Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Does the Milky have a QSO? What is the observational evidence concerning QSOs?

  1. Aug 10, 2012 #1
    There is a confusing article in the August, 2012 Scientific America concerning the recent discovery of a massive gamma radiation emission from the Milky Way galaxy, from the very recent past. As our solar system is one of the many members of the Milky Way this is an interesting subject.

    If viewed from a distance galaxy, say M31, this massive gamma radiation emission would appear to be a Quasar, a QSO, a quasi-stellar object. As there are no QSOs in the local universe this presents an interesting puzzle. Why are there no QSOs in the local universe and how the heck can there be a QSO in the Milky Way?

    To have an intelligent conversation concerning the Milky Way's hypothesized QSO it is necessary to review the observational evidence concerning QSOs. i.e. One can compare the toy model for QSOs to the observations and see if the observations match what is observed.


    http://arxiv.org/pdf/1205.5852v1.pdf

     
  2. jcsd
  3. Aug 11, 2012 #2

    Chalnoth

    User Avatar
    Science Advisor

    Quasars are active galactic nuclei (AGN's). The nucleus of the Milky Way is not currently active. We do see the jets from previous activity, however.

    I believe it is generally expected that the nuclei of galaxies become active when they first form, and when the galaxy undergoes a large disruption such as a merger with another galaxy.

    And by the way, there are quite a few AGN's that are relatively close-by. The nearest is the nucleus of Centaurus-A, a mere 10-16 million light years away.
     
  4. Aug 11, 2012 #3
    Thank-you for the correction.

    Centaurus-A is also a gamma emitting AGN and is located 10 to 16 million light years away.

    Very high energy gamma-rays from the radio galaxy Centaurus A

    http://www.obspm.fr/actual/nouvelle/mar09/cena-f1.jpg [Broken]

    http://www.obspm.fr/actual/nouvelle/mar09/cena.en.shtml [Broken]
     
    Last edited by a moderator: May 6, 2017
  5. Oct 7, 2012 #4
    These are the papers I was thinking of. High luminosity quasars are no longer found in the local universe. This was assumed to be due to a difference in the feeding of the quasar due to a change in the environment from high redshift to the present.

    As these two papers indicate. That belief is not correct.

    The super massive black holes that power Quasars have down sized. At high redshift the most massive super massive BH is roughly 10^10 solar masses. In the local universe the most massive super massive black hole is 10^7 solar masses.

    Our Milky Way super massive black holes is a growing baby massive object with an estimated mass of 3.6 10^6 solar masses.

    It is interesting how our Milky Way super massive black hole and the other super massive BH holes in the local universe reach their plateau.

    As this paper notes, as high redshift quasars must be very distant objects as they have high redshifts, then they must have a very massive super massive BH to produce the extraordinary high luminosity.

    Those super large BH disappear and are no longer found in the local universe.

    The spectral emissions of the Quasar curiously does not evolve with redshift.

    As this paper notes, the authors of the paper do not know of any mechanism by which a super massive BH can lose significant mass, yet it appears based on observations that must have lost mass based on the assumptions and observations.


    http://arxiv.org/abs/0902.3151v1

    http://iopscience.iop.org/1674-4527/12/3/002

     
  6. Oct 7, 2012 #5

    Chalnoth

    User Avatar
    Science Advisor

    Yes it is quite correct. The supposed discrepancies claimed by these papers are pretty trivially explained by two effects:
    1. Selection: extremely massive black holes are going to be most visible when they are most luminous, i.e. at high redshift.
    2. Volume: there is vastly more observable universe at high redshift than at low redshift, so that any exceptional regions in the universe are more likely to be at high redshift than low redshift.
     
  7. Oct 7, 2012 #6
    Chalnoth,

    The explanation is not selection.

    The mass of the central galactic BH can also be estimated by the size of the spiral galaxy bulge as there is a tight relation of the size of the spiral galaxy bulge to the mass of the central BH.

    The anomaly is not only that high redshift quasars are more luminous.

    The galaxy central BH get smaller with redshift (10^10 solar masses down to 10^7 solar masses). Downsizing of the central galaxy BH mass with redshift is anomalous, as there is no known mechanism by which a BH can lose significant mass. i.e. A 10^10 solar mass BH that formed at high redshift should be 10^10 or larger at in the local universe which is not observed. The 10^10 solar mass BH downsizes to 10^7 solar masses.

