Evolution of Black Hole Masses from Spectra of Quasar Gas Dynamics Amanda Schilling, University of Arkansas Mentor: Dr. Julia Kennefick, University of Arkansas Strategy Spectra Every chemical element has a unique spectrum Because of the wave nature of light an object in motion will have a shifted spectrum - called Doppler shift Example of Doppler shift2 SDSS has cataloged hundreds of quasar spectra Sample quasar spectrum from SDSS3 Velocity of gas from the Broad Line Region can be determined from spectra broad line: the slope on the left of a peak corresponds to blueshift and on the right to redshift gas in BLR has blue and red shifts indicating its orbit around the black hole Dynamics Keplerian motion gives a correlation between the orbital velocity of the gas in the BLR and the black hole it is orbiting Introduction - Quasars Active galactic nuclei that are an intense source of radiation First discovered as radio-wave emitting objects in the 1960s though most found since are not radio emitters Unique because: billions of light years away and yet luminous enough to be detected More numerous in the distant past powered by massive black holes Believed to be early galaxies Objective - Calculate masses of the black holes that power quasars Why? To determine if the mass evolves with redshift The sample: 47 quasars with redshifts between 1.8 and 4.3 correlating to look-back-times of 10-12 billion years (most quasars have a redshift around 2) Data: spectra of quasars from SDSS, Sloan Digital Sky Survey, database Anatomy of a Quasar Massive Black Hole in center powers the quasar Accretion Disk - disk of gas and dust orbiting the black hole Jets perpendicular to accretion disk can extend very far from the black hole emit some visible but mostly radio light waves BLR - broad line region gas orbiting at high velocities noticeable Doppler shifts in spectra- broad lines refers to the width of a peak on a spectrum NLR - narrow line region, larger in volume than BLR but gas is slower and less dense Torus of cool gas and dust Quasar diagram1 References 1. Strobel, Nick. “Doppler Effect.” <http://www.astronomynotes.com/light/s10.htm> 2. From “Introduction to Active Galactic Nuclei” NASA’s HEASARC: Education & Public Information. <http://heasarc.gsfc.nasa.gov/docs/objects/agn/agntext.html> 3. <http://cas.sdss.org/dr6/en/tools/explore/obj.asp?ra=157.13368&dec=-0.76863>