The remarkable soft X-ray emission
of the Broad Line Radio Galaxy 3C445
V. Braito,
R.M. Sambruna, J.N. Reeves
BLRG in the Unification Scheme of AGN:
Is the circumnuclear gas in BLRG different
with respect to radio quiet Seyfert
galaxies?
BROAD LINE RADIO GALAXIES IN THE
UNIFICATION SCHEME OF AGN
Blazar
BLRG: direct view of the
the AGN and of the jet
inner region of
Narrow-line Radio Galaxies
Orientation explains the different
“flavors” of AGN.
Viewing angle of the obscuring
torus: Broad vs Narrow lines AGN
Viewing angle of the jet: BLAZARS
vs Radio Galaxies
Modified from Urry & Padovani 1995
Radio Quiet AGN
Sensitive X-ray observations are a key to disentangle
the contributions from warm and cold gas in AGN
Warm
gas photoionized
by the central engine:
X-ray
emission
and
absorption
features
(O, N, Ne Mg, Si and Fe)
detected in Sy 1 and Sy2
and QSOs
high velocity outflowing
gas (Reeves talk)
Cold gas:
Fe K line at 6.4 keV
compton Reflection hump
Absorption
from outflow

Compton
Reflection hump
X-ray
Iron K Line Continuum
Soft Excess
How are RL different from RQ AGNs?
No evidence of warm absorbers in RL AGN; weak reflection and
generally the soft X-ray emission is featureless.
BLRG are a key class to investigate the inner region of RL AGN
since seen at intermediate angles wrt the jets.
Only few examples of X-ray bright BLRGs at low z and with an
optimal inclination angle -i.e. to minimize the jet contribution.
One of the best candidate is 3C445:
Bright in the X-ray band (7e-12 cgs; 2-10 keV)
low redshift (z=0.056)
Large inclination angle: i=60deg
(Eracleous & Halpern 98)
ASCA, BeppoSAX, and XMM-Newton
BeppoSAX detected 3C445 up to 50 keV
the X-ray emission
reflection component.
suggested
(Grandi et al. 06, Dadina 07)
the
presence
of
a
high
Large FOV prevent from a detailed modeling; possible
contamination from a nearby cluster (A2440, z=0.094)

XMM observation:
I.
Continuum composed by
3 power law (=1.4)
with
two
layer
of
neutral absorption and a
reflection component
5 lines clearly detected with
the EPIC-CCD: OVII He-,
OVIII Ly, MgXI and SiXIII
II. Narrow Fe k line;
confirming ASCA results
(Sambruna et al. 98)
Overall the X-ray emission of 3C445 is similar to Compton thin
Seyfert 2
The short XMM observation
Soft X-ray emission lines

The soft X-ray emission
lines are likely produced in a
photoionized medium similar
to Sy2 galaxies
Two ionization states:
1. log =-0.1 responsible for
the lower ionization emission
lines (Si and Mg)
2. log =1.86 (OVIII and OVII)
Lack of spectral resolution
detailed plasma diagnostic
and statistic to perform a more
The low exposure time (~15 ksec) did not allow a meaningful analysis
of the RGS spectra (less than 300 net counts for RGS1 and RGS2)
Suzaku I: the 0.4-40 keV continuum
Suzaku smaller FOV: there is no
contamination from the nearby
cluster.
Apparent lack of strong
reflection component
Two possible models for the underlying
continuum:
I.
A
partial
covering
neutral
23
-2
absorber (NH~10 cm ; covering
80%;  ~1.7).
II.
The absorber can be replaced
with a mildly ionized absorber
(NH~1023cm-2; log~0.9).
The Fe -K complex
Narrow Fe K
Narrow Fe K E=6.4 keV
<50 eV (FWHM <5000km/s)
EW ~100 eV
H-like Fe+Fe K
Weak broad Fe K?
Residuals can be explained
with two narrow lines (Fe Hlike+ Fe k).
Red wing could be due to a
weak broad Fe line with
Ewbroad~60 eV.
To confirm the presence of an underlying weak broad Fe line we
need to wait for the correct calibration for the observation
performed with CI
The Soft X-ray emission:
We condirm the several Xray emission in the 0.4-3
keV range detected with
XMM
with
a
better
spectral resolution (XIS1BI) especially below 1keV
OVII He-
Ne IX+ OVIII RRC
Mg XI
Si XIII
The EW of these lines
ranges from 30 eV (Mg
and Si) to 160 eV (OVII
He-).
2 ionized emitters as
seen with XMM
Conclusion: X-ray vs optical properties.
Obscured in the X-ray but unobscured in the optical
A non uniform (cloud like) ionized absorber extending down to the
“broad line regions” offers a way to reconcile X-ray and optical
band.
NO EVIDENCE OF NH VARIABILITY
HIGH COVERING FACTOR FOR THIS ABSORBER
Our line of sight intercept a significant number of clouds, but
at the same time intercepts the innermost BLR clouds if they
are lifted some height above
A possibility is that the BLR emission is produced also near the
the inner region surrounding the outflow/jet
Conclusion II: the soft X-ray emission
We have evidence of two ionized emitting regions.
Two possible scenarios for the location of these regions:
1. they are located outside the absorbing medium (i.e like the
narrow line regions);
2. the ionized emitters and absorber
with a range of ionization state.
are
the same medium
An intriguing scenario is that this medium is coincident with the
inner part of an outflow which could be related to the formation
of the jet.
BLRG in the X-ray: what’s next…
I.
We need to establish the density and ionization and location
of absorbing emitting ionized media in 3C445
-resolve the soft X-ray emission lines and measure possible
velocity shifts wrt to systemic.
This possible only with spectral resolution offered by grating
observations
II. Compare with other BLRG. Extend the sample of BLRG with
adequate deep X-ray observation to establish how common
are warm gas in BLRGs and in RL AGN.