Slide 1Slide 2Slide 3Slide 4Slide 5Slide 6Slide 7Slide 8Slide 9Slide 10Slide 11Slide 12Black Holes - ObservationHow do you see something you can’t see ?????How do objects emit em waves?When an charged object accelerates, it must change it’s energy if the acceleration causes a change in speed. If the acceleration of the charged object results in a loss of energy of the object, that energy will be released in the form of electromagnetic energy.How do objects emit em waves?Peculiar discovery of EinsteinElectromagnetic energy is not released in the form of an electromagnetic “wave” but rather is released in the form of an electromagnetic “particle” called a photon.The energy of motion of this photon is not the usual kinetic energy, but the energy of the photon is given byE = h fWhere h is called Planck’s constant and f is the frequency of the EM wave.h = 6.6 x 10-34 J secPhotonA black hole will accrete nearby matter through the event horizon because of the black hole’s strong gravitational field. Black Holes – ObservationAccretionAs the matter falls into the event horizon, it experiences strong accelerations. As this happens, they will radiate energy in the form of photons (recall the Aurora Borealis) Black Holes – ObservationAccretionBlack Holes – ObservationAccretionThe accelerations are very high for the particles as they collapse into and through the event horizon. Calculations show that the photons emitted should be in the X-ray region of the electromagnetic spectrum.These X-ray photons can be distinguished from X-ray bursters because there is no regularity (or periodicity) to the emission.The emission of X-rays as matter collapses into the event horizon is somewhat continuous.Black Holes – ObservationEffect on the Motion of Objects in Orbitvorbit = G MR( )1/2Recall:Black Holes – ObservationEffect on the Motion of Objects in Orbitvorbit = G MR( )1/2Speeds of objects and the orbital radius can be determined by direct observation (we have talked about this in the past). Once these are known, it is possible to determine the mass of the object producing the warpage of space.Space WarpsOrbit with Space WarpsRvorbitBlack Holes – ObservationEffect on the Motion of Objects in OrbitCalculation of the mass of the object occupying the focus is strong (but circumstantial?) evidence for a black hole if the mass is above the minimum mass required to form a black hole (3M)Black Holes – ObservationGravitational Waves - Ripples in SpaceBlack Holes - ObservationLaser Interferometer Gravitational Wave Observatory
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