Two years of blazar monitoring with the OVRO 40m telescope at 15GHz in support of the Fermi GST

1. Two years of blazar monitoring with the OVRO 40m telescope at 15GHz in support of the Fermi GST Vasiliki Pavlidou (Caltech)on behalf of the OVRO 40m team

2. The team:

3. The plan: • Science • Observational Program • Preliminary Results

4. Science Jets: how are they launched, accelerated, collimated, confined? Blazars (~aligned AGN) What is the jet composition? beamed & boosted How are particles accelerated to relativistic energies? fast variability superluminal motions high apparent luminosity What are the details of the emission mechanism, and where in the jet is the observed emission coming from? high-energy emission

5. Blandford & Levinson 1995 Marscher et al. 2008 Dermer, Schlickeiser & Mastichiadis 1991 Lind et al. 1989 Sikora, Begelman & Rees 1994 McKinney 2006 Blandford & Znajek 1977 Blandford & Payne 1982 Science: theory

6. Science: phenomenology What is the correlation between variability, luminosity, beaming? Blazars (~aligned AGN) How is emission at different wavelengths correlated? beamed & boosted fast variability Timelags between flares at different frequencies? superluminal motions high apparent luminosity Dependence of variability on spectral properties? high-energy emission Cosmic evolution of blazar properties?

7. Phenomenology: strategy • Sensitive dependence of observed properties on  • Physical processes: everything goes?(different for different blazars or even for different flares of single blazar?) • Most impressive behavior need not be typical behavior • Need: • Large sample • Statistically well-defined sample • Regular monitoring • multiwavelength • GeV: Fermi • Radio (15 GHz): OVRO 40m

8. The OVRO 40m program: sample and strategy • Sample: all CGRaBS sources at >200 (additional sources monitored, not used in population studies, e.g.:non-CGRaBS LAT AGN within accessible sky VERITAS monitoring…) • Strategy: twice-a-week flux observations at 15GHz selected based on radio spectral index, radio flux, and X-ray flux

9. The OVRO 40m program: data filters and calibration

10. The OVRO 40m program: data policy • Data: available to Fermi collaboration • released to public at ~ time of Fermi public data release • regularly updated thereafter http://www.astro.caltech.edu/GLAST/

12. OVRO 40m program: First Results • Richards et al. (2009): description of program, lightcurves, statistics of variability for individual objects • Max-Moerbeck et al. (2009): population studies of radio variability • (also: Fuhrmann et al. 2009: F-GAMMA program description)

13. Results: Lightcurves Preliminary

14. Results: Lightcurves Preliminary

15. Results: Variability Amplitude • One blazar: quantify using intrinsic modulation indexflux rms in units of meanm=/<S> • Obtain through likelihood analysisaccounting for: • uncertainties in individual observations • number of observations

16. Preliminary

17. Preliminary

18. Preliminary bimodality!

19. Results: Variability Amplitude Preliminary • Population Studies

20. Results: Variability Amplitude Preliminary • Population studies • Is the distribution of modulation indices the same at high and low redshifts? Low z (<1.1) High z (>1.1)

21. Results: Time Domain Preliminary

22. Results: Correlation with gamma-ray emission Preliminary • Need longer lightcurves! Fermi LAT data OVRO data

23. Summary • Regular multiwavelength monitoring of large and uniform samples critical for blazar science • OVRO 40m telescope is monitoring ~1200 CGRaBS blazars @15 GHz ~twice a week • Fermi is continuously monitoring the GeV sky • First results tantalizing, coming soon at a preprint server near you • The future is bright, tune (and/or join) in!

25. Variability Amplitude - population studies High z / Low z (FSRQs only) 2 random equally-sized subsamples Preliminary FSRQs vs BLLs