Browsing by Subject "radiation pressure"
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Item Broad-Line Reverberation In The Kepler-Field Seyfert Galaxy Zw 229-015(2011-05) Barth, Aaron J.; Nguyen, My L.; Malkan, Matthew A.; Filippenko, Alexei V.; Li, Weidong; Gorjian, Varoujan; Joner, Michael D.; Bennert, Vardha Nicola; Botyanszki, Janos; Cenko, S. Bradley; Childress, Michael; Choi, Jieun; Comerford, Julia M.; Cucciara, Antonino; da Silva, Robert; Duchene, Gaspard; Fumagalli, Michele; Ganeshalingam, Mohan; Gates, Elinor L.; Gerke, Brian F.; Griffith, Christopher V.; Harris, Chelsea; Hintz, Eric G.; Hsiao, Eric; Kandrashoff, Michael T.; Keel, William C.; Kirkman, David; Kleiser, Io K. W.; Laney, C. David; Lee, Jeffrey; Lopez, Liliana; Lowe, Thomas B.; Moody, J. Ward; Morton, Alekzandir; Nierenberg, A. M.; Nugent, Peter; Pancoast, Anna; Rex, Jacob; Rich, R. Michael; Silverman, Jeffrey M.; Smith, Graeme H.; Sonnenfeld, Alessandro; Suzuki, Nao; Tytler, David; Walsh, Jonelle L.; Woo, Jong-Hak; Yang, Yizhe; Zeisse, Carl; Comerford, Julia M.The Seyfert 1 galaxy Zw 229-015 is among the brightest active galaxies being monitored by the Kepler mission. In order to determine the black hole mass in Zw 229-015 from H beta reverberation mapping, we have carried out nightly observations with the Kast Spectrograph at the Lick 3 m telescope during the dark runs from 2010 June through December, obtaining 54 spectroscopic observations in total. We have also obtained nightly V-band imaging with the Katzman Automatic Imaging Telescope at Lick Observatory and with the 0.9 m telescope at the Brigham Young University West Mountain Observatory over the same period. We detect strong variability in the source, which exhibited more than a factor of two change in broad H beta flux. From cross-correlation measurements, we find that the H beta light curve has a rest-frame lag of 3.86(-0.90)(+0.69) days with respect to the V-band continuum variations. We also measure reverberation lags for H alpha and H gamma and find an upper limit to the H delta lag. Combining the H beta lag measurement with a broad H beta width of sigma(line) = 1590 +/- 47 km s(-1) measured from the rms variability spectrum, we obtain a virial estimate of M-BH = 1.00(-0.24)(+0.19) x 10(7) M-circle dot for the black hole in Zw 229-015. As a Kepler target, Zw 229-015 will eventually have one of the highest-quality optical light curves ever measured for any active galaxy, and the black hole mass determined from reverberation mapping will serve as a benchmark for testing relationships between black hole mass and continuum variability characteristics in active galactic nuclei.Item Giant Enhancement of Stimulated Brillouin Scattering in the Subwavelength Limit(2012-01) Rakich, Peter T.; Reinke, Charles; Camacho, Ryan; Davids, Paul; Wang, Zheng; Wang, ZhengStimulated Brillouin scattering (SBS) is traditionally viewed as a process whose strength is dictated by intrinsic material nonlinearities with little dependence on waveguide geometry. We show that this paradigm breaks down at the nanoscale, as tremendous radiation pressures produce new forms of SBS nonlinearities. A coherent combination of radiation pressure and electrostrictive forces is seen to enhance both forward and backward SBS processes by orders of magnitude, creating new geometric degrees of freedom through which photon-phonon coupling becomes highly tailorable. At nanoscales, the backward-SBS gain is seen to be 10(4) times greater than in conventional silica fibers with 100 times greater values than predicted by conventional SBS treatments. Furthermore, radically enhanced forward-SBS processes are 10(5) times larger than any known waveguide system. In addition, when nanoscale silicon waveguides are cooled to low temperatures, a further 10-100 times increase in SBS gain is seen as phonon losses are reduced. As a result, a 100-mu m segment of the waveguide has equivalent nonlinearity to a kilometer of fiber. Couplings of this magnitude would enable efficient chip-scale stimulated Brillouin scattering in silicon waveguides for the first time. More generally, we develop a new full-vectorial theoretical formulation of stimulated Brillouin scattering that accurately incorporates the effects of boundary-induced nonlinearities and radiation pressure, both of which are seen to have tremendous impact on photon-phonon coupling at subwavelength scales. This formalism, which treats both intermode and intramode coupling within periodic and translationally invariant waveguide systems, reveals a rich landscape of new stimulated Brillouin