an explanation to the diffuse gamma-ray emission fiorenza donato @ physics dept., un. torino in...
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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