compiled quasar catalog from lamost dr1
DESCRIPTION
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 . From Fan, X. 2014, Xian. q uasar selection. - PowerPoint PPT PresentationTRANSCRIPT
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
From Fan, X. 2014, Xian
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
unification model and observed spectra
Urry & Padovani, 1995 Narrow lines only
Broad permitted lines: Ha, Hb
Similar quasar spectra
Vanden Berk et al. 2001
composite spectra at redshift 0.04---4.
Characterize by featureless continuum and series emission linesRemarkably similar from one quasar to another, compared to galaxy and stars
SDSS photometric system
Richards et al. 2006
Quasar selection I ≈16,000 quasars found by SDSS based on multi-color optical selection (UV-excess)
Fan et al. 1999
Star
quasar
quasar selection -- Ilow completeness at redshift 2 –3 as optical
colors of quasars similar to those of stars
Richards et al. 2006
low completeness
to improve selection completeness variability selection( Butler 2011) combined optical—infrared color ----- LAMOST quasar selection
Quasar selection -- IIOptical– infrared color selection ( K-band excess)
Maddox et al. 2008
Early K star
Early M star
Unreddened QSO z=3
Reddened QSO z=3
Quasar selection III
QSO z < 2.2QSO 2.2< z< 4QSO z >4
Wu 2010
SDSS_UKIDSSSDSS_WISE
Wu 2012
QSO z < 2.2QSO 2.2< z< 4QSO z >4
LAMOST quasar candidates
LEGAS team
Mostly from SDSS-UKIDSSSDSS-WISE
Partly from X-ray, radio, and other selections
Observed quasar candidates ≈80,000 observed in pilot survey and first year
of regular survey≈60,000 classified as ‘unknown’ with featureless
“unknown”
Magnitude distribution of ‘unknown’
≈5000 identified QSOsLines move in cross-over between blue and red channel
≈ 3000 covered by SDSS DR10 possible emission line variation continuum variation but “should be carful”
visually checking againFor 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
≈1400 new quasars identified Z--Mi distribution
Median S/N ratio of emision lines
Emission line fitting and measurements• ≈1000 with high enough S/N for spectra modelling
Continuum flux estimation with SDSS photometry
use SDSS ugriz photometry and quasar continuum and emission line template
Black hole mass estimation
Black hole mass distribution
Optical –infrared color of the quasar
mostly from SDSS-UKIDSS, SDSS-WISE selection
more to do
≈40 X-ray source matched with XMM-Newton≈100 radio source matched with FIRST≈20 with repeated LAMOST spectraspecial quasar identified, such as, double-
peaked quasar, broad-absorption line quasar
double-peaked quasar
Broad absorption quasar
谢谢