index_0.html
* XMM-Newton scores 1000 top-class science results
http://www.esa.int/esaCP/SEMAB0NZCIE_index_0.html
* ESA's Integral and XMM-Newton missions extended
http://www.esa.int/esaCP/SEM31GVLWFE_index_0.html
* XMM-Newton sees 'hot spots' on neutron stars
http://www.esa.int/esaCP/SEMLY9NQS7E_index_0.html
* ESA is hot on the trail of Geminga
http://www.esa.int/esaCP/SEMQB4YO4HD_index_0.html
* XMM-Newton probes formation of galaxy clusters
http://www.esa.int/esaCP/SEMDW5A5QCE_index_0.html
* XMM-Newton's fifth anniversary in orbit
http://www.esa.int/esaSC/SEMZ5CXJD1E_index_0.html
IMAGE CAPTION:
[http://www.esa.int/esaCP/SEM94Q8ATME_index_1.html]
These X-ray images of the clusters of galaxies 'Sersic 159-03' (right) and
'2A 0335+096' (left) were taken by the European Photon Imaging Camera (EPIC)
on-board ESA's XMM-Newton, in November 2002 and August 2003 respectively.
Thanks to these observations, astronomers could determine the abundances of
nine chemical elements in the clusters 'plasma' -- a gas containing charged
particles such as ions and electrons. These elements include oxygen, iron,
neon, magnesium, silicon, argon, calcium, nickel, and -- detected for the
first time ever in a galaxy cluster -- chromium. The distribution of silicon
(produced by 'type Ia' and 'core collapse' supernova types) relative to iron
(mainly produced by 'type Ia' supernovae) in these two clusters is very
different, showing that they had a different evolution.
Credits: ESA and the XMM-Newton EPIC consortium
http://www.esa.int
10 May 2006
XMM-Newton reveals the origin of elements in galaxy clusters
Deep observations of two X-ray bright clusters of galaxies with ESA's
XMM-Newton satellite allowed a group of international astronomers to measure
their chemical composition with an unprecedented accuracy. Knowing the
chemical composition of galaxy clusters is of crucial importance to
understanding the origin of chemical elements in the Universe.
Clusters, or conglomerates, of galaxies are the largest objects in the
Universe. By looking at them through optical telescopes it is possible to
see hundreds or even thousands of galaxies occupying a volume a few million
light years across. However, such telescopes only reveal the tip of the
iceberg. In fact most of the atoms in galaxy clusters are in the form of hot
gas emitting X-ray radiation, with the mass of the hot gas five times larger
than the mass in the cluster's galaxies themselves.
Most of the chemical elements produced in the stars of galaxy clusters --
expelled into the surrounding space by supernova explosions and by stellar
winds -- become part of the hot X-ray emitting gas. Astronomers divide
supernovae into two basic types: 'core collapse' and 'Type Ia' supernovae.
The 'core collapse' supernovae originate when a star at the end of its life
collapses into a neutron star or a black hole. These supernovae produce lots
of oxygen, neon and magnesium. The Type Ia supernovae explode when a white
dwarf star consuming matter from a companion star becomes too massive and
completely disintegrates. This type produces lots of iron and nickel.
Respectively in November 2002 and August 2003, and for one and a half day
each time, XMM-Newton's made deep observations of the two galaxy clusters
called 'Sersic 159-03' and '2A 0335+096'. Thanks to these data the
astronomers could determine the abundances of nine chemical elements in the
clusters 'plasma' -- a gas containing charged particles such as ions and
electrons.
These elements include oxygen, iron, neon, magnesium, silicon, argon,
calcium, nickel, and -- detected for the first time ever in a galaxy cluster
-- chromium. "Comparing the abundances of the detected elements to the
yields of supernovae calculated theoretically, we found that about 30
percent of the supernovae in these clusters were exploding white dwarfs
('Type Ia') and the rest were collapsing stars at the end of their lives
('core collapse')," said Norbert Werner, from the SRON Netherlands Institute
for Space Research (Utrecht, Netherlands) and one of the lead authors of
these results.
"This number is in between the value found for our own Galaxy (where Type Ia
supernovae represent about 13 percent of the supernovae 'population') and
the current frequency of supernovae events as determined by the Lick
Observatory Supernova Search project (according to which about 42 percent of
all observed supernovae are Type Ia)," he continued.
The astronomers also found that all supernova models predict much less
calcium than what is observed in clusters and that the observed nickel
abundance cannot be reproduced by these models. These discrepancies indicate
that that the details of supernova enrichment is not yet clearly understood.
Since clusters of galaxies are believed to be fair samples of the Universe,
their X-ray spectroscopy can help to improve the supernova models.
