r = Ag / Aopt > 2 or more, so Compton dominance varies. News concerning Blazars: 1) mirror effects in Flat Spectrum Radio Quasars 2) cyclic modulation in BL Lacertae Objects (V.Vittorini, M. Tavani, A. Cavaliere) 1) FSRQs: Remarkable flares g (0.1 ÷ 5 GeV) in 3C 454.3, 3C 279, PKS 1830-211 … show ratios of optical to g-ray variations r = Ag / Aopt > 2 or more, so Compton dominance varies. (vs. standard EC r = 1) Moreover, in these flares correlation of g-ray and optical bands is often complex or absent, g-flux doubles in a few hours, high energy spectrum may be very hard.

3C 279 shows orphan r = 6 r = 1 r = 0 r = 4 different degrees of correlation g - O, down to absence. The decay of Flare 2 is abrupt. To account for such complex behaviors, some variations are required in the external photon field

The source contains moving plasmoids like knots observed in radio superluminal counterparts. External photon seeds for IC is provided by a leading plasmoid that partially reflects S emissions from following ones. Photons are IC upscattered in the gap d = Rm (2Ge)-2 by electrons accelerated in situ (see below). G IC from gaps attains luminosities LIC ~ B2 G8÷10 ~ 1048 erg / cm2 s on timescale ~ d / (c Ge2) hours Here Ge ~ 5 is the relative boost between mirror and emitter.

mirror flares The model yields strong IC emission in g rays L ~ B2 G10 ≤ 1048 erg / cm2 s delayed by Rm / (cG2) ~ week relative to plateau emitted within the BLR  de-correlated g-ray flares! spiky plateau month zoom to hours Rise-time Rm / (4cG4) ~ hours. Low absorption by g g interactions.

2) Cyclic emissions g – O from BL Lac PG 1553 + 113 observed T ≈ 2.18 yr w. high significance Ackermann et al. 2015: multi l (g, soft X, O) observations w. cyclic modulation + X-ray outbursts A strong case for a binary SMBH system, M1 ~ 108 Msun M2/M1 ~ 10-1 , r ~ 10-2 pc

Non - circular, non - Keplerian orbits in a long inspiral stage Bulk properties of main jet affected by squeezing and shearing due to differential gravitational stresses Topology of B lines changed, by rearrangement and reconnections, known to cause plasmoid formation and electron acceleration to a flat power law with gcut ~ 103 and above (see Kagan, Sironi, Cerutti, Giannios 2015 also Melzani et al. 2014) Main parameters: magnetizations for bulk stability sj = B2 / 4p c2 mp np G2 ≈ 1, for acceleration se = G2 (mp / me) sj compressed / increased B rises sj and se ~ 104 sj  sheared / reconnected B-lines with se ~ 104 sj stir electron acceleration to high g

Increased B and high g yield strong X-ray outburst beyond the first SED peak

Here we plot the relative boost factor Ge = Gm Gint ( 1 – bm bint ) between mirror and emitter as a function of the mirror boost Gm and the emitter boost Gint

With a jet opening angle The knot K10 emerges from the core T=160 days after the flare (Jorstad et al. 2012). With a jet opening angle 1.6° K10 traveled Rc=16 pc before being resolved. For G = 10 and q = G-1 the predicted lag is T=(1-bcosq) Rc / c T=G-2Rc / c = 0.5 years 21 Apr 2011 10

PKS 1830: an extreme instance Orphan gamma-flare during a montly activity (Ag=3): Optical and X-ray remain at hystorical steady levels. Peak (Oct. 14) Flare (Oct. 14 – 18) 1 month enhancement Oct. 8 – Nov. 8 Steady g (EGRET) A second component of shocked particles (red dotted lines) can account for this monthly enhancement in gamma-rays with little or no contributions in optical and X-rays. But the fast orphan flare (Ag = 5 on 6 hours) around Oct. 14 would require some variation in the external field of seed photons ! Ciprini et al. 2010; Donnarumma et al. 2011

The November 2010 super flare of 3C 454 (Vercellone et al. 2011) start plateau precursor jump peak No gamma-ray counterpart: r = 0 at the precursor, whereas at the start r = 1 Faint soft X-ray counterpart (SC plays a secondary role!) MgII line flux variations of 30% (Leon Tavares 2013) Strong 1 day optical flare (energization of a new component in the inner jet) With courtesy of E. Striani and J. Leon Tavares 4

FSRQ standard model External: galaxy frame (z) , radiation connected with accretion External photons Next and jet electrons ne (g) produce External Compton (EC) Jet: blob moving with Lorentz factor G, beamed, non thermal radiation Electron distribution ne (g) and magnetic field B produce G Synchrotron + Inverse Compton (SSC) 14