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Does anyone know where I can find numbers (or how to derive) the CMB flux density (W/m^2)? I'm only really interested in our present cosmological time, so a solution may assume the CMB to be at a constant temperature.
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Well, the CMB is almost a perfect black body as T=2.725K. So you can compute it directly from the black body spectrum (Planck's Law):Nabeshin said:Does anyone know where I can find numbers (or how to derive) the CMB flux density (W/m^2)? I'm only really interested in our present cosmological time, so a solution may assume the CMB to be at a constant temperature.
Also the energy absorbed per unit surface area. This works for the CMB because it's isotropic (as opposed to the light from a star which only comes from a small area of the sky). So you don't multiply that value by any area to get the flux density of the CMB.Nabeshin said:First, using Planck's law would give the energy radiated per unit surface area at that temperature,
Yup. Just bear in mind that "A" there would be dependent upon how you are doing the measurement, and would typically be the area of the beam of the detector on a telescope.Nabeshin said:So just [tex]A \sigma T^4[/tex] should work for total power absorbed, then? Interesting that it should turn out to be so simple!
CMB flux density, also known as cosmic microwave background flux density, is a measure of the amount of energy emitted by the cosmic microwave background radiation. It is usually expressed in units of watts per square meter per Hertz (W/m²/Hz).
CMB flux density is derived by analyzing the temperature and polarization of the cosmic microwave background radiation. This data is collected by telescopes and satellites, and then analyzed using mathematical models and equations to determine the flux density at different frequencies.
The CMB flux density is an important tool for understanding the early universe and the current state of cosmology. By studying the fluctuations in the CMB flux density, scientists can gain insights into the composition, geometry, and evolution of the universe.
CMB flux density has a relatively uniform distribution across the electromagnetic spectrum, with its peak at a wavelength of about 1.9 mm. However, it does show slight variations at different frequencies, which can provide valuable information about the properties of the universe.
One of the main challenges in deriving CMB flux density for present cosmology is the presence of foreground noise, such as emissions from dust and gas in our galaxy. This noise must be carefully filtered out in order to accurately measure the CMB flux density. Additionally, technological advancements in telescopes and detectors are constantly being made to improve the precision and accuracy of CMB flux density measurements.