1. 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 …
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.

2. 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

3. 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 ~ erg / cm2 s
on timescale ~ d / (c Ge2) hours
Here Ge ~ 5 is the relative boost between mirror and emitter.

4. mirror flares
The model yields strong IC emission
in g rays L ~ B2 G10 ≤ 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.

5. 2) Cyclic emissions g – O from BL Lac PG 1553 + 113
observed T ≈ 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

6. 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

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

9. 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

10. 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

12. 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

13. 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

14. 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