Cosmic Gamma-ray Background Radiation. Yoshiyuki Inoue (JAXA International Top Young ISAS/JAXA)

Transcription

1 Cosmic Gamma-ray Background Radiation Yoshiyuki Inoue (JAXA International Top Young ISAS/JAXA)

2 Cosmic Background Radiation Spectrum E dn/de [erg cm - s -1 sr -1 ] CMB Galaxies (Inoue et al. 13) Pop-III Stars (Inoue et al. 13) AGNs (All) Radio-quiet AGNs (Inoue et al. 08) Blazars (Inoue and Totani 09) Radio Galaxies (Inoue 11) Galaxies? AGNs? Photon Energy [ev]

3 Cosmic X-ray Background (CXB) The origin of CXB is thought to be Seyferts. >90 % of CXB at 0.5- kev has been resolved. Gilli+ 07 But, CXB above kev is not well resolved. Astro-H & NuSTAR will probe this.

4 Cosmic MeV Gamma-ray Background Sky COMPTEL

5 Cosmic MeV Gamma-ray Background Spectrum E dn/de [kev cm - s -1 kev -1 sr -1 ] Photon Energy [kev] ASCA XTE INTEGRAL HEA01-A4 COMPTEL HEA0-I Swift-BAT Nagoya-Ballon SMM COMPTEL Fermi-LAT The origin of cosmic X-ray background is thought to be active galactic nuclei (AGNs). Smooth connection to the cosmic X-ray background. Type Ia Supernovae? (e.g. Clayton+ 75, Zdziarski+ 96) Insufficient (e.g. Strigari+ 05, Horiuchi+ ) Radio galaxies? (e.g. Strong+ 76) Insufficient (e.g. Massaro & Ajello 11, YI 11) MeV Dark Matters? (e.g. Olive & Silk 85, Ahn & Komatsu 05, 06) no natural DM particle candidates from particle physics

6 Active Galactic Nuclei (AGNs) Blazar Seyfert Radio Galaxy CXB is explained by AGNs.

7 E dn/de Hard X-ray Spectra (Seyfert) corona w/ nonthermal thermal Input photon Mushotzky+93 Comptonization in a hot corona above the disk. Energy (kev) YI+ 08 If non-thermal electrons exist in a corona, non-thermal tail is expected (e.g. YI+ 08). MeV power-law tail is observed in a Galactic X-ray binary (Cyg X-1).

8 Typical Spectra (Blazar) Log L (erg s -1 ) Log (νlν [erg/s]) FSRQ Log E (ev) Log (Energy [ev]) BL Lac Fossati+ 98, Kubo+ 98, YI & Totani 09 Non-thermal emission from radio to gamma-ray Two peaks Synchrotron Inverse Compton Luminous blazars (Flat Spectrum Radio Quasars: FSRQs) tend to have lower peak energies (Fossati+ 98, Kubo + 98)

9 Seyferts and Cosmic MeV Gamma-ray Background E dn/de (kev/cm /s/sr) thermal w/ nonthermal Required non-thermal electron distribution is similar to that in solar flares and Earth s magnetotail Magnetic reconnection-heated corona scenario? (Liu, Mineshige, & Shibata 0) Energy (kev) YI+ 08

10 Blazars and Cosmic MeV Gamma-ray Background Based on Swift-BAT Based on Fermi-LAT sr -1 ] s -1 - dn/de [kev cm E 1 Nagoya balloon - Fukada et al ASCA - Gendreau et al SMM - Watanabe et al COMPTEL - Weidenspointner et al. 000 RXTE - Revnivtsev et al. 003 Swift/BAT - Ajello et al. 008 FSRQs, this work Gilli et al. 007 s -1 sr -1 ] - dn/de [MeV cm E -1 Nagoya balloon - Fukada et al SMM - Watanabe et al COMPTEL - Weidenspointner et al. 000 EGRET - Strong et al. 004 Swift/BAT - Ajello et al IGRB (Abdo et al. 0b) IGRB + Sources (Abdo et al. 0b) Contribution of FSRQs Energy [kev] 3 FSRQs explain the GeV gamma-ray background with a peak at ~0 MeV (e.g. YI & Totani 09, Ajello + 1) FSRQs need another peak at ~1 MeV to explain the MeV background. Two components in gamma-ray spectra? 4 Ajello Energy [MeV] Ajello+ 1

11 Cosmic MeV Gamma-ray Background Anisotropy C l p [(ph/cm /s) sr -1 ] Astro-H/ SGD Radio-quiet AGNs (Ueda+ 03) Radio-quiet AGNs (Inoue+ 08) Blazars (Ajello+ 09) Poisson term only F lim =1e- erg/cm /s Energy [MeV] YI+ 13b Astro-H (SGD) / future MeV satellites will distinguish Seyfert & blazar scenarios through anisotropy in the sky.

