What Is the Highest Redshift for Star Formation?

[damasgate]

If gas has to be cooled below, say, 100 K, in order for stars to form, what is the highest redshift
for star formation?

What would be the necessary equations to solve this problem??

 

[ideasrule]

I don't understand. In order for stars to form, you need enough hydrogen at and a sufficiently high temperature, in the order of millions of degrees. What does this have to do with redshifts, or cooling the gas?

 

[damasgate]

It's somehow relating it to the CMB, What I'm not understanding is the procedure to solve the question. Do I use Friedmann equations?

full text

Gas temperature and star formation. Gas, immersed in the CMB photon bath
continuously, behaves like the Earth in problem 1 and is heated up to a temperature
comparable to the CMB temperature. CMB photons are a blackbody with temperature 
3000K at a redshift of 1100. And the blackbody has been cooling down as T(t) / 1=a(t),
since the expansion of the universe redshifts the wavelengths of CMB photons. If gas has
to be cooled below, say, 100 K, in order for stars to form, what is the highest redshift
for star formation? For reference, the galactic halo star HD 1523-0901 is determined to
have an age of 13:2 Gyrs, corresponding to a redshift of approx 10 in our current cosmological
model.

 

[Chalnoth]

If gas has to be cooled below, say, 100 K, in order for stars to form, what is the highest redshift
for star formation?

What would be the necessary equations to solve this problem??

You only need to know the redshift and temperature at one point, and the fact that temperature scales linearly with redshift (well, z+1). That is, if you halve the redshift, you halve the temperature.

This sort of idea is sensible, by the way, because a hot gas will not collapse to form stars. A gas needs to cool sufficiently before its atoms are slow enough to fall into gravitational potential wells.

 

[paranormal]

The maximum redshift for star formation can be determined by using the relationship between gas temperature and redshift. As the universe expands, the wavelength of light from distant objects is stretched, resulting in a higher redshift. This can be described by Hubble's law, which states that the redshift (z) is proportional to the recessional velocity (v) of an object: z = v/c, where c is the speed of light.

To determine the maximum redshift for star formation, we can use the relationship between the gas temperature and the redshift known as the Sunyaev-Zel'dovich effect. This effect describes the distortion of the cosmic microwave background (CMB) radiation by hot gas in galaxy clusters. The amount of distortion is dependent on the temperature of the gas, which is in turn related to the redshift.

Therefore, we can use the Sunyaev-Zel'dovich effect to determine the maximum redshift for star formation by calculating the temperature of gas at different redshifts. The temperature of the gas can be estimated using the Planck's law, which describes the energy distribution of blackbody radiation. By comparing the estimated gas temperature at different redshifts to the required temperature of 100 K for star formation, we can determine the maximum redshift at which gas can cool enough for stars to form.

In summary, to solve this problem, we would use the equations for Hubble's law, the Sunyaev-Zel'dovich effect, and Planck's law to calculate the maximum redshift for star formation based on the required gas temperature of 100 K. This would provide valuable insights into the conditions for star formation in the early universe and help us understand the evolution of galaxies over time.