Download Standard model for AGNs

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 accretes
AGN Classification
According 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 bands
Light 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 FSRQs
291 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:
Borrowed from Benoit Lott presentation
3c279
Mrk 421
Variation of Spectral Index with Flux
Future Plan
 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.