12 Cosmic GeV Gamma-ray Background Fermi 3-year survey >0 MeV Numerous sources are buried in the cosmic gammaray background (CGB).

13 Cosmic Gamma-ray Background Spectrum at >0.1 GeV CGB Spectrum Softening around ~400 GeV. Fermi resolves CGB more at higher energies? APS, HEM14 s -1 ) - dn/de (erg cm Differential Flux E Crab Nebula Synchrotron LAT - yrs (inner Galaxy) LAT - yrs (extragalactic) 3 4 CTA - 00 hrs Photon Energy (MeV) 5 6 Inverse Compton H.E.S.S. - 0 hrs CTA - 0 hrs 7 8 Funk & Hinton 13

14 Possible Origins of CGB at GeV The origin of the EGB in the LAT energy range. Unresolved sources Blazars Dominant class of LAT extragalactic sources. Many estimates in literature. EGB contribution ranging from 0% - 0% Non-blazar active galaxies 7 sources resolved in FGL ~ 5% contribution of radio galaxies to EGB expected. (Inoue 011) Star-forming galaxies Several galaxies outside the local group resolved by LAT. Significant contribution to EGB expected. (e.g. Pavlidou & Fields, Diffuse processes Intergalactic shocks widely varying predictions of EGB contribution ranging from 1% to 0% (e.g. Loeb & Waxman 000, Gabici & Blasi 003) Dark matter annihilation Potential signal dependent on nature of DM, cross-section and structure of DM distribution (e.g. Ullio et al. 00) Interactions of UHE cosmic rays with the EBL dependent on evolution of CR sources, predictions varying from 1% to 0 % (e.g. Kalashev et al. 009) 00) GRBs High-latitude pulsars small contributions expected. (e.g. Dermer 007, Siegal-Gaskins et al. 0) Extremely large galactic electron halo (Keshet et al. 004) CR interaction in small solar system bodys (Moskalenko & Porter 009) M. Ackermann Markus Ackermann 0th AAS meeting, Anchorage 06/11/01 Page 4

15 Cosmological Evolution of Blazars FSRQs BL Lacs ) -1 ] 48 / γ (L -3,z) [Mpc γ Φ(L LogL = γ LogL = γ LogL = γ LogL = γ ] -3,z) [Mpc 48 / γ Φ(L = logl γ = logl γ = logl γ = logl γ FSRQs show positive evolution. z Ajello Figure z Ajello+ 14 LBLs & IBLs show positive evolution. HBLs show negative evolution. Half of BL Lacs lack spectroscopic redshift information. Various redshift constraints are used.

16 Blazars s -1 sr -1 MeV] - dn/de [cm -3-4 LAT GeV Diffuse background Unresolved sources in GeV band Unresolved sources in bands s -1 sr -1 ] - dn/de [MeV cm E Nagoya balloon - Fukada et al SMM - Watanabe et al COMPTEL - Weidenspointner et al. 000 EGRET - Strong et al. 004 Swift/BAT - Ajello et al. 008 IGRB (Abdo et al. 0d) Contribution of FSRQs E -5 3 Energy [MeV] 4 5 Energy [MeV] Padovani+ 93; Stecker+ 93; Salamon & Stecker 94; Chiang + 95; Stecker & Salamon 96; Chiang & Mukherjee 98; Mukherjee & Chiang 99; Muecke & Pohl 00; Narumoto & Totani 06; Giommi + 06; Dermer 07; Pavlidou & Venters 08; Kneiske & Mannheim 08; Bhattacharya + 09; YI & Totani 09; Abdo+ ; Stecker & Venters ; Cavadini+ 11, Abazajian+ 11, Zeng+ 1, Ajello+ 1, Broderick+ 1, Singal+ 1, Harding & Abazajian 1, Di Mauro+ 14, Ajello+ 14,Singal Blazars explain ~3% of GeV CGB. FSRQs explain ~9% of GeV CGB.

