Review of Radio Observations

Tiziana Venturi

tventuri@ira.inaf.it

Bologna, 5 Novembre 2009

Galaxy Evolution and Environment

Outline

Radio emission in galaxies:

- AGN, starburst, HI

Same cosmic epoch:

- Local radio luminosity function for rich and poor environments

- Radio galaxies in dense environments

Radio source evolution with the cosmological epoch:

- Radio luminosity functions for AGNs and starbursts compared to the local RLF

- Relation with the environment

- Steep spectrum radio galaxies and search for protoclusters

Present and future available radio facilities

Radio Loud AGNs

Radio galaxies are associated with elliptical galaxies. The radio emission is non thermal (synchrotron) and it origins in the galaxy nucleus.

The radio emission takes the form of (a)symmetric jets and a central component (core) coincident with the optical nucleus.

The local environment shapes the radio lobes

Head Tail

Wide angle tail

Symmetric double

Radio galaxies are classified as low power (FRI) and high power (FRII), the divide being

P(1.4 GHz)~ 1024.5 W/Hz

The two FR classes also differ in morphological details

FRIIFRI

Starburst Galaxies

Arp 299 z=0.0103 M82 z=0.000677

NGC 253

Z=0.000811

Perez-Torres et al. 2009

Non thermal radio sources whose radio emission is dominated by supernova remants and radio supernovae (P1.4GHz < 1021.5 - 22 W/Hz)

HI emission in spiral galaxies

VIVA project (VLA)THING Survey - VLA

HI emission in spirals is known to be strongly affected by the environment (field, groups, clusters, merging clusters): morphology & HI deficiency (Vollmer 2009, Virgo)

Dependance of HI on cosmological epochs (up to z~0.25) only recently started (Catinella et al.)

Detailed study of HI emission possible only in the very local Universe (z<0.1)

AGN and Starbust radio emission

Environment …

Same redishift: local environment

AGN and Starbust radio emission

… & Evolution

Different redshift: evolution

Local Universe and role of the environment on the radio

emission

- High galaxy density in clusters compared to the field

- galaxy-galaxy interaction

- Large scale interaction (cluster merger)

Does this affect the radio luminosity function for AGN and starburst galaxies?

I. Statistical properties of radio galaxies and cluster environment

Auriemma et al. 1977 Ledlow & Owen 1996

Field galaxies Cluster galaxies

The dense cluster environment does not seem to influence the RLF for AGN, whose main dependance is on the optical magnitude

But analysis on individual merging clusters seem to deviate in opposite directions:

“Universal” RLF

A3558 Shapley complex

Venturi et al. 2000

Mauduit & Mamon 2007

Comparison sample

Miller & Owen 2003

Galaxies in the 6dFG sample

Mauch & Sadler 2007

A2255A3558

A3556

A3562

SC

Same conclusions on the radio emission from starburst galaxies

Faint end of the RLF includes starbusts

A2255 higher than the comparison cluster sample

Miller & Owen 2003

Shapley galaxies and re-analysis of MO03 do not show significant enhancement of startburst emission in merging custers

Giacintucci et al. 2004

Local Universe and role of the environment on the radio

emission

II. Radio galaxies at cluster centres: morphology, feedback and cycles of radio emission

A large fraction of brightest cluster members (BCG) is radio loud (~60%) Their radio morphology can be broadly divided into two classes:

Abell 400 Abell 2052

WATs and extended with radio power close to the FRI/FRII divide

Both in cooling and non cooling clusters

Core-Halo radio galaxies

Only in cooling clusters

Mittal et al. 2009

Radio emission and ICM at the cluster centres know of each other

Feedback from the central AGN may stop the cooling - Cavities in the ICM filled by radio lobes from the central galaxies prove the role of the central AGNs.

McNamara & Nulsen (2007, ARAA 45, 117)

Pca

v(104

2 e

rg/s

)

Lradio(1042 erg/s) LICM(1042 erg/s)

1

1

HPBW 18’’ , f.c. 0.15 mJy/b

HPBW 22’’ f.c. 0.7 mJy/b

current burst

SE cold front

GMRT 610 MHz

GMRT 240 MHz

Same old burst? α> 1.6

Giacintucci et al 2009

Steep spectrum emission not obviously connected with the central galaxy: old radio emission?

