Radio/gamma connection: Study of cm/mm-band radio and gamma-ray - PowerPoint PPT Presentation

Radio/gamma connection: � Study of cm/mm-band radio and gamma-ray correlated variability in Fermi bright blazars � Lars Fuhrmann S. Larrson, J. Chiang, E. Angelakis, V. Pavlidou, I. Nestoras, J. A. Zensus et al. on behalf of the F-GAMMA & Fermi LAT collaborations

Introduction do gamma-ray flares usually have radio counterparts? what is the relative timing/delay? � where in the jet are the gamma-rays produced (close to BH or pc-scale jet, how far from BH etc.)? several approaches: VLBI studies, flux r -flux γ studies, direct light curve analysis… EGRET times - limited studies: ”gamma-ray flares/activities appear to occur during the raising phase (i.e. after the onset) of high frequency radio flares” i.e. gamma-ray flares happen in the mm-shocks further out! � Now we have Fermi/LAT! � early study: Many studies emerged � Long time baseline needed: � now 3 yrs of LAT LCs! �

Project overview � The sample and data sets � Aim: a study focusing on the possible connection between 2007.0 2008.0 2009.0 2010.0 2011.0 2012.0 7 2.64 J0238+1636 4.85 8.35 radio and gamma-ray flares/activity periods in the 3 yr long- 10.45 6 14.60 23.05 32.00 42.00 5 term light curves of about 60 Fermi -GST detected blazars 86.00 142.33 228.39 Flux Density (Jy) 4 through a detailed cross-band analysis 3 2 1) radio bands: F-GAMMA program since Jan. 2007: 1 0 54000.0 54500.0 55000.0 55500.0 56000.0 Time 2007.0 2008.0 2009.0 2010.0 2011.0 2012.0 9 3-4.5 yrs of Effelsberg 100-m/IRAM 30-m monthly 2.64 J0721+7120 4.85 8.35 8 10.45 14.60 23.05 monitoring data at 10 different frequencies (110, 60, 36, 7 32.00 42.00 86.00 142.33 6 228.39 Flux Density (Jy) 28, 20, 13, 9, 7, 3, 2, (1) mm) 5 4 3 “the best suitable” 58 1FGL sources 2 1 (best sampl., frequency & time coverage) 0 54000.0 54500.0 55000.0 55500.0 56000.0 Time 2007.0 2008.0 2009.0 2010.0 2011.0 2012.0 45 2.64 J2253+1608 Type # 4.85 8.35 40 sample statistics: 10.45 14.60 23.05 35 32.00 FSRQ 33 42.00 86.00 142.33 30 228.39 Flux Density (Jy) BL Lac 17 25 cross-band study: selection of 4 20 RG 2 frequency bands (3, 9, 20, 60mm) 15 10 Blazar 5 5 NLSy1 1 0 54000.0 54500.0 55000.0 55500.0 56000.0 Time

Project overview � The sample and data sets � 2) Fermi/LAT: 3 yr light curves starting in Aug. 2007.0 2008.0 2009.0 2010.0 2011.0 2012.0 7 2.64 J0238+1636 4.85 8.35 10.45 6 14.60 2008 23.05 32.00 42.00 5 86.00 142.33 228.39 Flux Density (Jy) 4 specific time boundaries to best match the radio light 3 2 curves – start Aug. 15, 2008 1 0 54000.0 54500.0 55000.0 55500.0 56000.0 Time RSP pipeline, energy range 0.1 – 300 GeV using power 2007.0 2008.0 2009.0 2010.0 2011.0 2012.0 9 2.64 J0721+7120 4.85 8.35 8 10.45 law over that energy range 14.60 23.05 7 32.00 42.00 86.00 142.33 6 228.39 Flux Density (Jy) 5 1FGL sources for ROI, ROI size etc. 4 3 2 future: switch to pass 7, 2 FGL sources, more careful 1 0 54000.0 54500.0 55000.0 55500.0 56000.0 spectral model for each source (e.g. broken power law for Time 2007.0 2008.0 2009.0 2010.0 2011.0 2012.0 45 2.64 J2253+1608 some etc.), LCs at different energy ranges etc. 4.85 8.35 40 10.45 14.60 23.05 35 32.00 42.00 86.00 142.33 30 228.39 Flux Density (Jy) 25 20 15 10 5 0 54000.0 54500.0 55000.0 55500.0 56000.0 Time