17 Radio Galaxies log (L γ [erg/s]) FRI FRII log (L 5 GHz [erg/s]) YI 11 E dn/de [MeV cm - s -1 MeV -1 sr -1 ] Photon Energy [MeV] Intrinsic Absorbed Cascade Total HEAO-I Swift-BAT SMM COMPTEL Fermi-LAT YI 11 Padovani+ 93; YI 11; Di Mauro+ 13; Zhou & Wang 13 Use gamma-ray and radio-luminosity correlation. ~5% of CGB

18 Star-forming Galaxies SFR (M yr -1 ) ) -1 (erg s L GeV SMC LAT Non-detected (Upper Limit) LAT Non-detected with AGN (Upper Limit) LAT Detected LAT Detected with AGN Best-fit Fit Uncertainty Dispersion Calorimetric Limit 50 (E η = erg) SN M33 LMC 9 M31 NGC 4945 M83 NGC 53 NGC 6946 IC 34 Milky Way M8 L 8-00 µm (L ) SFR (M yr -1 ) NGC NGC 68 1 Arp 0 3 Ackermann+ 1 s -1 sr -1 ) - dn/de (GeV cm E Thompson et al. 007 (Γ =.) Fields et al. 0 (Density-evolution) Fields et al. 0 (Luminosity-evolution) Makiya et al. 011 Stecker & Venters 011 (IR) Stecker & Venters 011 (Schecter) -1 1 E (GeV) Isotropic Diffuse Star-forming Galaxies Milky Way Spectrum, 0<z<.5 Power Law Γ =., 0<z<.5 Ackermann+ 1 Soltan 99; Pavlidou & Fields 0; Thompson + 07; Bhattacharya & Sreekumar 009; Fields et al. 0; Makiya et al. 011; Stecker & Venters 011; Lien+ 1, Ackermann+ 1; Lacki+ 1; Chakraborty & Fields 13 Use gamma-ray and infrared luminosity correlation 4-3% of CGB

19 Components of Cosmic Gamma-ray Background Preliminary FSRQs (Ajello+ 1), BL Lacs (Ajello+ 14), Radio gals. (YI 11), Star-forming gals. (Ackermann+ 1) are guaranteed. little room for dark matters? Ajello at HEM14

20 Anisotropy of Cosmic Gamma-ray Background JOINT ANISOTROPY AND SOURCE COUNT CONSTRAINTS... PHYSICAL REVIEW D 86, (01) Cp(E) MAGN+FSRQ+BLLAC Fermi-LAT MAGN LISP Bl Lac HSP Bl Lac FSRQ TOT Cp [(cm- s-1 sr-1) sr] E [GeV] Cuoco+ 1 4 Di Mauro+ 14 E Cp/( E) MAGN+FSRQ+BLLAC FIG. 3 (color online). Left: Constraints on blazar logn-logs parameters (break flux, Sb, and faint-end slope, ") from the intensity and anisotropy of the IGRB. Regions in which blazars provide 0% of the observed IGRB anisotropy and mean intensity in the 1 GeV energy band are shown; the widths of the regions indicate the 68% confidence intervals. Below these regions blazars overproduce the anisotropy and mean intensity. Labeled contours show the fraction of the blazar contribution to the IGRB intensity. The best-fit 1! parameter region from the Fermi source count analysis [4] is marked, along with the best-fit Sb [4] (dot-dashed line). -17 Right: Expanded view around the region of parameter space in the left panel where blazars contribute 0% of both the measured IGRB anisotropy and intensity. Anisotropy puts strong constraints on the evolutionary models of blazars (Cuoco+ 1). CGB anisotropy is well explained by known radio-loud AGN achieved quite naturally since some proposed contributors the IGRB, such as star-forming galaxies [8], are populations (Di Mauro+ 14). toexpected to contribute negligibly to the anisotropy. On -18 the other hand, this result implies strong constraints on source populations with large intrinsic anisotropy. We emphasize that the anisotropy and intensity contribu4 scenarios we test an alternative fit to the blazar logn-logs obtained by Stecker and Venters [13]. A notable feature of this alternative fit is that it can account for!60% of the IGRB intensity in the 1 GeV energy band. We have calculated CP from the logn-logs of the Stecker and Venters model [13,14] and, using a threshold of 5:0 " Cp/( E) [(GeV cm- s-1 sr-1) sr] Fermi-LAT MAGN LISP BL Lac HSP BL Lac FSRQ TOT

21 Upper Limit on Cosmic Gamma-ray Background Cascade Absorbed Intrinsic UL Violates the Limit YI & Ioka 1 YI & Ioka 1 Cascade component from VHE CGB can not exceed the Fermi data (see also Murase+ 1). Negative evolution is required. If we try to explain CGB at <GeV by known sources, the observation violates the limit.

