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Radiative Efficiency and Content of Extragalactic Radio Sources

Investigating scaling relations, radiative efficiencies, aging effects, and content of extragalactic radio sources using radio and X-ray data to estimate AGN feedback. Findings reveal insights on patterns and contributors to radiative efficiencies and scaling relations.

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Radiative Efficiency and Content of Extragalactic Radio Sources

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  1. Radiative Efficiency and Content of Extragalactic Radio Sources Laura Bîrzan Collaborators: Brian McNamara (U. Waterloo), Paul Nulsen (CfA), Chris Carilli (NRAO), Mike Wise (U. Amsterdam)

  2. Radiative Efficiency / Scaling Relations • An understanding of how scales with is important in order to estimate AGN feedback across a wide range of environments and masses (e.g.,Magliocchetti & Bruggen 2007,Best et al. 2007). • Our first attempt (Bîrzan et al. 2004): but with large scatter. • Using the 5 GHz core radio luminosity, Merloni & Heinz (2007) find a tighter scaling relation. • How does the lobe radio luminosity scale with the mechanical power?

  3. Radio and X-ray: Complementary Data R spectrum at t0 a b spectrum at t1 spectrum at 5t1 MS 0735.6+7421 • X-ray data (Rafferty et al. 2006): • Measure p,V • Ages: tcav (tbuoy,trefill,tcs ) X-ray Image MS 0735.6+7421 • Radio data: • Synchrotron break frequency is indicative of the age 330 MHz Radio Image

  4. The Sample 24 systems from Chandra Data Archive which show X-ray cavities (Bîrzan et al. 2004, Rafferty et al. 2006). • Redshift range: 0.0035 < z < 0.545 • Radio sources associated with the central galaxy. • VLA observations at 330 MHz, 1.4 GHz, 4.5 GHz and 8.5 GHz.

  5. Is the wide range in k due to aging? Young sources tend to have smaller k. But, range in age can not fully account for the range ink. Entrainment of heavy particles may play a role. Particle Content and Aging radio-filled cavity ghost cavity older younger

  6. Radiative Efficiencies (lower limit – shocks not included) • Most objects: a~100 (Nipoti & Binney 2005, Bicknell et al. 1997, De Young 1993). • Ghost cavities generally require higher a. • Scaling relations: • Scatter = 0.65 dex • Scatter = 0.31 dex for radio filled only radio-filled cavity ghost cavity

  7. No clear trend is present. However, there is a tendency for younger objects to be radiatively efficient. Aging contributes to scatter in the radiative-efficiencies plot, but can not account for all of it. The scatter may also be due to entrainment, which would increase k and reduce Lrad. Aging and Radiative Efficiencies radio-filled cavity ghost cavity older younger

  8. Scaling Relations: Pcav and Lradio • Including the dependence of the radiative efficiencies on C: • Scatter is reduced by ≈50% (to 0.33 dex) • However, need radio data at several frequencies radio-filled cavity ghost cavity

  9. Conclusions • The radiative efficiency is around 1%, but can be much lower. • Scatter about scaling relation is large. • Aging and entrainment may be important contributors. • By accounting for differences in age (break frequency), scatter is reduced by ≈ 50%. • k (=Epart/Ee) ranges between a few and a few thousands (for equipartion assumptions). • Again, aging and entrainment may contribute to large range in k.

  10. Radio Spectra

  11. 325 and 1400 MHz Scaling Relations • P327: Scatter = 0.75 dex • P1400: Scatter = 0.83 dex

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