Project overview � The light curves � Examples: J0854+2006 J2253+1608 3.5e-07 2.5e-05 PRELIMINARY Fermi LAT PRELIMINARY Fermi LAT 3e-07 -1 ] -1 ] -2 s -2 s 2e-05 flux (E>100 MeV) [ph cm 2.5e-07 flux (E>100 MeV) [ph cm 2e-07 1.5e-05 1.5e-07 1e-05 1e-07 5e-06 5e-08 0 40 0 14 3mm PV 9mm EFF 12 20mm EFF 30 60mm EFF 10 flux density [Jy] flux density [Jy] 8 20 6 4 3mm PV 10 9mm EFF 2 20mm EFF 60mm EFF 0 0 54800 55000 55200 55400 55600 55800 54800 55000 55200 55400 55600 55800 MJD MJD

Project overview � Three different approaches � J1159+2914 J0721+7120 8e-07 5e-07 PRELIMINARY Fermi LAT PRELIMINARY Fermi LAT -1 ] -1 ] 4e-07 -2 s -2 s 6e-07 flux (E>100 MeV) [ph cm flux (E>100 MeV) [ph cm 3e-07 4e-07 2e-07 2e-07 1e-07 0 4 0 8 3mm PV 9mm EFF 20mm EFF 60mm EFF 3 6 flux density [Jy] flux density [Jy] 4 2 3mm PV 9mm EFF 2 20mm EFF 1 60mm EFF 0 54800 55000 55200 55400 55600 55800 54800 55000 55200 55400 55600 55800 MJD MJD 1 ) statistical Discrete Cross-Correlation Function (DCCF analysis) 2) flux r – flux γ analysis using simultaneous, monthly fluxes 3) direct LC analysis

1) DCCF analysis � The setup � compute DCCFs for each source: for all gamma-ray – radio ( ν , ν = 86, 32, 15, 5 GHz ) combinations following Edelson & Krolik (1988) caveats: 3yrs – still small number of events, complicated flare structures (multiple sub-flares), “broad DCCFs”, what correlates?, “monthly smoothing” etc. determine significances of correlations: test of chance correlations by mixing source’ gamma-ray LCs: e.g. source 1 (radio) with source 2 to N (gamma-ray), find “upper envelop” confidence levels time lags with uncertainties are estimated by Monte Carlo simulations (Peterson et al.) apply method to the whole sample plus sub-dividing according to FSRQs, BL Lacs, spectral type etc. stacking of DCCFs: increasing the significance, study of averaged behavior of the sample

1) DCCF analysis � First results � 3mm vs LAT: examples of single source’ DCCFs - single source cases mostly not significant: ”only” 18 out of 58 sources so far! - no obvious, simple 1:1 correlation - not yet long enough data trains PRELIMINARY - conservative upper envelops 2.0 1.5 2.0 DCCF DCCF DCCF J0102 J0217 J0050 1.5 1.5 1.5 1.0 1.0 PRELIMINARY 1.0 DCCF 0.5 0.5 0.5 0.0 0.0 0.0 1.0 -0.5 -0.5 -0.5 -1.0 -1.0 -400 -200 0 200 400 -400 -200 0 200 400 -400 -200 0 200 400 LAG (Days) LAG (Days) LAG (Days) 2.0 2.0 2.0 2.0 0.5 DCCF DCCF DCCF DCCF J0222 J0237 J0238 J0319 1.5 1.5 1.5 1.5 1.0 1.0 1.0 1.0 0.5 0.5 0.5 0.5 0.0 0.0 0.0 0.0 0.0 -0.5 -0.5 -0.5 -0.5 -1.0 -1.0 -1.0 -1.0 -400 -200 0 200 400 -400 -200 0 200 400 -400 -200 0 200 400 -400 -200 0 200 400 -0.5 LAG (Days) LAG (Days) LAG (Days) LAG (Days) 2.0 2.0 2.0 2.0 -400 -200 0 200 400 DCCF DCCF DCCF DCCF J0336 J0339 J0418 J0423 1.5 LAG (Days) 1.5 1.5 1.5 2.0 1.0 PRELIMINARY 1.0 1.0 1.0 DCCF 0.5 0.5 0.5 0.5 1.5 0.0 0.0 0.0 0.0 -0.5 -0.5 -0.5 -0.5 1.0 -1.0 -1.0 -1.0 -1.0 -400 -200 0 200 400 -400 -200 0 200 400 -400 -200 0 200 400 -400 -200 0 200 400 LAG (Days) LAG (Days) LAG (Days) LAG (Days) 2.0 2.0 2.0 2.0 DCCF DCCF DCCF DCCF J0530 J0721 J0654 J0730 1.5 1.5 1.5 0.5 1.5 1.0 1.0 1.0 1.0 0.5 0.5 0.5 0.5 0.0 0.0 0.0 0.0 0.0 -0.5 -0.5 -0.5 -0.5 -0.5 -1.0 -1.0 -1.0 -1.0 -400 -200 0 200 400 -400 -200 0 200 400 -400 -200 0 200 400 -400 -200 0 200 400 LAG (Days) LAG (Days) LAG (Days) LAG (Days) -1.0 -400 -200 0 200 400 LAG (Days)

