The Sample

A Detailed Study of the Beam Power, Hot Spot Properties, and Gaseous Environments of Eleven Powerful Classical Double Radio

Galaxies

Ruth A. Daly

In collaboration with Chris O’Dea, Preeti Kharb, Stefi Baum, George

Djorgovski, Megan Donahue, Kenny Freeman, Eddie Guerra, & Matt

Mory.

Published in a Series of Papers

Daly, (add authors)

The Sample

A special & select subset of FRII radio sources are studied: the most powerful FRII radio galaxies (P178MHz > 3 x 1026 W/Hz/sr). Leahy, Muxlow, & Stephens (1989) found that these sources form a special & select subset of radio sources. They have very regular bridge structure —> an overall rate of growth that is well into the supersonic regime (so equations of strong shock physics apply), & have negligible backflow velocity (LMS89). Form a very homogenous population. Radio galaxies (not quasars) are selected to minimize projection effects.

For example, here is the 1.5 GHz image of 3C 44

3C6.1 (0.84)

3C34 (0.69)

3C41 (0.794)

3C44 (0.66)

3C54 (0.827)

3C114 (0.815)

3C142.1 (0.406)

3C169.1 (0.633)

3C172 (0.519)

3C441 (0.707)

3C469.1 (1.336)

The Sample and z

These 11 new radio galaxies from Kharb et al. (2007) are added to our previous sample of 19 radio galaxies, which were from the studies of Leahy, Muxlow, & Stephens (1989), Liu, Pooley, & Riley (1992), and Guerra, Daly, & Wan (2000).

The total sample includes 30 radio galaxies with redshifts from zero to 1.8.

Velocities obtained from spectral aging study & combined with data of LMS89, LPR92, & GDW00 (O’Dea et al. 2007)

illustrates b = 1

No correlation bet. v & D —> v = const.

illustrates b = 0.25

No correlation bet v & z —> v = const.

Source Pressures and Widths are measured 10 kpc behind the hot spot (toward the core) to obtain the time-averaged post shock conditions (from O’Dea et al. 2007)

For example, here is the 5 GHz image of 3C 34

The beam power is obtained by applying the equations of strong shock physics:

Lj ~ a2 P v

Lj does not depend on b

No correlation between L and D —> Lj = const.

(from O’Dea et al. 2007)

The ambient gas density is obtained using the equation of ram pressure confinement (shown for b = 0.25)

na ~ P/v2

na(.25) ~ D-1.9 ± 0.6

na(1) ~ D-1.4 ± 0.3

As Expected for these values of D

(from O’Dea et al. 2007)

This special category of VP-RG can be used for cosmology. Good Agreement between SN and RG

(from Daly et al. 2007)

Y’ = dy/dz obtained from data or y(z). Provides a direct measure of H(z)/H0

(D.etal.07; Daly & Djorgovski 2003, ‘04)

Y” = d2y/dz2 can also be obtained directly from the data and allows a model-independent measure of q(z).

(D.etal.07, DD03, 04).

Cosmology with this special type of RG:

To understand the evolution of source size with redshift, hypothesize that the Total Source Lifetime TT ~ Lj

-β/3 . If the system is Eddington limited, we expect a value of β = 0.

Daly et al. (2007) find that β = 1.5 ± 0.15, so TT ~ Lj

-0.5 & the Total Energy, ET ~ Lj0.5 or Lj ~ ET

2 [Eddington limited outflows are quite clearly ruled out]

The values of β obtained by combining the radio galaxy and supernovae type Ia samples follow.

Constraints on β, Ω, and w in a quintessence model using 30 radio galaxies and 192 supernovae. Clearly β ~ 0 is ruled out with very high significance. (from Daly et al. 2007).

Constraints on parameters in a Λ model that allows for non-zero space curvature, obtained with 30 RG + 192 SN. Clearly β ~ 0 is ruled out. (from Daly et al. 2007)

For β ~ 1.5, the Total Source Lifetime

TT ~ Lj-0.5

& ET ~ Lj0.5

Shown here for b=0.25;

TT are about a factor of 6 lower for b = 1.

(from O’Dea et al. ‘07)

The Total Energy that will be processed through the jets during the source lifetime. Shown here for b = 0.25. Total energies are about a factor of 6 lower for b=1. (from O’Dea et al. 2007)

The data suggest that there may be a relationship between the ratio of the beam power and the hot spot structure and substructure ----

in the sense that the side of the source with the larger beam power may be distributing this power over a larger angle.

It appears that the side of the source with larger beam power has more structure and substructure in the hot spot vicinity, and has a lower hot spot intensity, than the side of the source with lower beam power.

3C 6.1

Ratio of beam powers is 1.7 ± 0.3

South has larger Lj

More substructure in South

Fainter single HS in South

3C 54

Ratio of Beam Powers is 1.5 ± 0.3

Larger Lj is in the North

More substructure in North

Fainter Single HS in North

Summary and Conclusions

Only very FRII RG with 178 MHz powers > 3 h-2 x 1026 W/Hz/sr are included in the study. These sources form a very homogeneous population; have regular bridge/lobe structure; & an overall rate of growth that is supersonic.

Use the sources for cosmological studies; find good agreement between results obtained with RG & SN. Empirically, this specific type of FRII source provides a cosmological tool like type Ia SN. (Note, type Ia SN are a very special subset of SN.)

From the model parameter β ~ 1.5, —> Lj ~ E2 & T ~ E; the outflows from the systems are clearly not Eddington limited. The total source lifetimes are ~ 106 to 107 years. The total source energies are ~ 105 to 106 Ms.

Perhaps a relationship between the ratio of Lj & HS structure; the side of the source with the larger Lj may be distributing this power over a larger solid angle —> the side of the source with the higher Lj to have more structure in the vicinity of the HS, and the single primary HS on that side to have a lower intensity.