fermi lat observations of galactic and extragalactic diffuse emission jean-marc casandjian, on...

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Fermi LAT Observations of Galactic and Extragalactic Diffuse Emission Jean-Marc Casandjian, on behalf of the Fermi LAT collaboration 7 questions addressed during this presentation What are the origins of the Milky-Way γ-ray diffuse emission ? Is the cosmic ray (CR) density uniform within ~1 kpc from the sun ? How does the CR density vary with the Galactocentric distance ? Are the CR and ISM density coupled ? Does FERMI see the EGRET GeV excess ? Can we model the Galactic diffuse emission ? Can the EGB be explained by unresolved AGN ?

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Page 1: Fermi LAT Observations of Galactic and Extragalactic Diffuse Emission Jean-Marc Casandjian, on behalf of the Fermi LAT collaboration 7 questions addressed

Fermi LAT Observations of Galactic and Extragalactic Diffuse Emission

Jean-Marc Casandjian, on behalf of the Fermi LAT collaboration

7 questions addressed during this presentationWhat are the origins of the Milky-Way γ-ray diffuse emission ?Is the cosmic ray (CR) density uniform within ~1 kpc from the sun ?How does the CR density vary with the Galactocentric distance ? Are the CR and ISM density coupled ?Does FERMI see the EGRET GeV excess ?Can we model the Galactic diffuse emission ?Can the EGB be explained by unresolved AGN ?

Page 2: Fermi LAT Observations of Galactic and Extragalactic Diffuse Emission Jean-Marc Casandjian, on behalf of the Fermi LAT collaboration 7 questions addressed

Fermi LAT Observations of Galactic and Extragalactic Diffuse Emission

Jean-Marc Casandjian, on behalf of the Fermi LAT collaboration

100%11%

Page 3: Fermi LAT Observations of Galactic and Extragalactic Diffuse Emission Jean-Marc Casandjian, on behalf of the Fermi LAT collaboration 7 questions addressed

100%89%

Fermi LAT Observations of Galactic and Extragalactic Diffuse Emission

Jean-Marc Casandjian, on behalf of the Fermi LAT collaboration

Page 4: Fermi LAT Observations of Galactic and Extragalactic Diffuse Emission Jean-Marc Casandjian, on behalf of the Fermi LAT collaboration 7 questions addressed

What are the origins of the Milky-Way γ-ray diffuse emission ?

1.

Page 5: Fermi LAT Observations of Galactic and Extragalactic Diffuse Emission Jean-Marc Casandjian, on behalf of the Fermi LAT collaboration 7 questions addressed

Processes for HE γ production :

Diffuse Emission : study of CR, ISM and ISRF

Page 6: Fermi LAT Observations of Galactic and Extragalactic Diffuse Emission Jean-Marc Casandjian, on behalf of the Fermi LAT collaboration 7 questions addressed

Abdo et al., ApJ 703, 1249 (2009), C.A.: T. Mizuno

No H2, γ intensity is proportional to HI column density

γ-ray intensities (sources and IC removed) versus HI column densities

200º≤ l ≤ 260º , 22º ≤ |b| ≤ 60º

Page 7: Fermi LAT Observations of Galactic and Extragalactic Diffuse Emission Jean-Marc Casandjian, on behalf of the Fermi LAT collaboration 7 questions addressed

89%

LAT minus sources

Page 8: Fermi LAT Observations of Galactic and Extragalactic Diffuse Emission Jean-Marc Casandjian, on behalf of the Fermi LAT collaboration 7 questions addressed

74%

LAT minus sources, isotropic

Page 9: Fermi LAT Observations of Galactic and Extragalactic Diffuse Emission Jean-Marc Casandjian, on behalf of the Fermi LAT collaboration 7 questions addressed

26%

LAT minus sources, isotropic, HI

Page 10: Fermi LAT Observations of Galactic and Extragalactic Diffuse Emission Jean-Marc Casandjian, on behalf of the Fermi LAT collaboration 7 questions addressed

17%

LAT minus sources, isotropic, HI, H2

Page 11: Fermi LAT Observations of Galactic and Extragalactic Diffuse Emission Jean-Marc Casandjian, on behalf of the Fermi LAT collaboration 7 questions addressed

<1%

LAT minus sources, isotropic, HI, H2, Inverse Compton

Page 12: Fermi LAT Observations of Galactic and Extragalactic Diffuse Emission Jean-Marc Casandjian, on behalf of the Fermi LAT collaboration 7 questions addressed

<1%

LAT minus sources, isotropic, HI, H2, Inverse Compton, dark gas

Page 13: Fermi LAT Observations of Galactic and Extragalactic Diffuse Emission Jean-Marc Casandjian, on behalf of the Fermi LAT collaboration 7 questions addressed

LAT diffuse

Fermi diffuse model

The diffuse emission can be modelled with a linear combination of various templates

Page 14: Fermi LAT Observations of Galactic and Extragalactic Diffuse Emission Jean-Marc Casandjian, on behalf of the Fermi LAT collaboration 7 questions addressed

Is the cosmic ray density uniform within ~1 kpc from the sun ?

