AGN X-ray Variability
Galactic Nucleus (AGN), powered by a supermassive
black hole, is a type of astronomical objects. There are many
many of them in the sky. For example, for any patch of sky equaling
the area of full Moon, you can find > 2000 AGNs. AGNs often emit
X-rays (yes, the rays doctors use to see your bone), and the X-ray
emission is not constant over time (yes, AGN twinkles like stars).
Astronomers have built a giant X-ray telescope satellite, Chandra,
to study AGNs. With the help of Chandra, astronomers can
characterize AGNs with great details. Our group (led by Prof.
Niel Brandt) is doing an awesome project called Chandra
Deep Field-South (CDF-S) survey. We use Chandra to observe a
small patch of sky over 100 times totaling exposure time of 7
million seconds! The observations started from 1999 and ended in
2016, spanning 17 years. The great data give us an opportunity to
characterize long-term X-ray variability (twinkle) of AGNs. The
movies below show the pictures taken by Chandra at different
time. Note that AGNs really twinkle. We have conducted a variability
study based on CDF-S data, and published our results in The
Astrophysical Journal (http://adsabs.harvard.edu/cgi-bin/bib_query?arXiv:1608.08224).