Rubin Planetarium Video - Black Holes

A black hole is an object that is sufficiently massive and compact so that its strong gravity creates a region of spacetime around it from which nothing can escape, including light. The warping of spacetime near a black hole is explained by the general theory of relativity.

Stellar-mass black holes are created when a massive star (roughly more than 40 times the mass of the Sun) explodes as a “core-collapse” supernova. Supermassive black holes, which have masses upwards of a billion times the mass of the Sun, are known to exist at the centers of most large galaxies. It is not yet well understood how they form.

Black holes are so named because light cannot escape from within their event horizons; however, it is possible to detect black holes by the gravitational lensing they cause. A gravitational lens is an optical illusion produced when a concentration of mass is located between the observer and a distant object. The intermediate mass serves as a lens, bending and magnifying the light of the background object in an effect known as “strong lensing.”

Related to strong lensing, gravitational microlensing events occur when a compact foreground object passes directly in front of a distant object. Microlensing causes the brightness of the background object to briefly increase. During its ten-year survey of the night sky, it is anticipated that LSST will detect over 10,000 microlensing events, many of which will be due to black holes.

Storyboard

The visual narrative and camera motion within this animation is simple: approach a 5 solar mass black hole along a spiraling arc. The sequence starts at a significant distance and concludes over an order of magnitude closer. As we approach the black hole, gravitational lensing of light from a background nebula will be visible.

The relative scale of the event horizon and its angular extent have been calculated for these parameters:

• Camera range: 4000 km (initial) – 100 km (final)
• Black hole mass: 5x the mass of the Sun
• Black hole diameter: 30 km

Note: Due to the linear scaling of event horizon with black hole mass, the range/mass/diameter numbers may be scaled uniformly up or down to represent different scales, e.g., this animation could also be used to illustrate a 10 solar mass black hole with a 60 km diameter seen at a range from 8000 to 200 km.

The black hole can only be seen because it distorts background light, thus it is shown in projection against a nebula with a strong variations in color. The asymmetric colors help to visually interpret the inverted sky image seen within the Einstein ring.

00:00

The black hole remains, in dome coordinates, at its initial location of 30° above the horizon. It is only barely visible at the beginning due to its distance.

00:10

The first hint of the Einstein ring and inverted interior projection can be seen as a bright star passes above the black hole.

00:24

The inverted distortion within the Einstein ring becomes more identifiable as the event horizon starts to straddle the blue nebula on the left and the yellow one on the right; the internal projection shows these colors in reversed orientation.

00:45

At closest approach, the effect on the background cluster stars is now maximally visible.

00:55

As our viewpoint starts to project it against a more blank area of sky, the black hole becomes less visible since it no longer has as much of a bright backdrop to contrast against the black event horizon.

Contact and Usage Survey

If you use this video for any purpose, please fill out this survey so the LSST team can understand usage and make any improvements necessary: https://forms.gle/yJS2mMrSja2PvGHCA

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

Additional References

https://arxiv.org/abs/1806.06372