1) DCCF analysis � First results � 3mm vs. LAT: stacking of DCCFs averaged DCCFs averaged DCCFs averaged over whole LAT / 3mm radio 0.3 LAT / 3mm radio all sources FSRQs sample: we start seeing BL Lacs 0.3 0.2 significant correlations ! 0.2 0.1 DCCF DCCF 0.1 99% confidence levels 0 0 -0.1 asymmetry -0.1 PRELIMINARY PRELIMINARY -0.2 -0.2 -400 -300 -200 -100 0 100 200 300 400 -400 -300 -200 -100 0 100 200 300 400 LAG [days] LAG [days] averaged DCCFs averaged DCCFs All sources: LAT / 3mm radio LAT / 3mm radio 0.3 0.3 FSRQs BL Lacs <lag> 3mm = 36 days 0.2 0.2 FSRQs: 0.1 0.1 DCCF DCCF <lag> 3mm = -1 days 0 0 -0.1 -0.1 BL Lacs: PRELIMINARY PRELIMINARY -0.2 -0.2 <lag> 3mm = 37 days -400 -300 -200 -100 0 100 200 300 400 -400 -300 -200 -100 0 100 200 300 400 LAG [days] LAG [days]

1) DCCF analysis � First results � 60mm vs LAT: stacking of DCCFs averaged DCCFs averaged DCCFs 0.3 0.3 LAT / 60mm radio LAT / 60mm radio PRELIMINARY 0.2 0.2 0.1 0.1 DCCF DCCF 0 0 -0.1 -0.1 all sources FSRQs BL Lacs PRELIMINARY -0.2 -0.2 -400 -300 -200 -100 0 100 200 300 400 -400 -300 -200 -100 0 100 200 300 400 LAG [days] LAG [days] delay origin: synchrotron self-absorption/opacity All sources: (e.g. Pushkarev et al. 2010) <lag> 60mm = 197 days 1) pos. delay: gamma from inside “3mm-core” FSRQs: <lag> 60mm = 197 days 2) distance between “gamma-origin” and 86 GHz t=1 surface: Δ r ~ 0.8 pc (3mm), ~ 8 pc (60mm) BL Lacs: <lag> 60mm = 77 / 239 days 3) DCCF just sensitive to peaks/mins! which originates first?

2) flux-flux analysis � The setup + first results � ~ monthly, multi-frequency simultaneous fluxes over 3 years: interpolated LAT fluxes for each radio flux measurement 86 GHz: total number of data points: 1017 (FSRQs: 499, BL Lacs: 359, other: 8) Gamma vs. radio flux Gamma vs. radio flux 86 GHz / 3mm 86 GHz / 3mm PRELIMINARY PRELIMINARY 1e-05 1e-05 -1 ] -1 ] -2 s -2 s flux (E>100 MeV) [ph cm 1e-06 flux (E>100 MeV) [ph cm 1e-06 1e-07 1e-07 1e-08 1e-08 1e-09 1e-09 FSRQs ALL SOURCES BL Lacs 0.1 1 10 100 0.1 1 10 100 radio flux density [Jy] radio flux density [Jy]