On the spectro-photometric properties of the bulk of Radio-Loud AGN population

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On the spectro-photometric properties of the bulk
of Radio-Loud AGN population
Baldi Capetti 2009, 2010

• Ranieri D. Baldi1,
• Alessandro Capetti2

1 SISSA, Trieste 2 Osservatorio Astronomico di
Torino
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Radio-AGN link

• The fundamental question is
• Do the classical powerful radio sources, FRI and
  FRII, provide us with the correct view of AGN in
  radio galaxies?

Method spectro-photometric analysis of a sample
of samples of low-luminous radio sources
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Core Galaxies
3CR/FRI
CoreG
The Core Galaxies are miniature radio-galaxies
(FR I). (Balmaverde Capetti 06 and
Balmaverde,Baldi Capetti 08).
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Core Galaxies
UGC 8745
20kpc
lt a gt 0.7
The properties of the radio emission are similar
to those of 3C/FRI.
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Core Galaxies
3CR
CoreG
The CoreG show a Core Dominance of a factor 100
larger than the classical 3C/FRI.
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Core Galaxies
3CR/LEG
Kewley et al. (2006)
The Core Galaxies are Low Excitation Galaxies
(LEG) like 3C/FRI.
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Core Galaxies
(erg s-1)
(erg s-1)
(erg s-1)
The nuclear properties of CoreG are similar to
those of FRI. CoreG show a genuine extended
radio emission deficit of a factor 100.
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..and so?
Deficit in radio extended emission?? But, their
radio core is fainter than that typical of
FRI/LEG. Let us look for other core dominated
sources in sample of higher power.
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B2 sample
From Giovannini et al. (1988) B2 sample, 11
objects with core dominance gt 0.1
B2
B2
3CR/FRI
(erg s-1)
B2
CoreG
(erg s-1)
(erg s-1)
High core dominated sources with higher radio
core power!
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bulk of RL AGN population
Our interpretation The prevalence of low core
dominance sources in low frequency flux limited
samples is due to a selection bias.
To test this scenario..
Best et al (2005) of RL AGN crossmatching the
212000 galaxies drawn from the SDSS DR2 with the
NVSS and FIRST radio surveys. Selection
F_at_1.4GHz gt 5 mJy
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Best et al (2005) sample
0.03 lt z lt 0.1
Seyfert
3CR correlation
(erg s-1)
The bulk of the population of this SDSS/NVSS AGN
sample shows a large deficit of total radio
emission, similar to that observed in CoreG.
LEG
F_at_1.4GHz gt 5 mJy At z0.1 Lr 1039 erg s-1
(erg s-1)
CoreG
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Best et al (2005) sample
The bulk of the population of this SDSS/NVSS AGN
sample shows a large deficit of total radio
emission, similar to that observed in CoreG.
F_at_1.4GHz gt 5 mJy At z0.1 Lr 1039 erg s-1
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Selection Bias
If we use the B2 sample flux selection
criterion, low core dominance radio galaxies are
the dominant population.
3CR correlation
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SDSS/NVSS Sample

• Are there differences between SDSS/NVSS sources
  and 3CR/LEG?
• Spectral classification
• Host mass, morphology and colors
• Black hole mass distribution

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Spectroscopic Diagnostic diagrams
HEG
HEG
HEG
Kewley et al. (2006)
SFG
SFG
LEG
SFG
LEG
LEG
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comparison with LEG
z lt 0.1
Most of the radio-loud AGN of the SDSS/NVSS
sample are LEG and UG they reach the LOIII
- Lext relation of the 3CR/LEG.
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Unclassified Galaxies LEG
UnclassifedGalaxies (UG) are consistent with
being low-luminous LEG
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Photometric Diagnostic Diagrams
The host galaxies associated with the SDSS/NVSS
sample are mostly red early-type galaxies (ETG)
with no active star formation.
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Comparison with LEG
The most of the SDSS/NVSS shows host properties
statistically indistinguishable from those of the
3CR/LEG hosts
The host galaxies associated with the SDSS/NVSS
sample are mostly massive ETG with large black
hole masses.
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Radio Structures
FIRST radio images FWHM 5 arcsec
FR0
All morphological classes are represented, but
80 do not show extended radio structures.
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Radio Structures
Extended radio structures LEG 5 UG 27
UG Line emission
LEG Line emission
The higher fraction of UG with extended radio
structures can be du to an evolution of part of
the LEG population, from small radio sources of
high L(OIII), to larger size and smaller
L(OIII).
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Radio-quiet/Radio-loud AGN
0.03 lt z lt 0.3
HEG
There is no a clear discontinuity in either the
host or nuclear properties as they span from
radio-quiet and radio-loud AGN.
LEG
After a detailed analysis on a object by object,
we concluded that no bona fide radio-loud AGN
with LEG spectra could be found in a late-type
galaxies or with log MBH lt 108 Msun.
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Conclusions

• Selection bias in radio flux-limited sample
  causes the inclusion only of radio-galaxies with
  well developped extended structures. The bulk of
  RL AGN population is virtually unexplored -gt
  SDSS/NVSS sample.
• the SDSS/NVSS AGN sample is mostly composed of
  quiescent red, massive (10.5 lt log Mgallt 12 Msun)
  ETG with large black hole masses (7.7 lt log MBH lt
  9 Msun), statistically indistinguishable from
  hosts of low-redshift 3CR/LEG
• No genuine radio-loud LEG in late-type galaxies
  and MBH lt 108 Msun
• A minority (10) of the sample are in spiral
  galaxies, with small black hole masses or with
  HEG spectra (contamination from Seyfert and SF
  galaxies)
• For HEG no separation from radio-quiet/radio-loud
  AGN in host properties.
• Possible interpretations for low extended power
• Link between age and radio extended emission.
  Young, recurrent?
• Influence of environment on the jets properties.

Baldi Ranieri D.

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