Review of Radio Observations
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Transcript of Review of Radio Observations
Review of Radio Observations
Tiziana Venturi
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…