NGC5044

3C317 in A2052

Steep spectrum dominated

by the diffuse emission

VLBI Active nucleus

Venturi et al. 2004

Evidence of restarted activity in radio galaxies at the cluster centres further links the radio filled cavities with the central AGN

Redshift Evolution

- Evolution of the radio source population

- Massive black hole formation and evolution with cosmic time

- Star formation and its evolution with cosmic time

- Relation with the environment

Statistical properties of radio AGN and starburst galaxies

Samples of galaxies with radio and optical information (spectroscopic or photometric)

radio luminosity functions in different redshift bins

Recent determinations of the Local Radio Luminosity Function

6dFGS D2+ NVSS SDSS + NVSS + FIRST

Mauch & Sadler 2007 Best et al. 2005

Strong evolution of powerful radio sources established long ago

High power & low power radio galaxies

Dunlop & Peacock 1990

Evolution of powerful radio galaxies up to z=0.55 from SDSS+NVSS (Donoso et al. 2009)

0.1≤z≤0.35 0.35<z≤0.6

0.6<z≤0.9 0.9<z≤1.3

For low power radio galaxies in the COSMOS field the evolution is much weaker than at high power (Smolcic et al. 2009)

Different evolution with cosmic time

Low Power

FRI

High Power FRI

Dependance on the environment

AGNs in the SDSS z ≤ 0.55

Radio loud AGN are more strongly clustered than control galaxies of the same mass and quasars at the same redshif

Adapted from Kauffmann et al. 2009

RLF for central radio galaxies in the NEP sample (0.3<z<0.8)

Local RLF

NEP clusters

Possible evolutionary effects for the radio loud galaxy population (Branchesi et al. 2006)

Evolution of “passive” AGNs and star forming galaxies

zCOSMOS field (0.1<z>0.9)

Radio-based AGN definition: Two classes of AGN, with “passive” and with star forming (non-passive) galaxy host

AGN

SFG

Only “passive” AGN show environmental dependence:black hole masses or emission mechanism difference?

Number of AGN over control sample vs local overdensity Control sample

Black Hole Masses distribution irrespective on environment ==> difference in feeding the black hole

Radio AGN

Triangles:High densitiesPoints: low densities

L1.4GHz Mstar

L1.4GHz Cooling flow of group/cluster

Only the red “passive” AGN show a density dependency

In higher environments the ratio between stellar mass and emissivity is higher (signature of the cooling of the group or cluster) ==> Feedback

No environmental effect on AGN hosted by star forming ==> trigger by secular (i.e. bars) phenomena (Bardelli et al. 2009)

High redshift radio galaxies and the Early Universe

Tracers of massive galaxy formation and protoclusters

Powerful (P500MHz >1027 W/Hz) steep spectrum (α> 1) radio galaxies at high redshift (z>2)

Rare objects: 178 known to date

4C41.17 at z=3.8

1.4 GHz VLA over Lyα

PKS1138-282 - z=2.2 X-ray over radio MRC1182-262 proto cluster:

host galaxy surrounded by giant Lyα halo in a 3 Mpc scale structure of M>2x1014 MSun

Miley & De Breuck, 2008 AARev 15,67

Present and future radio facilities

Wide fields and the “weak” Universe

ALMA 10 bands from 35 to 850 GHz

EVLA

Complete frequency coverage from 1 to 50 GHz

eVLBI and MERLIN from 1.6 to 22 GHz

LOFAR

30-80 MHz 120-240 MHz

GMRT

1.4 GHz – 240 MHZ

New and upgraded observational facilities over the whole radio window ready or to be operational over the next 12-16 months

GMRT

μJy sensitivity from 1 to 50 GHz at resolutions from milliarcsecond to arcsecond scale and from ~20 μJy to few mJy at the ALMA frequencies

Sub-mJy to mJy sensitivity at the LOFAR frequencies

… some examples …

Low power end of the RLF for AGN

Starburst galaxies locally and at high z

Starburst & starforming galaxies at high z

Very distant radio galaxies

HI at high z

HI dynamics in the

Local Universe … and much more…