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