The Spatial Morphology of the Secondary Emission in the ...

TheSpatialMorphologyoftheSecondaryEmissionintheGalacticCenterGamma-Ray

ExcessChrisGordon(UniversityofCanterbury)

Basedon:ThomasLacroix,OscarMacias,CG,PaoloPanci,CelineBœhm,andJosephSilk,PRD,2016

�2�

0�

2�

Galactic

Latitude

(b)

�2�0�2�

Galactic Longitude (l)

Sgr CSgr A*

the Arc

Sgr B

2FGLJ1748.6-2913

bkgA

40

80

120

160

200

240

280

Counts

�2�

0�

2�

Galactic

Latitude

(b)

�2�0�2�

Galactic Longitude (l)

Sgr CSgr A*

the Arc

Sgr B

2FGLJ1748.6-2913

bkgA

15

30

45

60

75

90

105

Counts

�2�

0�

2�

Galactic

Latitude

(b)

�2�0�2�

Galactic Longitude (l)

Sgr CSgr A*

the Arc

Sgr B

2FGLJ1748.6-2913

bkgA

30

45

60

75

90

105

120

135

Counts

Fermigamma-ray

data

DiffuseGalactic

Background

DarkMatter

orMSPs

• WeusedFermi-toolswith45

monthsofpass7data,and300

MeVto100GeV energyrange.

100 101 102

E� [GeV]

10�7

E2dN/dE

[GeV

cm

�2s

�1]

2 ⇥ 10�8

Inner slope:� = 1.2

MDM = 30 GeV, 100% bb̄

MSPorDarkMatterSpectrum

100 101

E� [GeV]

10�8

10�7

10�6

E2dN/dE

[GeV

cm

�2s

�1]

MDM = 10 GeV13e+e� + 1

3µ+µ� + 1

3⌧+⌧�

Spectra + SpatialTotal emission

Prompt

IC

Bremss

�3 �2 �1 0 1 2 3Latitude (b) [deg]

0.0

0.2

0.4

0.6

0.8

1.0

Relative

Flux

IC+Brem+Prompt (1st band)

Prompt (1st band)

IC+Brem+Prompt (5th band)

Prompt (5th band)

Teststatisticofsecondaries=2Log(Likelihood withsecondaries/likelihood withoutsecondaries)=102

P-valueofspectralfitforpromptonly=8⨉10-5

P-valueofspectralfitforprompt+secondaries=8⨉10-2

100 101

E� [GeV]

10�8

10�7

10�6

E2dN/dE

[GeV

cm

�2s

�1]

MDM = 10 GeV13e+e� + 1

3µ+µ� + 1

3⌧+⌧�

Spectra onlyTotal emission

Prompt

IC

Bremss

100 101

E� [GeV]

10�8

10�7

10�6

E2dN/dE

[GeV

cm

�2s

�1]

MDM = 10 GeV13e+e� + 1

3µ+µ� + 1

3⌧+⌧�

Spectra + SpatialTotal emission

Prompt

IC

Bremss

TestStatisticof secondaries=2Log(Likelihood withsecondaries/likelihood withoutsecondaries)=102

P-valueofspectralfitforpromptonly=8⨉10-5

P-valueofspectralfitforprompt+secondariesusingspatialinfo=8⨉10-2

P-valueofspectralfitforprompt+secondaries=1⨉10-3

�3 �2 �1 0 1 2 3Latitude (b) [deg]

0.0

0.2

0.4

0.6

0.8

1.0

Relative

Flux

IC+Brem+Prompt (1st band)

Prompt (1st band)

IC+Brem+Prompt (5th band)

Prompt (5th band)

100 101

E� [GeV]

10�8

10�7

10�6

E2dN/dE

[GeV

cm

�2s

�1]

MDM = 10 GeV

0.25µ+µ� + 0.75⌧+⌧�

Spectra + SpatialTotal emission

Prompt

IC

Bremss

TestStatisticof secondaries=2Log(Likelihood withsecondaries /likelihood withoutsecondaries)=6.5

P-valueofspectralfitforpromptonly=4⨉10-4

P-valueofspectralfitforprompt+secondaries=1⨉10-3

Usedadeltafunction injectionof20GeVelectronsandpositrons forthesecondaries.

TestStatisticof secondaries=2Log(Likelihood withsecondaries /likelihood withoutsecondaries)=42

P-valueofspectralfitforpromptonly=0.2

P-valueofspectralfitforprompt+secondaries=0.2

100 101

E� [GeV]

10�9

10�8

10�7

10�6

E2dN/dE

[GeV

cm

�2s

�1]

Millisecond Pulsars

Spectra + SpatialTotal emission

Prompt

IC

Bremss

�3 �2 �1 0 1 2 3Latitude (b) [deg]

0.0

0.2

0.4

0.6

0.8

1.0

Relative

Flux

IC+Brem+Prompt (1st band)

Prompt (1st band)

IC+Brem+Prompt (5th band)

Prompt (5th band)

Conclusions

• ExaminedmodelsoftheGalacticCenterGeVgamma-rayexcesswhich

havesignificantsecondaryemission.

• Developedamethodfortestingthegoodnessoffitwhensecondary

emissionhasdifferentmorphologytothepromptemission.

• Foundanexamplewheretheneedforsecondarieswasnotrevealed

byexaminingtheTestStatisticbutinsteadrequiredexaminingthefit

ofthespectrum.

InterstellarMediumParameters

• Magneticfield:

• Diffusion:

• Interstellarradiationfield:GALPROP• AtomicandmoleculargasDensity3Dmaps:Ferriereetal.(2007)