Hundreds of Missing Black Holes Found

A black hole is a region of space in which gravity is so strong that not even light can escape. Typical black holes range in size from stellar-mass black holes (which form mainly via the collapse of a massive star) to supermassive black holes which reside in the cores of galaxies. It is assumed that most galaxies contain a supermassive black hole at their core. Till recently, many black holes had been "missing." However, using both Spitzer (an infrared space telescope) and Chandra (an x-ray space telescope), a large fraction of these black holes have been found. The picture to the right is an artists conception of a growing black hole/quasar.

These black holes, due to their energetic nature, are considered quasars. A quasar or QUASi-stellAR radio source is a compact halo of matter surrounding a supermassive black hole within a young galaxy. These black holes/quasars were found within Milky Way mass galaxies of irregular shape at 9 to 11 billion light years away.


A team lead by Emanuele Daddi (of the Commissariat a l'Energie Atomique in France) studied 1,000 galaxies and found that, using Spitzer, 200 of those had an overabundance of infrared light. When studied with Chandra, the team found quasars within those 200 galaxies. The picture on the left shows an area of the sky containing galaxies with quasars in them (those galaxies are circled). This picture was taken using the Spitzer space telescope. It is thought that the quasars heat the dust surrounding them, thus giving off infrared light.

The finding of these new quasars has helped to change the way we think that massive galaxies evolve. It is now believed that the stars and black holes in massive galaxies form together until the black hole gets too massive, at which point it stops star formation. Additionally, in the past, it was believed that galaxy mergers played a large part in ignition of quasar activity, but seeing so many unscathed galaxies, it is now believed this is not true.

Finding so many new black holes in old galaxies will help us further refine our theories on galaxy/black hole formation in the early universe. This further knowledge can also aid us in our studies in the future. I also look forward to finding out what else Spitzer and Chandra can find and tell us about the universe.

NASA article:
http://www.nasa.gov/mission_pages/spitzer/news/spitzer-20071025.html
Space.com article:
http://www.space.com/scienceastronomy/071025-missing-bholes.html

Cluster monitors convection cells over the polar caps

A European Space Agency (ESA) spacecraft named Cluster has recently helped to uncover important information regarding convection cells of matter found above the polar ice caps.

The Cluster mission, which is actually four spacecraft, launched in 2000, is designed to study small-scale plasma structures and processes.

A convection cell, which is a fluid dynamical phenomenon, occurs in situations where there are temperature difference within a liquid or gas. Cold gas or liquid moves underneath warmer liquid or gas, which then forces the warmer areas to rise and creates a cycle called convection (wherein the moving mass itself is called the convection cell). These convection cells, which are related to the Earth's magnetic field and the activities of the sun, were mapped with data collected for various solar conditions.












Normally, the Earth's magnetic field or magnetosphere, is stretched and compressed by the force of the solar wind (or charged particles emitted from the sun) as seen in the picture on the left. This magnetosphere deflects most of the particles, however, it can also allow the particles to pass through to the Earth's atmosphere. This action can create what is known as the aurora borealis or northern lights.

One method for studying the magnetosphere and convection cells is by looking at plasma at hundreds of kilometers above the Earth's poles. This region, called the high-latitude ionosphere, works well for studying these such convection cells and their interactions with the Earth and its magnetosphere.

After six years of collecting data, a full convection map has been created. Previously, partial maps have been produced via ground based observations from projects such as SuperDARN (Super Dual Aurora Radar Network), however, this is the first time a space based mission has made these maps (as seen below).


The map on the left is for the southward field and the one on the bottom right is for the northward field. As can be seen, the two maps differ in the number of convection cells seen.

These observations and future observations can be used to monitor coronal flares, coronal mass ejections and other such outbursts from the sun. This data can further be used to help safe guard astronauts and satellites in orbit above the Earth.















I think that it is interesting to see the different convection cell structures on the north and south poles and how changes in the sun affect the structures seen. It should be interesting to see what more data from the Cluster satellites can produce and what the effects of this research will be.


ESA article:
http://clusterlaunch.esa.int/science-e/www/object/index.cfm?fobjectid=41454
Space.com article:
http://www.space.com/scienceastronomy/071023-st-sun-earth-connection.html