Polaroid Sunglasses let astronomers take a closer look at Black Holes
An international team led by an Edinburgh astronomer have discovered that by studying polarised light from black holes they can focus much more closely on what exactly is going on around them. The work is published this week in the monthly notices of the Royal Astronomical Society on November 11th.
Studying black holes at the centre of galaxies is difficult. A huge amount of material is falling on to the centre in an active black hole system, and this falling material is thought to power the black hole, but scientists still dont understand this powering mechanism. One critical reason is that these black holes are just too far away for astronomers to isolate the light from them - or more accurately, the light from the compact region where the black holes are actually producing their energy.
However, Kishimoto at the University of Edinburgh and the international team of Antonucci at UC Santa Barbara, Boisson at Paris Observatory, and Blaes also at UC Santa Barbara, have used the Keck I telescope in Hawaii and European Southern Observatorys Very Large Telescope in Chile, to do this isolation of the light. They have looked at a small part of the light emitted from black holes - light that has been scattered as it passes through the clouds very nearby. This scattered light can cleverly be picked up by looking through a polaroid filter just like the lens of polaroid sunglasses, which essentially blocks the unwanted light from elsewhere in the galaxy. The scattered light is polarised so the light waves all line up in the same direction and can pass through the Polaroid filter, but light from the surrounding area which is not polarised is excluded by the filter.
Dr Kishimoto, who leads the team, explained the importance of the new method: "For the first time we can use visible light to focus on the part of a galaxy that is very close to the black hole. We are interested in an area only about one light-day across. Until now, without using Polaroid filters, we couldnt separate the visible light from the black hole from the light coming from a much larger region about 100 light-days across." To put this in context, the galaxies surrounding the black holes are about 30,000 light years across.
As a result of this closer look the team have found a new signal in the observed light that can provide information about the material around a black hole. The signal, called a Balmer edge feature, reveals properties of the material and will allow the team to carry out more detailed modelling of the temperature and density of the region near black holes than has been possible before now. This feature is commonly used to diagnose the nature of the surface of the Sun and other stars, but has never before been seen in visible light from black holes.
The next step is for Kishimoto and his team to take a look at more black holes using this technique to see if the black holes at the centre of different types of galaxy all look the same. They can then try to understand the mechanism that powers a black hole. Kishimoto and the team are now observing many other black holes using other large telescopes.
1. One light-day is the distance light travels in one day i.e. 1/365 of a light-year.
Julia Maddock | alfa
The most recent press releases about innovation >>>
Die letzten 5 Focus-News des innovations-reports im Überblick:
Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.
Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...
For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.
While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...
An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.
The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...
A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.
Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...
Researchers from the University of Miami (UM) Rosenstiel School of Marine and Atmospheric Science, the Italian Space Agency (ASI), and the Instituto Geofisico--Escuela Politecnica Nacional (IGEPN) of Ecuador, showed an increasing volcanic danger on Cotopaxi in Ecuador using a powerful technique known as Interferometric Synthetic Aperture Radar (InSAR).
The Andes region in which Cotopaxi volcano is located is known to contain some of the world's most serious volcanic hazard. A mid- to large-size eruption has...