APOD: The Antennae Galaxies in Collision (2014 Mar 16)

[neufer]

one more, considering this is Sunday. Are black holes still considered singularities acting as giant magnets ?

Giant magnets? They were never considered to act like magnets.

• Perhaps you are thinking of a magnetar or a Dirac string:

<<A Dirac string is a hypothetical one-dimensional curve in space, conceived of by the physicist Paul Dirac, stretching between two Dirac magnetic monopoles with opposite magnetic charges, or from one magnetic monopole out to infinity. The gauge potential cannot be defined on the Dirac string, but it is defined everywhere else. The Dirac string acts as the solenoid in the Aharonov–Bohm effect, and the requirement that the position of the Dirac string should not be observable implies the Dirac quantization rule: the product of a magnetic charge and an electric charge must always be an integer multiple of 2π. The Dirac string is the only way to incorporate magnetic monopoles into Maxwell's equations, since the magnetic flux running along the interior of the string maintains their validity.>>

• However, black holes may possibly have a little "hair":

Black Holes May Have "Hair"
Oct 21, 2013 |By Megan Gannon and SPACE.com

<<Astronomer John Wheeler, who coined the term "black hole" nearly 50 years ago, famously said that "black holes have no hair" because of their simplicity. Now "hair" is used as a colloquial term among physicists as a stand-in for any other measure needed to describe a black hole that departs from: their mass, their angular momentum (how fast they spin) and their electric charge. [However,] Thomas Sotiriou, a physicist at the International School for Advanced Studies of Trieste and his colleagues looked at black holes in the context of the equations of scalar-tensor theories of gravity. The researchers found that [such non-Einsteinian] black holes [may] develop scalar "hair" when ordinary matter surrounds them.>>

See: http://www.scientificamerican.com/artic ... have-hair/

[alter-ego]

... But what actually happens beyond the event horizon, and especially very near the center, isn't certain.

I'll add that what happens at or near the event horizon isn't certain either. Since we haven't been able to really observationally (indirect or direct) probe that close, there is active interest in the details near the event horizon.

[walker1001]

Antennae ???? I think it looks more like Africa. We have celestial bodies named after North America, California, etc. why not rename this one to Africa ?

Second that.

[Chris Peterson]

Antennae ???? I think it looks more like Africa. We have celestial bodies named after North America, California, etc. why not rename this one to Africa ?

Second that.

You're not seeing the whole picture.

Click to view full size image

This is why it's called the Antennae. Africa would make no sense at all.

[JohnD]

... But what actually happens beyond the event horizon, and especially very near the center, isn't certain.

I'll add that what happens at or near the event horizon isn't certain either. Since we haven't been able to really observationally (indirect or direct) probe that close, there is active interest in the details near the event horizon.

The Black Hole at the Core of the Milky Way, Sagittarius A*, is about to consume a giant gas cloud, later this year (or rather later in a year 25,000 years ago)
https://www.calacademy.org/sciencetoday ... d/5512937/

During the part of our history in which we could have 'seen' such things, SgtA* has been quiet and well-behaved, for a galactic centre Mega BH, so this will be an event of great interest, precisely for those reasons. For the first time we will see, close-up, an enormous mass hit a black hole, and if theory is are correct form an accretion disc, galactic jets and some actually enter the event horizon. Now THAT will be an APOD to remember!

John