THE HST VIEW OF LINERS AND OTHER LOCAL AGN

MARCO CHIABERGECNR - Istituto di Radioastronomia - Bologna

Alessandro Capetti (INAF-OATo)Duccio Macchetto (STScI)

NGC 4438 - HST/WFPC2

What are LLAGN?

Radio quiet Radio loud

(Nearby) galaxies with evidence for AGN activityand nuclear emission lines L(H) < 1040 erg s-1 (Ho et al. 1997)

Low Ionization Nuclear Emission-line Regions LINERs

Seyferts

Low Luminosity Radio Galaxies

> 30% of nearby galaxies are LLAGN

[OIII] / [OII] < 1

[OIII] / [OII] > 1

Compact radio cores in LINERs and Seyferts: a clear signature of an active nucleus Unresolved on the mas scale TB > 108 K

Flat radio spectrum ~ 0.0 - 0.6 (F-)

The radio cores are variable

Radio cores are synchrotron emission from a jet (Nagar et al 2002, Falcke et al. 1999)

SIMILAR TO THE CORES OF RADIO GALAXIES

THE SAMPLE of LLAGNs

FR I radio galaxies from the 3CR catalog

LINERs all liners with d < 19 Mpc from the Palomar sample of nearby galaxies• Radio data from Nagar et al. 2001• 18/21 have HST images

Seyfert 1 from Ho & Peng 2001 Seyfert 1 from Palomar sample (dmed = 20 Mpc) + Seyfert 1 from the CfA sample (dmed = 80 Mpc)

25/32 have HST images

THE LOCAL AGNs ARE WELL REPRESENTED BY THE 3 COMBINED SAMPLES

LLAGN - LINER nuclei

NGC 4278 - HST WFPC2- I band NGC 4589 - HST WFPC2- I band

15’’ 15’’

LLAGN - Seyfert 1 nuclei

NGC 5033 - HST WFPC2 - V band

3C 338

3C 31

FR I RADIOGALAXIES:

synchrotron nuclei

Chiaberge, Capetti, Celotti 1999Chiaberge et al. 2003

DETECTION RATE of optical nuclei

LINERs 7/18 39%

Seyfert 1 100%

FR I radio galaxies 85%

EXPECTED: Type1 = clearview of the nucleus, by def

intrinsically fainter?

LLAGN IN THE RADIO-OPTICAL PLANE

LINERs

FR I

Sy1

Radio galaxy - like

Seyfert --like

Synchrotron radiation in optical and radio (CCC 1999)

Thermal excess

NUCLEAR RADIO LOUDNESS OF LLAGN

Seyfert 1’s nuclei are NOT radio loud!!

A fraction of LINERs is RADIO LOUD

RLRQ

2 populations of LINERS

Radio quiet, Seyfert - like

radio: non thermaloptical: thermal emission from the accretion process

Radio -loud, radio galaxy - like

radio AND optical: non-thermal emission from the jet

RADIO LOUNDESS TELLS US WHAT IS THE PHYSICALMECHANISM WE ARE OBSERVING IN THE TWO BANDS

BLACK HOLE MASS VS. RADIO LOUDNESS

RQ

RL

QSO at z ~1-2:

RL only for MBH /M > 109

(Dunlop et al. 2003)FR I

SY 1

LINER

MBH from direct measurements or correlations (e.g. Tremaine et al. 2002)

ACCRETION EFFICIENCY VS. RADIO LOUDNESS

M black hole

m.

RLRQ

FR ISY 1

LINERs

LEdd = 1.3 x 1038 (MBH/M) erg s-1

CONCLUSIONS

Seyferts small BH M < 108 M

high accretion rate m <~ 1

RQ LINERs small BH M < 108 M

low accretion rate m << 1

RL LINERs large BH M > 108 M

low accretion rate m << 1

.

Radio galaxies

.

There are two types of LINERS: Sy-like and RG - like RQ RL

ADAFs observed in the optical?

.