17 April 2015

Extremely Powerful Magnetic Field Detected At Edge of Supermassive Black Hole

A very powerful magnetic field has been detected at the edge of a supermassive black hole in the distant PKS 1830-211 galaxy.

The magnetic field is far more powerful than anything previously detected in the core of a galaxy.

Supermassive black hole are found at the center of almost all the galaxies and are a million times more massive than the Sun. These black holes accrete (come or bring together under the influence of gravitation) vast amounts of matter in the form of a disc. This matter is sucked in the black hole but some escape and are flung out into space at close to the speed of light as part of a jet of plasma.

This discovery can help astronomers understand the structure and formation of supermassive black holes and the the twin high-speed jets of plasma they frequently eject from their poles.

The artist's impression show accretion of matter forming a brilliant hot disk around the black hole. There are also often high-speed jets of material ejected at the black hole’s poles that can extend huge distances into space. Observations with ALMA have detected a very strong magnetic field close to the black hole at the base of the jets and this is probably involved in jet production and collimation.

Spheroid Galaxies Shut Down Star Formation From Inside Out

Astronomers have shown for the first time how star formation in “dead” galaxies sputtered out billions of years ago. ESO’s Very Large Telescope and the NASA/ESA Hubble Space Telescope have revealed that three billion years after the Big Bang, these galaxies still made stars on their outskirts, but no longer in their interiors. The quenching of star formation seems to have started in the cores of the galaxies and then spread to the outer parts. The results will be published in the 17 April 2015 issue of the journal Science.

Spheroid galaxies are elliptical shaped galaxies and are common in the Universe. The center of these galaxies are densely packed with stars; about then times more than in the Milky Way.

Observing 22 galaxies , spanning a range of masses, from an era about three billion years after the Big Bang, the researchers noted that the galaxies were still producing stars at the outskirts but not in the center. The Star formation in the bulging center slowed down and stopped starting at the center of the galaxies and spread outwards towards the edges.