Are quasars / blazars signifigantly blue shifted?
Order of Kilopi
Are quasars / blazars signifigantly blue shifted?
Established Member
No, they are red shifted due to their distance.
Why would they be blueshifted?
Order of Kilopi
due to their proximity to a black holeOriginally Posted by alainprice
Order of Kilopi
that would still be redshifted.
Established Member
Huh? What do you think a quasar is?
Anyway, quasars are demonstrably redshifted. Very red-shifted. Regardless of the nature of the redshift, that is the observation.
Order of Kilopi
This board confuses me at times. When I first got here I asked about red-shift / blue-shift near gravity ... and people corrected me and said as light passed through gravity it blue shifted to an external observer ... and redshifted an internal observer. So I started changing my statements to follow what the board thought now I am finding out that it is wrong. uggg ...
Sorry if I am confused here. I may need to reword some of my posts.
Member
It's more complicated than that. Most of the universe is. Gravity affects light, but it does so in many different ways such that what sometimes seems obviously wrong isn't.
I hope you'll pardon the personal element here, but posting so frequently and with such related topics you seem to be diffusing the efficacy of everyone's effort (yours and theirs).
Perhaps asking a single question, and sussing it out from crown to toe before asking your next would greatly aid the peace of mind of the answerers and the content of mind of the asker. There's a good reason you don't learn calculus at the same time as long division.
Order of Kilopi
I guess you can say I multithread my thoughts ... basically I work on problems simultaneously. I have started new threads because important points get reached and I feel that sometimes the point needs to be fully discussed. I will try to keep new threads to a minimum ... but the truth is that most threads start off differently but end up in the same place. I am not doing that intentionally. But again I will try.
Established Member
Massive Confusion
Really? Can you point out where in your too many threads anyone told you this? After all, yesterday in another thread you asked me ..
Why did you have no problem with gravitational redshifts yesterday, but today you suddenly say you thought it was a blueshift. Setting aside for a moment whether or not you understand other people's posts, do you understand your own?
Order of Kilopi
um ... my statement is wrong ... look closely.
it is now when we are in a gravitational well ... it is when the light came from a gravitational well. If we are in a gravitational well we would see stuff blue shifted ...What we see from gravitational redshifting is when we are in a gravitational well right?
I dont get what you are hinting at ... are you accusing me of something ... if so please PM me with your accusations.
Newbie
Hi everyone!
I know this is an old post, but I want to try to clarify some things. I am not an expert, but as I understand it, a redshift occurs when a large body of gas and energy is moving away from us at a great speed; the redshift is positively proportional to the velocity at which the object is moving away.
However, a blueshift is caused by the converse: a mass of energy moving toward us.
So this would mean, in order for a quasar to even possibly cause a blueshift, it would have to be rotating significantly faster than it is moving away, during which the side of the rotation which is moving toward the earth would potentially cause a light blueshift phenomenon. but let me guess: this has never been observed?
and also, the strength of the redshift would have more to do with the speed than the distance? or would they be both equally important?
Order of Kilopi
The effects of rotation are well observed. A spectral line is smeared out because of local blueshift of the side moving toward us and local redshift of the side moving away. This is relative to the mean value of the system as a whole. Thus a spinning object that is receding from us overall would have broadened lines with their centers redshifted.
For nearby objects such as galaxies in the Local Group, the differing relative velocities are dominant. Thus M31 is blueshifted from our point of view. For very distant systems, the overall cosmological redshift overwhelms the local variations.
Member
Non expert answering.
The light we receive from the quasar is an amalgam of all the light emitted. While I'm not sure of the specifics of a light "cocktail" of multiple frequencies, it would seem that since the proportion of spinning-to light and spinning-away light never changes, the equal parts balance out since we don't look at just the left or right side. Also, since relative to us, no two spots on a spherical object would be moving toward or away at the exact same speed, we'd get a gradient.
It also depends at least slightly on the orientation of the axis of rotation relative to the observer.
So I guess my answer is that rotation does cause a shift, but since it doesn't effect the light uniformly it's not that it isn't observed, it's just that it is considered a wash.
Well, speed is a change of distance over time, so I'm not sure it could be more than one or the other. Due to expansion, though, distance results in a faster increase of distance than any local motion could ever achieve. So at greater distances, the local motion of an object becomes less significant as the expansion of space (as observed) approaches the speed of light.
Established Member
Try here:
http://en.wikipedia.org/wiki/Blue_shift
There aren't many galaxy-size blue shifted objects. Red shift due to expansion wins out.
