X-ray background/peculiar velocities and the Big Bang

In summary, the X-ray background and peculiar velocities provide evidence that supports the Big Bang model. The X-ray background, although originally thought to be a microwave background, is now believed to be the result of individual sources at high redshifts. There are still unanswered questions about the X-ray background and its relation to structure formation. Peculiar velocities, on the other hand, can be used as a test for cosmological models and the conditions for non-linear gravitational collapse and structure formation.
  • #1
xratx
3
0
I heard that the X-ray background and peculiar velocities provide evidence that leads scientists to believe in the Big Bang model. What exactly do they have to do with it?
 
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  • #2
The backgound is not x-ray, but microwave. According to theory about 300,000 yrs. after big bang, the universe was cool enough for atmos to form. The universe was filled with radiation at a high temperature. As the universe expanded, the radiation cooled down to its present value (slightly under 3 deg. K). There doesn't seem to be any other explanation.

The velocities that you refer to are those of galaxies which are going away from us with speed proportional to distance - characteristic of an expanding universe, which started a little less than 14 bil. yrs ago.
 
  • #3
There is actually a x-ray background that is diffuse at large scales, but that can be resolved in individual sources when observing with high angular resolution. The background is assumed to be the result of individual sources at high redshifts. There are however lots of unanswered questions regarding the x-ray background such as its relation to structure formation. I am not aware how this background can be used to discriminate between cosmological models.

On the other hand, statistical analysis of peculiar velocities can be a test of cosmological models or at least classes of models. This is because the model-dependent spectrum of perturbations determines the conditions for non-linear gravitational collapse and how structure is formed. Thus for example a cold dark matter model with a hierarchical bottom-up structure formation history predicts high peculiar velocities due to collisions and tidal forces.
 

1. What is the X-ray background and how does it relate to the Big Bang?

The X-ray background is a diffuse glow of X-ray radiation that is observed in all directions in the sky. It is believed to be the result of supermassive black holes and hot gas in galaxies and galaxy clusters. The X-ray background is related to the Big Bang because it provides evidence for the existence of supermassive black holes and hot gas, which are important components of the early universe predicted by the Big Bang theory.

2. How do peculiar velocities affect the expansion of the universe?

Peculiar velocities are the velocities of galaxies or other objects relative to the overall expansion of the universe. They can be caused by gravitational interactions between objects, and can either add to or subtract from the overall expansion of the universe. Peculiar velocities do not significantly affect the expansion of the universe on a large scale, but they can help explain the movement and distribution of galaxies in the universe.

3. Can X-ray background and peculiar velocities be used to study the history of the universe?

Yes, both the X-ray background and peculiar velocities can provide valuable insights into the history of the universe. The X-ray background can reveal information about the early universe and the formation of galaxies and galaxy clusters. Peculiar velocities can help us understand the distribution of matter in the universe and how it has evolved over time.

4. How does the observation of X-ray background support the Big Bang theory?

The observation of the X-ray background provides strong evidence for the Big Bang theory. According to the theory, the early universe was extremely hot and dense, and as it expanded, it cooled down. This cooling process would have left behind a remnant of radiation, which is the X-ray background. The existence of the X-ray background is consistent with the predictions of the Big Bang theory and supports the idea that the universe began with a hot and dense state.

5. Are there any current studies or experiments being conducted to further understand X-ray background and peculiar velocities?

Yes, there are several ongoing studies and experiments aimed at further understanding X-ray background and peculiar velocities. For example, the Chandra X-ray Observatory and the XMM-Newton satellite are both dedicated to studying X-ray radiation in the universe. Additionally, projects such as the Dark Energy Survey and the Large Synoptic Survey Telescope are focused on mapping the distribution of matter in the universe, which can help us better understand peculiar velocities.

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