1 / 28

Theoretical Astrophysics at GSU

Theoretical Astrophysics at GSU. Paul J. Wiita Department of Physics & Astronomy www.chara.gsu.edu/~wiita. Brief CV. Born 1953, The Bronx, New York Attended NYC public schools, graduated from The Bronx HS of Science in 1969

kibo-nelson
Download Presentation

Theoretical Astrophysics at GSU

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Theoretical Astrophysics at GSU Paul J. Wiita Department of Physics & Astronomy www.chara.gsu.edu/~wiita

  2. Brief CV • Born 1953, The Bronx, New York • Attended NYC public schools, graduated from The Bronx HS of Science in 1969 • BS in Physics in 1972 from The Cooper Union for the Advancement of Science and Art • PhD in Physics in 1976 from Princeton University • Post-doctoral fellowships at U. of Chicago and Cambridge U.; 3 month visit to Warsaw • Assistant Prof at U. Pennsylvania, 1979-1986 • Assistant (‘86), Associate (‘89) and Full Professor (‘93) at GSU. Astronomy Graduate Director, ‘95-’00 • Visiting Prof. at TIFR, IIA, & RRI (India) & Princeton • Affiliated Faculty @ Princeton; Adjunct Prof @ GaTech

  3. Research Interests • Theoretical astrophysics • Mainly extragalactic • Specifically Active Galactic Nuclei • More specifically, Quasars & Radio Galaxies • Other interests: accretion disks, black holes, variability in AGN classes, microquasars • Tools: combination of analytical modeling and numerical simulations (jet propagation) • Requirement: close interaction with observational astronomers, so models can be checked against data

  4. Big Radio Telescopes • NRAO Very Large Array • NRAO Very Long Baseline Array • NRAO Green Bank Telescope • TIFR Giant Metrewave Radio Telescope • MPIfRA Effelsberg Radio Telescope • NAIC Arecibo Radio Dish

  5. VLA in Closest Array

  6. More VLA photos • 27 antennas, each 25 m diameter • Maximum baseline 36 km

  7. VLBA:10 25m dishes, 8000km baseline

  8. GBT:largest single dish steerable RT: • Asymmetric design (110x100 m) keeps feeds off to side: no struts and diffraction from them • Works from 3m down to 3mm • Best for pulsar studies and molecular lines

  9. GMRT: largest collecting area • Mesh design, good enough for long wavelengths • 30 telescopes, 45 m aperture, maximum baseline, 25 km: near Narayangoan, India

  10. Arecibo: 305m fixed dish

  11. Radiographs • Colors usually indicate fluxes: red is (ususally) brightest, blue faintest • Images of supernova remnants • Pulsars and nearby shocks and jets • Black holes: jets in microquasars • Galactic structure • Radio galaxies • Quasars

  12. Tycho’s SN remnant

  13. W50, SNR home of microquasar SS433

  14. SN 1993J in M81 from some VLBA+ VLA+ EVN+ NASA

  15. “The Duck”, pulsar moving at ~500 km/s

  16. SS 433: bullets at 0.26c

  17. Microquasar GRS 1915+105Apparent v = 1.25 c from v = 0.92 cBH mass about 16 Suns

  18. Superluminal Motion? • Vapp=Vsin/[1-(V/c)cos] • =1/(1-2)1/2 , with =V/c • =1/ (1- cos) • Sobs=Sem n+ , with n=2 for smooth jet and n=3 for knot or shock • For large  and small  (~1/ ) this boosting factor can be > 10000!

  19. Atomic H in Our Galaxy: GBT et al.

  20. M33: Doppler shifts show rotation • Used VLA measuring H 21cm spin-flip line to map atomic hydrogen, with spatial resolution of 10” • Color coded to blue approaching and red receding: velocity resolution - 1.3 km/s, • Includes Westerbork data for total intensity

  21. 3C31: FR I Radio Galaxy

  22. 3C 130 & 3C 449: FR I’s

  23. M87 Jet to Bubble Montage

  24. Canonical FR II: Cygnus A

  25. Quasar: 3C 175

  26. 3C353: Peculiar FR II

  27. VLBA of 3C279:Apparent Superluminal Motionwith Vapp=3.5c: really V=0.997c at viewing angle of 2 degrees

  28. The Theory Side • My collaborators, graduate students and I have produced models that explain (some aspects) of all of these objects. • We use many branches of physics to do this: hydrodynamics (mechanics for gases) plasma physics (magnetohydrodynamics) electricity & magnetism (for radiation processes) general relativity (if close to central black hole) • Equations are set up and (with any luck) solved • Usually at least some numerical work is needed to solve the equations that describe the situation • Approximations sometimes allow analytical solutions using algebra, calculus & differential equations • Sometimes, full bore simulations on supercomputers are necessary

More Related