Presentation on theme: "Radio properties of BAL quasars Takayuki HAYASHI (Univ. Tokyo, NAOJ/VLBI) Akihiro Doi (ISAS/JAXA) Hiroshi Nagai (ALMA/NAOJ)"— Presentation transcript:
Radio properties of BAL quasars Takayuki HAYASHI (Univ. Tokyo, NAOJ/VLBI) Akihiro Doi (ISAS/JAXA) Hiroshi Nagai (ALMA/NAOJ)
Broad Absorption Line (BAL) quasars –Blue-shifted absorption line (e.g., C IV, Mg II ) at rest UV Many sources are found at z~2 –It is broad : –It has large velocity : – ~15% of SDSS quasars show BAL (SDSS DR5, Gibson+ 2009) ⇒ thermal accretion disk wind is absorber? Gregg+ 2000 CIV 2 Proga+ 2000 Introduction 1 : Disk wind disk
Galaxy evolution and BAL quasars –The disk wind could suppress star formation –BAL works as AGN feedback in the course of galaxy evolution? Pure disk galaxy Pseudo-bulge No correlation between BH and bulge mass Major merger Starburst, buried quasar ? Quasar phase Classical bulge Ellliptical Correlation between BH mass and bulge mass BAL works as AGN feedback to the galaxy ?? (Kormendy+ 2011) Hopkins+ BAL Introduction 1 :
Current issue: which is dominant ? –Difference of the viewing angle –Difference of the central engine 4 BAL fraction suggests covering factor BAL fraction suggests time possessing the wind disk wind ： v ～ 0.1c disk wind ： v ～ 0.1c Introduction 1 :
Radio studies for BAL quasars is meaningful !! –The state of the disk can be obtained through radio jet Do BAL quasars and non-BAL quasars have a same central engine?? –Viewing angle to the sources can be determined Morphology Spectral index Introduction 2 : Osuga+ 2011 NGC1052 NRAO/AUI Edge-on 3C380 Kameno+ pole-on
Radio spectrum and orientation of the source Introduction 2 : 3C175 NRAO Orientation Spectral index Fine+ 2011 Flux Frequency Flux Frequency NGC1052 NRAO/AUI Edge-on 3C380 Kameno pole-on lobe core Radio spectral index depends on the orientation
Radio Properties of BAL quasars –~ 1990s (before SDSS and FIRST) No radio-loud BAL quasars was found (Stock+ 1992) –2000s ~ (after SDSS and FIRST) BAL quasars are moderately radio loud (Becker+ 2000, 2001) Large scale, FR2-BAL quasars are rare (Gregg+ 2000, 2006) BAL quasars are steeper than non-BAL quasars (DiPompeo+ 2011) Introduction 2 : cutoff Shankar+ 2008 DiPompeo+ 2011 steepflat/inverted What does the distribution indicate ? difference of the central engine ? or the viewing angle ?
Radio Spectral Index of BAL quasars Spectral index can be explained by viewing angle ? Introduction 2 : DiPompeo+ 2011, 2012 steepflat/inverted
Basic information –SDSS DR5 quasars at C VI BAL quasars from Gibson+ 2009 Constructing Radio loud quasars catalog using VLA FIRST survey (Selecting radio sources within 3 arcsec of each quasar) Statistical Study : Sample Radio QuietRadio Loud with core non C VI BAL22,8931,874 C VI BAL3,540292
Luminosity distribution –Assuming Spectral index at 1.4-5 GHz, obtained by DiPompeo+ 2011 –Reducing 5-GHz Luminosity Statistical Study : Sample DiPompeo+ 2011
Assumption –Assuming Power-low distribution of Lorentz factor ;, Viewing angle of non-BAL quasars ; Viewing angle of BAL quasars is ; Then Doppler factor is obtained as; No correlation between and Study 1: Monte-Carlo Simulation
Schematic picture Study 1: Monte-Carlo Simulation
a = -1.4 Result : Cannot be explained by viewing angle
Schematic picture Result : At least considering, edge-on BAL cannot be denied.