22 IceCube Neutrinos and Cosmic Gamma-ray Background, )! -./0 1 #) 3 #! 34 #! 5!" #(!" #'!" #&!" #%!" #$ ( 6/47 )"!" 6/47 )"!)!"#$ % & % ' )*+,-.+ /01 log [4πL(ε,Ω) erg s -1 ] FSRQ, flaring Γ = 30, γ pk = 7.5, t var = 4 s νl ν pk,syn = 47 erg s -1 IR BLR Internal Synchrotron Disk!" #!"!" "!"!!" )!" *!" +!" (!" '!" &!" %,-./05 Murase Extragalactic pp scenario (galaxies or clusters) for IceCube events will provide 30-0 % of CGB (Murase+ 13). Extragalactic pγ scenario (FSRQs) will have a low-energy cut-off feature at ~PeV (Murase, YI, & Dermer 14, Dermer, Murase, & YI 14). E ν (ev) Dermer, Murase, & YI 13

23 Summary CGB at MeV band may be come from blazars or Seyferts. Anisotropy measurement will distinguish these two scenarios. CGB above >0 MeV is composed of blazars, radio galaxies, and star-forming galaxies. Cascade emission put a strong limit on the origin of the VHE CGB. Need to check consistency with IceCube neutrino measurements.

24 Backup

25 Cosmic MeV Background sr -1 ] s -1 Nagoya balloon - Fukada et al ASCA - Gendreau et al SMM - Watanabe et al COMPTEL - Weidenspointner et al. 000 RXTE - Revnivtsev et al. 003 Swift/BAT - Ajello et al. 008 FSRQs, this work Gilli et al. 007 Seyfert? - dn/de [kev cm E 1 FSRQ? YI Energy [kev] Type Ia Supernovae? (e.g. Clayton+ 75) -> not enough (e.g. Horiuchi+ 09). 3 4 Ajello+ 09 Radio Galaxies? (e.g. Strong+ 76) -> not enough (e.g. Massaro & Ajello 11, YI 11) MeV Dark Matters? (e.g. Olive & Silk 85) -> Mass of DM candidates are mostly in GeV-TeV ranges Seyferts? (Schoenfelder 78; YI+ 08) -> Magnetic Reconnection Heated Corona (Liu+ 0)? FSRQs? (Ajello+ 09) -> Two (MeV & GeV) components in gamma-ray spectra?

26 It is not easy to resolve the MeV sky. Takahashi+ 13 Answers are in Anisotropy. Cosmic background radiation is not isotropic. There is anisotropy due to the sky distribution of its origins.

27 Cosmic Gamma-ray Background Spectrum CGB Spectrum 1 Fraction of CGB Fraction against total CGB Unresolved Resolved Unresolved CGB (Bechtol at HEM014) Resolved CGB (Bechtol at HEM014) Bechtol+@ APS, HEM Photon Energy [MeV] Softening around ~400 GeV. Fermi resolves CGB more at higher energies? s -1 ) - dn/de (erg cm Differential Flux E Crab Nebula Synchrotron LAT - yrs (inner Galaxy) LAT - yrs (extragalactic) 3 4 CTA - 00 hrs Photon Energy (MeV) 5 6 Inverse Compton H.E.S.S. - 0 hrs CTA - 0 hrs 7 8 Funk & Hinton 13

28 Two VHE (>0 GeV) gamma rays from PKS at z= GeV Flux Photon Energy [GeV] [ -7 photons cm - s -1 ] E dn/de [erg cm - s -1 ] Observed EBL corrected (Franceschini et al. 008) EBL corrected (Inoue et al. 013) Broken PL model MJD Energy [GeV] Tanaka, YI, + 13 VHE photons at flaring states, but not an exact correspondence to the peak of each flare. Spectral hardening from ~30 GeV.

