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Register a new userThe 2.4 $mu$m Galaxy Luminosity Function as Measured Using WISE. III. Measurement Results
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The WISE satellite surveyed the entire sky multiple times in four infrared wavelengths (3.4, 4.6, 12, and $22,mu$m; Wright et al. 2010). The unprecedented combination of coverage area and depth gives us the opportunity to measure the luminosity function of galaxies, one of the fundamental quantities in the study of them, at $2.4 mu$m to an unparalleled level of formal statistical accuracy in the near infrared. The big advantage of measuring luminosity functions at wavelengths in the window $approx 2$ to $3.5,mu$m is that it correlates more closely to the total stellar mass in galaxies than others. In this paper we report on the parameters for the $2.4,mu$m luminosity function of galaxies obtained from applying the spectroluminosity functional based methods defined in Lake et al. (2017b) to the data sets described in Lake et al. (2017a) using the mean and covariance of $2.4,mu$m normalized SEDs from Lake & Wright (2016). In terms of single Schechter function parameters evaluated at the present epoch, the combined result is: $phi_star = 5.8 pm [0.3_{mathrm{stat}},, 0.3_{mathrm{sys}}] times 10^{-3} operatorname{Mpc}^{-3}$, $L_star = 6.4 pm [0.1_{mathrm{stat}},, 0.3_{mathrm{sys}}] times 10^{10}, L_{2.4,mumathrm{m},odot}$ ($M_star = -21.67 pm [0.02_{mathrm{stat}},, 0.05_{mathrm{sys}}]operatorname{AB mag}$), and $alpha = -1.050 pm [0.004_{mathrm{stat}},, 0.03_{mathrm{sys}}]$, corresponding to a galaxy number density of $0.08operatorname{Mpc}^{-3}$ brighter than $10^6, L_{2.4,mumathrm{m},odot}$ ($10^{-3} operatorname{Mpc}^{-3}$ brighter than $L_star$) and a $2.4,mu$m luminosity density equivalent to $3.8times10^{8},L_{2.4,mumathrm{m},odot}operatorname{Mpc}^{-3}$. $ldots$
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The WISE satellite surveyed the entire sky multiple times in four infrared (IR) wavelengths ($3.4, 4.6, 12,$ and $22, mu$m, Wright et al. 2010). This all-sky IR photometric survey makes it possible to leverage many of the large publicly available spectroscopic redshift surveys to measure galaxy properties in the IR. While characterizing the cross-matching of WISE data to a single survey is a straightforward process, doing it with six different redshift surveys takes a fair amount of space to characterize adequately, because each survey has unique caveats and characteristics that need addressing. This work describes a data set that results from matching five public redshift surveys with the AllWISE data release, along with a reanalysis of the data described in Lake et al. 2012. The combined data set has an additional flux limit of $80,mu$Jy ($19.14$ AB mag) in WISEs W1 filter imposed in order to limit it to targets with high completeness and reliable photometry in the AllWISE data set. Consistent analysis of all of the data is only possible if the color bias discussed in Ilbert et al. (2004) is addressed (for example: the techniques explored in the first paper in this series Lake et al. 2017b). The sample defined herein is used in this papers sequel paper, Lake et al. 2017a), to measure the luminosity function of galaxies at $2.4, mu$m rest frame wavelength, and the selection process of the sample is optimized for this purpose.
