Landscape Poster Template by dfhdhdhdhjr

VIEWS: 1 PAGES: 1

									           Broad Absorption Line, Radio, and Optical Quasars: A SDSS View
       Xinyu Dai (Univ. of Oklahoma), Francesco Shankar (MPI), Gregory R. Sivakoff (Univ. of Virginia),
                                 Marianne Vestergaard (Copenhagen Univ.)
                                      Abstract                                                                                                                                                               Relative Growth between Optical and Radio Quasars
 It is a main theme in AGN studies to understanding various sub-samples of quasars
 within coherent schemes. We study the origin of the broad absorption line quasars,
 radio quasars, and optical quasars, based on the parent SDSS quasar catalog. We
 find the intrinsic fractions of BALQSOs, LoBALs, and FeLoBals are 2, 5, and 7                                                                                                                                                                              Fig. 7. The distributions of
 times the observed fractions in the optical bands by studying the infrared and radio                                                                                                                                                                       optical and radio quasars in
 properties of these quasars. In particular, the intrinsic fraction of BALQSOs can be                                                                                                                                                                       the L-z, M-z, and M-L
 as high as 43% when using a less strict BAL definition. We also find that the                                                                                                                                                                              planes. We use the black hole
 fractions of quasars with BAL features are functions of radio luminosity, where in                                                                                                                                                                         mass       and       bolometric
 the low radio luminosity range, the BAL fractions are consistent with their intrinsic                                                                                                                                                                      luminosity      reported     in
 fractions, and the BAL fractions are significantly smaller at high radio luminosities.                                                                                                                                                                     Vestergaard et al. (2008).
 These observations can be explained under a geometric model of BALQSOs for the                                                                                                                                                                             There is no significant
 majority of the BALQSOs. We argue that a small portion of LoBALs and                                                                                                                                                                                       difference between the optical
 FeLoBALs with excess infrared luminosity may be explained under the                                                                                                                                                                                        and radio quasar distributions
 evolutionary model. We also present the relative growth of radio and optical                                                                                                                                                                               in the three panels.
 quasars, based on the relative evolution of Eddington ratios between radio and           Fig. 4. The increase of BAL fractions from optical to NIR band can be modeled using an obscuration
 optical quasars. We find complex growth history for radio and optical quasars, and       model for BALs (Dai, Shankar, Sivakoff 2008, ApJ, 672, 108).
 that the radio emission is not apparently associated with the BH mass or Eddington
 radio.                                                                                               Dependence of BALQSO Fractions on Radio Luminosity
                      Intrinsic Fraction of BALQSOs                                       We match the SDSS BALQSO catalog (Trump et al. 2006) with the FIRST survey (Becker et al.
                                                                                          1995), and measure the BAL fractions as a function of radio luminosity.
 Using the SDSS, 2MASS, and FIRST surveys, we are able to measure the intrinsic
 fraction of BALQSOs. We find the raw BALQSO fractions from optical surveys
 are significantly biased, and the intrinsic fraction is about two times the optical
 fraction.