29 Is VHE Spectral Hardening Universal? -9 - H z = RX J z = ES z = ES 11-3 z = E dn/de [TeV/cm /s] ES z = RBS 0413 z = ES z = 0.1 1ES z = 0.87 Γ S z = Energy [TeV] 4C+1.35 z = 0.43 Energy [TeV] 3C 66A z = Energy [TeV] 3C 79 z = Energy [TeV] YI+ 13a z z Essey Γ & Kusenko = Γ 1Γ Spectra of blazars at z > 0.15 show hardening from a few hundred GeV.

30 Secondary Gamma Rays? Stochastic Acceleration? KUV (z=0.61) Secondary Gamma Rays E F E [erg cm - s -1 ] γ-induced (low IR) γ-induced (best fit) CR-induced (low IR) CR-induced (best fit) Becherini et al. (01) H.E.S.S. I CTA 1ES (z=0.1396) Stochastic Acc. log vf v [erg.sec.cm ] F v v 1/3 1ES (z=0.1396) E Exp[-(E/E c ) 3 ] H.E.S.S. low level EBL - E Exp[-E/E c ] H.E.S.S. high level EBL SWIFT -.5 F v v 1/ E [ev] Takami log v [Hz] = Lefa+ 11 Secondary gamma rays from cosmic rays along line of sight (Essey & Kusenko, Essey+, Essey+ 11, Murase+ 1, Takami+ 13,YI+ 14). Stochastic (nd-order Fermi) acceleration (Stawarz & Petrosian 08, Lefa+ 11).

31 Another component in radio galaxies -7-8 Cen A Cen A νf ν [erg s -1 cm - ] log E dn de erg cm s ν [Hz] Abdo log E GeV Sahakyan + 13 Spectral hardening from ~4 GeV (Sahakyan+ 13). BH magnetosphere? multi components? hadronic? knots? cascade in torus? IC of host galaxy starlight?

32 Star Forming Galaxies ) -1 dn/de (erg s E 41 Starbursts NGC 68 NGC 68 (H.E.S.S.) Energy (MeV) M8 M8 (VERITAS) NGC 4945 NGC 53 NGC 53 (H.E.S.S.) Local Group Milky Way Global Model M31 LMC SMC 7 9 Ackermann+ 1 Optical Depth τ γγ M8 : SK07 M8 : dcdp09 NGC 53 : SK07 NGC 53 : DST Energy [TeV] YI 11 Hadronic origin as same as our Galaxy. > a few TeV gamma rays may be internally absorbed.

33 Photopion Production Efficiency Photopion Production Efficiency LLGRB, Γ = SGRB LGRB Γ = SGRB BL Lac, quiescent LLGRB, Γ = 30 Γ = 3 Γ = 5 LGRB BL Lac, flaring Γ = E p (ev) Photopion Production Efficiency Quiescent Γ = FSRQ E max = 0 ev IR E p (ev) BLR Disk Internal Synchrotron Flaring Γ = 30 Fig. 3 Minimum photopion production efficiency for parameters typical of quiescent and flaring states of FSRQs. The efficiency for interactions with synchrotron radiation is determined by the dynamical timescale t dyn Γt var, using values from Table 1, and t dyn = R ext/(cγ) for external processes, using values for the physical extent R ext = 0.1 and 1 pc of the BLR and IR radiation fields, respectively. Separate contributions from photopion production with Ly α radiation ϵ 0 = trum trum sma cuto subs F roun 1]}, u IR blac T is ap u disk ity, a ume Γ(4/ temp bit, radia F ficie pare diati radia Dermer, Murase, & YI 13

34 Fermi did this for the GeV gammaray background (C l C N )/W [(cm s 1 sr 1 ) sr] DATA DATA:CLEANED (C l C N )/W [(cm s 1 sr 1 ) sr] DATA DATA:CLEANED GeV GeV Multipole l Multipole l (C l C N )/W [(cm s 1 sr 1 ) sr] DATA DATA:CLEANED (C l C N )/W [(cm s 1 sr 1 ) sr] DATA DATA:CLEANED GeV GeV Multipole l Multipole l

35 Upper Limit on EGB w/ other models Residual appears If we try not to violate the limit, residual appears at <GeV.

36 Upper Limit on EGB w/ known sources Violates the Limit If we try to explain EGB at <GeV, the observation violates the limit. UL: E dn/de < 4.5 x -5 (E/0 GeV) -0.

