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Topic: Intergalactic gas

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	Chandra :: Photo Album :: Hot Intergalactic Gas :: 13 Jul 02
		Four independent teams of scientists have detected intergalactic gas with temperatures in the range 300,000 to 5 million degrees Celsius by observing quasars with the Chandra X-ray Observatory.
		It is thought that this gas forms part of a gigantic system, or web, of hot gas and dark matter that defines the cosmic landscape.
		Eventually, astronomers will be able to use the hot gas to map of the distribution of dark matter in the universe and perhaps understand its origin.
	chandra.harvard.edu /photo/2002/igm/index.html (335 words)

	Intergalactic space - Wikipedia, the free encyclopedia
		Generally free of dust and debris, intergalactic space is very close to a vacuum.
		Surrounding and stretching between galaxies, there is a rarefied gas that is thought to possess a cosmic filamentary structure and that is slightly denser than the average density in the Universe.
		The reason the IGM is thought to be mostly ionized gas is that its temperature is thought to be quite high by terrestrial standards (though some parts of it are only "warm" by astrophysical standards).
	en.wikipedia.org /wiki/Intergalactic_space (346 words)

	Galaxies, Colliding Galaxies, Cluster Of Galaxies at SPACE.com
		A Galaxy, or nebula, is any large-scale system of stars, interstellar gas, dust, and plasma within the universe.
		The Milky Way galaxy is believed to contain more than three hundred billion stars, and has a total mass of six hundred billion times the gross mass of the sun.
		Intergalactic space, or the space between the galaxies of the universe, is filled with an unsubstantiated plasma matter that has an average density less than one atom per cubic meter.
	www.space.com /galaxy (379 words)

	ISO proves that intergalactic space is dusty (Site not responding. Last check: 2007-10-25)
		The intergalactic dust is concentrated towards the centre of the cluster.
		Intergalactic dust may very well be present nearby, but it is likely to be sparse and scattered.
		Emissions indicating the presence of intergalactic dust were much stronger towards the crowded centre of the cluster than at the edges.
	www.iso.vilspa.esa.es /outreach/esa_pr/in9737.htm (1103 words)

	Intergalaktische Wetterstation meldet Schockfront
		In the presented work the unusual shaped plumes of radio gas from the radio galaxy NGC 315 is serving as such a weather station in the several hundred lightyears long Pisces-Perseus filament of galaxies.
		The gas presumably originates from the vicinity of a supermassive fl hole in the center of the galaxy.
		Two opposite oriented jets of radio emitting gas start in the center of the galaxy and become stopped after a few million lightyears by the collision with the dilute intergalactic gas.
	www.mpa-garching.mpg.de /HIGHLIGHT/2002/highlight0203_e.html (901 words)

	THE INFINITE UNIVERSE Chapter 4-3
		The major galaxy rotates and so the smaller objects, like gas clouds/smaller galaxies, may be likely to end up orbiting in a plane that is perpendicular to the rotation axis of the major galaxy (the same may be the case with solar system formation, 7-1, as well as cluster formation, 4-4).
		Gas and dust may be present in the halo in very low concentrations so that we can't detect it (yet), but the total amount may be huge.
		But rather than such intergalactic gas being spit out by the galaxies themselves I think that the gas should be looked upon as coming out of intergalactic and, especially, intercluster space streaming to clusters (and their galaxies), thus fuelling (luminous) galaxies (as well as dark galaxies/g-galaxies) with new gas that triggers star-bursts.
	www.eitgaastra.nl /timesgr/part4/3.html (10227 words)

	Rennan Barkana and Avi Loeb: Nature Article (Site not responding. Last check: 2007-10-25)
		So when the galaxy finally forms along with the quasar inside it, gas from all around is in the process of falling toward the galaxy, and this gas is already much denser than typical intergalactic gas.
		This gas infall pattern should be reflected in the absorption pattern that the gas produces on background light.
		In analyzing gas infall due to gravity, we must remember that the mass that produces this gravity is thought to consist mostly of "dark matter".
	wise-obs.tau.ac.il /~barkana/nature.html (1539 words)

