Density of the inter-cluster medium

In summary: We have cold gas clouds that leave the Lynman forest imprint on distant quasar spectra, WHIM (Warm/Hot Intergalactic Matter), primordial or otherwise Black Holes and any member of the exotic particle zoo that you care to dream up! Anything else I have forgotten? Ah yes! and a Dark Energy contribution; any way of measuring this?There is a lot of speculation on the amount and nature of dark energy in the universe, but currently there is no way to directly measure it.
  • #1
Garth
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SpaceTiger said:
Well, firstly, I don't think there's any reason that all of the gas in an overdensity should have to collapse into galaxies (note that there is still material falling in from outside of clusters).
That is interesting ST. How dense is the inter-galactic-cluster medium?
Garth
 
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  • #2
Garth said:
That is interesting ST. How dense is the inter-galactic-cluster medium?
This is a great question Garth ... and if I may add a rider: and how is such density measured/inferred?

If you don't mind, I'd like to keep this thread to just QSO absorption lines (and closely related topics) - May I split this off as the start of a new thread?
 
  • #3
Nereid said:
But first, for those not quite in the know, what is the "WHIM"?
WHIM stands for Warm-Hot Intergalactic Medium, a low density phase at 105 - 107 K, mainly located in the filaments and not part of any virialized system. About 30% - 40% of all baryons of the present universe (z < 2) were assumed to reside in this phase. It was postulated http://arxiv.org/astro-ph/0007217 in the meanwhile.
 
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  • #4
Garth said:
That is interesting ST. How dense is the inter-galactic-cluster medium?

There are two main components to the intergalactic medium, the cold component (T<105 K) and the warm-hot component (105-107 K). The former is only a few times the critical density:

[tex]\rho_c=\frac{3H^2}{8\pi G}[/tex]

corresponding to a density of about 10-5 cm-3. The warm-hot component is about a factor of ten more dense than this. Finally, intracluster gas has densities of order 10-3 cm-3 and temperatures of around 107 K.

You can determine these conditions from a lot of things, including fitting absorption lines in quasar spectra, looking at X-ray emission and absorption, and the Sunyaev-Zeldovich effect.
 
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  • #5
SpaceTiger said:
There are two main components to the intergalactic medium, the cold component (T<105 K) and the warm-hot component (105-107 K). The former is only a few times the critical density:

[tex]\rho_c=\frac{3H^2}{8\pi G}[/tex]

corresponding to a density of about 10-5 cm-3. The warm-hot component is about a factor of ten more dense than this. Finally, intracluster gas has densities of order 10-3 cm-3 and temperatures of around 107 K.

You can determine these conditions from a lot of things, including fitting absorption lines in quasar spectra, looking at X-ray emission and absorption, and the Sunyaev-Zeldovich effect.
These densities seem very high ST - with the critical density at around 10-29 cm-3?

Nereid yes please let's start another thread.

Garth
 
  • #6
Garth said:
These densities seem very high ST - with the critical density at around 10-29 cm-3?

That's 10-29 g cm-3. I was quoting densities in terms of atoms per unit volume (instead of mass per unit volume).
 
  • #7
Doh!
Homer

Sometimes I just read too fast for my brain to catch up with my eyes.

ST what's that in real money? i.e. in terms of gms.cm-3 and as a component of Omega?

Garth
 
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  • #8
Garth said:
ST what's that in real money? i.e. in terms of gms.cm-3 and as a component of Omega?

The cold component corresponds to, as you said, about 10-29 g cm-3. The other two are a factor of 10 and 100 larger, respectively.

In terms of omega, it depends on the redshift you're referring to. I don't know the numbers off the top of my head, but I'll look it up later.
 
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  • #10
Thank you Neried.

The first question is that of the inventory of the IGM and the contribution it makes to the total Omega density parameter of the universe; that is both of baryonic and non-baryonic dark matter.

We have cold gas clouds that leave the Lynman forest imprint on distant quasar spectra, WHIM (Warm/Hot Intergalactic Matter), primordial or otherwise Black Holes and any member of the exotic particle zoo that you care to dream up! Anything else I have forgotten? Ah yes! and a Dark Energy contribution; any way of measuring this?

Garth
 

Related to Density of the inter-cluster medium

What is the inter-cluster medium?

The inter-cluster medium (ICM) is a diffuse, hot gas that fills the space between galaxy clusters in the universe. It is primarily composed of hydrogen and helium, with some heavier elements, and has a density of about 10^-29 g/cm^3.

How is the density of the ICM measured?

The density of the ICM is measured using X-ray observations. The hot gas emits X-rays due to its high temperature, and the intensity of these X-rays can be used to calculate the density of the gas.

Why is the density of the ICM important?

The density of the ICM is important because it provides crucial information about the structure and evolution of galaxy clusters. It also plays a role in the formation and growth of galaxies within these clusters.

How does the density of the ICM vary between different galaxy clusters?

The density of the ICM can vary significantly between different galaxy clusters, depending on factors such as the size and mass of the cluster, as well as its location within the universe. On average, however, the ICM density tends to decrease with increasing distance from the center of the cluster.

What effects can impact the density of the ICM?

The density of the ICM can be affected by various processes such as gas cooling, heating, and turbulence. Additionally, interactions between galaxy clusters or the presence of supermassive black holes can also impact the density of the ICM.

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