The disk-jet link:
X-ray and radio monitoring of PKS 0558-504
Mario Gliozzi (GMU)
I. Papadakis (Crete)
W. Brinkmann (MPE)
L. Kedziora-Chudczer (Sidney)
*Disk-jet connection
*AGN-GBH analogy
*PKS 0558-504 in Grand Unification Model
*Results from RXTE & radio monitoring
*Conclusions & future work
Disk & Jet
*Basic Ingredients of BH systems:
Most evident manifestations of BH presence
*Growing evidence (theory, observations, simulations)
of strong accretion-ejection link:
No jet without accretion but not vice versa
*Main Goals:
1) Understand the conditions leading to jet formation/quenching
2) Assess jet role in energetics of the system
X-ray & Radio monitoring
Previous studies demonstrate crucial role of radio X-ray monitoring:
X-rays track the accretion activity
Radio tracks the jet activity
Microquasar GRS1915+105
[Mirabel et al. 1998]
BLRG 3C120
[Marscher et al. 2002]
Same phenomena occur on different scales: analogy GBHs -AGN
Grand Unification Model
GBHs scaled down versions of AGN:
AGN classes correspond to GBHs in different spectral states
[e.g., Mc Hardy et al. 2006]
2 main spectral states:
1) Low/Hard State (LS) and 2) High/Soft State (HS)
LS energy spectrum:
E [keV]
HS energy spectrum:
E [keV]
[Fig from Zdziarski & Gierlinski 2004]
Grand Unification Model
GBHs scaled down versions of AGN:
AGN classes correspond to GBHs in different spectral states
[e.g.,Mc Hardy et al. 2006]
2 main spectral states:
1) Low/Hard State (LS) and 2) High/Soft State (HS)
LS power spectrum:
HS power spectrum:
[GX 339-4 Homan & Belloni 2004]
Grand Unification Model
GBHs scaled down versions of AGN:
AGN classes correspond to GBHs in different spectral states
[e.g.,Mc Hardy et al. 2006]
2 main spectral states:
1) Low/Hard State (LS) and 2) High/Soft State (HS)
LS radio properties:
Persistent radio emission
Correlation with X-rays: LR~LX0.7
Emission from compact jet
HS radio properties:
Weak/absent radio emission
Jet quenching
[Cyg X-1 Sterling et al. 2001]
[Fender et al. 2004; E. Gallo et al. 2004;]
GBH Intermediate State
HID: model-independent
way to describe GBH
evolution
Existence of Intermediate
spectral State (IS)
[GX 339-4 Homan & Belloni 2004]
IS energy spectrum:
[Fig from Zdziarski & Gierlinski 2004]
GBH Intermediate State
HID: model-independent
way to describe GBH
evolution
Existence of Intermediate
spectral State (IS)
IS power spectrum:
[Fig from Homan & Belloni 2004]
GBH Intermediate State
HID: model-independent
way to describe GBH
evolution
Existence of Intermediate
spectral State (IS)
IS radio properties:
Transient & strong radio emission
Steep spectrum
Large bulk Lorentz factor
Most powerful jet ejections
[GRS1915+105 Mirabel & Rodriguez 1998]
AGN-GBH Correspondence
LS
LLAGN
Based on generalization of HID [Koerding et al. 2006]
Based on “fundamental plane” [Merloni et al. 2003; Falke et al. 2004]
HS
Seyfert 1
Based on PSD
[Uttley et al. 2002; Markowitz et al. 2003; McHardy et al. 2006]
IS
?
Importance of finding IS-analog AGN:
frozen look of BH systems during major ejections
IS requirements:
* high accretion rate
* strong radio emission
* steep energy spectrum
* PSD with QPOs
PKS 0558-504
In principle any radio-loud NLS1 satisfies basic requirements for IS,
but only few of these objects [Komossa et al. 2005]
only PKS 0558-504 bright enough for RXTE monitoring
(F2-10 keV ~ 2x10-11 erg cm-2 s-1, L2-10 keV ~ 1045 erg s-1)
Radio-loud:
R~30
BH mass: MBH~4x107 Msolar
X-rays: Bright, Steep PL (Г~2.2), Variable
Extremely variable: 67% flux variation in 3’
[Siebert et al. 1999]
[Wang et al. 2001]
[Gliozzi et al. 2007]
[Remillard et al. 1991]
Requirements for IS
High accretion rate?