Small number of BAL quasars have large-scale radio sources Study 2 : FR2 quasars survey 100kpc rare Gregg+ 2006 Shankar+ 2008
Radio QuietRadio Loud (not FR2) Radio Loud (FR2) non C VI BAL22,8931,782133 C VI BAL3,54028810 Study 2 : FR2 quasars survey FR2 quasars at –Constructing SDSS DR7 FR2 quasars catalog with method taken by DeVries+ 2006 –Fraction of FR2 quasars is – 0.5 ± 0.1% for non-BAL quasars – 0.3 ± 0.2% for BAL quasars –There are not so large difference. –Do both BAL/non BAL possess the same central engines ?
Do both BAL/non BAL possess the same central engines ? –FR2-BAL quasars have large Blackhole mass and low Eddington ratio. –But sample is too small (10 sources) Study 2 : FR2 quasars survey 500pc Hayashi, Doi & Nagai submitted
Radio-loud BAL quasars were said to be … –steeper than non-BAL quasars It can be explained by viewing angle (DiPompeo+ 2011,2012) –moderately radio loud Beaming effect cannot be denied (this work) –more compact than non-BAL quasars It was observational bias (this work) –Polar BAL (Ghosh+ 2007) ??? Summary
29 1.7–4.9GHz Jet Spectral index map – スペクトル指数のコントラスト ⇒ 中心エンジンの同定 –1kpc スケールの双対ジェット – 複数の成分から成るジェット 500pc : Spectral index 中心エンジン Result :
How can we identify the radio counterparts? –Do visual inspection ? (e.g., Best+ 2005, Kimball+ 2008) –Here, we take statistical method taken by “de Vries+ 2006” Study 2 : FR2 quasars survey search center
1. Extracting the radio core –3 and 10 arcsec within each search center for FIRST and NVSS Method search center
2. Searching for candidates for radio lobe –450 and 600 arcsec within each search center for FIRST and NVSS Method search center
2. Searching for candidates for radio lobe pair –Selecting a radio pair which has maximum value of Method search center 1 0 2 3 4
Faint Images of the Radio Sky at Twenty-Centimeters (R. H. Becker+ ) –Radio imaging survey at 20 cm –Coverage : 10,635 square deg. –Resolution : ~5 arcsec –r.m.s. level : ~0.14 mJy/beam The arrival of the FIRST VLA survey Kimball+ 2008 VLA
Finding of radio-loud BAL quasars –FIRST Bright Quasars Survey Spectroscopic survey for radio selected sources. Many moderately radio-loud BAL quasars are found. Lack of RL-BAL in previous study was affected by selection effect. 2000s : “pioneering age” Radio loud cutoff Becker+ 2000Becker+ 2001
Nature of the radio sources –Radio-loud BAL quasars have … compact morphology less than a few kpc convex spectra peaked at 100 MHz-10 GHz 2000s : “pioneering age” VLA image FRII large structure is rare (Montenegro-montes+ 2008) Gregg+ 2006 VLA image
low high peak frequency low frequency high yrs 1kpc yrs 100pc yrs 10kpc ～ 10 5-6 yrs 10kpc ～ 10 4-5 yrs 1kpc ～ 10 2-3 yrs 100 pc General radio nature of AGN -Compact sources suffers from absorption at low frequency -Spectral peak shifts toward lower frequency as sources evolve Snellen+ 2000 2000s : “pioneering age”
Orientation scheme of BAL quasars –Large degree of polarization at BAL deeply-absorbed direct ray and less-absorbed scattered ray with edge-on disk wind ? Can the edge-on model explain the fraction of BAL completely? 1990s : “dark age” Cohen+ 1995
Finding of Polar BAL quasars –Pole-on viewed quasars shows large flux variability due to relativistic effect. –Significant amount of variable sources (~15) are found via comparison of NVSS and FIRST survey. (Zhou+2006, Ghosh+ 2007) Polar BAL quasars ? The edge-on scheme breaks down? 2010s : “golden age” UMRA O (Ghosh+ 2007)
Radio spectrum and orientation of the source 2010s : “golden age” 3C175 NRAO Orientation Spectral index Fine+ 2011 Flux Frequency Flux Frequency NGC1052 NRAO/AUI Edge-on 3C380 Kameno pole-on lobe core Radio spectral index depends on the orientation
Radio spectrum of BAL quasars –Multi-frequency survey for 74 radio-loud BAL quasars with control sample. The orientation effect must works. BUT the fraction cannot explain only by the orientation. 2010s : “golden age” DiPompeo+ 2011, 2012 BAL quasars are more edge-on than non-BAL quasars edge-onpole-on
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