Rubin Planetarium Video - Quasars

A quasar, also known as a QSO or quasi-stellar object, is a type of active galactic nucleus (AGN) found at the center of a galaxy. There is evidence that most galaxies contain a supermassive black hole at their centers. In the case of a quasar, tremendous amounts of energy are released by hot gas as it is falling towards the black hole. Quasars are therefore extremely luminous, producing energy at all wavelengths- from radio waves to gamma rays. The energy output from the AGN can outshine all of the stars inside the galaxy. Because of their intense luminosity, quasars can be seen out to the edge of the observable Universe. The luminosity of quasars varies depending on several factors, including how much material is accreted by the central black hole. Quasars are therefore variable in brightness.

Currently about 200,000 quasars are known, most of which were discovered by the Sloan Digital Sky Survey. LSST will discover an estimated ten million more. Over the ten-year lifetime of the survey LSST will calculate the brightnesses of these quasars over a hundred times each, generating a light curve for each object. Astronomers will use these light curves to understand their characteristics (e.g., the mass of the supermassive black hole and its accretion rate).

Storyboard

This animation shows a quasar from two perspectives: an external view of an elliptical galaxy that, from certain angles, appears dramatically brighter; and a view of the inner active galactic nucleus (AGN) accretion disk swirling around the black hole (not pictured due to scale).

The consistent visual element in both views is the AGN-driven jet, seen at the galactic scale, as well as actively shooting away from the inner accretion disk at the local scale. In both views it is the visual cue that when we are sighting down the jet we are seeing into a much brighter/hotter region immediately surrounding the black hole.

00:00

We begin with a static moment of a star-like glow seen at the front of the dome. After 3 seconds this glare reduces significantly revealing a fuzzy galaxy that was previously lost in the glow. Quasars are so named because they look pointlike, like stars, when seen from far away.

00:10

As we start to move closer we can now see the galaxy in which the AGN resides. We can perceive our rotational motion around the galaxy due to the shiing orientation of the jets.

00:20

By this time we have revolved a full 180° around the elliptical galaxy and now we can see with greater clarity that the core of the galaxy lights up dramatically as we again sight down the jet.

00:30

We now move rapidly into the galaxy, transitioning into its core.

00:35

We now are surrounded by a very dense starfield, in the core of the host elliptical galaxy. Our virtual camera has now adjusted its exposure to show the bright inner region of the accretion disk around the black hole (unseen due to its tiny scale at this distance).

00:55

Our vantage point now shifts over the accretion disk, and the glare pouring out from the center establishes that there is an exceptionally bright region here that can only be seen from the correct angle. Note that the black hole is too small to see at this scale.

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Contact: Amanda Bauer, Head of LSST Education and Public Outreach abauer@lsst.org

Additional References

https://arxiv.org/abs/1312.3963