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Svetlana J.: 1. theoreticians have to pay attention to these behaviors. 2. what theoreticians want form from MW campaigns/observations? 3. there are needs to justifications in maintain VLBI monitor for example.
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Main goals of time-series (variability) analysis:
(1) identifying nature and gain physical understanding of the phenomenon/object producing the observed time series;
(2) forecasting (predicting future behavior and future values of the time series quantity).
What we can learn from short timescales (<1 day) of variability that can be pserberved by the LAT for very bright flares.
Search for breaks in the PDS (relation with physics, SMBH mass like for X-rays in Seyferts?).
Can the LAT allows systematic nulti-wavelength multiwavelength variability studies measuring the PDS-SED-plane (i.e. timescale-energy plane)?.
Broad-band MW studies: cross-correlation and time lags. MW SED modeling. Gamma-ray-synchrotron amplitude ratio studies, orphan flares, Physics physics of the gamma-ray emission in AGN, identification of newly discovered gamma-ray sources, spectral index hysteresis, etc.
PHYSICS OF GAMMA-RAY EMITTING AGN (includes mainly blazars and radio galaxies)
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-- C.3 WHERE are the X-rays/gamma-rays produced ?
AGN studies with GLAST: Science GoalsFermi LAT: some pre-launch science goals:
(1): Does the "blazar sequence" scheme hold for a large sample of objects?
(2): Are SSC models in trouble for the HBL-type blazars?
(3): Are single-zone synchrotron + Compton models applicable?
(4): Are synchrotron and Compton components produced co-spatially?
(5): What is the content of the innermost part of the relativistic jet?
(6): Total charged particle content / kinetic energy of the blazar jets as compared to the radiative output
(7): are gamma-ray flares related to dissipation of magnetic energy?
(8): Do blazars and radio galaxies accelerate ultra-high energy cosmic rays?
(9): Tests of the Compton-scattered CMBR interpretation of extended X-ray (Chandra) jets
(10): Energization Sites and Bulk Relativistic Speeds of Blazar Jets
(11): Constaints/hints on matter composition of gamma-ray emitting jet region
Variability analysis of LAT and MW data is required in most of these topics.
Problem of faint sources: real variable source or background fluctuations?
High degree (up to 30%) and variability of the optical polarization (OP) is one of the defining properties of blazars (especially the classical BL Lac objects and high-pol. quasars HPQ). This means that OP observations are might be an important element in confirmation of new blazar candidates.
Results from the LAT paper on blazars (106 spurces) gamma-ray variability studies (first 11 month data):
LAT gamma-ray blazars are displaying 2 “flavors” of variability:
1) constant baseline with sporadic flaring activity showing also intermittence (flatter PDS, red noise); 2) a few sources showing strong activity with complex and structured time profiles characterized by the long-memory, steeper PDS slopes (random walk processes).
Dave T.:
Fermi Gamma-ray Space Telescope characteristics and experience from 7 years in orbit.
Methods for simultaneous studies: 1.Wide-field telescopes 2.Monitoring programs 3.Dedicated multiwavelength campaigns 4.Good luck
Methods for near-simultaneous/follow-up studies: Rapid sharing of information
The Fermi wide-field instruments are an approximation to “all the sky, all the time,” which would be needed across the electromagnetic spectrum to catch everything of interest. Probably not practical. LOFAR, MAXI, HAWC, Swift-BAT are examples of other wide-field instruments, along with multimessenger facilities like IceCube, Antares, and Advanced LIGO/Virgo. This is a developing field.
Monitoring programs are being carried out for classes of objects known to show variability or transient behavior.For Fermi, blazars and pulsars are classes of interest that are monitored (at least for a subset) at many wavelengths. Example monitoring programs include MOJAVE, OVRO (radio), Tuorla, SMARTS (optical), Swift (X-rays).
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