<p>Are there observations/theoretical calculations that prove or disprove a cyclic activity of the galactic nucleus (I mean the nucleus is active than stops than become newly active with a time comparable to the galaxy rotation)?</p>
<p>I remember a lecture given by an astronomer two or three years ago in Arcetri that was speaking of a period of activity and inactivity of the Galaxy Nucleus. The speaker was referring to this phenomena as something that was emerging from observations, so this might very be a well known answered question but I couldn't find anywhere.</p>

CC BY-SA 4.0
2020-12-05T12:24:45.520Z
Have you any prior research? For example, why did this question occur to you?  Why might a AGN show cyclic activity that is comparable (=correlated with?) the time for the galaxy to rotate (and what about elliptical galaxies?)
James K
CC BY-SA 4.0
2020-12-05T13:00:52.910Z
I kind of remember a lecture given by an astronomer two or three years ago in Arcetri that was speaking of period of activity and inactivity of the Galaxy Nuclei. The speaker was referring at this phenomena as something that was emerging from observation, but I couldn't find any reference at a first glance so I was wondering If I misunderstood
Dac0
<galaxy><galaxy-center><active-galaxy>
The activity of the galactic nucleus is cyclic?
Dac0
# The activity of the galactic nucleus is cyclic?

(Asked by: username_0 on 2020-12-05)

Are there observations/theoretical calculations that prove or disprove a cyclic activity of the galactic nucleus (I mean the nucleus is active than stops than become newly active with a time comparable to the galaxy rotation)?

I remember a lecture given by an astronomer two or three years ago in Arcetri that was speaking of a period of activity and inactivity of the Galaxy Nucleus. The speaker was referring to this phenomena as something that was emerging from observations, so this might very be a well known answered question but I couldn't find anywhere.

**Tags:** galaxy, galaxy-center, active-galaxy

> **Comments:**
> **username_1**: Have you any prior research? For example, why did this question occur to you?  Why might a AGN show cyclic activity that is comparable (=correlated with?) the time for the galaxy to rotate (and what about elliptical galaxies?)  
> **username_0**: I kind of remember a lecture given by an astronomer two or three years ago in Arcetri that was speaking of period of activity and inactivity of the Galaxy Nuclei. The speaker was referring at this phenomena as something that was emerging from observation, but I couldn't find any reference at a first glance so I was wondering If I misunderstood  

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