    As the paper notes the spectral energy distribution of the quasar does not change with redshift which is also curious.

    Metallicity also does not change with redshift which is also anomalous. One would expect metallicity should decrease with redshift. It does not.

    http://arxiv.org/abs/0902.3151v1

     
  8. Oct 8, 2012 #7

    Chalnoth

    User Avatar
    Science Advisor

    Extrapolating a poorly-understood empirical relationship with substantial variance far beyond where it is empirically-measured is not convincing.

    I don't think you're getting it. Of course the higher-luminosity ones are going to be visible earlier: they're brighter! More dense regions will also form more quickly, and turn off more quickly. One of the things we're learning about quasars now is that they can very rapidly push away the material that would otherwise support their growth, and that means that if they are to get any significant amount of mass, it has to be done very quickly.

    The spectral energy distribution of AGN's varies dramatically from AGN to AGN. And their emission also tends to vary in time rather rapidly. The take away is just that AGN's are extremely variable objects, so that any apparent evolution of AGN environments is buried in the noise.

    And these statements also don't surprise me at all, considering that AGN's aren't going to form until there's been a good amount of star formation in the area first.
     
  9. Oct 8, 2012 #8
    You may be confusing variation in quasar luminosity with distribution of quasar spectral energy by frequency. QSO luminosity does very quickly and cyclically however the QSO spectral energy distribution continues to follow a power law.

    The X-ray spectrum of QSOs shows a very simple spectral shape in the form of a power law, S υ = υ^- α where α≈ 0.7. The pattern of the QSO spectral energy distribution vs frequency is how Hawkins has able to show that QSOs do not show time dilation with redshift. This is the third paper that Hawkins has published that shows that QSOs do not show time dilation with redshift.

    http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2966.2010.16581.x/abstract
    http://arxiv.org/abs/1004.1824

    One of the quasar puzzles is how to generate jets, x-rays and gamma radiation that has spectral energy vs frequency that follows a power law, from an accreting disk and how to get the jet, x-ray and gamma radiation mechanism to turn on and off.

    There appears to be connected, structured anomalies concerning the explanation of what is observed in this picture.

    http://www.obspm.fr/actual/nouvelle/mar09/cena.en.shtml [Broken]

    This thread starts with the observation that the Milky Way super massive BH in the very recent past created gamma ray excited jets similar to this picture. The puzzle is the Milky Way is not merging with another galaxy. Why would the Milky Way in the recent past produce gamma ray exited jets?

    http://arxiv.org/pdf/1205.5852v1.pdf


    As the Chandra x-ray paper notes the quasar x-ray spectrum does not evolve with redshift. The following is Kundt’s thoughts has to how to generate x-ray and gamma radiation that follows a power law.

    http://arxiv.org/pdf/astro-ph/0503301v1.pdf
     
    Last edited by a moderator: May 6, 2017
  10. Oct 8, 2012 #9

    Chalnoth

    User Avatar
    Science Advisor

    No, I'm absolutely not mistaking the two. There is substantial variance in the actual emission spectra of quasars. See here:
    https://www.google.com/search?q=qua...HJKea0QHPx4HwAw&ved=0CCAQsAQ&biw=1199&bih=626

    That's a different beast, because it's driven by the physics of the accretion disk. And I think you're really misunderstanding what that paper shows: redshift itself is time dilation. Hawkins was instead looking for time dilation due to the motion of the matter in the accretion disk. I'd have to look more into it to see what it implies about AGN's.

    Right. AGN's are complicated beasts, and there's still a lot we don't know about them.

    The Milky Way is currently merging with the Small and Large Magellanic clouds.
     
  11. Oct 9, 2012 #10
    I don't see the puzzle here. There is a supermassive black hole in the middle of the Milky Way. At some earlier time, that massive black hole was getting matter dumped into into producing massive amounts of gamma and X-rays. Now that the black hole has eaten up most of the gas, there's nothing left to produce a quasar.

    A quasar is just an early phase of a normal galaxy.

