1 / 42

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

hana
Download Presentation

Talking About S pectrum

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. 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

More Related