3 regions were investigated:➡200º≤ l ≤ 260º , 22º ≤ |b| ≤ 60º Abdo et al., ApJ 703, 1249 (2009), C.A.: T. Mizuno

➡100º≤ l ≤ 145º , -15º≤ b ≤ 30º (local arm) Abdo et al., ApJ 710, 133 (2010) C.A.: L. Tibaldo, I. Grenier

➡210º≤ l ≤ 250º , -15º≤ b ≤ 20º (local arm) Abdo et al., submitted, C.A.: T. Mizuno, L. Tibaldo, I. Grenier

2.

Page 15: Fermi LAT Observations of Galactic and Extragalactic Diffuse Emission Jean-Marc Casandjian, on behalf of the Fermi LAT collaboration 7 questions addressed

200º≤ l ≤ 260º , 22º ≤ |b| ≤ 60º100º≤ l ≤ 145º , -15º≤ b ≤ 30º

210º≤ l ≤ 250º , -15º≤ b ≤ 20º

Preliminary

Page 16: Fermi LAT Observations of Galactic and Extragalactic Diffuse Emission Jean-Marc Casandjian, on behalf of the Fermi LAT collaboration 7 questions addressed

•It is uniform within systematics •the local CR nuclei spectra are close to those directly measured at the Earth

Is the cosmic ray density uniform within ~1 kpc from the sun ?

Page 17: Fermi LAT Observations of Galactic and Extragalactic Diffuse Emission Jean-Marc Casandjian, on behalf of the Fermi LAT collaboration 7 questions addressed

How does the CR density vary with the Galactocentric distance ?

3.

2 regions were investigated:

➡100º≤ l ≤ 145º , -15º≤ b ≤ 30º Abdo et al., ApJ 710, 133 (2010) C.A.: L. Tibaldo, I. Grenier

➡210º≤ l ≤ 250º , -15º≤ b ≤ 20º Abdo et al., submitted, C.A.: T. Mizuno, L. Tibaldo, I. Grenier

Page 18: Fermi LAT Observations of Galactic and Extragalactic Diffuse Emission Jean-Marc Casandjian, on behalf of the Fermi LAT collaboration 7 questions addressed

Preliminary

Preliminary

flat source distribution in R>=Rbk (dotted line)

SNR distribution (solid line)Zh=1, 2, 4, 10, 15 and 20 kpc

Preliminary

Preliminary

GALPROPprediction using PSR distribution as input sources

this work

Varying the HALO size Varying the source distribution

100º≤ l ≤ 145º , -15º≤ b ≤ 30º

210º≤ l ≤ 250º , -15º≤ b ≤ 20º

Page 19: Fermi LAT Observations of Galactic and Extragalactic Diffuse Emission Jean-Marc Casandjian, on behalf of the Fermi LAT collaboration 7 questions addressed

How does the CR density vary with the Galactocentric distance ?

Decrease of CR densities but with a gradient flatter than expectations for SNR sources as traced by PSR -> larger halo ?

Page 20: Fermi LAT Observations of Galactic and Extragalactic Diffuse Emission Jean-Marc Casandjian, on behalf of the Fermi LAT collaboration 7 questions addressed

Are the CR and ISM density coupled ?

Association of CR sources with regions of massive clouds ?Confinement of CRs by magnetic fields associated with the gas ?

4.

Page 21: Fermi LAT Observations of Galactic and Extragalactic Diffuse Emission Jean-Marc Casandjian, on behalf of the Fermi LAT collaboration 7 questions addressed

is there an arm/inter arm CR effect

Page 22: Fermi LAT Observations of Galactic and Extragalactic Diffuse Emission Jean-Marc Casandjian, on behalf of the Fermi LAT collaboration 7 questions addressed
Page 23: Fermi LAT Observations of Galactic and Extragalactic Diffuse Emission Jean-Marc Casandjian, on behalf of the Fermi LAT collaboration 7 questions addressed
Page 24: Fermi LAT Observations of Galactic and Extragalactic Diffuse Emission Jean-Marc Casandjian, on behalf of the Fermi LAT collaboration 7 questions addressed
Page 25: Fermi LAT Observations of Galactic and Extragalactic Diffuse Emission Jean-Marc Casandjian, on behalf of the Fermi LAT collaboration 7 questions addressed
Page 26: Fermi LAT Observations of Galactic and Extragalactic Diffuse Emission Jean-Marc Casandjian, on behalf of the Fermi LAT collaboration 7 questions addressed
Page 27: Fermi LAT Observations of Galactic and Extragalactic Diffuse Emission Jean-Marc Casandjian, on behalf of the Fermi LAT collaboration 7 questions addressed
Page 28: Fermi LAT Observations of Galactic and Extragalactic Diffuse Emission Jean-Marc Casandjian, on behalf of the Fermi LAT collaboration 7 questions addressed
Page 29: Fermi LAT Observations of Galactic and Extragalactic Diffuse Emission Jean-Marc Casandjian, on behalf of the Fermi LAT collaboration 7 questions addressed
Page 30: Fermi LAT Observations of Galactic and Extragalactic Diffuse Emission Jean-Marc Casandjian, on behalf of the Fermi LAT collaboration 7 questions addressed
Page 31: Fermi LAT Observations of Galactic and Extragalactic Diffuse Emission Jean-Marc Casandjian, on behalf of the Fermi LAT collaboration 7 questions addressed
Page 32: Fermi LAT Observations of Galactic and Extragalactic Diffuse Emission Jean-Marc Casandjian, on behalf of the Fermi LAT collaboration 7 questions addressed