An explanation to the diffuse gamma-ray emission

Fiorenza Donato @ Physics Dept., UN. Torino

In collaboration with:M. Ajello, T. Bringmann, F. Calore, A. Cuoco, M. Di Mauro, G. Lamanna

L. Latronico, D. Sanchez, P.D. Serpico, J. Siegal-Gaskins

“Astroparticle Physics” - Amsterdam, June 26, 2014

The Fermi-LAT isotropic diffuse emission

The origin of the IGRB

Undetected sources: AGN (blazars: BL Lacs, FSRQ; mis-aligned AGN) star forming galaxies, (galactic) milli-second pulsars (MSP), […]Diffuse processes: UHECRs interacting with EBL, dark matter annihilation, intergalactic shocks, […]

L. Baldini, this conference

Active Galactic Nuclei

3

Radio quiet AGN: Quasars, Seyfert, Liners

Radio loud AGN: Blazars: BL Lacs (no emission lines, closer, less luminous) FSRQ (stronger emission lines, farther, more luminous) Quasars (SSRQ, FSRQ) Radio Galaxies (FRI, FRII) (decreasing view angle)

Fermi-LAT data on |b|>10: 1042 sources, 873 associated out of which

357 are BL Lacs and 318 FSRQs

Urry & Padovani 1995

1. Diffuse γ-ray emission from unresolved BL Lacs

M. Di Mauro, FD, G. Lamanna, D. Sanchez, P.D. Serpico ApJ 2014

• Spectral energy distribution (SED) derived from Fermi-LAT data AND TeV catalogs

• Luminosity function derived from Fermi-LAT data

• EBL absorption included (> 100 GeV)

• Blazars studied according to radio and X-ray classification: Low (High) synchrotron peaked LSP: νS < 1014 Hz ISP: 1014 Hz < νS < 1015 Hz HSP: νS > 1015 Hz

We work with: 80 HSP, 34 ISP, 34 LSP (68 LISP)

Observed Spectral Energy Distribution (SED)

5

Power-law with exp cut-off provides better fits

(huge uncertainties in the cut-off)

LSP BL Lac SED

HSP BL Lac SED

Diffuse γ-ray emission from unresolved BL Lacs

Di Mauro, FD, Lamanna, Sanchez, Serpico ApJ2014

• Softening at > 100 GeV due to EBL absorption: data are nicely reproduced!

• Treating LSP and HSP separately gives non negligible differences

2. Diffuse γ-ray emission fromMisaligned Active Galactic Nuclei

(MAGN) M. Di Mauro, F. Calore, FD, M. Ajello, L. Latronico ApJ 2014

MAGN: AGN with jet not aligned along the line-of-sight (l.o.s.) Doppler boosting negligible Radio galaxies (RG) and steep-spectrum radio quasars (SSRQs)

RG have been classified by Fanaroff&Riley (1974)•FRI edge-darkened, less powerful, Bl Lacs parent•FRII edge-brightened, more powerful, FSRQs parent

Abundant RADIO data: total (including lobes) and central compact region (core)

Fermi-LAT observed 15 MAGN between 0.1-100 GeV (Fermi-LAT ApJ 720, 2010)

γ-ray vs radio luminosity function for MAGN

Correlation between luminosity of radio core at 5 GHz and γ-ray luminosity > 0.1 GeV

The strength of the correlation has been confirmed by the Spearman test and the modified Kendall τ rank correlation test: chance correlation excluded at 95% C.L.

Constraints from logN-logS

The cumulative source number above a given flux:

Our assumptions (core radio – γ-ray correlation, link between core and total

radio emission, …) are consistent with the Fermi-LAT MAGN number count

Consistency also for k=1 (equal number of radio and γ-ray emitters)

Trend at lowest fluxes intensity of diffuse flux

Diffuse γ-ray emission from unresolved misaligned AGN

Best fit MAGN diffuse flux: 20-30% Fermi-LAT IGRB, |b|>10o

Estimated uncertainty band: factor 10

Di Mauro,Calore,FD, Ajello, Latronico ApJ2014

EGB: sum of astrophysical contributionsDi Mauro et al. 2014

The sum of all the contributions to fits Fermi-LAT (preliminary) EGB data

3. Diffuse γ-ray emission fromgalactic milli-second pulsars (MSPs)

Calore, Di Mauro, FD 1406.2706

Galactic MSPs contribution to the IGRB is negligible at all energies

Anisotropy power spectra from astrophysical sources

We study angular power for classes of AGN:-BL Lacs: LISP and HSP (Low, Intermediate and High Synchrotron Peak)-Misaligned AGN (MAGN) -Flat Spectrum Radio Quasar (FSRQ)