	Hot Halo Find Confirms Theory (Site not responding. Last check: 2007-10-25)
		The halo encompassing the immense spiral galaxy is comprised of hot gas that extends more than 60,000 light years on either side of the disk of the galaxy.
		Spiral galaxies are thought to form from enormous clouds of intergalactic gas that collapse to form giant, spinning disks of stars and gas.
		Hot gas has previously been detected around spiral galaxies in which vigorous star formation is ejecting matter from the galaxy, but until now hot halos due to the inflow of intergalactic matter have not been detected.
	www.scienceagogo.com /news/20060105174910data_trunc_sys.shtml (745 words)

	Intergalactic
		Gas dynamics is also included; it manifests itself as gentle pressure forces felt by diffuse intergalactic gas clouds as well as shock heating when supersonic streams of gas fall into the outer layers of galaxies.
		Including intergalactic radiative transfer is one of the latest improvements and is one of the things I currently work on.
		The extremely sparse gas cannot be seen in emission since it produces too few photons.
	info.phys.cmu.edu /welcome/news/Interactions/2003/Intergalactic.html (968 words)

	Scientific American: Our Growing, Breathing Galaxy (Site not responding. Last check: 2007-10-25)
		Between the stars lie gas and dust, forming the interstellar medium, most of which also moves in nearly circular orbits around the galactic center and is even more narrowly concentrated in a disk than the stars are.
		Unlike the gas found by Münch, these clouds did not follow the overall rotation of the galaxy; instead they seemed to be falling toward the galactic disk at high speed, so they became known as HVCs.
		This corona is not dense enough to strip gas from the Magellanic Clouds, but once the gas has been drawn out by tidal forces, friction with the corona causes it to decelerate, slowly rain down on the galaxy and contribute to the growth of the Milky Way.
	www.sciam.com /print_version.cfm?articleID=0000107A-6236-1FD5-A23683414B7F0000 (3647 words)

	CERN Courier - Missing baryons found in hot - IOP Publishing - article
		By assuming that the detected gas has a heavy-element abundance that is one-tenth of that of the Sun, which is typical for intergalactic gas, Nicastro and colleagues were able to extrapolate the total density of baryons along the line of sight to Markarian 421.
		Indeed, before the detection of this intergalactic gas, simulations of the large-scale structure formation predicted the existence of a warm-hot diffuse gas.
		This gas, one-millionth of the density of the interstellar medium in our galaxy, is shock-heated by the continuous interaction between galaxies.
	www.cerncourier.com /main/article/45/2/14 (624 words)

	Galaxy - InfoSearchPoint.com (Site not responding. Last check: 2007-10-25)
		The space between galaxies is relatively empty, except for intergalactic gas clouds.
		In 1944, van de Hulst predicted microwave radiation at a wave length of 21 centimetres, resulting from interstellar atomic hydrogen gas; this radiation was observed in 1951.
		In the 1970s it was realized that the total visible mass of galaxies (from stars and gas) does not properly account for the speed of the rotating gas, thus leading to the postulation of dark matter.
	www.infosearchpoint.com /display/Galaxy (1123 words)

	USATODAY.com - Ongoing growth: Galaxies grab intergalactic gas (Site not responding. Last check: 2007-10-25)
		It is therefore unlikely that the detected halo is produced by gas ejected out of the galaxy, which was something astronomers detected in 2001.
		Instead, the researchers believe the galaxy's immense gravity is attracting the gas and shaping it into a spherical halo.
		The gas falls inward toward the galaxy's central core and fuels the birth of new stars.
	www.usatoday.com /tech/science/space/2006-02-06-galaxy-halo_x.htm?csp=34 (521 words)

	The Search for the Intergalactic Medium
		This gas - composed almost entirely of hydrogen and helium, the two lightest elements - is the material that was formed during the first few minutes after the Big Bang, some 10 to 20 billion years ago.
		The Hopkins Ultraviolet Telescope is well-suited to the task of observing intergalactic helium.
		HUT may also be able to measure the density and degree of ionization of such gas, and perhaps study its evolution with time, since smaller redshifts correspond to more recent epochs in the history of the Universe.
	praxis.pha.jhu.edu /astro2/astro2_science/HS1700.html (954 words)

	Intergalactic hydrogen gas
		The distribution of neutral hydrogen gas (within a narrow velocity range) as obtained with the ATCA is shown in blue, overlaid onto optical images.
		The overall distribution of neutral hydrogen gas as obtained with the ATCA is shown in blue, overlaid onto optical and infrared images.
		It is a striking example of neutral intergalactic gas without stars, apart from one clump which is associated with a dwarf galaxy.
	outreach.atnf.csiro.au /images/astronomical/hydrogengas.html (292 words)

