All-Sky Earth Occultation Observations with the Fermi Gamma-ray - - PowerPoint PPT Presentation

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Oct 16, 2022 49 likes •139 views

All-Sky Earth Occultation Observations with the Fermi Gamma-ray Burst Monitor Occultation step Visible Crab Nebula C.A. Wilson-Hodge (NASA/MSFC ), Count rate detected to 300keV G. Case, M. Cherry, J. Rodi (LSU), M. Not visible Finger, P.

SLIDE 1

Count rate Time Visible Not visible Occultation step

Crab Nebula detected to 300keV

All-Sky Earth Occultation Observations with the Fermi Gamma-ray Burst Monitor

C.A. Wilson-Hodge (NASA/MSFC),

G. Case, M. Cherry, J. Rodi (LSU), M.

Finger, P. Jenke (USRA), A. Camero-Arranz (NSSTC), V. Chaplin, V. Connaughton, P.N. Bhat, M. Briggs (UAH), E. Beklen (METU), R.H. Haynes (NASA Academy) for the GBM Earth Occultation Team

SLIDE 2

GBM Bismuth Germanate (BGO) Detector GBM Sodium Iodide (NaI) Detector LAT

GBM
12 NaI detectors
8keV - 1 MeV
2 BGO detectors
150 keV - 40 MeV

Fermi Gamma Ray Burst Monitor (GBM)

SLIDE 3

Earth Occultation Step Fitting

Predict occultation times
Determine detectors

viewing source of interest

Fit to each detector and

energy channel

– Background model – Model count rates for each source

Detector responses
Assumed energy

spectrum

Atmospheric

transmission

Compute best scale factor

for all detectors to estimate fluxes.

Fermi/CGRO differences

– Fermi rocks to +/-50 deg from Zenith every orbit – Detector blockages – Low/High energy coverage

SLIDE 4

Crab Nebula detected to >300keV

GBM Earth occultation monitoring

Initial catalog of 47

sources

– X-ray binaries – Crab – Cen A

Developing software

– Energy spectra – Source monitoring using BGOs – Imaging (Poster P5.209 Case et al.)

Crab in BGO Energy Spectra

SLIDE 5

Black Hole Binaries with GBM and Swift/BAT

Cyg X-1 GRS 1915+105 Cyg X-3

SLIDE 6

More Black Hole Binaries

Swift J1753.5-0127

New BH Transient!

XTE J1752-223

See Poster P5.195 Cherry et al. for more detections above 100 keV!

SLIDE 7

Accreting Pulsars with GBM Earth Occultation

Vela X-1

GX301-2 A0535+26

A0535+262

Vela X-1

SLIDE 8

AGNs with GBM Earth Occultation

SLIDE 9

Summary

GBM Earth occultation technique is working

nicely

Agreement with Swift/BAT is good
Source monitoring is underway for 47 sources
7 sources detected in the 100-300 keV band

(Poster P5.195 Cherry et al.)

Watch our website for new light curves
http://gammaray.nsstc.nasa.gov/gbm/science/occultation/