37 Possible Explanations Hard spectrum with sub-tev E max and β<0 No known sources. TeV HBL? Low-luminosity GRBs? New Physics: Axion or Lorentz invariance violation? Dark matter in local? ~GeV sources pulsars? radio-quiet AGNs? Foreground uncertainty? See also Murase+ 1 Our limit is useful for future: Fermi, CTA, & CALET

38 Gamma-ray Attenuation by Cosmic Optical & Infrared Background blazar Extragalactic Background Light IACT γ VHE γ EBL e + e -

39 Cosmic Optical & Infrared Background (COB & CIB) I [nw/m /sr] 0 1 Stars Dust Madau & Pozzetti 00 (HST) Elbaz et al. 0 (ISO) Papovich et al. 04 (Spitzer) Fazio et al. 04 (Spitzer) Xu et al. 05 (GALEX) Dole et al. 06 (Spitzer) Frayer et al. 06 (Spitzer) Gardner et al. 00 (HST) Berta et al. 11 (Hershel/PEP) Wright & Reese 00 (DIRBE) Wright 04 (DIRBE) Levenson et al. 07 (DIRBE) Levenson & Wright 08 (DIRBE) Bernstein 07 (HST) Matsuoka et al. 11 (Pioneer) Matsumoto et al. 11 (IRTS) Matsuura et al. 11 (AKARI) CambrØsy et al. 01 (DIRBE) Dwek & Arendt 98 (DIRBE) Gorijian et al 00 (DIRBE) Finkbeiner et al 00 (DIRBE) Hauser et al 98 (DIRBE) Lagache et al 00 (DIRBE) Edelstein et al 00 (Voyger) Brown et al 00 (HST/STIS) Albert et al 08 (MAGIC) (X, z c )=(1.0, 0.0) (X, z c )=(50.0,.0) (X, z c )=(0.0,.0) [µm] YI+ 13a

40 Constraints from Gamma rays LAT best fit -- 1 sigma LAT best fit -- sigma Franceschini et al. 008 Finke et al model C Stecker et al High Opacity Stecker et al Low Opacity Kneiske et al highuv Kneiske et al best fit Kneiske & Dole 0 Dominguez et al. 011 Gilmore et al fiducial Abdo et al. 0 ] sr -1 - ME1 exclusion region H.E.S.S. low energy H.E.S.S. full dataset H.E.S.S. high energy H.E.S.S. contour (sys + stat ) low full high Direct measurements τ γ γ 1 [ nw m λ F λ -1 z~1.0 z Galaxy counts Energy [GeV] Ackermann Fermi derived the COB opacity using the combined spectra of blazars (see also Gong & Cooray 13, Dominguez + 13). H.E.S.S. derived the COB intensity using the combined spectra of blazars. λ [ µm ] Abramowski + 13 ig. 5. Flux density of the extragalactic background light versus wave-

41 Direct Measurements of COB & CIB Pioneer /11 AKARI Matsuoka + 11 Tsumura + 13 Pioneer /11 measurements are consistent with the galaxy count lower limit. But, recent AKARI measurement is consistent with IRTS. Peak at near infrared? CIBER rocket experiment will provide more information.

42 CIB Model with First Stars YI+ 13 YI+ 13 First stars contribution to EBL at z=0 is minor, and difficult to distinguish through gamma-ray attenuation even with high-z objects.

43 Constraints on First Stars Cosmic Star Formation Rate Density [M sun /yr/mpc 3 ] Fernandez & Komatsu 06 Raue, Kneiske, & Mazin 09 Gilmore 1 C = 3.0, f esc = 0. C = 3.0, f esc = 0.5 C = 1.0, f esc = 0. Bromm & Loeb 06 Trenti & Stiavelli 09 de Souza, Yoshida, & Ioka Redshift z YI+ 14 Combining reionization and distant gamma-ray data (E<0 GeV). The required first star formation rate density is inconsistent with reionization data (e.g. Madau & Silk 05; YI+ 14)

44 Excess in the NIR Sky Fluctuation Kashlinsky+ 1 Matsumoto + 11 AKARI & Spitzer reported NIR background fluctuation at.4, 3., 3.6, 4.1 and 4.5 um (Kashlinsky+ 05, 07, 1, Matsumoto+ 11, Cooray+ 1). 15-0% of CIB fluctuation is correlated with CXB (Cappelluti+ 13). The angular power spectrum at large scales is close to the shape of a Rayleigh-Jeans spectrum, λ -3 (Matsumoto+ 11, Cooray+ 1)