	Intergalactic magnetism runs deep and wide: Science News Online, May 6, 2000 (Site not responding. Last check: 2007-10-25)
		Both in the gaps between galaxies that are clustered and in the lonelier neighborhoods outside those clusters, magnetic fields are remarkably strong, a scientific team reports.
		The stronger the magnetism there or the denser the gas that the field pervades, the more the field rotates the light's polarization.
		The scientists found to their surprise that the cluster's dilute intergalactic gas had magnetic fields of 2 to 3 microgauss (ìG), similar in strength to those in the Milky Way.
	www.sciencenews.org /20000506/fob5.asp (866 words)

	White Paper
		We will discover and analyze intergalactic gas which is dissipating gravitational energy and collapsing to form galaxies.
		Figure shows schematically the collapse of gas into structure (bold arrows), and the sensitivity of emission lines measurements vs. the minimum density and scale which gas clouds must subtend in order to be detectable.
		Gas moving at several 100 km/s will dissipate strongly in these lines even if CNO are present in only trace amounts (e.g., 1% solar).
	www.srl.caltech.edu /sal/white_paper.htm (4272 words)

	[No title] (Site not responding. Last check: 2007-10-25)
		The tenuous gas between the galaxies, also called the intergalactic medium, is composed primarily of hydrogen and helium.
		Hydrogen does not work as a tracer of the intergalactic medium because practically all hydrogen atoms have lost their electrons and are therefore incapable of absorbing light.
		Helium atoms in the intergalactic gas are able to absorb extreme-ultraviolet light, effectively blocking the QSO from view.
	fuse.pha.jhu.edu /~williger/gp_pr.txt (681 words)

	CERN Courier - Gas reveals secrets of unive - IOP Publishing - article
		Most ordinary matter in the universe is in the hot gas that makes up the intergalactic medium.
		ROSAT observed X-ray emission from this gas, both in small groups of galaxies (where it has a temperature of around 10 million degrees) and in large clusters (around 100 million degrees).
		The original phase of galaxy formation heated up the intergalactic gas so much that it is too energetic to collapse and form stars.
	www.cerncourier.com /main/article/39/02/7 (228 words)

	The GSMT Book: Chapter 2, Section 2.1 (Site not responding. Last check: 2007-10-25)
		Although galaxies are the traditional tracers of large scale structure, additional emphasis has recently been given to the intergalactic gas distribution, as typically observed in absorption, because the gas that gives rise to the Ly forest is expected to be a nearly direct (i.e., nearly unbiased) tracer of the total matter distribution (see Figure 4).
		Measuring the structure traced by both galaxies and intergalactic gas would be very useful, because it would allow us to construct a high dynamic range, three-dimensional tomographic map of the universe that can be used to test theories of structure formation.
		In this case, the high-density sampling in the angular dimensions as traced by galaxies would be complemented by high-density sampling in the redshift dimension, as traced by the intergalactic gas.
	www.aura-nio.noao.edu /book/ch2/2_1.html (1847 words)

	GSFC Press Release 99-001
		This tenuous gas, composed primarily of hydrogen and helium, is the stuff from which the first galaxies were made.
		The intergalactic helium gas closer to Earth (and thus observed as it existed more recently) is fully ionized and transparent to extreme ultraviolet light.
		The quasar shining through the intergalactic gas is extremely remote, at a redshift of 3.3, which corresponds to a time when the Universe was less than ten percent of its current age.
	www.gsfc.nasa.gov /news-release/releases/1999/99-001.htm (1060 words)

	Research
		Polluting the surrounding intergalactic gas this way affects the formation of new galaxies because most of the normal matter in the universe has yet to cool down and condense into galaxies.
		Gas cooling and reheating are thought to determine the basic form of the galaxy luminosity function.
		Adding new measurements from Keck echellete spectra, Crystal recently showed that cool gas is accelerated to the predicted speed of the hot wind in ultraluminous galaxies and argued that dwarf starburst winds simply lack enough momentum (essentially mass in this case) to accelerate the cooler gas to the velocity of the hot wind (Martin 2005).
	www.physics.ucsb.edu /~cmartin/research.html (1424 words)