Banned
Neverfear, Mugs is here!
(cough, kuh! gag...)
Think of it this way: As light travels from a region of higher intensity gravity to lower intensity, the light is redshifted. Thus, if light is emitted near a strong source of gravity, as it goes from the higher gravity region to the lower gravity region, it becomes redshifted.
In addition, light is also redshifted due to expansion. Thus, the further away something ise, the faster it is receeding, and the more redshifted it will be.
Newbie
wow, thanks for the explanations!
The theory of relativity posits that space, time, gravity, matter is all related--or "relative" to one another I suppose.
So, the farther away these quasars are, the longer they've been "out there",
By knowing the redshift, we know the speed. But how does gravity affect the redshift specifically? Isn't it basically a 'type' of dopplar effect? This effect is observed in objects without a large gravitational force is it not?
How does gravity play into it? I understand what you are saying on a thechnical level, but I don't understand it on a conceptual level.
In that case, time is directly related to distance (or
So, May I ask, is there a theory of what is propelling or pulling these objects through space? Is the result of something occuring from the center, out (like the big bang explosion I suppose). Or...
Could it be that there is a greater gravitational force we don't know of which is causing the universe to expand (which lies beyond the farthest objects we know of)? I'm sure this is highly unlikely.
If the universe is expanding, then is there no end to this expansion? I suppose all energy may die off eventually....after trillions of years. So, will energy really fizzle, or is energy contually renewed or recycled?
I know there's a lot of questions here, and I don't know all the of termonology.
Order of Kilopi
I've been going through this of a conspiracy lover friend of mine.
Question :So, May I ask, is there a theory of what is propelling or pulling these objects through space?
no object is moving through space because of the expansion of the universe. Space is just being filled in everywhere at a certain rate. On smaller scales gravity keeps objects close together. At larger distance where the gravity is to weak to overcome the amount of expansion of space between 2 objects then they appear to be moving apart but it is more correct to say that they are not moving and the space between them is getting larger.
Question: Is the result of something occuring from the center, out (like the big bang explosion I suppose)
This is one of the most misunderstood concepts of the "Big Bang" and is tied to the answer above. People think of the big bang as an explosion. But the better analogy is of a loaf of raisin bread. As the dough rises the space between any 2 raisin increases. The raisins are not moving through the dough to different locations. Where this analogy breaks down is a loaf of raisin bread has edges. Currently the thought is that the universe is infinite in size. The size of the universe 13 billion years ago was infinite to. But today the universe is still infinite but larger then it was 13 billion years ago. Even if the universe is "closed" meaning that it some how loops back on itself the expansion has no centre that is visible from our 4 dimensional view of the universe.
Question :Could it be that there is a greater gravitational force we don't know of which is causing the universe to expand (which lies beyond the farthest objects we know of)?
like you said it is unlikely. The reason I recently thought of that disproves this, according to GR, is because of the rate of expansion. The rate is fairly linear as we go out. For a gravitational shell around the universe to be the cause of expansion the milkyway would have to be at the center of the universe, as all galaxies seem to be moving away from us, outside of our local group. Also if it was gravity causing the expansion the progression would be an inverse square law and not linear like we observe.
Question :If the universe is expanding, then is there no end to this expansion?
This has to do with the search for the value of Omega which deals with the mass density of the universe. The universe will expand forever at the current rate (Omega = 0). Will it expand forever (Omega <= 1) while slowing down. The universe will slow down and start to collapse back on itself (Omega > 1)
What was found was a negative Omega value meaning that currently the universe is expanding faster then it has in the past.
http://en.wikipedia.org/wiki/Metric_expansion_of_space
Will it stay at this rate? Who knows. Until we understand what is driving the expansion we can't say.
Question :I suppose all energy may die off eventually....after trillions of years. So, will energy really fizzle, or is energy continually renewed or recycled?
Well if the expansion rate keeps increasing (Omega continues to clime in the negative direction) then eventually space will expand at a rate at which even atoms would be ripped apart (overcome the strong force). That is a deep freeze. As the universe gets bigger the energy (and matter is part of this) spreads out and thus the temperature drops. There is no known injection of energy into our universe. A universe that collapses on itself could be considered as recycling but that does not appear to be what will happen.
I think Spiff has a great explanation with lots of links on one of the threads dealing with expansion.
