May 16, 2013
Composite Image Shows Emissions Driven By Black Hole
John P. Millis, Ph.D. for redOrbit.com — Your Universe Online
Astronomy is more than merely using optical telescopes to take pretty pictures of distant nebulae and galaxies. Researchers also seek to understand complex systems in the universe by observing how objects interact and what types of radiation are produced.
To do this requires telescopes capable of observing over several energy bands, working together to construct a complete physical picture of the object of interest. This is particularly true of systems that are masked by multiple layers of gas clouds, stars, charged particles, and powerful magnetic fields.
Recently, scientists released details of a system studied using data from NASA's Chandra X-ray Observatory, the Hubble Space Telescope, and the NSF's Very Large Array contributing the radio component. The composite image depicts the galaxy 4C+29.30 and the powerful jets emanating from its black hole core.
The radio emission details the jet structure, where very high-energy charged particles are accelerated around powerful magnetic field lines, causing the particles to radiate away energy through the synchrotron process. At the end of the jet particles, where the charged particles impact the surrounding intergalactic medium, huge lobes glow with radio light.
The optical light reveals the stellar make-up of the galaxy itself. The central region is so dense with hot gas that the optical radiation is blocked, hiding the black hole lurking within. For this reason, astronomers refer to this type of system as a hidden or buried black hole galaxy.
Study of the X-ray emission from the galaxy shows streams of million-degree hot gas surrounding the 100 million solar mass black hole. Eventually some of this gas may be consumed by the black hole, causing a flare of radiation in the jets.
It is not until the complete image of the galaxy is constructed that the true nature and structure of the system can be understood.