1. The Radio Properties of Type II Quasars PLAN Type II quasars Motivations Our sample Radio observations Basic radio properties Compare our results with other subsamples … Lal, Dharam Vir (Institute of Astronomy and Astrophysics, Academia Sinica, Taiwan) Ho, Luis C. (The Carnegie Institution of Washington, USA)

2. Type II Quasars Introduction Unified Schemes for Radio-Loud AGN (Urry & Padovani 1995) The TEN most important questions (1) Is there … ? … (9) Where are the narrow-line (type II) quasars? (10) what are … ?

3.  Unification model predicts  AGN output is a decent fraction of their bolometric luminosity in the far-IR  In the obscured (type II) AGNs  strong optical continuum is hidden from the observer  large far-IR-to-optical ratios  At high-luminosity end, there should exist high-luminosity obscured (type II) AGNs.  Why interest in type II quasars?  cosmic hard X-ray background  type II quasars might account for a large fraction (Madau et al. 1994, Barger et al. 2003, …) Type II Quasars Introduction

4.  Methods to discover type II quasars  Narrow permitted lines with high-ionization line ratio (Djorgovski et al. 2001)  Powerful IR source (Kleinmann et al. 1988)  Unusual hard X-ray spectra (Dawson et al. 2001, Stern et al. 2002, …)  Sloan Digital Sky Survey (York et al. 2000, …)  Candidate type II quasars : Sample of 291 sources (Zakamska et al. 2003)  First spectroscopically selected complete sample,  0.3 < Z < 0.83,  with known optical properties.  Narrow (FWHM < 2000 km s -1 ), high equivalent width emission lines  with high-ionization line ratios. Type II Quasars Introduction

5.  Candidate Type II quasars from the SDSS (Zakamska et al. 2003)  Basic observational radio properties  Flux densities  Radio morphology  Compare these radio properties  with optical properties  with control/comparison samples Type II Quasars Our Goal

6.  Type II SDSS quasar sample (Zakamska et al. 2003)  Control sample  Palomar Bright Quasar sample (BQS)  Radio properties (Kellermann et al. 1989, 1994)  Optical properties (Schmidt & Green 1983, Ho et al., ….)  The two subsamples have similar  Redshift range  [OIII] 5007 luminosity,  a tracer of AGN activity and  an orientation independent parameter.  59 type II quasars Type II Quasars The sample

7. Redshift distribution  Median redshift  0.45  subsample is representative of parent SDSS type II quasar sample (0.3 < Z < 0.8).  Therefore, we believe that the observed radio properties would be representative of parent type II quasar sample. Type II Quasars The sample

8. Radio Observations  VLA B-array configuration  8.4 GHz (X-band)  Snapshot mode  15-18 min of t integration  50 MHz bandwidth (2 IFs)  24 July 2006 Map parameters  Noise level  30  Jy  Dynamic range  3500  Synthesized beam  0.7" Type II Quasars Observations

9. Type II Quasars Our radio results Detection rate:  35 detections out of 59 (  60%) sources Our sample results  10 sources core-jet morphology,  3 are double sources, and  rest of the detected sources are point sources. Radio morphology (8.4 GHz)

10. FIRST survey results 6 of 59 sources show extended morphology and rest of the detected sources are point sources. FIRST maps + DDS2 red images. Detection rate: 57 sources using FIRST (+ 2 sources using NVSS) 36 detections (  60%) and 23 non-detections Type II Quasars FIRST results FIRST radio morphology (1.4 GHz)

11. Radio Luminosity distribution (8.4 GHz)  Monochromatic radio luminosity, L = 4  S d 2 (1 + z), in ergs s -1 Hz -1. Where d is the luminosity distance.  Although beaming factors can be important, we compute radio luminosities assuming uniform emission into 4  steradians.  SFR  10 2 M sun yr -1 Type II Quasars Results

12. Radio Luminosity distribution (1.4/8.4 GHz) Type II Quasars Results

13. Spectral Index (1.4 and 8.4 GHz) Our data and FIRST survey results: S   Median : -0.75 similar to typical values for RGs! Type II Quasars Results

14. Source dependences I. Radio luminosity vs. Redshift “Complete samples”  a single flux limit in  a chosen observing band and  a chosen sky area.  tight correlation between luminosity and redshift (Blundell et al. 1999) Luminosity-redshift plane   = 0.38 and probability = 0.0027 Type II Quasars Results

15. Source dependences II. Radio vs. [OIII] 5007 luminosity  Radio power and [OIII] 5007 luminosity correlation  surprisingly, poorly correlated!  Are they indeed AGNs?

16.  Our type II quasar sample  Detection rate :  60%  BQS sample  Detection rate : 96 of 114 (84%) at 5 GHz  CfA Seyfert sample  (Magnitude limited, spectroscopically selected)  Detection rate : 16 type I +18 type II of 22 type I + 22 type II (77%) at 8.4 GHz  Palomar Seyfert sample  Detection rate : 44 of 52 (85%) at 5 GHz Type II Quasars Results Comparison with other samples

17.  Radio loudness  How radio loud are these sources?  Comparison with control subsamples  BQS (PG Type Is)  Origin of the activity  Are all these sources AGNs?  Starburst vs. AGN  Space density of type II quasars  Radio luminosity function (Meurs & Wilson 1984)  … Type II Quasars Future

18. The Radio Properties of Type II Quasars Question: What is the basic nature of type II quasars from the SDSS? Preliminary results suggest,  Not all of these are AGNs  These objects seem to probe SFR history 0.3 < Z < 0.83

19. Radio Luminosity distribution (1.4/8.4 GHz) Type II Quasars Results

20. Source dependences I. Radio luminosity (1.4/8.4 GHz) vs. Redshift Type II Quasars Results

21. Source dependences II. Radio luminosity (1.4/8.4 GHz) vs. [OIII] 5007 luminosity

22. Type II Quasars Results Source dependences II. Radio luminosity (1.4/8.4 GHz) vs. [OIII] 5007 luminosity