Cuoco, Di Mauro, FD, Siegal-Gaskins, in preparation

PRELIM

INARY

AGN angular power and Fermi-LAT data

HSP BL Lacs contribute the most to the anisotropy; high energy spectrum MAGN are very numerous by faint, little amount of AP

Fermi-LAT data explained by AGN

PRELIMINARY

Cuoco, Di Mauro, FD, Siegal-Gaskins, in preparation

The anisotropy – integrated flux consistency

MAGN contribute the most to the IGRB, being very numerous whilst faintHSP BL Lacs get relevant to the highest energies, but sub-dominant

Our emission models for AGN are compatible with Fermi-LAT data on anisotropy AND diffuse emission

PRELIMINARY

Cuoco, Di Mauro, FD, Siegal-Gaskins, in preparation

Q: Which room is left to

Dark Matter annihilation

into gamma-rays

in the halo of the Milky Way?

Bounds on WIMP annihilation cross section

• Standard halo assumptions I(ψ)• Prompt and IC photons• BR=1 at fixe annih. channel

• Bkgd= MAGN + ΣBMS

• ΣBMS = MSPs (Calore+2012)+ BL Lac (Abdo+2010) + FSRQs (Ajello+2012) +

SF galaxies (Ackermann+2012)

• DM + bkgd must not exceed any data point (at 2σ)

Effect of MAGN contribution

Bringmann, Calore, FD, Di Mauro, PRD 2013

Constraints to DM from diffuse γ-ray emission

High latitude data: |b|>10:Bringmann, Calore, Di Mauro, FD 2013

-Negligible the choice for ρ(r) -crucial the backgrounds from extra-galactic unresolved sources

Halo 5<|b|<15,|l|<80:Fermi-LAT Coll. 1204.6474

-Models for the diffuse galactic emission improve the limits- Important the choice for ρ(r)

Conclusions

• The IGRB is studied for |b|>10o: faint, diffuse, isotropic flux

• We present new estimations of the diffuse emission from unresolved BL Lacs, MAGN, MSPs: Fermi-LAT data for the IGRB are very well explained by astrophysical sources

• Anisotropies for the astrophysical sources compatible with Fermi-LAT data

• Dark matter: anisotropies depend on the behavior of the density profile extrapolated at low radii

• We show how much the MAGN background reduces the room left to Dark Matter annihilation

Testing Lγ-Lr correlation: upper limits from undetected FRI&FRII

GREAT!!! they do not violate the correlation It looks physical

We derive upper limits for FRI and FRII having strong radio core fluxes

Effect of Inverse Compton contribution from e+e- DM annihilation

The inclusion of the IC scattering (on CMB, infrared radiation, stellar light) is non-negligible for Wimp Dark Matter masses >~ 100 GeV.At mDM=1 (10) TeV the constraints on <σv> increase by a factor 10 (50)!

Fermi-LAT MAGNs: main radio and gamma properties

• Some of Fermi-LAT sources are variable

• Radio CORE data taken at 5 GHz, and contemporary to Fermi-LAT data

• Up to z~0.7

• 4 FRII and 8 FRI

BL Lacs data

BL Lacs can be classified according to their synchrotron peak frequency νS

(low, intermediate, high synchrotron peak):

LSP: νS < 1014 Hz ISP: 1014 Hz < νS < 1015 Hz HSP: νS > 1015 Hz

We work with:80 HSP34 ISP34 LSP (68 LISP)

M. Di Mauro, FD, G. Lamanna, D. Sanchez, P.D. Serpico, ApJ

2014

Effect of unresolved (smaller) sub-haloes

• Black lines: Aquarius Aq-A-1 simulated sub-haloes, Einasto profile (Springer+2008)

• More massive and cored haloes give a flattening at high l (red line)

• The smaller haloes give more power and a Poisson-like trend

Calore, De Romeri, Di Mauro, FD, Herpich, Macciò, Maccione MNRAS 2014

Simulated all-sky maps

E=4 GeVmDM=200 GeV<σv>=3×1026 cm3/s

Emission from Einasto profile is more clustered.

Calore, De Romeri, Di Mauro, FD, Herpich, Macciò, Maccione MNRAS 2014

EinastoMoore-Stadel

MS profile shows more extended cores

Spatial information: Anisotropies in γ-rays

Fornasa et al. 2012

Peculiar DM over-dense regions may imprint spatial signatures in high resolution data

Fermi-Lat Coll. 1202.2856

Fermi-LAT: detected angular power >3σ in 1-10 GeV range at high l

Predicted angular power spectrum:galactic and extragalactic