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Radiative Efficiency and Content of Extragalactic Radio Sources

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Using the 5 GHz core radio luminosity, Merloni & Heinz (2007) find a tighter scaling relation. ... 24 systems from Chandra Data Archive which show X-ray ... – PowerPoint PPT presentation

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Title: Radiative Efficiency and Content of Extragalactic Radio Sources


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

MS 0735.67421
  • X-ray data (Rafferty et al. 2006)
  • Measure p,V
  • Ages tcav (tbuoy,trefill,tcs )

X-ray Image

MS 0735.67421
  • 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 lt z lt 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
Particle Content and Aging
  • 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 in k.
  • Entrainment of heavy particles may play a role.

radio-filled cavity ghost cavity
older
younger
6
Radiative Efficiencies
  • (lower limit shocks not included)
  • Most objects a100 (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
Aging and Radiative Efficiencies
  • 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.

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
(No Transcript)
11
Radio Spectra
12
325 and 1400 MHz Scaling Relations
  • P327 Scatter 0.75 dex
  • P1400 Scatter 0.83 dex
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