processes when applied to nanoscale systems.Item The Lick AGN Monitoring Project 2011: Reverberation Mapping of Markarian 50(2011-12) Barth, Aaron J.; Pancoast, Anna; Thorman, Shawn J.; Bennert, Vardha N.; Sand, David J.; Li, Weidong; Canalizo, Gabriela; Filippenko, Alexei V.; Gates, Elinor L.; Greene, Jenny E.; Malkan, Matthew A.; Stern, Daniel; Treu, Tommaso; Woo, Jong-Hak; Assef, Roberto J.; Bae, Hyun-Jin; Brewer, Brendon J.; Buehler, Tabitha; Cenko, S. Bradley; Clubb, Kelsey I.; Cooper, Michael C.; Diamond-Stanic, Aleksandar M.; Hiner, Kyle D.; Hoenig, Sebastian F.; Joner, Michael D.; Kandrashoff, Michael T.; Laney, C. David; Lazarova, Mariana S.; Nierenberg, A. M.; Park, Dawoo; Silverman, Jeffrey M.; Son, Donghoon; Sonnenfeld, Alessandro; Tollerud, Erik J.; Walsh, Jonelle L.; Walters, Richard; da Silva, Robert L.; Fumagalli, Michele; Gregg, Michael D.; Harris, Chelsea E.; Hsiao, Eric Y.; Lee, Jeffrey; Lopez, Liliana; Rex, Jacob; Suzuki, Nao; Trump, Jonathan R.; Tytler, David; Worseck, Gabor; Yesuf, Hassen M.; Walsh, Jonelle L.The Lick AGN Monitoring Project 2011 observing campaign was carried out over the course of 11 weeks in spring 2011. Here we present the first results from this program, a measurement of the broad-line reverberation lag in the Seyfert 1 galaxy Mrk 50. Combining our data with supplemental observations obtained prior to the start of the main observing campaign, our data set covers a total duration of 4.5 months. During this time, Mrk 50 was highly variable, exhibiting a maximum variability amplitude of a factor of similar to 4 in the U-band continuum and a factor of similar to 2 in the H beta line. Using standard cross-correlation techniques, we find that H beta and H gamma lag the V-band continuum by tau(cen) = 10.64(-0.93)(+0.82) and 8.43(-1.28)(+1.30) days, respectively, while the lag of He II lambda 4686 is unresolved. The H beta line exhibits a symmetric velocity-resolved reverberation signature with shorter lags in the high-velocity wings than in the line core, consistent with an origin in a broad-line region (BLR) dominated by orbital motion rather than infall or outflow. Assuming a virial normalization factor of f = 5.25, the virial estimate of the black hole mass is (3.2 +/- 0.5) x 10(7) M-circle dot. These observations demonstrate that Mrk 50 is among the most promising nearby active galaxies for detailed investigations of BLR structure and dynamics.Item The Mass of the Black Hole in Arp 151 from Bayesian Modeling of Reverberation Mapping Data(2011-06) Brewer, Brendon J.; Treu, Tommaso; Pancoast, Anna; Barth, Aaron J.; Bennert, Vardha N.; Bentz, Misty C.; Filippenko, Alexei V.; Greene, Jenny E.; Malkan, Matthew A.; Woo, Jong-Hak; Greene, Jenny E.Supermassive black holes are believed to be ubiquitous at the centers of galaxies. Measuring their masses is extremely challenging yet essential for understanding their role in the Formation and evolution of cosmic structure. We present a direct measurement of the mass of a black hole in an active galactic nucleus (Arp 151) based on the motion of the gas responsible for the broad emission lines. By analyzing and modeling spectroscopic and photometric time series, we find that the gas is well described by a disk or torus with an average radius of 3.99 +/- 1.25 light days and an opening angle of 68.9(-17.2)(+21.4) deg, viewed at an inclination angle of 67.8 +/- 7.8 deg (that is, closer to face-on than edge-on). The black hole mass is inferred to be 10(6.51 +/- 0.28) M-circle dot. The method is fully general and can be used to determine the masses of black holes at arbitrary distances, enabling studies of their evolution over cosmic time.Item Slow Light Through Tightly-Coupled Light Waves And Acoustic Waves In Nanoscale Waveguides(2013-03) Wang, Z.; Qiu, W. J.; Rakich, P.; Shin, H.; Dong, H.; Wang, Zheng; Dong, HuiWe develop a general framework of evaluating slow-light performance using Stimulated Brillouin Scattering (SBS) in optical waveguides via the overlap integral between optical and elastic eigen-modes. We show that spatial symmetry of the optical force dictates the selection rules of the excitable elastic modes. By applying this method to a rectangular silicon waveguide, we demonstrate the spatial distributions of optical force and elastic eigen-modes jointly determine the magnitude and scaling of SBS gain coefficient in both forward and backward SBS processes. We further apply this method to inter-modal SBS process, and demonstrate that the coupling between distinct optical modes is necessary to excite elastic modes with all possible symmetries.