Was the Milky Way ever a quasar?

  • Is there any evidence that the Milky Way could have been a quasar in it's early history? Is it thought that most galaxies come from quasars?


    Well, I don't know the answer, which is why I asked the question. Seemed like it had enough support and research.

  • A quasar is simply an active galactic nucleus (AGN) that is viewed from a particular angle; see the picture below, in which quasars are labeled "QSO". This is really a remarkable figure because historically all of the names in the figure were thought to correspond to different types of objects, when really they all refer to the same thing! AGN



    Your question really shouldn't be "Was there ever a quasar in the Milky Way?", since the dotted line in the figure would correspond to the Galactic plane and we would not see Sagittarius A* (the Milky Way's super-massive black hole) from the correct angle. A better question might be, "Has Sagittarius (Sgr) A* ever been active?" The answer to that question is yes; according to this page it was probably active (very bright with a jet) about 10,000 years ago. However, at the moment, it isn't really doing anything, since it isn't currently accreting anything (to put it plainly, it isn't eating anything, so it doesn't have enough energy to be active). However, many astronomers (myself included!) are anxiously waiting for a cloud of gas called G2 to fall into Sgr A*. We are hoping that Sgr A* will burp or do something interesting.


    Awesome image. I haven't seen that one before and puts the various types of AGNs together well.

    Nice answer! But if you claim my answer as incorrect, so please show in which way it is incorrect, or just drop that claim. I can't see that fundamental difference, just a different focus.

    Yeah, for some reason I remember reading something in your answer that I didn't like, but looking at it again it seems mostly okay. There are a few details that are still inaccurate: black holes do not form by accretion, although they do grow into SMBH's that way; if the jet points towards earth, it is a blazar (BL Lac or FSRQ), not a quasar; your answer somewhat confuses a quasar state with an active state.

    Thanks! I've been inaccurate in some detail, that's accepted.

    Actually, I think the question "Has the Milky Way gone through a quasar phase?" is a fine question to ask. You claim that a mere 10,000 years separates us in time from it being considered an AGN. Fine, but AGN can be incredibly violent. Surely there must be remnants from this phase left behind for us to see - especially since the Sun is about 27,000 lightyears from the center of the MW. I'm not sure I believe your claim (which is not a claim which your source makes).

    I didn't say the question wasn't a good one; merely that concept of quasar and an active AGN had been confused. Of course there are remnants of Sgr A*'s active phase (the Fermi bubbles are thought to be an example). If you had read the link I posted, you would have found that the "10,000 year claim" was the result of radio evidence of a SNR. According to the page, a supernova may have exploded near Sgr A*, starving it of matter to accrete. It is not my claim at all (see the paragraph below the picture pointing to Saggitarius A*); read more carefully.

    I don't believe Sagittarius A being "Active" and "A very bright jet" makes it a quasar. Even in the article you quoted, it says "looked like a faint Quasar". Quasars are enormously bright, many times brighter than the Entire Milky way (Often brighter and much longer lasting than a super-nova). http://www.astronomy.com/news/2015/02/ancient-super-bright-quasar-with-massive-black-hole-found A single brilliant jet does not a quasar make, imho. I still love the article you quoted, but I wouldn't call that a quasar.

    If and when Sgr A* becomes very active, would it ever produce enough light to be visible with the naked eye (mag 6)? Or with a small telescope (mag 12-ish)?

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