High-resolution observations High-resolution observations of powerful radio sourcesof powerful radio sources

Monica Orienti

Almudena Prieto

13/12/2007 Monica Orienti – IAC

OutlineOutline

1. Powerful radio sources

2. Hot-spot

3. Young radio sources

1.Powerful radio sources1.Powerful radio sources

• L1.4 GHz > 1024 W/Hz

• Size: from pc to a few Mpc

• Elliptical galaxies and quasars;

• 10% of AGN population 1.04 Mpc

Radio morphologyRadio morphology

CoreJet

Hot spot

Lobe

Lobe

Hot spot

Cygnus A

1. Powerful radio sources

The central componentThe central component

B

P E2B2

E2B

e-

Synchrotron radiation

1. Powerful radio sources

The external componentThe external component

• Reacceleration in the hot-spots

• Electrons are deposited in the lobes where they age:

tsyn 108 years

• Transient phenomenon

Jet Hot-spot

Lobe

1. Powerful radio sources

2. Hot-spot2. Hot-spot

S

S0.5

br

S

br B E2

tsyn br-1/2

B-3/2

Sample selectionSample selection

- 9 hot-spots observed with VLA and VLT with high-resolution < 1”

- All hot-spots are characterized by:

• Low magnetic field• Low radio power

2. Hot-spot

ResultsResults

• 4 hot-spots (45%) detected

• 3 hot-spots show extended optical emission

2. Hot-spot

The goalThe goal

What originates the

extended features?

2. Hot-spot

3. Young radio sources3. Young radio sources

• LLS < 1 kpc;

• P1.4 GHz > 1025 W/Hz;

• t ~ 103 – 5 yr

300 pc

The ISM and the source growthThe ISM and the source growth

Strong flux-density and arm-

length asymmetries in

compact (< 15 kpc) radio

sources

3. Young radio sources

The goalThe goal

How the ambient

medium influences the

source growth?

Evidence of jet-cloud

interaction?

3. Young radio sources

Seyfert galaxiesSeyfert galaxies

• Usually not powerful in radio

• Unresolved non-thermal component in the centre

• High-resolution radio observations to characterize the SED of the central region

(A. Prieto, J. Acosta, J.A. Fernandez-Ontiveros)