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Register a new userA Near-Infrared Analysis of the Submillimeter Background and the Cosmic Star-Formation History
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We use new deep near-infrared (NIR) and mid-infrared (MIR) observations to analyze the 850$~mu$m image of the GOODS HDF-N region. We show that much of the submillimeter background at this wavelength is picked out by sources with $H(AB)$ or 3.6um (AB)<23.25 (1.8 uJy). These sources contribute an 850um background of 24pm2 Jy deg^-2. This is a much higher fraction of the measured background (31-45 Jy deg^-2) than is found with current 20cm or 24um samples. Roughly one-half of these NIR-selected sources have spectroscopic identifications, and we can assign robust photometric redshifts to nearly all of the remaining sources using their UV to MIR spectral energy distributions. We use the redshift and spectral type information to show that a large fraction of the 850um background light comes from sources with z=0-1.5 and that the sources responsible have intermediate spectral types. Neither the elliptical galaxies, which have no star formation, nor the bluest galaxies, which have little dust, contribute a significant amount of 850um light, despite the fact that together they comprise approximately half of the galaxies in the sample. The galaxies with intermediate spectral types have a mean flux of 0.40pm0.03 mJy at 850um and 9.1pm0.3 uJy at 20cm. The redshift distribution of the NIR-selected 850um light lies well below that of the much smaller amount of light traced by the more luminous, radio- selected submillimeter sources. We therefore require a revised star-formation history with a lower star-formation rate at high redshifts. We use a stacking analysis of the 20cm light in the NIR sample to show that the star-formation history of the total 850um sample is relatively flat down to z~1 and that half of the total star formation occurs at redshifts z<1.4.
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We present a linear clustering model of cosmic infrared background (CIB) anisotropies at large scales that is used to measure the cosmic star formation rate density up to redshift 6, the effective bias of the CIB and the mass of dark-matter halos hosting dusty star-forming galaxies. This is achieved using the Planck CIB auto- and cross-power spectra (between different frequencies) and CIBxCMB lensing cross-spectra measurements, as well as external constraints (e.g. on the CIB mean brightness). We recovered an obscured star formation history which agrees well with the values derived from infrared deep surveys and we confirm that the obscured star formation dominates the unobscured one up to at least z=4. The obscured and unobscured star formation rate densities are compatible at $1sigma$ at z=5. We also determined the evolution of the effective bias of the galaxies emitting the CIB and found a rapid increase from $sim$0.8 at z$=$0 to $sim$8 at z$=$4. At 2$<$z$<$4, this effective bias is similar to that of galaxies at the knee of the mass functions and submillimeter galaxies. This effective bias is the weighted average of the true bias with the corresponding emissivity of the galaxies. The halo mass corresponding to this bias is thus not exactly the mass contributing the most to the star formation density. Correcting for this, we obtained a value of log(M$_h$/M$_{odot}$)=12.77$_{-0.125}^{+0.128}$ for the mass of the typical dark matter halo contributing to the CIB at z=2. Finally, we also computed using a Fisher matrix analysis how the uncertainties on the cosmological parameters affect the recovered CIB model parameters and find that the effect is negligible.
The cosmic near-infrared background (NIRB) offers a powerful integral probe of radiative processes at different cosmic epochs, including the pre-reionization era when metal-free, Population III (Pop III) stars first formed. While the radiation from metal-enriched, Population II (Pop II) stars likely dominates the contribution to the observed NIRB from the reionization era, Pop III stars -- if formed efficiently -- might leave characteristic imprints on the NIRB thanks to their strong Ly$alpha$ emission. Using a physically-motivated model of first star formation, we provide an analysis of the NIRB mean spectrum and anisotropy contributed by stellar populations at $z>5$. We find that in circumstances where massive Pop III stars persistently form in molecular cooling haloes at a rate of a few times $10^{-3},M_odot mathrm{yr}^{-1}$, before being suppressed towards the epoch of reionization (EoR) by the accumulated Lyman-Werner background, a unique spectral signature shows up redward of $1,mu$m in the observed NIRB spectrum sourced by galaxies at $z>5$. While the detailed shape and amplitude of the spectral signature depend on various factors including the star formation histories, IMF, LyC escape fraction and so forth, the most interesting scenarios with efficient Pop III star formation are within the reach of forthcoming facilities such as the Spectro-Photometer for the History of the Universe, Epoch of Reionization and Ices Explorer (SPHEREx). As a result, new constraints on the abundance and formation history of Pop III stars at high redshifts will be available through precise measurements of the NIRB in the next few years.