Banned
While it's called the "Doppler effect," technically, he based his theory on waves which move through a medium (air, water...). The term is still used for waves, such as light, which do not move through a medium. Thus, the calculations are a tad different, particularly when you induce relativistic (Minkowski) components, expansion, and gravity.
It's observed in all objects of any mass. But the effect is proportional to the square root of the mass. Thus, with four times the mass, you only get a doubling of the effect at any given radius.This effect is observed in objects without a large gravitational force is it not?
Established Member
I think Wayne Francis is referring to this posting of mine.
Established Member
Quasars are known for their Blue shift also. But now a days they were taken as Red Shifted only.
You see the authors in2000 in their abstract said
Basu, D.; Haque-Copilah, S.; Valtonen, M.
at web address
Blueshifted Quasars Associated with Nearby Galaxies?
International Journal of Modern Physics A, Volume 15, Issue 07, pp. 1057-1077 (2000).
It is possible that supermassive black holes are ejected from centers of galaxies at high speeds. If the ejection happens in a nearby galaxy, then some black holes will travel towards us and may appear quasar-like with a blueshifted spectrum due to the Doppler effect. But quasar spectra are as a rule interpreted as having been redshifted even when there is an equally good or better case for a blueshifted spectrum. Here we study the quasars which are apparently associated with galaxies. We look for alternative identification for the spectral lines reported in the quasar spectra and offer blueshift values whenever it is consistent with the available information. We present a list of five candidates predicting the lines for future observation to confirm blueshifts. We also present a composite IR spectra which can be adjoined to existing composite spectra of lines in the optical and the UV region. We suggest that many of these objects are much less massive satellite bodies which have been ejected from nearby galaxies during binary black hole mergers.
DOI: 10.1142/S0217751X00000513Can anybody tell …..The Present day concept for quasar redshift is approximately:
http://homepages.wmich.edu/~korista/quasars.html
by Kirk Korista
…..Because the universe is expanding with time, the light we receive from a quasar is "redshifted," i.e., shifted to longer wavelengths compared to the light that was emitted by the quasar long ago….
when this “quasar redshift” concept actually started?
What was the initial paper?
What was the initial logic?
Order of Kilopi
No, they are not. The article by Dr. Korista (an occasional forum participant) is reliable. Nowhere does he say anything about blueshifting. The other paper is highly questionable.
Everyone is entitled to his own opinion, but not his own facts.
Order of Kilopi
No, they are not. Interpretations of Quasars having blue shifts are fringe, are usually limited to certain authors, and even those authors can't agree on the mechanism.
They were taken as red-shifts from the very beginning....
1963
3C 273 : A Star-Like Object with Large Red-Shift
It's in the paper.
Moderator
Now you've gone and done it! The word blue is in the paper...
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Established Member
I did not say he said any thing about blue shifting. I was just giving background.
Established Member
Thank you for all the nice information and excellent help , I will go through the link and come back to you...
Established Member
I want your opinion please......
.The first Redshifted Quasar 3C273 by Schmidt in 1963 is BLUE SHIFTED 07082012
I. The first Redshifted Quasar 3C273:
The author Schmidt in 1963 published the first paper on a quasar declaring it as red shifted [1]. He said:
“Spectra of the star were taken with the prime-focus spectrograph at the 200-in. telescope with dispersions of 400 and 190 Å per mm. They show a number of broad emission features on a rather blue continuum. The most prominent features, which have widths around 50 Å, are, in order of strength, at 5632, 3239, 5792, 5032 Å. These and other weaker emission bands are listed in the first column of Table 1.”
He concluded that this quasi stellar object now well known as Quasar. It is the nuclear region of a galaxy with a cosmological red-shift of 0.158, corresponding to an apparent velocity of 47,400 km/sec. The distance would be around 500 megaparsecs, and the diameter of the nuclear region would have to be less than 1 kiloparsec.
II. The first Redshifted Quasar 3C273 is that Blue shifted?
The Table 1 shown below embeds the table 1 of Dr Schmidt in the first 4 columns. The remaining columns show how the quasar is blue shifted for the same wavelengths. I.e., the same wave lengths of his observations were used in this paper to show this same quasar 3C273 is Blue shifted. To support further on this, the spectrum observations made by other three more authors were also discussed in this paper. The checking of the first Redshifted Quasar 3C273 for a possibility of blue shift was tried mainly because of the observation of Dr. Schmidt saying this Quasars 3C273’s spectrum is in the “blue continuum” [1]. The Quasars are known for some of the irregularities in the spectrum like some spectral lines match exactly with the some elemental lines with some blue / redshift ratio while some other prominent lines don’t match for the same ratio.
