Redshift Definition and 369 Threads

Homework Statement We are to assume the recombination happens at redshift z_{rec} when the number density of photons n_{\gamma}(z_{rec}) capable of ionizing hydrogen is exactly equal to the number density of baryons n_{b}(z_{rec}) . Use the measured number density of baryons, the...

So, I have read that the SZ effect is virtually independent of redshift. I follow the argument that the factor of (1+z)^-4 in the surface brightness cancels the (1+z)^4 factor in the photon energy density at the cluster (three factors from space being smaller in each dimension, one from the...

If light from billions of years ago were trapped within a perfectly reflecting mirrored box, will it be redshifted in a way comparable to light from galaxies billions of light-years away? I had made up this http://blog.chungyc.org/2009/03/redshift-puzzle/" as a supposed illustration of how the...

As I understand it, the conclusion that our spatially flat universe is expanding at an accelerating rate is supported by observations of 'standard candles' (type S1a supernovae) which appear less bright than expected when their z exceeds about 0.3 --- . Robert Kirschner has discussed these...

This is my first time on physics forums, and I am glad to have the chance to participate. My questions have been asked many times by others, but after lots of research, including among these threads on physics forums, especially “hurk4” on Feb 14-07 and Will Kastens, I can find no definitive...

arXiv:0902.0229 [ps, pdf, other] Title: Large-scale fluctuations in the distribution of galaxies from the Two Degree Field Galaxy Redshift Survey Authors: Francesco Sylos Labini, Nikolay L. Vasilyev, Yurij V. Baryshev Comments: 20 pages, 31 figures, to be published on Astronomy and...

http://arxiv.org/PS_cache/arxiv/pdf/0712/0712.3833v2.pdf Fourier spectral analysis has been carried out on the quasar number count as a function of redshift calculated from the quasar data of the Sloan Digital Sky Survey DR6 data release. The results indicate that quasars have preferred...

I find it helpful to conceptualize radial redshift as nothing more than a longitudinal stretching out or elongation of an incoming light beam segment, as measured in the observer's rest frame. For example, a light beam segment which has been redshifted by a factor of 2 has been stretched to...

Light sources A & B begin at the same location. Then, source A begins moving directly (and soon inertially) away from Observer at 0.8c, while source B begins moving directly (and soon inertially) toward Observer at 0.8c. SR Doppler redshift causes the light received by Observer from A to be...

[i asked this question in my blog..but i know it would be better answered here] what are the calculations of the wave lengths of a cosmological redshift? (meaning them all) i just wanted to know what precises wavelength determines which red shift.. thanks guys

A new paper on the Hubble redshift: [PLAIN]www.ptep-online.com/index_files/2009/PP-16-L1.PDF[/URL]

I heard there are many alternative hypoteses for cosmological redshift, e g Fred Hoyle' s variation of mass and tired light. There are other ones? Thanks.

arXiv:0808.1081 (cross-list from physics.pop-ph) [ps, pdf, other] Title: The kinematic origin of the cosmological redshift Authors: Emory F. Bunn, David W. Hogg Comments: 14 pages. Submitted to Am. J. Phys Subjects: Popular Physics (physics.pop-ph); Astrophysics (astro-ph); General...

I'm taking the liberty of revising and restating this topic which started in a separate thread. Comments are welcome. A lively debate is underway today by mainstream cosmologists as to whether the expansion of the universe implies that empty space between galaxies is also expanding. When...

How Relativity say about redshift in terms of curvature?

The formula for redshift according to the special relativity is f = \sqrt{\frac{c-v}{c+v}} f_0. Here f\to 0 when v\to c. So for arbitrarily strong redshift effect we can always solve the corresponding velocity v<c of the emitter moving away. Why then does Carrol explain this: "As an example...

Hey! :smile: I have a few questions regarding redshift. Firstly are there example of a shift in frequency of light other than the one seen in redshift or blueshift. I mean are there experiments that have been conducted that prove that this noted shift to the red end of the spectrum mean that...

Based on the quote below and the link to Wikipedia, I believe the implication is that gravitational redshift will occur when a photon climbs out of the gravity well, while blueshift will occur when falling into the gravity well. However, I am trying to clarify whether both time dilation and...

An extremely elementary question but... Lets say we had a spaceship sitting on Earth under the influence of gravity. Light travels from the ship's floor to the ceiling. An observer 'A' stands near the ceiling. Hence the light loses gravitational potential energy, and therefore decreases...

How far into space do we need to look before we can see the first signs of redshift?

The far away galaxies are moving faster which Hubble concluded from their redshift. Could he also have come to the conclusion that the observed redshift is of gravitational (or more generally: geometrical, as resulting from a "weird" metric) origin ? Does anybody know what a vacuum solution...

http://space.newscientist.com/article/dn12233-baby-galaxies-sighted-at-dawn-of-universe.html great. (of course must be cautious with first report and wait to see if confirmed...but looking good) galaxies from when the universe was only half a billion years old SciAm has this...

Does anyone know how much percentage of the total redshift of a quasar is contributed by Gravitational redshift considering light from the Quasar is emitted by heavy active galactic nuclei ? If there is a significant contribution from gravitational redshift then how will the Hubbles law hold...

how do you calculate the redshift at which the universe shifted from radiation dominated to mass dominated i was told to assume a flat universe with H0 = 70 also the temperature, to which i was given the formula density rad = aT^4 for the first part, i tried using density is propotional...

Hi i am confused as to how to calculate the age of the universe with redshift say for example The age of the universe now is 13.4 billion years old (and a critical universe). How do i find the age of the universe if it was a redshift at say 0.6?? Do i have to find the scale factor first...

