Monitoring of Blazars for variability from MIRO. Kiran S Baliyan Physical Research Laboratory, Ahmedabad, India

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1 Monitoring of Blazars for variability from MIRO Kiran S Baliyan Physical Research Laboratory, Ahmedabad, India Black-holes, Jets and Outflows, Kathmandu, Nepal, October 14, 2013

2 Enigmatic AGNs AGNs- Huge energy from very compact size, Energy engine non-resolvable- Even by sub-mm VLBI How to study structure/energy mechanism? Option available for study: Use their properties Observables for the study Most AGNs, Blazars in Particular, are highly variable Flux varies at time-scales from years to minutes Polarization, radio and optical : High and variable Flux variations noticed at all frequencies in EM mm/sub-mm VLBI imaging is able to resolve sub-pc jet

3 ENIGMATIC AGN High luminosity & short timescale variability implies that AGN power is produced by more efficient process than stellar Standard Model:Supermassive Black Hole at the Center, surrounded by accretion disk Clouds of line emitting gas Obscuring torus of gas & dust VARIABILITY- a Tool! (Urry & Padovani 1995)

4 Blazar: Characteristics Blazars (Ed Spegel): Quasars + Bl Lacs Variability at all wavelengths: Long term & rapid High & variable optical polarization Viewed close to jet direction (Padovani & Urry 1992) Jet dominated emission Double humped SEDs: Blazar sequence?

5 Spectral Energy Distribution: Blazars Classification based on position of Synchrotron peak Synchrotron peak Freq. increasing : FSRQ > LBL > IBL > HBL FSRQ: Broad emission lines BL Lacs: weak/no Emission lines LIC/Lsyn Decreases as peak frequency increases FSRQ: IC component dominant

6 Monitoring of Blazars: Multi-frequency light-curves Variations in the Blazar lightcurves manifest in flares and outbursts at various time scales and shapes. Such features appear in LCs for all the energy regimes Correlation in such features at different frequencies provides clues to the emission processes, location and size of the emission regions. These, in combination with SEDs, help constrain the models proposed for AGN emission.

7 Blazar monitoring from MIRO Lat. 24O 39' 10'' Long. 73O 46' 47''E, Alt: 1680 Mts ATVS: CDK-20 Telescope Mounted with EMCCD 1kx1k FOV ~ 13' x 13' Optical CCD 1296 x 1152 pixels FOV ~ 6'.5 x 5'.5

8 Blazar monitoring from MIRO Blazar observations since 1996 InfraRed Telescope 1.2 m Detectors: CCD 1024x1024, 1296x1152 Optical CCD NICMOS-3 256x256 Near IR Long Term monitoring of a set of blazars 3C66A, 3c434.3, 3c279, S , Mrk 421, Mrk 501, OJ287, Wcom, etc ATVS: CDK-20 Telescope Mounted with EMCCD 1kx1k FOV ~ 13' x 13' Blazar Monitoring Collaborators: Shashi Ganesh, UC Joshi, Sunil Chandra (Student)

9 Monitoring: Intra-night Optical variations S : March 2010 Intra-night 0.4 mag in 1.42 Hrs Microvariations 15s -35 secs from light travel time: Emission Region Size: 1015cm Mass of BH 109Mo R-band LC showing rapid variations during Jan 20, 2012, 0.2 msg in 2.3 Hrs Such variations are seen at very high, upto 90% duty cycle in FSRQ/LBLs. HBLs show low duty cycles of variation Sunil et al ApJ 2011

10 Mt Abu Observations: S Light Curve Significant intra and inter-night variations in S , during March 14-19, 2010 Inter-night variations ranging from 0.2 mag to 0.8 mag are seen Bluer when brighter : electrons injected Mild chromatic behaviour rules out geometric effects as cause of variation Sunil et al ApJ 2011 R-band LC showing rapid variations during Mar 14-20, 2010

11 MIRO Blazar Monitoring: Long Term S How frequent are the 'short-term' intra-night variations? Observations during : Only Nights showing IDV

12 MIRO Blazar Monitoring: Long Term How frequent are the 'short-term' intra-night variations? Observations during : Only Nights showing IDV

13 Long Term Optical monitoring of blazars : MIRO Duty cycle of variation in S Statistical study with 68 nights having observation time >2 hrs Duty cycle of variation for S If observed for more than 2 hrs over the night, probability that source shows variability: 84% (with 99% confidence)

14 Optical Monitoring of Blazars : MIRO Long-term (Dec 2005-Nov 2012) multi-band optical light-curve for S

15 Optical Monitoring of Blazars : MIRO Long-term (Dec 2005-Nov 2012) multi-band optical light-curve for S How the color changed with brightness: BWB- as explained by Shock-in-jet

16 Optical Linear Polarization observations : MIRO Long-term (Dec 2005-Nov 2012) multi-band optical light-curve for S Amplitude of variation as a function of blazar brightness S Unexpected trend Show larger Amp of variation towards fainter side Flaring state, base level high? Quiet state, variation feature shows Dominently?

