Fermi LAT Main OP313

The Fermi LAT analysis has been performed on a large time scale to derive a long-term light curve and run a Bayesian block analysis to defined bocks of observation

Parameters

RA      =        197.6324  degrees
Dec     =        32.3547  degrees
Start   =        715617241.0   MET (s)
Stop    =        727281241.0   MET (s)
ROI     =        10.0  degrees
E min   =        100.0  MeV
E max   =        300000.0  MeV
E min ext       =        50.11872336272722  MeV
E max ext       =        598578.6944906638  MeV
IRFs    =        P8R3_SOURCE_V3
evclass =        128
evtype  =        3

Long term Fermi-LAT Light curve

This plot is the Fermi-LAT LC with the final bayesian block description. The block are given in the table after

Fermi-LAT BB light-curve

In the High state, I used bins of around 12 hours, 1 day in the Mid state and 3 days in the low state

Date	MET start	MET stop	N bins
high	722300909	722984524	16
	723877193	724823786	22
Mid	722104724	722300909	2
	722984524	723877193	10
	724823786	725266164	5
	726394414	726767552	4
Low	716277470	722104724	22
	725266164	726394414	4
	726767552	727281241	2

SEDs

For each SED, a powelaw and a logparabola model were tested

Low

The spectrum is best described by a logparabola with a TS = 7

Decorrelation energy : 4.14e+02 MeV
TS :  1356.0178181243173
norm :  108.86 +/-  6.16 [ -6.05, + 6.27 ] 1e-12
alpha :  2.03 +/-  0.08 [ -0.08, + 0.07 ] 1e+00
beta :  0.08 +/-  0.04 [ -0.03, + 0.04 ] 1e+00
Eb :  414.00   1e+00

Fermi-LAT SED Low

Mid

The spectrum is best described by a logparabola with a TS = 8
Decorrelation energy : 4.66e+02 MeV
TS :  2584.4997249984517
norm :  238.16 +/-  11.60 [ -11.40, + 11.80 ] 1e-12
alpha :  1.79 +/-  0.05 [ -0.06, + 0.05 ] 1e+00
beta :  0.06 +/-  0.02 [ -0.02, + 0.02 ] 1e+00
Eb :  466.00   1e+00

Fermi-LAT SED Mid

High

The spectrum is best described by a logparabola with a TS = 80

Decorrelation energy : 5.66e+02 MeV
TS :  8991.45
norm :  467.06 +/-  14.19 [ -13.97, + 14.41 ] 1e-12
alpha :  1.57 +/-  0.03 [ -0.03, + 0.03 ] 1e+00
beta :  0.10 +/-  0.01 [ -0.01, + 0.01 ] 1e+00
Eb :  564.00   1e+00

Fermi-LAT SED high

All in a SED

This plot show the same 3 SED but in one plot

Fermi-LAT SED high

Sanity checks

I ran a Fermi-LAT analysis in each block to see differences within each block

Fermi-LAT SED high

Fermi-LAT SED mid

Fermi-LAT SED low

Fermi-LAT analysis on the LST GTI

The Fermi-LAT pipeline allow to run an analysis based on pre-defined GTI. This has been done using the LST observation time. For this the December and January data set were separated since they correspond to 2 different flux states.

GTI correspond to the LST observation time after data selection, plus or minus 1 hour

December

• GTI definition :

723873640.4679999 723885814.544
723961205.0 723972636.3690003
724045627.3670001 724058152.8549998
724131722.0 724143939.893
724218276.9149997 724231900.1550002
724304640.2630002 724318201.9809997
724390555.44 724404422.1790001
724477321.222 724491352.339
724563718.779 724577641.8430002
724650067.315 724663888.9659998

• results

The spectrum is best described by a logparabola with a TS = 8

Decorrelation energy : 6.36e+02 MeV
TS :  485.58040012843094
norm :  319.83 +/-  42.96 [ -37.51, + 0.00 ] 1e-12
alpha :  1.47 +/-  0.14 [ -0.15, + 0.14 ] 1e+00
beta :  0.15 +/-  0.06 [ -0.06, + 0.07 ] 1e+00
Eb :  631.00   1e+00

Fermi-LAT SED in LST GTI (December 2023

January

• GTI definition :

726552297.6990001 726561947.6859998
726892290.0700003 726907611.6300001
727240316.6290002 727249629.2620002
727413535.0709997 727427037.5470002
727591996.0049999 727601886.3499998

The spectrum is best described by a PowerLaw

Decorrelation energy : 7.50e+02 MeV
Diffential flux  at the Decorrelation energy : 9.45e-11 +/-  3.38e-11 ph/cm2/s/MeV
SED value at the Decorrelation energy : 8.51e-11 +/-  3.04e-11 erg/cm2/s
TS :  35.69191921871675
Prefactor :  12.46 +/-  5.67 [ -4.97, + 6.36 ] 1e-12
Index :  -1.92 +/-  0.27 [ -0.28, + 0.25 ] 1e+00
Scale :  2158.74   1e+00

Fermi-LAT SED in LST GTI (Janvier 2024