	Visible Matter: Once lost but now found: Science News Online, Aug. 10, 2002
		The gas clouds range in temperature from 300,000° to 5 million°C. Ultraviolet detectors had previously revealed the coolest components of this gas (SN: 5/13/00, p.
		Studies of gas clouds so distant that they reveal conditions in the early universe also provided evidence for a much higher amount of visible matter than astronomers had found locally.
		The new studies "reveal that most of the visible matter in the universe is in the intergalactic medium," says theorist Jeremiah P. Ostriker of the University of Cambridge in England.
	www.sciencenews.org /articles/20020810/fob1.asp (641 words)

	Chandra catches early phase of cosmic assembly
		"We may be seeing hot intergalactic gas in a relatively pristine state before it has been polluted by gas from galaxies," said Q. Daniel Wang of the University of Massachusetts in Amherst, and lead author on an upcoming Astrophysical Journal article describing the study.
		The gas in the pristine cloud, which is still several million light years away from the core cluster, is conspicuous for its lack of iron atoms.
		Over time, as the cluster merges with the other clusters and the hot gas pressure increases, the dust grains will be driven from the galaxies, mixed with the hot gas, and destroyed, liberating the iron atoms.
	www.eurekalert.org /pub_releases/2004-08/nsfc-cce081304.php (569 words)

	[No title] (Site not responding. Last check: 2007-10-25)
		Astronomers can estimate the amount of gas in the intergalactic medium by essentially counting up the number of atoms that absorb the light from distant quasars.
		If the gas is there, many of the atoms must be ionized, that is stripped of some of their electrons, so that they cannot absorb the radiation.
		If all the radiation from the first generations of stars that formed in galaxies were to escape, it could easily ionize the intergalactic gas.
	praxis.pha.jhu.edu /astro2/science/starburst.deroff (680 words)

	ATNF Science Highlights
		Neutral hydrogen gas (HI) is abundant in most galaxies, but it is also found well outside their stellar envelopes where it contributes to the intergalactic medium.
		Koribalski and her collaborators are using observations taken with the Compact Array to study the HI gas found in the outskirts of galaxies and between galaxies.
		The only intergalactic HI gas cloud detected in the HIPASS Bright Galaxy Catalog lies at a projected separation of 250 kiloparsecs from the galaxy NGC 2442 (distance = 15.5 Mpc) which is part of a loose group of galaxies.
	www.atnf.csiro.au /research/highlights/2003/koribalski/koribalski.html (1024 words)

	Newswise
		Chandra observations of the massive spiral galaxy NGC 5746 revealed a large halo of hot gas (blue) surrounding the optical disk of the galaxy (white).
		Spiral galaxies are thought to form from enormous clouds of intergalactic gas that collapse to form spinning disks of stars and gas.
		Hot gas has been detected around spiral galaxies in which vigorous star formation is ejecting matter from the galaxy, but until now, hot halos due to infall of intergalactic matter had not been detected.
	www.newswise.com /articles/view/517765 (775 words)

	Clouds Dominate the Galactic Halo
		High-velocity clouds are vagabond clumps of intergalactic gas, possibly left over from the formation of the Milky Way and other nearby galaxies.
		According to the researcher, the ubiquitous nature and dynamics of these newly discovered clouds support the theory that they are condensing out of the hot gas that is lifted into the halo through supernova explosions.
		When a massive star dies, it produces a burst of cosmic rays and an enormous expanding bubble of gas at a temperature of several million degrees Celsius.
	www.nrao.edu /pr/2003/honeclouds (853 words)

	Intergalactic gas
		A problem which remains unresolved is whether some fraction of this emission arises from clouds within the background cluster, a controversy which began with the original HI survey (Haynes and Roberts 1979; Arp 1985).
		A more concerted campaign has detected ionized gas in clouds MS II-IV along the stream (Weiner and Williams 1996); this result is discussed in the Bland-Hawthorn and Maloney (1997).
		An exciting claim was made by Williams and Schommer (1993) that they had detected ionized gas from a nearby absorption-line system observed towards 3C273, even while HI had not been found in this direction.
	www.atnf.csiro.au /pasa/14_1/hawthorn/paper/node2.html (553 words)

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