17 Optical Linear Polarization observations : MIRO Polarization measurements play important role in the magnetic field configuration and hence in the study of jet structure Optical linear polarization observations are made with PRL-Photopolarimeter, mounted at 1.2m Mt Abu telescope. Optical Polarimeter

18 Polarization & Blazars Sequence Synchrotron emission in the jet gives rise to polarization- radio to x-rays. Jet has local and extended magnetic field and shocks/disturbances moving down the jet interacting with local inhomogeneities. Jet emission shows distinct behaviour for FSRQ and BL Lacs

19 Optical Polarization & Flux in blazar High energy gamma-rays and optical emission show flares which are almost simultaneous. Timing of these and availability of Optical polarization, VLBI imaging at mm-submm help locate the location of high energy emission. Shocks move in spiral streamline and cover most cross section of jet, creating flares. Spiral streamline is due to flow rotation & helical field.

20 Blazars: Polarization variations FSRQs and LBLs show high degree of variable polarization, intra- as well as Night to night variation. Mrk 501, an HBL, shows 3-4 % DP While OJ287 (LBL) shows upto 40% DP Joshi, Baliyan, Koul et at 1998) Large Change in P%! About 15% increase in the degree of polarization during December 17, 2006 to January 15, 2007(OJ287)

21 Blazar CGRaBSJ : MIRO 2011 Observations Listed in Ist FERMI Catalog (Abdo et al 2010) On Jan 23, 2011, Fermi(LAT) detected flaring activity- flux 25 times the average SWIFT, Jan 25, 2011: U=13.77, V= 14 mag (Atel 3120,29) Jan 27, Nesci(Atel 3127) Rc= mag, Bright by 1.3m vis-a-vis 2010 Kudelina(Atel 3131) White light pol= 12% on Jan 28 Polarization observations during Jan 30 (21% Pol) Feb 3, 2011 Significant Inter-night & PINOV detected z=0.201, Host gal I=16.89 (S Chandra et al ApJ 746, 92, 2012)

22 Polarization of CGRaBSJ :MIRO 2011 Rapid. large amplitude polarization flashes on Feb 2 & 3, mins to 45 mins > Turbulence in the jet PA remains range bound during the night Polarization increases with frequency : smaller cells? High & Variable DP: LBL?

23 Polarization of CGRaBSJ :MIRO 2011 Large night-to-night variation in DP & PA Sudden changes in PA, with increase in DP on Jan 30 (from 12% on Jan 26) and Feb 2 Fresh injection of plasma in the jet DP and PA Jan 30-31, Feb 1-3, Cm telescope: EMCCD

24 Optical Linear Polarization observations : MIRO Performed a statistical study using maximum DP detected in LBL(+FSRQs) and HBLs, 47, 46 sources, respectively. 1. More than 80% LBL show DP > 10% 2. More than 50% HBLs, Show less than 5% DP LBLs are more highly polarized than HBLs High and variable DP in CGRaBS J : Proposition: an LBL

25 Optical Linear Polarization observations : MIRO Spectral energy distribution CGRaBS J : LBL Confirmed Synchrotron peak falls at 1.3x 1014 Hz: LBL

26 Polarization Variation in Blazars OJ 287: Jan May 2007 Average polarization ~10% Outburst shows increased polarization and rotating PA Correlated enhancement in optical polarization and Xray flux during outburst phase of OJ287 >> SSC model Optical

27 Summary Blazars have jet dominated emission- high, variable optical polarization long-term monitoring of blazars- large amount of data. S monitored for more than 10 years: Show IDV, short and long term variation Amplitude increases with Freq. High duty cycle of variation (>84%), BWB behaviour CGRaBS J First detailed detection of high and variable polarization Significant intra-night variations on Feb 2 & 3, > turbulence in the shock Large night to night variations detected with sudden change in polarization angle indicating injection of fresh plasma in the jet. High, variable polarization suggests it to be an LBL blazar. LBL suggestion is confiremd by SED which has Synchrotron component peaking at low frequency.

28 I STOP HERE!! Thanks a lot for your Kind attention!!