Hi, I really need help with this question I've tried everything! let's assume a critical/flat universe. Ho=70 km/s/Mpc. I computed Boltzmann law for energy (volume) density by integrating Planck's law p rad= alpha*T^4. alpha= 7.56*10^-15 ergs/cm^3/K^4 (Which I computed to be 7.56*10^-16...

Hi i am confused as to how to calculate the age of the universe with redshift say for example The age of the universe now is 13.4 billion years old (and a critical universe). How do i find the age of the universe if it was a redshift at say 0.6?? Do i have to find the scale factor first...

Has there been any progress in clarifying this anomaly? I am a bit confused as to how people can ignore this problem?

hey everyone... so I am tryna solve this problem : a galaxy shows an emission line at a wavelength of 6610.2 A, which we identify as the H-alpha line in the Balmer series of Hydrogen. what is the redshift and velocity of the galaxy relative to us. period= 4.3 days magnitude= 26.25...

I don't understand whether this is true or false. It goes like this: if a distant galaxy has a substantial redshift ( as viewed from our galaxy) then anyone living in that galaxy would see a substantial redshift in a spectrum of the Milky Way galaxy. I know redshift is when the object is...

Based on general relativity (see book Gravity; an introduction to Einstein's General relativity by James B. Hartle), the frequency of light (emitted at R) is modified by the factor SQRT (1 - 2 G M / c**2 R) (see page 191). On the other hand, based on the equivalence principle, one arrives at...

Is it possible that redshift, though correct in it's theory, is not what we are viewing in terms of expansion of the universe? Is it possible that what we think is redshift is actually the strength of the light/energy fading, being absorbed or blocked over hundreds of millions of light years...

http://en.wikipedia.org/wiki/Angular_size_redshift_relation the Wiki entry for this declares itself a stub What they have is just a few sentences serving as a place-holder until somebody contributes a real article. the thing about angular-size redshift relation is that out beyond a certain...

So what if no distant galaxy showed any redshift of blueshift? what would that mean? What would this imply about the universe? What-if any –effects would this have on the Earth? I figure this would support the steady state theory and that it was static and infinite. anything else?? thanks

Greetings--this is from Ryden's Introduction to Cosmology, question # 5.2. Let me restate the question: Here w is the equation of state parameter for whatever the universe is made of (e.g. w = 0 for matter, 1/3 for radiation). Here is my best attempt so far: Simplify notation by...

...With Galaxy Explorer 2.0 Hi! I'm doing some personal reaserch on Sloan Digital Sky Survey, and I was wondering if anyone here uses this software? If so, could you tell me what the center is? For details of the SDSS project check the websites: GalaxyExplorer: a 3D...

I read this recently, but did not understand how one calculates this, since I'm used to: Distance = Recessional Velociy / Hubble's Constant = Beta x C / Hubble's Constant ALSO SEE ATTACHMENT I thought that as Z approaches infinity, Recessional Velociy approaches C...

Hi, what is the highest redshift observed for any 'object' in the Universe? Also, is the Abell-lensed 'object' still viewed as a possible candidate (at Z=10) or have people further studied this lensed 'object' and determined its high redshift as an error? Thanks you.

Hi! I just read an article about galactic redshift anomalies discovered by Halton Arp. Do these pose a problem for Big Bang Theory? Thanks in advance!

How would one use hubble's law to find the redshift of a galaxy 10^10 light years away? (in other words 3*10^9 pc) All I know however is the version of hubble's where v=H_o d, with H_o=71 \frac{m}{s*pc}, which tells me that v= 2.2*10^11 m/s. But this violates the second principle of...

The gravitational redshift to light at emission is known as the Einstein shift. There is a problem with it in General Relativity. It becomes infinite at the surface of a black hole. Light emitted there will be infinitely redshifted. GR predicts this energyless light. In this way as...

Hi, How can I prove that gravitational redshift preserves the characteristic shape of a blackbody spectrum?

In order to quell complaints from those members of the board who feel they are being discriminated against in my recent threads, I would like to directly address the issue of a non-cosmological interpretation of redshift. If you're a layman trying to learn about astronomy, I advise you to...

Since we have been taken readings of redshift, blueshift for sometime now, is there a consensus on a percentage of each?

I think the cosmological redshift, called the "Hubble" redshift which Edwin Hubble discovered and photographed, is caused by quantum decay in light and other electric field) waves, i.e. photoelectric radiation. When emitted, light from a particular elements electronic transitions are at the...

Hi i am confused as to how to calculate the age of the universe with redshift say for example The age of the universe now is 13 billion years old (and a critical universe). How do i find the age of the universe if it was a redshift at say 10?? Do i have to find the scale factor first? I...

generic redshift is characterised (defined) by z = (L-L0)/L0 where L is the wavelength at time of absorption (detection), and L0 was the wavelength at time of emission. for Doppler redshift z = v/c for small (non-relativistic) values of v. assuming the universe is expanding, I've read...

Hello I have been reading a textbook on cosmology and have come up against a self test question I just can't crack! Any help would be greatly appreciated: "The Cosmological redshift of a quasar is normally deduced from its emission lines. Let this redshift be ze. Suppose the quasar has...

Interestingly, the SDSS interactive learning site http://cas.sdss.org/dr3/en/ lists NGC 7603 and PGC 07041 as an interacting pair of galaxies, although their redshifts are very different. Go to the page below and find the image of NGC 7603 and PGC 07041. Click on the image to use the...

I'm a college freshman at the moment, so perhaps I'm just missing something simple. But none of my professors can give me an actual answer. If photons of light from distant galaxies undergo redshift because of the expanding universe. Also since particles have a wavelength according to...