Yes
Lbol ~ LEdd
Even considering MBH~ 5 Mvirial [Marconi et al. 2008]
and different bolometric corrections [Vasudevan & Fabian 2007]
Jet radio emission?
Maybe (wait and see)
PSD with QPO?
No (at least not yet)
Answer after XMM AO7
5 orbits (660ks PI Papadakis)
Energy spectrum match?
Maybe (but spectral degeneracy)
Comptonization [O’Brien et al. 2001; Brinkmann et al. 2004]
Ionized Reflection [Ballantyne et al. 2001; Crummy et al. 2006]
SLIM disk [Haba et al. 2008]
Beamed emission [Remillard et al. 1991; Gliozzi et al. 2001]
Additional diagnostics for IS
From model-independent studies of spectral variability:
1) Fractional variability flattens in IS from LS to HS
[Gierlinski & Zdziarski 2005]
LS
IS
HS
E [keV]
2) Short-term variability Cyg X-1 during IS characterized
large flux changes without spectral variations
[Malzac et al. 2006]
RXTE monitoring of PKS 0558-504
Campaign:
Started in March 2005;
monitoring campaign under way
Sampling:
1 observation every 2 days
+ 3 periods of denser coverage
(2 observations per day)
[Gliozzi et al. 2007]
Soft [2.5-5 keV] and
Hard [5-15 keV] fluxes
highly variable on day-month
timescales.
Flux variability accompanied
by weak spectral variability.
Flux-Flux Plot
Plot Hard [5-15 keV] versus Soft [2.5-5 keV] count rate
to characterize the spectral variability
[e.g., Churazov et al. 2001; Taylor et al. 2003] .
Two possible scenarios:
1) If power-law trend:
Spectral variability explained by pivoting.
2) If linear trend:
Constant spectral shape with 2 components
[Zdziarski et al. 2002]
Linear trend
no spectral pivoting
Intercept = 0
no contribution from
hard component
Common physical origin for Soft & Hard
Fvar- E Plot
Plot Fractional variability Fvar vs energy
Fvar=√(S2- <σerr2>)/<x>
Constant trend reminiscent
of GBHs in IS
[Gierlinski & Zdziarski 2005]
Different from typical
jet-dominated behavior:
Fvar α E
[Gliozzi et al. 2006]
Mrk 501
HR-ct Plot
Plot of hardness ratio
HR=[5-15 keV]/[2.5-5 keV] vs. count rate
Constant trend reminiscent of Cyg X-1
in IS
[Malzac et al. 2006]
Different from typical
jet-dominated behavior:
HR α ct
[Gliozzi et al. 2006]
Mrk 501
Radio Observations
ATCA Imaging:18 GHz
F.O.V= 9”x13”
beam=0.5”
(1”=2.4 kpc)
Source
unresolved
Radio Observations
ATCA Imaging: 8.6 GHz
F.O.V= 18”x27”
beam=1”
(1”=2.4 kpc)
2 symmetric
lobes resolved
(d=14 kpc)
Radio Observations
ATCA Imaging: 4.8 GHz
F.O.V= 38”x58”
beam=2”
(1”=2.4 kpc)
2 symmetric
lobes resolved
(d=14 kpc)
Radio Observations
VLBI Imaging [S. Tingay]
jet resolved
(R~100 pc)
Radio Monitoring
Radio emission highly variable
Timescales longer compared
to X-rays
No trivial correlation with X-rays
but longer baseline needed
PKS 0558-504 IS-analog ?
High accretion rate?
Yes
Jet radio emission?
Yes
Typical Spectral variability?
Yes
Energy spectrum match?
Maybe: no evidence for reflection
PKS 0558-504 extraordinary object:
high accretion rate AGN with strong radio jet,
very bright, highly variable on all timescales.
Future Work
- From September 2008 PKS 0558-504 weekly
monitored with SWIFT in Optical, UV, and soft X-ray
to complement hard X-rays (RXTE) and hopefully
radio monitoring.
-5 XMM-Newton orbits in AO7 for deep investigation
of PSD (QPOs) and breaking spectral degeneracy
via time-resolved spectroscopy.
- Further VLBI observations to investigate
possible changes in the inner jet structure.