                                                                                                                                                                                                  Fig. 8. (left) Mean Eddington ratio as a function of BH mass for sources at z < 1.5
                                                                                                                                                                                                  (upper plot) and at z ≥ 1.5 (lower plot). (right) Mean Eddington ratio as a function of
                                                                                                                                                                                                  redshift for BHs with mass logM < 9.0 (upper panel) and logM ≥ 9.0 (lower panel).
                                                                                                                                                                                                  With respect to optical quasars, massive radio quasars tend to have higher Eddington
                                                                                           Fig. 5. (left) The BAL fractions decreases with increasing radio luminosity. At the low/moderate       ratios at higher z and lower or comparable Eddington ratios at lower z. Also, radio
                                                                                           radio luminosity regime, the BAL fractions are consistent with the intrinsic BAL fractions measured    quasars tend to have higher Eddington ratios at z≥1.5, and lower Eddington ratios at
                                                                                           in NIR bands. This confirms our claim that the NIR fractions are close to the intrinsic fraction,      lower z.
Fig. 1. 2MASS K mag vs. SDSS i mag          Fig. 2.     K-i color distribution of          since there is also little absorption in the radio band. The drop of BAL fractions at high radio
for BALQSOs (red circles) and non-          BALQSOs (dashed line) and non-BALs             luminosity end can be explained using a geometric model for BALQSOs. (right) A geometric
BALs (black squares) detected in all of     (solid line). The inset shows the              model for BALQSOs, where BALs are located close the the equatorial plane. The radio emission
the J, H, and K bands in the redshift       cumulative distribution of the two             are composed of two components, one strong beamed emission close to the jet direction and one
range of 1.7 < z < 4.38.                    samples. The BALQSOs are redder than           weak isotropic component (Shankar, Dai, Sivakoff 2008, ApJ, 687, 859).
                                            the non-BALs based on the K-S test.
                                                                                                              Low-Ionization Borad Absorption Line Quasars
                                           The increase of BAL fractions from
                                           optical to NIR bands can be explained if        Since LoBALs are more obscured compared to HiBALs, we expect that the optical fractions are even
                                           one considers the spectral difference           more biased.                                                                                            Fig. 9. (left) Mean BH mass as a function of redshift for sources accreting with an
                                           between BALs and non-BALs (extra dust                                                                                                                   Eddington ratio logλ < −0.6 (upper plot) and logλ > −0.6 (lower plot). (right) same
                                           extinction and absorption lines in BALs).                                                                                                               pattern as left-hand panel considering only the subsample of sources with BH mass
                                                                                                                                                                                                   higher than 108.7Msun, for which no strong luminosity bias should be present. Radio
                                           The NIR fractions are close the intrinsic                                                                                                               sources with high λ have lower masses with respect to optical ones at z > 1.5, but
                                           fraction, and the optical fractions are                                                                                                                 have a tendency for higher BH masses at lower redshifts.
                                           significantly biased.

                                           The intrinsic fraction of BI-BALs is
                                           20±2%.
Fig. 3. BALQSO (circles for BI-
BALs and squares for AI-BALs)                                                              Fig. 6. (left) The fractions of LoBALs increases from optical to NIR bands, similar to HiBALs. We
                                           The intrinsic fraction of AI-BALs is
fractions increase from the g to K                                                         obtain intrinsic fractions of 4.0±0.5%, 7.2±0.6%, and 3.6±1.0% for BI-LoBALs, AI-LoBALs, and
                                           43±2%.
bands. The fitting results from our                                                        FeLoBALs, respectively. (middle) The fraction of LoBALs decrease with increasing radio
models (solid lines). The thick and                                                        luminosity, again, similar to HiBALs. At the low/moderate radio luminosity range, the LoBAL
                                           BALQSOs are not the minority of the
thin dashed lines show the true                                                            fractions are consistent with the intrinsic fractions measured in the NIR bands. The analogy between   Fig. 10. Mean accretion growth curves for BHs of different mass from z = 4 to 0 for
                                           QSO population. The larger fraction of
fraction of AI-BALs (43±2%) and                                                            LoBALs and HiBALs in the NIR and radio properties indicates that the majority of LoBALs and            radio quasars (left panel) and optical quasars (right panel). While radio sources only
                                           out-flowing AGNs makes wind a more
BI-BALs (20±2%) that satisfy                                                               HiBALs can be unified under the same physical scheme, either geometric or evolutionary, but not        grow by a factor of ~2, at the most, optical quasars grow more and at later times.
                                           prominsing candidate responsible for
Weymann et al. (1991) definition.                                                          belong to separate schemes. Using a geometric model, we can successfully fit the LoBAL fractions in
                                           carrying the feedback energy to the host
                                                                                           the radio band (lines in the middle panel).                                                            We find that no clear correlation between radio activity and BH mass and/or accretion
                                           galaxy.
                                                                                           Fig. 6. (right) The fractions of LoBALs increase with NIR luminosity. This behavior is the only        rate is evident from our data, pointing to other BH properties, possibly the spin, as the
                                                                                           difference we find between LoBALs and HiBALs. This suggests that LoBALs with excess IR                 driver of radio activity (Shankar, Sivakoff, Vestergaard, Dai 2010, MNRAS, 401,
                                                                                           luminosity may be at the early stages of quasar evolution (Dai et al. 2010, in preparation).           1869).

								
To top