Wednesday, February 25, 2015

Winds of Supermassive Black Holes Can Shape Galaxy-Wide Star Formation

Winds of Supermassive Black Holes Can Shape Galaxy-Wide Star Formation:



An illustration that shows the powerful winds driven by a supermassive black hole at the centre of a galaxy. The schematic figure in the inset depicts the innermost regions of the galaxy where a black hole accretes, that is, consumes, at a very high rate the surrounding matter (light grey) in the form of a disc (darker grey). At the same time, part of that matter is cast away through powerful winds. (Credits: XMM-Newton and NuSTAR Missions; NASA/JPL-Caltech;Insert:ESA)


An illustration that shows the powerful winds driven by a supermassive black hole at the centre of a galaxy. The schematic figure (inset) depicts the innermost regions of the galaxy where a black hole accretes, effectively consumes, at a very high rate the surrounding matter (light grey) in the form of a disc (darker grey). At the same time, part of that matter is cast away through powerful winds. (Credits: XMM-Newton and NuSTAR Missions; NASA/JPL-Caltech;Insert:ESA)
The combined observations from two generations of X-Ray space telescopes have now revealed a more complete picture of the nature of high-speed winds expelled from super-massive black holes. Scientist analyzing the observations discovered that the winds linked to these black holes can travel in all directions and not just a narrow beam as previously thought. The black holes reside at the center of active galaxies and quasars and are surrounded by accretion discs of matter. Such broad expansive winds have the potential to effect star formation throughout the host galaxy or quasar. The discovery will lead to revisions in the theories and models that more accurately explain the evolution of quasars and galaxies.



This plot of data from NASA's Nuclear Spectroscopic Telescope Array (NuSTAR) and the European Space Agency's (ESA's) XMM-Newton determines for the first time the shape of ultra-fast winds from supermassive black holes, or quasars. The winds blow in every direction, in a nearly spherical fashion, coming from both sides of a galaxy (Credit: NASA/JPL-Caltech/Keele Univ.;XMM-Newton and NuSTAR Missions)


This plot of data from NASA’s Nuclear Spectroscopic Telescope Array (NuSTAR) and the European Space Agency’s (ESA’s) XMM-Newton determines for the first time the shape of ultra-fast winds from supermassive black holes, or quasars. The winds blow in every direction, in a nearly spherical fashion, coming from both sides of a galaxy (Credit: NASA/JPL-Caltech/Keele Univ.;XMM-Newton and NuSTAR Missions, [Ref])
The observations were by the XMM-Newton and NuSTAR x-ray space telescopes of the quasar PDS 456. The observations were combined into the graphic, above. PDS 456 is a bright quasar residing in the constellation Serpens Cauda (near Ophiuchus). The data graph shows both a peak and a trough in the otherwise nominal x-ray emission profile as shown by the NuSTAR data (pink). The peak represents X-Ray emissions directed towards us (i.e.our telescopes) while the trough is X-Ray absorption that indicates that the expulsion of winds from the super-massive black hole is in many directions – effectively a spherical shell. The absorption feature caused by iron in the high speed wind is the new discovery.


X-Rays are the signature of the most energetic events in the Cosmos but also are produced from some of the most docile bodies – comets. The leading edge of a comet such as Rosetta’s P67 generates X-Ray emissions from the interaction of energetic solar ions capturing electrons from neutral particles in the comet’s coma (gas cloud). The observations of a super-massive black hole in a quasar billions of light years away involve the generation of x-rays on a far greater scale, by winds that evidently has influence on a galactic scale.



A diagram of the ESA XMM-Newton X-Ray Telescope. Delivered to orbit by a Ariane 5 launch vehicle in 1999. (Illustration Credit: ESA/XMM-Newton)


A diagram of the ESA XMM-Newton X-Ray Telescope. Delivered to orbit by a Ariane 5 launch vehicle in 1999. (Illustration Credit: ESA/XMM-Newton)
The study of star forming regions and the evolution of galaxies has focused on the effects of shock waves from supernova events that occur throughout the lifetime of a galaxy. Such shock waves trigger the collapse of gas clouds and formation of new stars. This new discovery by the combined efforts of two space telescope teams provides astrophysicists new insight into how star and galaxy formation takes place. Super-massive blackholes, at least early in the formation of a galaxy, can influence star formation everywhere.



The NuStar Space Telescope launched into Earth orbit by a Orbital Science Corp. Pegasus rocket, 2012. The Wolter telescope design images throughout a spectral range from 5 to 80 KeV. (Credit: NASA/Caltech-JPL)


The NuStar Space Telescope launched into Earth orbit by a Orbital Science Corp. Pegasus rocket, 2012. The Wolter telescope design – optics in the foreground, 10 meter truss and detectors at back – images throughout a spectral range from 5 to 80 KeV. (Credit: NASA/Caltech-JPL)
Both the ESA built XMM-Newton and the NuSTAR X-Ray space telescope, a SMEX class NASA mission, use grazing incidence optics, not glass (refraction) or mirrors (reflection) as in conventional visible light telescopes. The incidence angle of the X-rays must be very shallow and consequently the optics are extended out on a 10 meter (33 foot) truss in the case of NuSTAR and over a rigid frame on the XMM-Newton.



Diagram of one of three x-ray telescopes of the XMM-Newton design. Only a few of the grazing angle concentric mirrors are shown. Inset: a simplified illustration of how a Wolter telescope works. (Credits: Wikimedia, ESA)


Diagram of one of three x-ray telescopes of the XMM-Newton design. Only a few of the grazing angle concentric mirrors are shown. Inset: a simplified illustration of how a Wolter telescope works. (Credits: Wikimedia, ESA) [click to enlarge]


The spectral ranges of the XMM-Newton and NuSTAR Telescopes. (Credits: NASA, ESA)


The spectral ranges of the XMM-Newton and NuSTAR Telescopes. (Credits: NASA, ESA)
The ESA built XMM-Newton was launched in 1999, an older generation design that used a rigid frame and structure. All the fairing volume and lift capability of the Ariane 5 launch vehicle was needed to put the Newton in orbit. The latest X-Ray telescope – NuSTAR – benefits from tens years of technological advances. The detectors are more efficient and faster and the rigid frame was replaced with a compact truss which required all of 30 minutes to deploy. Consequently, NuSTAR was launched on a Pegasus rocket piggybacked on a L-1011, a significantly smaller and less expensive launch system.

So now these observations are effectively delivered to the theorists and modelers. The data is like a new ingredient in the batter from which a galaxy and stars are formed. The models of galaxy and star formation will improve and will more accurately describe how quasars, with their active super-massive black-holes, transition into more quiescent galaxies such as our own Milky Way.

Reference:

XMM-NEWTON AND NUSTAR SPECTRUM OF THE QUASAR PDS 456

ARTIST’S IMPRESSION OF BLACK-HOLE WIND IN A GALAXY



About 

Contributing writer Tim Reyes is a former NASA software engineer and analyst who has supported development of orbital and lander missions to the planet Mars since 1992. He has an M.S. in Space Plasma Physics from University of Alabama, Huntsville.

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