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Compiled quasar catalog from LAMOST DR1

Compiled quasar catalog from LAMOST DR1

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Compiled quasar catalog from LAMOST DR1

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  1. Compiled quasar catalog from LAMOST DR1 艾艳丽 Department of Astronomy, Peking University Collaborators : Xuebing Wu, Jinyi Yang, Feige Wang, Jianguo Wang, Xiaoyi Dong and LEGAS team LAMOST 用户培训会 兴隆 2014.07.02

  2. From Fan, X. 2014, Xian

  3. quasar selection • point source • contaminations are ≈100, million stars quasar selection:select candidates then with optical spectra confirmation and redshift measurement • how to select the quasar candidates • based on observed properties

  4. unification model and observed spectra Broad permitted lines: Ha, Hb Narrow lines only Urry & Padovani, 1995

  5. Similar quasar spectra Characterize by featureless continuum and series emission lines Remarkably similar from one quasar to another, compared to galaxy and stars VandenBerk et al. 2001 composite spectra at redshift 0.04---4.

  6. SDSS photometric system Richards et al. 2006

  7. Quasar selection I • ≈16,000 quasars found by SDSS • based on multi-color optical selection (UV-excess) Star quasar Fan et al. 1999

  8. quasar selection -- I • low completeness at redshift 2 –3 as optical colors of quasars similar to those of stars low completeness • to improve selection completeness • variability selection(Butler 2011) • combined optical—infrared color • ----- LAMOST quasar selection Richards et al. 2006

  9. Quasar selection -- II Optical– infrared color selection ( K-band excess) Unreddened QSO z=3 Early K star Reddened QSO z=3 Early M star Maddox et al. 2008

  10. Quasar selection III SDSS_UKIDSS SDSS_WISE QSO z < 2.2 QSO 2.2< z< 4 QSO z >4 QSO z < 2.2 QSO 2.2< z< 4 QSO z >4 Wu 2010 Wu 2012

  11. LAMOST quasar candidates LEGAS team Mostly from • SDSS-UKIDSS • SDSS-WISE Partly from X-ray, radio, and other selections

  12. Observed quasar candidates • ≈80,000 observed in pilot survey and first year of regular survey • ≈60,000 classified as ‘unknown’ with featureless Magnitude distribution of ‘unknown’ “unknown”

  13. ≈5000 identified QSOs Lines move in cross-over between blue and red channel

  14. ≈ 3000 covered by SDSS DR10 • possible emission line variation • continuum variation • but “should be carful”

  15. visually checking again For the ≈2000 newly identified quasars Visually checked again and double checked independently by numbers of our group ≈600 are misclassified as quasar by pipeline visually check redshift and correct some of them for the ≈1400 quasars

  16. ≈1400 new quasars identified • Z--Mi distribution

  17. Median S/N ratio of emision lines

  18. Emission line fitting and measurements • ≈1000 with high enough S/N for spectra modelling

  19. Continuum flux estimation with SDSS photometry use SDSS ugriz photometry and quasar continuum and emission line template

  20. Black hole mass estimation Black hole mass distribution

  21. Optical –infrared color of the quasar mostly from SDSS-UKIDSS, SDSS-WISE selection

  22. more to do • ≈40 X-ray source matched with XMM-Newton • ≈100 radio source matched with FIRST • ≈20 with repeated LAMOST spectra • special quasar identified, such as, double-peaked quasar, broad-absorption line quasar

  23. double-peaked quasar

  24. Broad absorption quasar

  25. 谢谢