july 4, 2006 p. padovani, unidentified -ray sources 1 the blazar sequence: validity and predictions...

July 4, 2006 P. Padovani, Unidentified -ray Sources 1

The Blazar Sequence: Validity and PredictionsThe Blazar Sequence:

Validity and Predictions

Paolo Padovani (ESO)

• Blazar properties

• The Blazar Sequence: observations and theory

• The Blazar Sequence: predictions

• The Blazar Sequence: tests

• Conclusions


Jet

BlackHole

ObscuringTorus

NarrowLineRegion

BroadLineRegion

AccretionDisk

Urry & Padovani (1995)

The AGN Paradigm: Unified Schemes

The AGN Paradigm: Unified Schemes


Blazar PropertiesBlazar Properties

• Smooth, broad, non-thermal continuum (radio to -rays)

• Compact, flat-spectrum (r< 0.5) radio sources (fcore >> fextended)

• Rapid variability (high L/t), high and variable polariz. (Popt > 3%)

• Superluminal motion

• Indication of “beaming”: strong flux amplification

BL Lacs and Flat-Spectrum Radio Quasars

Sites of very high energy phenomena: Sites of very high energy phenomena: EEmax max ~~ TeVTeV ((2 x 102 x 102626 Hz Hz)) and and max max ~~ 40 40 ((v ~ 0.9997cv ~ 0.9997c))


BL LacsBL Lacs

Low-energy peaked (LBL)

(Padovani et al. 2001)

synchrotron peak in UV/X-rays

synchrotron peak in opt/IR

X-rays: steep, synchrotron em.HBL ~ X-ray selected

X-rays: flat, IC emissionLBL ~ radio-selected

High-energy peaked (HBL)

low fx/fr

high fx/fr


Flat-spectrum Radio Quasars (FSRQ)Flat-spectrum Radio Quasars (FSRQ)

High-energy peaked(HFSRQ)

Low-energy peaked (LFSRQ)

3C 279 (Ballo et al. 2002)

?


The “Blazar Sequence”: Observations

Fossati et al. 1998, MNRAS, 299, 433

2 Jy, radio-selected

1 Jy, radio-selected

Slew, X-ray-selected


The “Blazar Sequence”: Theory

The “Blazar Sequence”: Theory

Ghisellini et al. 1998, MNRAS, 301, 451

peak B 2peak, peak determined by the

balance between acceleration and cooling processes Powerful sources higher energy densities (L/R2)

more cooling lower peak and peak

peak

Energy

FSRQ


The “Blazar Sequence”: Predictions

The “Blazar Sequence”: Predictions

FSRQ more powerful than BL Lacs + peak = f (L-1) HFSRQ (FSRQ with high peak) should not exist

Physical Implications: very high energy

emission (TeV ~ 2 1026 Hz); all known (few) TeV sources are HBL. HFSRQ would increase statistics and constrain IR background ( star formation history)

HE + IR e+ + e_ max for ~ 1.33 m (E/TeV)

Low-L sources more numerous than high-L sources [(L) L- ] HBL intrinsically more numerous than LBL

Physical Implications: 1) demography; 2) constraints on jet physics; peak B 2

peak , so if high peak more common, Nature prefers certain types of jets


The “Blazar Sequence”: Tests

The “Blazar Sequence”: Tests

high-L &high peak

low-L &low peak

1. Check the correlation

3. Counting sources: HBL vs. LBL

2. Finding the “forbidden” objects (outliers)


The Power – peak Correlation. 1The Power – peak Correlation. 1

Padovani et al. (2003)

No correlation, huge scatter, outliers



Caccianiga & Marchã (2004)CLASS Survey

Low-L outliers



Antón & Browne (2005)

No correlation, low-L outliers



Nieppola et al. (2006)

Correlation, scatter, mostly low-L outliers


The Power – peak Correlation. Summary

The Power – peak Correlation. Summary

1.No power - peak correlation (unless

non-homogeneous sample is used)2.Huge scatter (reaching 4-5 orders

of magnitude in power at given

peak)

3.Mostly low-power outliers found: slightly less beamed sources?


Looking for HFSRQ Looking for HFSRQ • HFSRQ: high power AND high peak• Need X-ray selected samples (as HBL

mostly found in the X-ray band)• Need to look in appropriate regions of

parameter space occupied by HBL (e.g., high fx/fr)

• After selection, need to build spectral energy distributions; check for UV bump

• Confirmation by X-ray observations is recommended: X-ray spectrum has to be synchrotron dominated [steep (x > 1)

or at least concave]


Selecting HFSRQ Selecting HFSRQ

HBL “box” fractions:

FSRQ ~ 9%

BL Lacs ~ 15%


95 % of HBL


BeppoSAX Spectra of HFSRQ Candidates

BeppoSAX Spectra of HFSRQ Candidateslog peak ~ 16.2log peak ~ 15.8

log peak ~ 14.6 log peak ~ 14.6

Discovery of first FSRQwith X-ray band dominated bysynchrotron emission(Padovani et al. 2002)

x ~ 1.5


The lack of extreme HFSRQThe lack of extreme HFSRQ

1.X-ray selected samples searched thoroughly, XMM and Chandra data taken

2.HFSRQ found! But their max peak ~ 0.1 keV; HBL typically reach ~ 1

keV and exceptionally ~ 100 keV

(MKN 501)3.Sedentary survey, designed to find

extreme BL Lacs (Giommi et al. 1999, 2005): all broad-lined sources are close to the radio-loud/radio-quiet border, no definite FSRQ

4.Physics or (still) selection effects?

LBL

HBL

Host galaxy

Giommi et al. (2005)


Counting sources: HBL vs LBL

Counting sources: HBL vs LBL

• Question: which sub-class is intrinsically more numerous?

• Selection band affects selected objects: X-ray mostly HBL; radio mostly LBL

• Would need unbiased selection method• Alternatively, make assumption, make

predictions, and test with radio and X-ray samples


Counting sources: HBL vs LBL. 1


Giommi, Menna & Padovani (1999)


Fossati et al. (1997)






NHBL ~ 0.1 NLBL

Padovani & Giommi (1995)


Summary Summary

1.There is no anti-correlation between power and synchrotron peak frequency in blazars, once selection effects are taken into account

2.Outliers exist: low-L/low peak and

high-L/high peak3.HFSRQ found!

4.Data consistent with NHBL ~ 0.1 NLBL

5.Blazar sequence in its simplest form not valid

6.But BL Lacs appear to reach peak ~ 100 x larger than HFSRQ

7.Physics or (still) selection effects: are there high-power TeV sources out there?

july 4, 2006 p. padovani, unidentified -ray sources 1 the blazar sequence: validity and predictions...

Documents

high peak

unidentified ray sources

low peak

peak peak energy fsrq

tev sources

blazar sequence

power peak correlation

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