We investigate the physics driving the cosmic star formation (SF) history using the more than fifty large, cosmological, hydrodynamical simulations that together comprise the OverWhelmingly Large Simulations (OWLS) project. We systematically vary the parameters of the model to determine which physical processes are dominant and which aspects of the model are robust. Generically, we find that SF is limited by the build-up of dark matter haloes at high redshift, reaches a broad maximum at intermediate redshift, then decreases as it is quenched by lower cooling rates in hotter and lower density gas, gas exhaustion, and self-regulated feedback from stars and black holes. The higher redshift SF is therefore mostly determined by the cosmological parameters and to a lesser extent by photo-heating from reionization. The location and height of the peak in the SF history, and the steepness of the decline towards the present, depend on the physics and implementation of stellar and black hole feedback. Mass loss from intermediate-mass stars and metal-line cooling both boost the SF rate at late times. Galaxies form stars in a self-regulated fashion at a rate controlled by the balance between, on the one hand, feedback from massive stars and black holes and, on the other hand, gas cooling and accretion. Paradoxically, the SF rate is highly insensitive to the assumed SF law. This can be understood in terms of self-regulation: if the SF efficiency is changed, then galaxies adjust their gas fractions so as to achieve the same rate of production of massive stars. Self-regulated feedback from accreting black holes is required to match the steep decline in the observed SF rate below redshift two, although more extreme feedback from SF, for example in the form of a top-heavy IMF at high gas pressures, can help.
We present the first cross-correlation measurement between Sloan Digital Sky Survey (SDSS) Type 1 quasars and the cosmic infrared background (CIB) measured by Herschel. The distribution of the quasars at 0.15<z<3.5 covers the redshift range where we expect most of the CIB to originate. We detect the sub-mm emission of the quasars, which dominates on small scales, as well as correlated emission from dusty star-forming galaxies (DSFGs) dominant on larger scales. The mean sub-mm flux densities of the DR7 quasars (median redshift <z>=1.4) is $11.1^{+1.6}_{-1.4}$, $7.1^{+1.6}_{-1.3}$ and $3.6^{+1.4}_{-1.0}$ mJy at 250, 350 and 500 microns, respectively, while the mean sub-mm flux densities of the DR9 quasars (<z>=2.5) is $5.7^{+0.7}_{-0.6}$, $5.0^{+0.8}_{-0.7}$ and $1.8^{+0.5}_{-0.4}$ mJy. We find that the correlated sub-mm emission includes both the emission from satellite DSFGs in the same halo as the central quasar and the emission from DSFGs in separate halos (correlated with the quasar-hosting halo). The amplitude of the one-halo term is ~10 times smaller than the sub-mm emission of the quasars, implying the the satellites have a lower star-formation rate than the quasars. The satellite fraction for the DR7 quasars is $0.008^{+0.008}_{-0.005}$ and the host halo mass scale for the central and satellite quasars is $10^{12.36pm0.87}$ M$_{odot}$ and $10^{13.60pm0.38}$ M$_{odot}$, respectively. The satellite fraction of the DR9 quasars is $0.065^{+0.021}_{-0.031}$ and the host halo mass scale for the central and satellite quasars is $10^{12.29pm0.62}$ M$_{odot}$ and $10^{12.82pm0.39}$ M$_{odot}$, respectively. Thus, the typical halo environment of the SDSS Type 1 quasars is found to be similar to that of DSFGs, which supports the generally accepted view that dusty starburst and quasar activity are evolutionarily linked.
[Abridged] This paper aims at providing new conservative constraints to the cosmic star-formation history from the empirical modeling of mid- and far-infrared data. We perform a non-parametric inversion of galaxy counts at 15, 24, 70, 160, and 850 microns simultaneously. It is a blind search (no redshift information is required) of all possible evolutions of the infrared luminosity function of galaxies, from which the evolution of the star-formation rate density and its uncertainties are derived. The cosmic infrared background (CIRB) measurements are used a posteriori to tighten the range of solutions. The inversion relies only on two hypotheses: (1) the luminosity function remains smooth both in redshift and luminosity, (2) a set of infrared spectral energy distributions (SEDs) of galaxies must be assumed. The range of star-formation histories that we derive is well constrained and consistent with redshift-based measurements from deep surveys. The redshift decompositions of the counts are also recovered successfully. Therefore, multi-wavelength counts and CIRB (both projected observations) alone seem to contain enough information to recover the cosmic star-formation history with quantifiable errors. A peak of the SFRD at z~2 is preferred, although higher redshifts are not excluded. We also find a good consistency between the observed evolution of the stellar mass density and the prediction from our model. Finally, the inability of the inversion to model perfectly and simultaneously all the multi-wavelength infrared counts (especially at 160 microns where an excess is seen around 20 mJ) implies either (i) the existence of a sub-population of colder galaxies, (ii) a larger dispersion of dust temperatures among local galaxies than expected, (iii) or a redshift evolution of the infrared SEDs of galaxies.
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