The spatial distribution of elements across a cluster also holds information
about the history of clusters themselves. The distribution of elements in 2A
0335+096 indicates an ongoing merger. The distribution of oxygen and iron
across Sersic 159-03 indicates that while most of the enrichment by the core
collapse supernovae happened long time ago, Type Ia supernovae still
continue to enrich the hot gas by heavy elements especially in the core of
the cluster.
Note to editors
This work is presented in two papers in the Astronomy & Astrophysics
journal. The first one, published in April 2006 and titled 'XMM-Newton
spectroscopy of the cluster of galaxies 2A 035+096' (A&A Volume 449, Page
475), is by N.Werner , J.S.Kaastra and J.A.M.Bleeker (SRON, Utrecht, The
Netherlands), J.de Plaa and J.Vink (SRON and Utrecht University, Utrecht,
The Netherlands), T.Tamura (JAXA, Kanagawa, Japan), J.R.Peterson (Stanford
University, CA, USA), F.Verbunt (Utrecht University, The Netherlands).
The second article, to appear in 2006 and titled 'Chemical evolution in
Sersic 159-03 observed by XMM-Newton' (A&A 2006 and astro-ph/0602582), is by
J.de Plaa, J.Vink and J.A.M.Bleeker (SRON and Utrecht University, Utrecht,
The Netherlands), N.Werner, J.S.Kaastra and M.Mendez (SRON, Utrecht, The
Netherlands), A.M.Bykov (A.F. Ioffe Institute for Physics and Technology,
St.Petersburg, Russia), M.Bonamente (University of Alabama, Hunstville, AL,
USA), J.R. Peterson (Stanford University, CA, USA).
This research is in particular the result of the cooperation between the
SRON Utrecht and the Utrecht University in the Netherlands.
For more information
Norbert Werner
SRON Netherlands Institute for Space Research, Utrecht, the Netherlands
Tel: +31 30 2535 721
Jelle de Plaa
SRON Netherlands Institute for Space Research, Utrecht, the Netherlands
Tel: +31 30 253 5712
Norbert Schartel, ESA XMM-Newton Project Scientist
Norbert.Schartel @ sciops.esa.int
More about ...
* XMM-Newton overview
http://www.esa.int/esaSC/120385_index_0_m.html
Related articles
* XMM-Newton 'spare-time' provides impressive sky survey
http://www.esa.int/esaCP/SEMA7OOFGLE_index_0.html
* XMM-Newton digs into the secrets of fossil galaxy clusters
http://www.esa.int/esaCP/SEMCFFOFGLE_index_0.html
* XMM-Newton reveals a tumbling neutron star
http://www.esa.int/esaCP/SEMSIWNFGLE_index_0.html
* Cannibal stars like their food hot, XMM-Newton reveals
http://www.esa.int/esaCP/SEM7T6OVGJE_index_0.html
* 'Deep impact' of pulsar around companion star
http://www.esa.int/esaCP/SEMK6HMVGJE_index_0.html
* XMM-Newton scores 1000 top-class science results
http://www.esa.int/esaCP/SEMAB0NZCIE_index_0.html
* ESA's Integral and XMM-Newton missions extended
http://www.esa.int/esaCP/SEM31GVLWFE_index_0.html
* XMM-Newton sees 'hot spots' on neutron stars
http://www.esa.int/esaCP/SEMLY9NQS7E_index_0.html
* ESA is hot on the trail of Geminga
http://www.esa.int/esaCP/SEMQB4YO4HD_index_0.html
* XMM-Newton probes formation of galaxy clusters
http://www.esa.int/esaCP/SEMDW5A5QCE_index_0.html
* XMM-Newton's fifth anniversary in orbit
http://www.esa.int/esaSC/SEMZ5CXJD1E_index_0.html
IMAGE CAPTION:
[http://www.esa.int/esaCP/SEM94Q8ATME_index_1.html]
These X-ray images of the clusters of galaxies 'Sersic 159-03' (right) and
'2A 0335+096' (left) were taken by the European Photon Imaging Camera (EPIC)
on-board ESA's XMM-Newton, in November 2002 and August 2003 respectively.
Thanks to these observations, astronomers could determine the abundances of
nine chemical elements in the clusters 'plasma' -- a gas containing charged
particles such as ions and electrons. These elements include oxygen, iron,
neon, magnesium, silicon, argon, calcium, nickel, and -- detected for the
first time ever in a galaxy cluster -- chromium. The distribution of silicon
(produced by 'type Ia' and 'core collapse' supernova types) relative to iron
(mainly produced by 'type Ia' supernovae) in these two clusters is very
different, showing that they had a different evolution.
Credits: ESA and the XMM-Newton EPIC consortium