    As far as I can tell, it fits pretty well. Young galaxies have massive amounts of gas and dust at the core. This generates a continuous stream of radiation. As the galaxy eats up the gas, the radiation goes down. At some relatively recent time, a gas cloud got dumped into the black hole in the Milky Way generating a "last gasp" of gamma rays.

    I don't see the mystery.
     
  12. Oct 9, 2012 #11
    1) I need to see references for this

    2) I'd be extremely skeptical at extrapolating relations from one set of galaxies to another. If you can show references that show that there is a relationship between one set of galaxies, there's no particular reason why it should apply to early quasars.

    I don't see any reason why it should. The spectral energy distribution is controlled by accretion disk physics and as long as you are feeding stuff in near the Eddington limit, you'd expect the spectral energy distribution to stay the same.

    Standard explanation is population III stars.
     
  13. Oct 9, 2012 #12
    The jet is a puzzle. The accretion disk, power law, and the energy generation mechanism aren't.

    You dump in a large gas cloud into Sagattarius A.

    1) First of all, the mystery is the jet. We don't have a good simple model for jets, and that's likely because we don't understand magnetic fields. People are working on this. We do have nice models for the disc and overall energy generation mechanism.

    2) Black holes can generate rotating magnetic fields.

    3) What you are describing is pretty standard. One thing that we are finding is that there is a lot of shared physics. You have a gravitational object, you dump stuff into that object. That object then emits jets and disks. You then have basically the same physics whether the central object is a star, a white dwarf, a neutron star, a stellar sized black hole, or a mega-black hole.

    All of this stuff is "standard day at the office" stuff, and I'm not seeing where the mystery is.
     
  14. Oct 9, 2012 #13
    One other thing is that journal papers are terrible for trying to background knowledge. Journal articles assume that you already know the background for the thing that they are talking about.

    The standard textbook for this sort of thing is....

    http://www.cambridge.org/gb/knowledge/isbn/item1158688/?site_locale=en_GB

    Also, I'm sure that is some good review paper out there that describes what the current state of research is, and if someone can point me do it, I'd be appreciative.
     
  15. Oct 12, 2012 #14
    There are structured anomalies. A suite of mysteries.

    Look at the SMBH mass' variance with redshift. Observationally it has been found that SMBH mass have a maximum mass at high redshift of 10^10 solar masses. The SMBH mass starts to down size at around z=2.5 and in the local universe the most massive SMBH is 10^7 solar masses. The question to answer is where did the SMBH mass go? (i.e. The galaxies we are observing at z less than 2.5 were formed when the universe was formed also.) SMBHs cannot based on their assumed nature loss significant mass.

    A related issue is why do quasars' spectrum not exhibit time dilation with redshift? Super nova exhibit time dilation with redshift. (Could someone explain time dilation and why is occurs in the standard cosmological model, i.e. an expanding universe.)




    As this paper also notes there are quasars with a SMBH mass of 10^10 solar masses 1 billion years after the formation of the universe. A basic back of the envelop calculation indicates even with accretion at the maximum theoretically possible that is not possible.



    http://arxiv.org/pdf/0902.3151v1.pdf

    See page 9 of the above paper link that has a copy of the graph from Vestergaard et al 2008 which from shows the SMBH (super massive Black hole) mass downsizes with redshift from 10^10 solar masses to 10^7 solar masses in the local universe. SMBH are not in allowed in the standard model to loss significant mass. Observationally, however, they do.
    FIGURE 4. (Estimated) mass distribution of 14,584 quasar central engines (CEs) with z ≥ 0.2, as functions of redshift z, from the Sloan Digital Sky Survey Data Release 3, within an effective sky area of 1644 deg2, taken from Vestergaard et al (2008). Squares denote median masses in each redshift bin. The dashed curve indicates faint SDSS flux limits.

    The AGN bulge scales at roughly 10^-3 to the SMBH mass. The better relationship SMBH mass to the velocity distribution of the AGN bulge.

