<p><a href="http://en.wikipedia.org/wiki/Quasar" rel="nofollow">Quasars</a> are thought to be <a href="http://en.wikipedia.org/wiki/Active_galactic_nucleus" rel="nofollow">active galactic nuclei</a>. The Milky Way contains a very dense region in its center, probably a <a href="http://en.wikipedia.org/wiki/Supermassive_black_hole" rel="nofollow">supermassive black hole</a>.</p>

<p>Such a dense region or black hole is thought to form by <a href="http://en.wikipedia.org/wiki/Accretion_%28astrophysics%29" rel="nofollow">accretion</a> of dust, gas and stars. This accretion process of a supermassive black hole releases huge amounts of energy emitted perpendicular to the <a href="http://en.wikipedia.org/wiki/Accretion_disc" rel="nofollow">accretion disk</a>. If such a <a href="http://en.wikipedia.org/wiki/Polar_jet" rel="nofollow">jet</a> at the center of a distant galaxy points towards Earth we may see it as quasar.</p>

<p>Hence the answer is most likely yes, the Milky Way or some of its predecessor galaxies will probably have had quasars at their centers, at some period when consuming lot of material, and seen from appropriate direction.</p>

<p>Most galaxies are thought to contain a supermassive black hole at their center. Therefore the same applies to most galaxies.</p>

<p>Here two nice simulations:</p>

<ul>
<li><a href="http://www.youtube.com/watch?v=FMPuujaldZk" rel="nofollow">A simulation of a merger of two galaxies forming active galactic nuclei</a>.</li>
<li><a href="http://www.youtube.com/watch?v=-feWoMSTiDY" rel="nofollow">Computer simulation of the formation of a disk galaxy</a>.</li>
</ul>

<p><a href="http://www.nasa.gov/mission_pages/chandra/multimedia/photo10-009.html" rel="nofollow">A rare ongoing merger of two quasars observed by Chandra</a>.</p>

CC BY-SA 3.0
2014-02-07T00:10:52.103Z
Hmm, I'm not so sure about your answer. I think the quasar phase of galaxies only occurs when you get major merging events - e.g. - two spiral galaxies coming together to form an elliptical galaxy. The fact that the Milky Way galaxy is not an elliptical may mean that it hasn't yet gone through this phase. It perhaps will one day when Andromeda and the Milky Way coalesce. I could also be very wrong about this. This is just from what I recall. I'll see if there are any papers on the end products of the quasar phase of galaxies.
astromax
CC BY-SA 3.0
2014-02-07T01:04:24.013Z
In Milky Way we should find several supermassive black holes, if they wouldn't have merged already from predecessor galaxies. Fusion of galaxies needs not lead to elliptic galaxies, as far as I can retrieve from the simulations. They should have occured rather frequently in the first few billion years of the universe.
Gerald
CC BY-SA 3.0
2014-02-14T09:45:08.430Z
-1 Because the Galaxy *does* have a SMBH in the centre, as proven by ESO/NACO. -1 (If I could) because the outcome of a major merger does depend on the amount of available cold gas. Further -1 Because cold gas does not necessarily come from major mergers.
astabada
CC BY-SA 3.0
2014-02-14T11:02:42.460Z
Did I say anything else?
Gerald
CC BY-SA 3.0
2014-02-18T17:41:56.700Z
I wanted to be kind of ironic. Hope you are not offended, in which case I apologize :)
astabada
CC BY-SA 3.0
2014-02-18T21:48:23.823Z
@astabada Don't mind. I'm aware, that discussions about astronomy must sound alien and nerdy from a distance. That's the same with all specialized topics. But I try to take questions serious, because people sometimes ponder for years, and really want to understand, and often don't dare to ask.
Gerald
CC BY-SA 3.0
2014-02-06T17:48:52.207Z
2014-02-07T01:15:00.530Z
2014-02-07T01:15:00.530Z
Gerald
<p>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! <img src="https://ned.ipac.caltech.edu/level5/March04/Torres/Figures/figure5.jpg" alt="AGN"></p>

<p>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 <a href="http://science1.nasa.gov/science-news/science-at-nasa/2002/21feb_mwbh/" rel="noreferrer">this page</a> 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 href="http://en.wikipedia.org/wiki/Sagittarius_A*#Discovery_of_G2_gas_cloud_on_an_accretion_course" rel="noreferrer">a cloud of gas called G2 to fall into Sgr A*</a>. We are hoping that Sgr A* will burp or do something interesting.</p>

CC BY-SA 3.0
2015-10-06T18:22:45.327Z
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.
userLTK
CC BY-SA 3.0
2015-10-06T19:01:59.840Z
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)?
Florin Andrei
CC BY-SA 4.0
2022-09-08T14:08:06.777Z
I'm not sure who is correct on the time frames here but other estimates I've seen suggest Sgr A was last active 6-9 million years ago rather than 10,000... either way seems like you and the other astronomers may be waiting a little while for another event... I wouldn't hold your breath
SwiftD
CC BY-SA 4.0
2022-10-08T14:26:49.430Z
The rotation axis of Sgr A* and structures around it are not (and may not have been) necessariy aligned with the plane of the Milky Way.
ProfRob
CC BY-SA 3.0
2014-02-14T09:25:17.403Z
Awesome image. I haven't seen that one before and puts the various types of AGNs together well.
Carl
CC BY-SA 3.0
2014-02-14T11:29:53.600Z
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.
Gerald
CC BY-SA 3.0
2014-02-14T21:34:48.190Z
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.
Scott Griffiths
CC BY-SA 3.0
2014-02-15T01:13:58.457Z
Thanks! I've been inaccurate in some detail, that's accepted.
Gerald
CC BY-SA 3.0
2014-02-24T05:57:01.713Z
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).
astromax
CC BY-SA 3.0
2014-02-24T07:06:42.933Z
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.
Scott Griffiths
CC BY-SA 3.0
2014-02-14T03:34:31.590Z
2014-02-14T21:26:06.360Z
2017-03-10T09:42:47.210Z
Scott Griffiths
<p>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? </p>