Basically many astronomers in their published papers said that sodium line, Carbon line CIV etc., are blue shifts other lines. There are observed variation in quasars in the lines w.r.t other lines in the known spectrums. If the quasars are taken as blue shifted such variation will be very very less or even cease to exist. To explain such phenomenon Bigbang based cosmologists take the help of million light years length of sodium with a velocity of jet at 50000000 meters / second in the case of this 3C273. How such length of sodium can exist I don’t know.
Many of these papers talk about such blue shifts. These references can be found at ADS [2,3]. For this, go to ADS search page try searching title and abstract with keywords “Blue shifted quasars”. If you search with “and’s i.e., ‘Blue and Shifted and Galaxies” [use “and” option not with “or “option] you will find 248 papers in ADS search. I did not go through all of them. Some of the papers will be discussed here later in this paper.
In the Table 1, in addition to the original values given by Dr. M. Schmidt, four new columns were added. These columns show the possible blue shift of ‘(-0.143122)’ of the Quasar 3C273 and the resulting wavelengths after the blue shift. SDSS website gives different possible wavelengths in angstrom units in their webpage on ‘Algorithms - Emission and absorption line fitting’ [4]. These wavelengths were chosen as they will be more authentic and accurate. Please note there are some slight differences in the numerical values in wavelengths as given by Schmidt and SDSS webpage.
Table 1 3C273 quasar blueshift.jpg
Note 1: Later measurements of this QUASAR 3C273 at wavelengths 4595 and 4793 show dips or flatter curves instead of peaks (absorption spectra instead of emission spectra).
References:
Dr. M. Schmidt’s paper “3C 273: A Star-like Object with Large Red-shift”, published in Nature 197, 1040 (1963)
http://www.nature.com/physics/lookin...idt/index.html
http://adsabs.harvard.edu/cgi-bin/np...=YES&version=1
http://vaksdynamicuniversemodel.blog...rs-in-ads.html
Algorithms - Emission and absorption line fitting of SDSS http://www.sdss.org/dr7/algorithms/speclinefits.html
Order of Kilopi
For example:
I'm afraid you are simply misunderstanding these references to blueshift. As the above quote makes clear, the so-called "blueshift" is only "with respect to the systemic redshift of the quasars." The so-called "blueshift" is relative to the quasar, not to earth. The C IV emission line is still measured to be redshifted, but just not as much as the other quasar lines. Why the discrepancy? "Wind" from the quasar. Think (solar wind)100*.
________________
* This number qualitative only.
Last edited by Cougar; 2012-Jul-15 at 10:28 AM. Reason: add link
Everyone is entitled to his own opinion, but not his own facts.
Order of Kilopi
I have what might or might not be a related question that occurred to me recently, so I'll ask it here. (or I can ask it separately or mods can move it if need be).
Are relativistic jets responsible for the creation of GRBs or are they sibling emissions? In other words, are the gamma photons we detect emitted from the stellar matter that's in a relatively stationary location or are the gamma photons emitted from matter that is moving at high relativistic speeds? I ask, because if it's the latter, would we expect to see a Doppler-based blue-shift? I thought remember reading somewhere that relativistic jets are more like flying pancakes and it made me wonder if they are stellar remnants that are emissive in their own right and how that might affect observations.
Et tu BAUT? Quantum mutatus ab illo.
Established Member
The gamma rays which are created in relativistic jets are produced by material which is indeed moving at relativistic speeds toward us. However, since the process creating the gamma rays is synchrotron emission, there are no spectral features -- just a smooth continuum. As a result, we can't derive any blueshifts or redshifts, since there are no strong lines in the spectrum.
In many cases, we lack the large numbers of photons which would be required to create a spectrum with high signal-to-noise ratio, so even if there _were_ strong features, we might not be able to distinguish them.
Order of Kilopi
It depends on the specifics. It's quite more complicated than just comparing cosmological and doppler shifting and thinking "it's moving towards me so doppler wins and i'll get a blueshift". It may be moving towards us and we'd still get a redshift, and it may even be moving away from us and we'd get a blueshift. The simple picture of cosmological redshift by expanding space only works for objects moving with the hubble flow, for things moving appreciatively relative to its "local hubble flow" there are no shortcuts and you'd have to specifically solve over the path taken from emission to reception. Whilst usually you'd get the expected result, ie moving away is redshift and moving towards us is blueshift, these are not the only possibilities, there are regions with the inverse results.
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