Sharper Fermi -LAT Images

Stephen K N PORTILLO, Harvard Universitywith Douglas P FINKBEINER26 June 2014Astroparticle Physics (TeVPA/IDM), Amsterdam

Sharper Fermi-LAT Images

Portillo & Finkbeiner, 1406.0507submitted to ApJ

Signal Region

Galactic Plane Leakage

Angular Resolution Matters

Galactic Plane (bright and hard to model!)

Point Spread Function

tungstensilicon

Multiple Coulomb scatteringin tungsten foils (low E)

Limited silicon stripposition resolution (high E)

Conversion insupport material

Hard scatteringMissed silicon hit

Track confusion

Idea

l Eve

ntUni

deal

Eve

nt

FRONT BACK

[TRANSIENT]

SOURCE

CLEAN

ULTRACLEAN

Event Classes + CTBCORE

Q2

Q1

Dividing the front-converting events…

Pulsars as Point Sources

- =

On-phase Off-phase Pulsar

(Bill Saxton, NRAO)

PSF Fitting ULTRACLEAN: Allfront, Q2, Q1

Effective Area

Surviving Fraction, CLEAN, Q2

×

Effective Area, CLEAN (m2)

(Fermi Science Support Centre)

1

0.22.5 4𝐥𝐨𝐠𝟏𝟎 (𝑬 /MeV )

𝐜𝐨𝐬𝜽

0.5

0

Effective Area Error Estimate

±0.01

0.3-0.5 GeV, CLEAN, Allfront

0.3-0.5 GeV, CLEAN, Q2

0.3-0.5 GeV, CLEAN, Allfront minus Q2

Before CTBCORE cut

After CTBCORE cutBefore CTBCORE

After CTBCORE

Daylan et al. (2014), arXiv

Conclusion

Galactic Plane Leakage

Galactic Plane- =

1

0.22.5 4𝐥𝐨𝐠𝟏𝟎 (𝑬 /MeV )

𝐜𝐨𝐬𝜽

0.5

0

Effective Area

Signal Region

Idea

l Eve

nt

Point-Spread Function

Check out the maps + IRFs at

http://fermi.skymaps.info/