CC BY-SA 3.0
2015-08-05T16:19:18.657Z
See also http://physics.stackexchange.com/questions/197585/history-of-the-milky-way-quasar.
HDE 226868
CC BY-SA 3.0
2014-02-18T15:55:59.887Z
Well, I don't know the answer, which is why I asked the question. Seemed like it had enough support and research.
Stu
<galaxy>
Was the Milky Way ever a quasar?
Stu
# Was the Milky Way ever a quasar?

(Asked by: username_0 on 2014-02-06)

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?

**Tags:** galaxy
> **Comments:**
> **username_0**: Well, I don't know the answer, which is why I asked the question. Seemed like it had enough support and research.  
> **username_1**: See also http://physics.stackexchange.com/questions/197585/history-of-the-milky-way-quasar.  

---

## 2 answers

### Answer by username_5 on 2014-02-14. Score: 18 | Accepted answer

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](https://ned.ipac.caltech.edu/level5/March04/Torres/Figures/figure5.jpg)

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](http://science1.nasa.gov/science-news/science-at-nasa/2002/21feb_mwbh/) 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\*](http://en.wikipedia.org/wiki/Sagittarius_A*#Discovery_of_G2_gas_cloud_on_an_accretion_course). We are hoping that Sgr A\* will burp or do something interesting.

> **Comments:**
> **username_10**: Awesome image. I haven't seen that one before and puts the various types of AGNs together well.  
> **username_2**: 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.  
> **username_5**: 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.  
> **username_2**: Thanks! I've been inaccurate in some detail, that's accepted.  
> **username_3**: 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).  
> **username_5**: 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.  
> **username_6**: 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.  
> **username_7**: 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)?  
> **username_8**: I'm not sure who is correct on the time frames here but other estimates I've seen suggest Sgr A was last active 6-9 million years ago rather than 10,000... either way seems like you and the other astronomers may be waiting a little while for another event... I wouldn't hold your breath  
> **username_9**: The rotation axis of Sgr A* and structures around it are not (and may not have been) necessariy aligned with the plane of the Milky Way.  

---

### Answer by username_2 on 2014-02-06. Score: 6

[Quasars](http://en.wikipedia.org/wiki/Quasar) are thought to be [active galactic nuclei](http://en.wikipedia.org/wiki/Active_galactic_nucleus). The Milky Way contains a very dense region in its center, probably a [supermassive black hole](http://en.wikipedia.org/wiki/Supermassive_black_hole).

Such a dense region or black hole is thought to form by [accretion](http://en.wikipedia.org/wiki/Accretion_%28astrophysics%29) of dust, gas and stars. This accretion process of a supermassive black hole releases huge amounts of energy emitted perpendicular to the [accretion disk](http://en.wikipedia.org/wiki/Accretion_disc). If such a [jet](http://en.wikipedia.org/wiki/Polar_jet) at the center of a distant galaxy points towards Earth we may see it as quasar.

Hence the answer is most likely yes, the Milky Way or some of its predecessor galaxies will probably have had quasars at their centers, at some period when consuming lot of material, and seen from appropriate direction.

Most galaxies are thought to contain a supermassive black hole at their center. Therefore the same applies to most galaxies.

Here two nice simulations:

* [A simulation of a merger of two galaxies forming active galactic nuclei](http://www.youtube.com/watch?v=FMPuujaldZk).
* [Computer simulation of the formation of a disk galaxy](http://www.youtube.com/watch?v=-feWoMSTiDY).

[A rare ongoing merger of two quasars observed by Chandra](http://www.nasa.gov/mission_pages/chandra/multimedia/photo10-009.html).

> **Comments:**
> **username_3**: Hmm, I'm not so sure about your answer. I think the quasar phase of galaxies only occurs when you get major merging events - e.g. - two spiral galaxies coming together to form an elliptical galaxy. The fact that the Milky Way galaxy is not an elliptical may mean that it hasn't yet gone through this phase. It perhaps will one day when Andromeda and the Milky Way coalesce. I could also be very wrong about this. This is just from what I recall. I'll see if there are any papers on the end products of the quasar phase of galaxies.  
> **username_2**: In Milky Way we should find several supermassive black holes, if they wouldn't have merged already from predecessor galaxies. Fusion of galaxies needs not lead to elliptic galaxies, as far as I can retrieve from the simulations. They should have occured rather frequently in the first few billion years of the universe.  
> **username_4**: -1 Because the Galaxy *does* have a SMBH in the centre, as proven by ESO/NACO. -1 (If I could) because the outcome of a major merger does depend on the amount of available cold gas. Further -1 Because cold gas does not necessarily come from major mergers.  
> **username_2**: Did I say anything else?  
> **username_4**: I wanted to be kind of ironic. Hope you are not offended, in which case I apologize :)  
> **username_2**: @astabada Don't mind. I'm aware, that discussions about astronomy must sound alien and nerdy from a distance. That's the same with all specialized topics. But I try to take questions serious, because people sometimes ponder for years, and really want to understand, and often don't dare to ask.  

---

