NuSTAR to probe the insides of super massive black holes

On a modest budget of 165 million $, NASA has developed NuSTAR (Nuclear Spectroscopic Telescope Array) which will probe the insides of the super massive black holes hidden inside of galaxies

Both space-based telescopes are sensitive to high-energy photons produced at the thresholds of supermassive black holes. NuSTAR will be ferried into orbit by a Pegasus rocket launched in mid-air from a carrier jet. It will detect hard X-rays at 5 to 80 kiloelectronvolts,
which is between the energy range probed by the Chandra X-ray Observatory and the ?-rays measured by satellite like the Fermi telescope.

This will be the first mission that can resolve these high-energy X-rays. Hard X-rays are difficult to focus because they penetrate mirrors, even those covered with dense metals such as gold and iridium. The new mirrors are coated with a sandwich of hundreds
of thin metallic films. Thickness of each layer is tuned to reflect photons of a specific energy. Once these layers are added up, they will reflect a number of photos large enough to produce a strong reflection.

The X-rays are so powerful that they can only be reflected at glancing angles, and the mirrors must be arranged in conical shells, like nested Russian dolls, which funnel the high-energy photons into a detector at the end of the structure. There are 133
of these mirror shells in two units and NuSTAR will be more powerful than the Chandra telescope, which has only four mirror shells, but they are stiffer and more finely polished, allowing Chandra to perceive objects in greater detail.

This means that the optics need a long focal length, which implies a bulky, costly spacecraft. The $2-billion Chandra could barely be squeezed into the cargo bay of the Space Shuttle. NuSTAR measures 10 m and will be just as long, but it had to fit into
the much smaller and cheaper Pegasus launcher. The telescope is built around a folded-up truss, which will only grow to full length once NuSTAR is deployed in low-Earth orbit.

NuSTAR will focus on active galactic nuclei (AGN) in the hearts of distant galaxies that contain high energy particles. NuSTAR should be able to stop several hundred new AGN that have been shrouded by gas from other detectors. This should allow astronomers
to ascertain how common AGN are and what role they play in the growth and evolution of galaxies. Another large X-ray telescope by the ESA, XMM-Newton, will be looking for distortions in the X-ray spectra resulting from the spin of the central super massive
black holes in galaxies. The spin rates themselves could give insight how the black holes in some AGN grew to masses of billions of Suns, by swallowing other AGN in galactic mergers or by steadily accumulating material from its host galaxy. XMM-Newton is devoting
10% of its time in a joint effort with NuSTAR.

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Posted by Taimoor Tariq on Mar 21 2012. Filed under Sci-Tech. You can follow any responses to this entry through the RSS 2.0. You can leave a response or trackback to this entry