VSOP Monitoring Observations of 1928 738

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VSOP Monitoring Observations of 1928738

• D. Murphy, JPL
• P. Edwards, ATNF
• H. Hirabayashi, ISAS/JAXA

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1928738 Introduction

• Relatively low redshift (z0.3) core-dominated
  quasar
• Well studied on pc and kpc scales
• In S5 polar-cap survey
• Interesting claims of binary-black hole system
  causing a precessing jet (Roos et al, 1993)
• High ecliptic latitude (79.6 degrees)
• Good source to monitor with VSOP
• Always meets VSOP solar constraints
• Always good 2-D VSOP UV-coverages
• Undertook 8-epoch 5 GHz monitoring program

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VSOP Observations and UV-coverages

• Epoch Obscod Date Length (h) GRTs

No H ALCA Data (TZ recorder problem)
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VSOP 1928738 5 GHz Images

• scale 7.4/h pc/mas
• v/c 18.7/h ? (mas/yr)
• Ho 71 h km/s/Mpc, ?m0.3, ?v0.7

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1928738 Ground-only 5 GHz Images
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• combine with other VLBI observations to
  constrain ejection times and proper motions
• inner jet components (lt 5 mas from core) best
  studied using VSOP images

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• combine with other VLBI observations to
  constrain ejection times and proper motions
• outer jet components (lt 5 mas from core) best
  studied using ground-only images

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Fitted proper-motions and ejection dates
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Precessing Jet Models

• Various types are possible
• Only going to consider ballistic models
• Previous work on this Roos, Kaastra Hummel,
  ApJ, 409, 130 (1993) and other sources 3C279
  Abraham Carrara, ApJ, 496, 172 (1998) has
  assumed a constant jet velocity cone angle
• We extend this geometry by introducing a variable
  cone angle due to orbital motion in a binary
  black hole (BBH) system

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Our BBH Precessing Jet Model 1

• BBH system
• BH masses m1, m2 (m1 has jet)
• BH orbital speeds/c ?1, ?2
• BH orbital period Torbital

• ?total ?jet ?orbital
• (use SR for )
• cos ? lt ?jet,unit,Lunitgt
• cos ? lt ?total,unit, ?jet,unit gt
• sin ?
• (?orbital/ ?jet) cos ? (1tan2(?)cos2(?orbital))
  1/2
• Previous work assumed
• constant velocity cone angle
• sin ? (?orbital/ ?jet) cos ? ? ? ltlt 1
• didnt use SR to add velocities

m2
m1
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Our BBH Precessing Jet Model 2

• ?orbital 2?(tejection-t0)/Torbital ?0
• ?PA PA - PA0
• Model has 8 parameters
• 2 speeds ?orbital, ?jet
• 5 angles ?los,?L,?L,?0,PA0
• 1 timescale Torbital

• Fit apparent speeds, PAs, and ejection dates to
  get these 8 parameters

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Best fit for all 8 parameters
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Best fit for all 8 parameters variation or
parameters
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1928738 Binary Black Hole Properties

• From fitting Torbital 4.3/(1z) 3.31 years,
  ?1 0.019
• Let ?sun Gmsun/c3 1.56 x 10-13 years
• m1/msun (1/2?) (Torbital/?sun)?13(1m1/m2)
• Unfortunately mass ratio m1/m2 cant be
  determined
• For m1 m2
• m1/msun 4.6 x 107
• BBH separation 1.46 x 1016 cm ?1 c Torbital
  
• ?gw ?13 million years
• Also 1928738 jet lies close to the BBH orbital
  plane!
• What about emission lines?

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