Local infrared (IR) luminosity functions (LFs) are necessary benchmarks for high-redshift IR galaxy evolution studies. Any accurate IR LF evolution studies require accordingly accurate local IR LFs. We present infrared galaxy LFs at redshifts redshifts of $z leq 0.3$ from AKARI space telescope, which performed an all-sky survey in six IR bands (9, 18, 65, 90, 140 and 160 micron) with 10 times better sensitivity than its precursor IRAS. Availability of 160 micron filter is critically important in accurately measuring total IR luminosity of galaxies, covering across the peak of the dust emission. By combining data from Wide-field Infrared Survey Explorer (WISE), Sloan Digital Sky Survey (SDSS) Data Release 13 (DR13), 6-degree Field Galaxy Survey (6dFGS) and the 2MASS Redshift Survey (2MRS), we created a sample of 15,638 local IR galaxies with spectroscopic redshifts, factor of 7 larger compared to previously studied AKARI -SDSS sample. After carefully correcting for volume effects in both IR and optical, the obtained IR LFs agree well with previous studies, but comes with much smaller errors. Measured local IR luminosity density is $Omega_{IR}=$ 1.19$pm$0.05 $times 10^{8}$ L$_{odot}$ Mpc$^{-3}$. The contributions from luminous infrared galaxies and ultra luminous infrared galaxies to IR are very small, 9.3 per cent and 0.9 per cent, respectively. There exists no future all sky survey in far-infrared wavelengths in the foreseeable future. The IR LFs obtained in this work will therefore remain an important benchmark for high-redshift studies for decades.
We determine the 22$mu$m luminosity evolution and luminosity function for quasars from a data set of over 20,000 objects obtained by combining flux-limited Sloan Digital Sky Survey optical and Wide field Infrared Survey Explorer mid-infrared data. We apply methods developed in previous works to access the intrinsic population distributions non-parametrically, taking into account the truncations and correlations inherent in the data. We find that the population of quasars exhibits positive luminosity evolution with redshift in the mid-infrared, but with considerably less mid-infrared evolution than in the optical or radio bands. With the luminosity evolutions accounted for, we determine the density evolution and local mid-infrared luminosity function. The latter displays a sharp flattening at local luminosities below $sim 10^{31}$ erg sec$^{-1}$ Hz$^{-1}$, which has been reported previously at 15 $mu$m for AGN classified as both type-1 and type-2. We calculate the integrated total emission from quasars at 22 $mu$m and find it to be a small fraction of both the cosmic infrared background light and the integrated emission from all sources at this wavelength.
The dielectric function of interstellar dust material is modeled using observations of extinction and polarization in the infrared, together with estimates for the mass of interstellar dust. The astrodust material is assumed to be a mix of amorphous silicates and other materials, including hydrocarbons producing an absorption feature at 3.4$mu$m. The detailed shape of the 10$mu$m polarization profile depends on the assumed porosity and grain shape, but the 10$mu$m spectropolarimetric data are not yet good enough to clearly favor one shape over another, nor to constrain the porosity. The expected 3.4$mu$m feature polarization is consistent with existing upper limits, provided the 3.4$mu$m absorption is preferentially located in grain surface layers; a separate population of non-aligned carbonaceous grains is not required. We predict the 3.4$mu$m polarization feature to be $(Delta p)_{3.4mu{rm m}}/p(10mu{rm m})approx 0.016$, just below current upper limits. Polarization by the same grains at submm wavelengths is also calculated.
We present an analysis of star formation and nuclear activity of about 28000 galaxies in a volume-limited sample taken from SDSS DR4 low-redshift catalogue (LRC) taken from the New York University Value Added Galaxy Catalogue (NYU-VAGC) of Blanton et al. 2005, with 0.005<z<0.037, ~90% complete to M_r=-18.0. We find that in high-density regions ~70 per cent of galaxies are passively evolving independent of luminosity. In the rarefied field, however, the fraction of passively evolving galaxies is a strong function of luminosity, dropping from 50 per cent for Mr <~ -21 to zero by Mr ~ -18. Moreover the few passively evolving dwarf galaxies in field regions appear as satellites to bright (>~ L*) galaxies. Moreover the fraction of galaxies with the optical signatures of an active galactic nucleus (AGN) decreases steadily from ~50% at Mr~-21 to ~0 per cent by Mr~-18 closely mirroring the luminosity dependence of the passive galaxy fraction in low-density environments (see fig. 1 continuous lines). This result reflects the increasing importance of AGN feedback with galaxy mass for their evolution, such that the star formation histories of massive galaxies are primarily determined by their past merger history.
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