Galaxy Evolution, Deep Galaxy Counts, and the Near‐Infrared Cosmic Infrared Background

Abstract

Accurate synthetic models of stellar populations are constructed and used in evolutionary models of stellar populations in forming galaxies. Following their formation, the late-type galaxies are assumed to follow the Schmidt law for star formation, while early-type galaxies are normalized to the present-day fundamental plane relations assumed to mimic the metallicity variations along their luminosity sequence. The stars in disks of galaxies are distributed with the Scalo IMF and in spheroids with the Salpeter IMF. We show that these assumptions reproduce extremely well the recent observations for the evolution of the rate of star formation with redshift. We then compute predictions of these models for the observational data at early epochs for various cosmological parameters ), and We Ðnd good ) " , H 0 . match to the metallicity data from the damped Lya systems and the evolution of the luminosity density out to z^1. Likewise, our models produce good Ðts for low values of ) to the deep number counts of galaxies in all bands where data are available ; this is done without assuming existence of extra populations of galaxies at high z. Our models also match the data on the redshift distribution of galaxy counts in B and K bands. They also provide good Ðts to the observed colors. We compute the predicted mean levels and angular distribution of the cosmic infrared background produced from the early evolution of galaxies. The predicted Ñuxes and Ñuctuations are still below the current observational limits, but not by a large factor. Finally, we Ðnd that the recent detection of the di †use extragalactic light in the visible bands requires for our models a high redshift of galaxy formation, otherwise, the proz f º (3È4) ; duced Ñux of the extragalactic light at optical bands exceeds the current observational limits.

Has the Optical Extragalactic Background Light Been Detected?

“…These results have been widely cited in the literature; see, e.g., Barger et al (2001), Guy et al (2000), Hauser (2001), Jimenez & Kashlinsky (1999), Longair (2001), Madau & Pozzetti (2000), Pagel (2002), Peebles (2001), Pozzetti & Madau (2001), Primack et al (1999), Renault et al (2001), andWright (2001). It is therefore important to point out the following puzzling situation that results from the comparison between the BFM98-01 and BFM02 results.…”

Cosmic infrared background and early galaxy evolution

“…Also, measurements of cluster galaxies out to z ∼ 1, or ∼ 1 2 look-back time, indicate that the fundamental plane preserves its logarithmic slope while the amplitude changes (Treu et al 2002, van Dokkum et al 2001, van der Wel et al 2004. The origin of this wavelength trend may lie in various quantities, like systematic variations in the IMF along the luminosity sequence , or with metallicity (Jimenez & Kashlinsky 1999). …”

“…They note that, for a wide range of the IMF, the agreement of the computed emissivities with estimates from the Canada-France Redshift Survey or CFRS (Lilly et al 1996) requires that the initial density parameter of material that went into stars and dust at z < ∼ 4 was between 10 −3 h −1 and 8 × 10 −3 h −1 . Jimenez & Kashlinsky (1999) used synthetic models of stellar populations to analyze the contribution of normal galaxies to near-IR CIB and its fluctuations. The galaxies were assumed to form at fixed z f and were divided into five morphological types from E to Sd/Irr.…”

“…This includes averaging over all morphological types and, within each type, averaging over the luminosity function. The first is important because earlytype galaxies contribute substantially to the near-IR EBL (Jimenez & Kashlinsky 1999). The second step is also important because, at least for early-type galaxies, the mass-to-light depends on galaxy mass or luminosity as suggested by the fundamental plane measurements for elliptical galaxies (Faber et al 1989, Djorgovski & Davis 1987).…”

“…Hence the data are probing the range of scales where galaxy clustering is in the non-linear regime. The lines show the amplitude for passively evolving galaxies with synthetic spectra from Jimenez & Kashlinsky (1999) for J and K bands. They are normalized to the observations of the galaxy luminosity densities in Fig.…”