High-resolution High-resolution observations of powerful observations of powerful radio sources radio sources Monica Orienti Almudena Prieto 13/12/2007 Monica Orienti – IAC
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)