Variability Study of Fermi Blazars

Students

Bindu Rani

Debbijoy Bhattacharya

Hüsne Dereli

Reham Mostafa Ayoub

Ravi Joshi

Renyi Ma Supervisors

Peter Willmore

Benoit Lott

Varsha Chitnis

Gulab Dewanga

Standard model for AGNs

An extragalactic object

More luminous than normal galaxies

Generally compact, point sources (stellar appearance) at the center of a galaxy. Supermassive Black hole, 108-109 solar masses.

Active Galactic Nucleus

The point source can be 10-100 times the brightness of the underlying galaxy

~ 10

Some exhibit jets

AGN Type

the angle between the observer and the object

the mass of the object

how much mass the black hole accretesAGN ClassificationAccording to Emission lines According to Radio-Optical flux ratio A) Radio-Loud AGNs (Jets) 1.Radio Galaxies 2.Radio-loud Quasars 3.Blazars a) BL Lac b) FSRQ (OVV) B) Radio-Quiet AGNs (No Jets) 1. Seyfert galaxies (Type I and Type II) 2. LINERs 3. Radio-quiet quasars/QSOs

Blazars

•AGNs with jets, pointing directly at us.

•Radiation from the jet swamps out all other sources

•Highly relativistic beams, particles in the jets, the observed gamma rays.

•Extreme variability at all frequencies

– FSRQs: lower polarization– BL Lac: high polarization,

FSRQs BLLacs

List of sources BL Lac :

AO 0235+164

3C 66A FSRQ :

B2 1520+31

3C 279 TeV Blazar

PKS 2155-304

Analysis methods :

Likelihood Analysis Spectral Analysis in energy bandsLight curves

Aperture Photometry Light curves

Results:

AO 0235+164

B2 1520+31

PKS 2155-304

3C 279

3C 66A

Summary

Blazar

FSRQs BL Lacs

281 FSRQs291 BL Lacs

The source We Studied

FSRQ BL Lac

3C 279 3C 66A (ISP)

B2 1520+31 AO 0235+164 (LSP)

PKS 2155-305 (HSP)

Our Results

1. BL Lacs have a relatively flat spectra than FSRQs.

2. For some sources the spectra is better fitted with broken power law than simple power law.

3. Do not show significant spectral index variation.

Results:

3c279

Mrk 421

Borrowed from Benoit Lott presentation

Variation of Spectral Index with Flux

More detailed study is needed in order to understand the emission mechanism of different source classes.

Study the variation of spectral index in greater detail.

To understand the energetics and dynamics of jet and accretion disk, one need to study the objects over a broad energy band.

The simultaneous multiwavelength study will help to constrain crucial parameters of jet emissions.

Study their evolution as a class.

Future Plan