     
  16. Oct 12, 2012 #15
    The observation that the quasar spectrum does not exhibit time dilation with redshift appears to be a paradox. The following is the third paper published by Hawkins which supports that conclusion. The paper includes possible solutions to solve the paradox.
    http://arxiv.org/abs/1004.1824
    http://arxiv.org/abs/astro-ph/0105073v1


    This is the link to the 2001 paper that noted that quasars do not exhibit time dilation.
    http://arxiv.org/abs/1009.3265v2
     
  17. Oct 13, 2012 #16

    Chalnoth

    User Avatar
    Science Advisor

    The fact that this paper was never published and never cited should cause you pause (well, technically, it was cited once in a paper, but that appears to be a mistake because the reference in the text is no longer there).

    There is no mention of time dilation here.
     
  18. Oct 13, 2012 #17
    Hi Chalnoth,
    Perhaps my links were not correct. The following is a complete set of links both to the pre-print and to the published papers.

    Hawkins is a quasar specialist. It seems he has proven unequivocally that quasars do not exhibit time dilation. That appears to be a paradox.

    It is interesting to look at the downsizing of the quasar SMBH from high redshift where they are 10^10 solar masses to low redshift where they are 10^7 solar masses and to simultaneously think about the observation that quasars do not exhibit time dilation. There are two connected paradoxes. The lack of any redshift evolution of metallicity in the quasar spectrum is a third paradox. The inability to form a 10^10 solar mass SMBH when the universe was only 800 million years old is a fourth paradox.

    It is very, very, unusual for a field of science that has sets of connected paradoxes in published papers. The quality of analysis of the observational data due to multi spectral analysis and surveys is outstanding in this field. It appears all or most of the observational data and analysis required to solve the problem is available. It is very, very, rare that a researcher has an opportunity to make multiple breakthroughs.

    It is truly astonishing that someone has not written a review paper that connects the paradoxical observations as a set laying out the completing logical paths.

    The observations (see other thread this forum) indicate that quasars are not turned on by mergers. Our own galaxy SMBH has turned on in the very recent past. Both of those observations indicate a galaxy's SMBH can turn on at all redshifts (The reason why SMBH are turning on is not known and needs an explanation.) The paradox (for the current quasar mechanism) is there are no observed 10^10 solar mass SMBH less than z=2. The SMBH mass can be determined both by luminosity of the quasar and by the velocity distribution of the AGN's bulge stars.

    The standard model for BHs does not allow the SMBH to lose significant mass.

    This is a link to the published 2001 paper.

    http://iopscience.iop.org/1538-4357/553/2/L97/fulltext/015104.text.html

    This is a link to the preprint of the published 2010 paper.

    http://arxiv.org/abs/1004.1824

    This the link to the published 2010 paper.

    http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2966.2010.16581.x/abstract

     
  19. Oct 13, 2012 #18

    Chalnoth

    User Avatar
    Science Advisor

    I see. That's a bit better. But there's basically no conceivable way this interpretation, that there is no time dilation, is accurate. The broadening of atomic spectral lines itself is proof positive of time dilation.
     
  20. Oct 14, 2012 #19

    Jonathan Scott

    User Avatar
    Gold Member

    Hawkins' paper describes observational results which very interestingly appear to contradict the expected result that quasar variability should show a time scale which correlates with the time dilation implied by the quasar's redshift, as there is no evidence of such correlation. Hawkins offers potential explanations such as the idea that the variation is caused by nearby effects in the line of observation, but this does not work very well and does not for example explain the observation that the variation of brighter quasars seems to be significantly slower than that of dimmer quasars, which suggests that the variation rate depends on the quasar's properties.

    You can choose between the explanations offered by Hawkins, or you can offer your own, or you can question the results and methods used to obtain the observations, but I don't think that simply denying the content of the paper is a valid scientific approach!

    I'd agree that broadening of atomic spectral lines is evidence of time dilation, but it does not prove that the time dilation is cosmological.
     
  21. Oct 14, 2012 #20

    Chalnoth

    User Avatar
    Science Advisor

    Or how about: AGN's are extremely variable sources whose properties are still pretty poorly-understood, and Hawkins is essentially just fitting to noise.

    That doesn't even make sense.

    Edit: let me issue a correction, however. I did not mean broadening. Broadening is an entirely different effect that is usually due to local motions, but can also be caused by intervening plasma. I was merely talking about the redshifting of spectral lines.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Does the Milky have a QSO? What is the observational evidence concerning QSOs?
Loading...