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Talking About S pectrum

Talking About S pectrum. Hou Saiyu 04/01/2014 Note: Four digital numbers referring to wavelength in unit of angstrom here. outline. Introduction Properties Important spectrum in astronomy AGN spectrum. outline. Introduction Properties Important spectrum in astronomy

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Talking About S pectrum

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  1. Talking About Spectrum HouSaiyu 04/01/2014 Note: Four digital numbers referring to wavelength in unit of angstrom here

  2. outline • Introduction • Properties • Important spectrum in astronomy • AGN spectrum

  3. outline • Introduction • Properties • Important spectrum in astronomy • AGN spectrum

  4. http://casswww.ucsd.edu/archive/public/tutorial/Stars.html

  5. http://www2.keck.hawaii.edu/inst/hires/

  6. outline • Introduction • Properties • Important spectrum in astronomy • AGN spectrum

  7. Forbidden Lines • Dipoleradiation, selectionrules • Meta stable state • Collisionde-excitation • Energy level life time • Critical density • Transition probabilities ~ 1 in 109

  8. Forbidden Line Examples Highest vacuum on earth <1000 atoms/cm3 http://www.astr.ua.edu/keel/galaxies/emission.html

  9. Semi Forbidden Line • eg. CIII]1909, NIII]1750, OIII]1663,NIV]1486 • Electric dipole transition, but ΔS ≠0 • CaI] λ65733P1 1S0 • Transition probabilities ~1 in 106

  10. Broadening • Thermal Doppler Broadening • Collision Broadening • Rotational Broadening Δ λ/λ = v/c • Natural Broadening • Turbulent Broadening • Zeeman Splitting • … www.astronomy.gatech.edu/Courses/Phys3021/Lectures/pdf/Line_Broadening.pdf

  11. ThermalBroadening http://astronomy.swin.edu.au/cosmos/t/thermal+doppler+broadening

  12. Rotational Broadening http://astronomy.nju.edu.cn/~lixd/GA/AT4/AT404/HTML/AT40404.htm

  13. Double Horned Line Profile Broad, asymmetric line profile with a sharp cutoff at high E

  14. Broadening Estimate: For hydrogen atoms in the Solar photosphere (T=5770K), Hα656.3nm broadening 0.04nm • The concept of Equivalent Width(EW) and Fullwidthathalfmaxium （FWHM） http://www.mssl.ucl.ac.uk/www_astro/agn/agn_rixos.html

  15. Searching For Exoplanets

  16. Reverberation Mapping • GM = f RBLR(ΔV)2 • ΔV measured from Doppler broadening of the gaseous emission lines • Measuring Black Hole Mass http://ned.ipac.caltech.edu/level5/Sept09/Gaskell/Gaskell3.html

  17. Narrow  low velocityForbidden  low material density

  18. outline • Introduction • Properties • Important spectrum in astronomy • AGN spectrum

  19. LymanαForest http://www.astr.ua.edu/keel/agn/forest.html

  20. Mg II absorption line Useful in finding galaxies with a background quasar http://astronomy.nmsu.edu/cwc/Research/MgIIreview/mgii-over.html

  21. H 21 cm Line http://hyperphysics.phy-astr.gsu.edu/hbase/quantum/h21.html • the birth of spectral-line radio astronomy • Mapping the rotation curve of the Galaxy • probe the "dark ages" from recombination to reionization • SETI: searching for extraterrestrial civilizations

  22. [OIII] line [OIII] 5006.843/4958.911 intensity ratio • strongest narrow line in AGNs at optical band • high abundance of doubly charged oxygen ions • isolated from other optical spectrum • Useful in studying NLR

  23. outline • Introduction • Properties • Important spectrum in astronomy • AGN spectrum

  24. AGN Spectrum http://www.astro.caltech.edu/~george/ay127/Ay127_AGN.pdf

  25. http://www.mpifr-bonn.mpg.de/1462499/padovani_lec1.pdf

  26. http://www.astro.caltech.edu/~george/ay127/Ay127_AGN.pdf

  27. http://en.wikipedia.org/wiki/Blazar RadioGalaxy/Seyfert2 Quasar/Seyfert1 Blazar

  28. NLR: Keplerian orbital speeds of the clouds much smaller => lines are narrow Spatially resolvable Narrow permitted/forbidden Lines No bright continuum from the obscured central engine, except infrared and X-ray Broad permitted lines Narrow Forbidden Lines Bright continuumfrom central engine http://abyss.uoregon.edu/~js/ast123/lectures/lec12.html

  29. Seyfert 1 & Seyfert 2 Type 1.2, 1.5, 1.8 and 1.9 Seyfert galaxies, due to H spectrum FWHMs~500km/s FWHMs~5000km/s Osterbrock, D. Astrophysics of Gaseous Nebulae and Active Galactic Nuclei

  30. Spectrum of a typical quasar Lyα1216 Quasar=quasi-stellar radio source http://loke.as.arizona.edu/~ckulesa/camp/spectroscopy_examples.html

  31. Peterson, B.M. An Introduction to Active GalacticNuclei

  32. Why νFν ~ ν plot • Power law spectrumFν~ ν-α • In case α=1, νFν ~ ν diagram: horizontal • In case α=0, νFν ~ ν diagram: proportional • Quasar α=0~1 • Convenient

  33. BL Lac & OVVs

  34. Featureless non-thermal continuum O[III] Hβ Hβ O[III] http://www.astr.ua.edu/keel/agn/spectra.html

  35. SDSS Quasar Survey

  36. DiagnosticLineRatios R. Cid Fernandeset al. 2010

  37. http://www.astro.caltech.edu/~george/ay127/Ay127_AGN.pdf

  38. VariabilityofAGNin various spectral domains Seyfert I http://www.astr.ua.edu/keel/agn/vary.html

  39. Thanks

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