CLUSTERING OF THE DIFFUSE INFRARED LIGHT FROM THE COBE DIRBE MAPS .1.C(0) AND LIMITS ON THE NEAR-INFRARED BACKGROUND

The cosmic infrared background (CIB) and its anisotropy have not yet b een measured but are important signatures of the early evolution and c lustering of galaxies. The near-IR is particularly interesting because redshift effects bring the peak luminosity of distant galaxies into t he near-IR, allowing high-redshift objects to dominate the theoretical predictions of the CIB and its fluctuations. This paper is devoted to studying the CIB through its correlation properties. We studied the l imits on CIB anisotropy in the near-IR (1.25, 2.2, and 3.5 mu m, or J, K, L) bands at a scale of 0.degrees 7 using the COBE(5) Diffuse Infra red Background Experiment (DIRBE) data. In single bands, we obtain the upper limits on the zero-lag correlation signal C(0)= [(v delta I-v)( 2)] < 3.6 x 10(-16), 5.1 x 10(-17), and 5.7 x 10(-18) W-2 m(-4) sr(-2) for the J, K, and L bands, respectively. The DIRBE data exhibit a cle ar color between the various bands with a small dispersion. On the oth er hand, most of the CIB is expected to come from redshifted galaxies, and thus it should have different color properties. We use this obser vation to develop a ''color subtraction'' method of linear combination s of maps at two different bands. This method is expected to suppress the dominant fluctuations from foreground stars and nearby galaxies, w hile not reducing (or perhaps even amplifying) the extragalactic contr ibution to C(0). Applying this technique gives significantly lower and more isotropic limits. For the J-K, J-L, and K-L combinations, these limits are C(0)< 6.3 x 10(-17) 1.4 x 10(-16), and 1.2 x 10(-17) W-2 m( -4) sr(-2), respectively. We also use simple no-evolution models to in terpret these numbers in terms of the total CIB levels, postponing a m ore detailed interpretation to a forthcoming paper. From the single-ba nd fluctuations, we estimate upper limits on the CIB from clustered ma tter of (vI(v))(z,rms) =[integral(dvI(v)/dz)(2) dz](1/2) < 200, 78, an d 26 nW m(-2) sr(-1) in the J, K, and L bands independently of the evo lution history or spectral energy distribution. The color-subtracted s ignals constrain strongly the color evolution of galaxy populations an d, if their degree of isotropy is indicative of a cosmological origin, they could allow determination of the total diffuse fluxes due to clu stered material.