Fermi Source Analyses and Identifying VERITAS Candidates 1 1 1. University of California, Berkeley
2 Overview Introduction VERITAS Fermi Analysis Likelihood Doppler Factor Estimation Motivations Blazars Open Questions Sources 3FGL J1250.2-0233 3FGL J2209.8-0450 B2 1215+30
3 Overview Introduction VERITAS Fermi Analysis Likelihood Doppler Factor Estimation Motivations Blazars Open Questions Sources 3FGL J1250.2-0233 3FGL J2209.8-0450 B2 1215+30
4 VERITAS Very Energetic Radiation Imaging Telescope Array System Atmospheric Cherenkov Radiation Telescopes Maximum sensitivity from 85 GeV 10 TeV Three level trigger system (pixel, pattern, array)
5 Fermi Telescope Fermi Large Area Telescope Uses pair conversion instruments Detection range from 20 MeV - 300 GeV First trigger is detection in three planes, followed by an anticoincidence systems
6 Overview Introduction VERITAS Fermi Analysis Likelihood Doppler Factor Estimation Motivations Blazars Open Questions Sources 3FGL J1250.2-0233 3FGL J2209.8-0450 B2 1215+30
7 Blazars Thermal processes alone cannot create γ-rays Disk-dominated AGNs Jet-dominated AGNs SEDs show two distinct peaks
8 Cosmology, Structure Formation, Space-Time, and Dark Matter Extragalactic Background Light constrains galactic formation history TeV γ-rays annihilate and pair produce on EBL absorption feature in blazar spectra TeV photon annihilation should result in GeV emission in blazar spectra. Not actually observed Intergalactic Magnetic Fields Blazar Heating Burst variability could constrain energy-dependent speed of light c 2 p 2 = E 2 1 + ξe + ηe2 E QG E QG 2 + Δt = ξ E E QG L c γ-ray energies well suited for dark matter particle candidate searches Finding possible sources for ultra high energy cosmic rays
9 Overview Introduction VERITAS Fermi Analysis Likelihood Doppler Factor Estimation Motivations Blazars Open Questions Sources 3FGL J1250.2-0233 3FGL J2209.8-0450 B2 1215+30
10 Fermi Likelihood Analysis Likelihood (L): probability of observing detected counts in a bin L = e N exp i m i N exp = total number of counts model predicts m i = expected number of counts in i-th bin Test Statistic (TS): 2ln L null L ; σ 2 Spectral Model Used: dn de = N 0( E E 0 ) γ Prefactor = N 0 Index = γ Scale = E 0
11 Doppler Factor Estimations Variability time scales can be calculated using light curve data during flares F t = F C + F 0 2 (t t 0) t var F c = average source flux F 0 = flux of flare at t 0 t var = variability time scale δ σ Td L 2 5hc 2 1 + z 2α F 1keV t var E γ GeV α 1 4+2α σ T = Thomson cross section d L = luminosity distance α = X-ray spectral index E γ = highest energy photon F 1keV = X-ray flux in μjy
12 Overview Introduction VERITAS Fermi Analysis Likelihood Doppler Factor Estimation Motivations Blazars Open Questions Sources 3FGL J1250.2-0233 3FGL J2209.8-0450 B2 1215+30
13 Population Studies Compared integrated fluxes to Crab Nebula Flux N0 ( E ) γ de E 0 F = Eth N 0 = Flux Density E 0 = Pivot Energy E th = 80 GeV γ = Spectral Index
14 3FGL J1250.2-0233 TS Map > 5% Crab Nebula Flux RA: 12h 50m 16.320s DEC: -02 0 33 50.40 Energy range: 5 GeV 100 GeV Time range: Sep 2008 Sep 2010 Source region radius: 10 0 ROI radius: 5 0
15 3FGL J1250.2-0233 TS Map > 5% Crab Nebula Flux RA: 12h 50m 16.320s DEC: -02 0 33 50.40 Energy range: 5 GeV 100 GeV Time range: Sep 2008 Sep 2010 Source region radius: 10 0 ROI radius: 5 0
16 5BZB J1246+0113 Counts Map BL Lac object in catalog BZCAT5 RA: 12h 46m 02.500s DEC: +01 0 13 18.80 Redshift (z): 0.386
17 3FGL J2209.8-0454 TS Map > 2% Crab Nebula Flux RA: 22h 09m 52.080s DEC: -04 0 51 00.00 Energy range: 5 GeV 300 GeV Time range: Sep 2008 Sep 2010 Source region radius: 10 0 ROI radius: 5 0
18 3FGL J2209.8-0450 Light Curve Time Range: Sep 2008 Sep 2012 Energy Range: 5 GeV 300 GeV Fixed Spectral Index: 1.13 ± 0.31 4 energy bins Monthly bins
19 3FGL J2209.8-0450 Associations? Swift-XRT survey of Fermi unassociated sources find: 1RXS J220942.1-045120 2.52 away NVSS J220941-045111 2.59 away
20 B2 1215+30 TS Map RA: 12h 17m 51.600s DEC: +30 0 07 04.80 Energy range: 100 MeV 100 GeV Time range: Jan 2015 Jul 2015 Source region radius: 20 0 ROI radius: 10 0
21 B2 1215+30 Light Curves Time Range: Jan 2015 Jul 2015 Energy Range: 100 MeV 100 GeV Fixed Spectral Index: 1.90 ± 0.02 8 energy bins
22 B2 1215+30 Light Curves Time Range: One week Energy Range: 100 MeV 100 GeV Non-Fixed Spectral Index 8 energy bins
23 Doppler Factor Estimations Variability time scales can be calculated using light curve data during flares F t = F C + F 0 2 (t t 0) t var F c = average source flux F 0 = flux of flare at t 0 t var = variability time scale δ σ Td L 2 5hc 2 1 + z 2α F 1keV t var E γ GeV α 1 4+2α σ T = Thomson cross section d L = luminosity distance α = X-ray spectral index E γ = highest energy photon F 1keV = X-ray flux in μjy
24 Doppler Factor Estimations Analysis by Floriana Zefi of B2 1215+30 conducted Fermi-Lat and VERITAS detected flare in February 2014 Variability time scale derived form Fermi light curve t var = 4.5h Minimum Doppler factor δ = 5.7
25 Conclusion Gamma-ray sources require some form of nonthermal emission for detection Blazars are common candidate 3FGL J1250.2-0233 not convincingly detected, but analysis reveals corresponding source in ROI from different catalog 3FGL J2209.8-0450 convincingly detected. Light curve needs improvement B2 1215+30 has significant detection. Doppler factor estimations help reveal jet properties
26 Acknowledgements I would like to thank Reshmi Mukherjee, Brian Humensky, and Marcos Santander for their guidance Congratulations to my fellow REU students for all of their accomplishments Thanks Mike Shaevitz, John Parsons, and Amy Garwood Brought to you by the National Science Foundation
27 QUESTIONS?