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

2. July 4, 2006 P. Padovani, Unidentified  -ray Sources 2 Jet Black Hole Obscuring Torus Narrow Line Region Broad Line Region Accretion Disk Urry & Padovani (1995) The AGN Paradigm: Unified Schemes

3. July 4, 2006 P. Padovani, Unidentified  -ray Sources 3 Blazar Properties Smooth, broad, non-thermal continuum (radio to  -rays) Compact, flat-spectrum (  r > f extended ) Rapid variability (high  L/  t), high and variable polariz. (P opt > 3%) Superluminal motion Indication of “beaming”: strong flux amplification BL Lacs and Flat-Spectrum Radio Quasars Sites of very high energy phenomena: E max ~ TeV (2 x 10 26 Hz) and  max ~ 40 (v ~ 0.9997c)

4. July 4, 2006 P. Padovani, Unidentified  -ray Sources 4 BL 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 emission LBL ~ radio-selected High-energy peaked (HBL) low f x /f r high f x /f r

5. July 4, 2006 P. Padovani, Unidentified  -ray Sources 5 Flat-spectrum Radio Quasars (FSRQ) High-energy peaked (HFSRQ) Low-energy peaked (LFSRQ) 3C 279 (Ballo et al. 2002) ?

6. July 4, 2006 P. Padovani, Unidentified  -ray Sources 6 The “Blazar Sequence”: Observations Fossati et al. 1998, MNRAS, 299, 433 2 Jy, radio-selected 1 Jy, radio-selected Slew, X-ray-selected

7. July 4, 2006 P. Padovani, Unidentified  -ray Sources 7 The “Blazar Sequence”: Theory Ghisellini et al. 1998, MNRAS, 301, 451 peak  B   2 peak,  peak determined by the balance between acceleration and cooling processes Powerful sources  higher energy densities (  L/R 2 )  more cooling  lower  peak and peak  peak Energy FSRQ

8. July 4, 2006 P. Padovani, Unidentified  -ray Sources 8 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 10 26 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

9. July 4, 2006 P. Padovani, Unidentified  -ray Sources 9 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)

10. July 4, 2006 P. Padovani, Unidentified  -ray Sources 10 The Power – peak Correlation. 1 Padovani et al. (2003) No correlation, huge scatter, outliers

11. July 4, 2006 P. Padovani, Unidentified  -ray Sources 11 The Power – peak Correlation. 2 Caccianiga & Marchã (2004) CLASS Survey Low-L outliers

12. July 4, 2006 P. Padovani, Unidentified  -ray Sources 12 The Power – peak Correlation. 3 Antón & Browne (2005) No correlation, low-L outliers

13. July 4, 2006 P. Padovani, Unidentified  -ray Sources 13 The Power – peak Correlation. 4 Nieppola et al. (2006) Correlation, scatter, mostly low-L outliers

14. July 4, 2006 P. Padovani, Unidentified  -ray Sources 14 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?

15. July 4, 2006 P. Padovani, Unidentified  -ray Sources 15 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 f x /f r ) 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]

16. July 4, 2006 P. Padovani, Unidentified  -ray Sources 16 Selecting HFSRQ HBL “box” fractions: FSRQ ~ 9% BL Lacs ~ 15% Padovani et al. (2003) 95 % of HBL

17. July 4, 2006 P. Padovani, Unidentified  -ray Sources 17 BeppoSAX Spectra of HFSRQ Candidates log peak ~ 16.2log peak ~ 15.8 log peak ~ 14.6 Discovery of first FSRQ with X-ray band dominated by synchrotron emission (Padovani et al. 2002)  x ~ 1.5

18. July 4, 2006 P. Padovani, Unidentified  -ray Sources 18 The 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)

19. July 4, 2006 P. Padovani, Unidentified  -ray Sources 19 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

20. July 4, 2006 P. Padovani, Unidentified  -ray Sources 20 Counting sources: HBL vs LBL. 1 Giommi, Menna & Padovani (1999) Padovani et al. (2006) Fossati et al. (1997)

21. July 4, 2006 P. Padovani, Unidentified  -ray Sources 21 Counting sources: HBL vs LBL. 2 Padovani et al. (2006) Fossati et al. (1997)

22. July 4, 2006 P. Padovani, Unidentified  -ray Sources 22 Counting sources: HBL vs LBL. 3 Padovani et al. (2006) Fossati et al. (1997) N HBL ~ 0.1 N LBL Padovani & Giommi (1995)

23. July 4, 2006 P. Padovani, Unidentified  -ray Sources 23 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 peak 3.HFSRQ found! 4.Data consistent with N HBL ~ 0.1 N LBL 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?

24. July 4, 2006 P. Padovani, Unidentified  -ray Sources 24 The DEEP X-RAY RADIO BLAZAR SURVEY (DXRBS) WGA Catalog (X-ray) ~70,000 sources, f x  5 ×10 -14 c.g.s. GB6 & PMN Catalogs (Radio) ~120,000 sources, f r  50 mJy P. Padovani, P. Giommi, H. Landt, E. Perlman, and others +  r < 0.7: ~ 350 blazar candidates Currently the faintest and largest flat-spectrum radio sample with nearly complete (~ 95%) identifications.

25. July 4, 2006 P. Padovani, Unidentified  -ray Sources 25 The Power – peak Correlation. 3 Antón & Browne (2005) No correlation, low-L outliers

26. July 4, 2006 P. Padovani, Unidentified  -ray Sources 26 The Power – peak Correlation. 4 Nieppola et al. (2006) Correlation, scatter, mostly low-L outliers