Evolution Of Luminosity Density Research Articles

Gaussian Process Reconstruction of Reionization History

Abstract We reconstruct the history of reionization using Gaussian process regression. Using the UV luminosity data compilation from Hubble Frontiers Fields we reconstruct the redshift evolution of UV luminosity density and thereby the evolution of the source term in the ionization equation. This model-independent reconstruction rules out single power-law evolution of the luminosity density but supports the logarithmic double power-law parameterization. We obtain reionization history by integrating ionization equations with the reconstructed source term. Using the optical depth constraint from Planck cosmic microwave background observation, measurement of UV luminosity function integrated until truncation magnitude of −17 and −15, and derived ionization fraction from high redshift quasar, galaxies, and gamma-ray burst observations, we constrain the history of reionization. In the conservative case we find the constraint on the optical depth as τ = 0.052 ± 0.001 ± 0.002 at 68% and 95% confidence intervals. We find the redshift duration between 10% and 90% ionization to be 2.05 − 0.21 − 0.30 + 0.11 + 0.37 . Longer duration of reionization is supported if UV luminosity density data with truncation magnitude of −15 is used in the joint analysis. Our results point out that even in a conservative reconstruction, a combination of cosmological and astrophysical observations can provide stringent constraints on the epoch of reionization.

Universe opacity and EBL

The observed extragalactic background light (EBL) is affected by light attenuation due to absorption of light by galactic and intergalactic dust in the Universe. Even galactic opacity of 10-20 percent and minute universe intergalactic opacity of $0.01\,\mathrm{mag}\,h\,\mathrm{Gpc}^{-1}$ at the local Universe have a significant impact on the EBL because obscuration of galaxies and density of intergalactic dust increase with redshift as $\left(1+z\right)^3$. Consequently, intergalactic opacity increases and the Universe becomes considerably opaque at $z > 3$. Adopting realistic values for galactic and intergalactic opacity, the estimates of the EBL for the expanding dusty universe are close to observations. The luminosity density evolution fits well measurements. The model reproduces a steep increase of the luminosity density at $z<2$, its maximum at $z=2-3$, and its decrease at higher redshifts. The increase of the luminosity density at low $z$ is not produced by the evolution of the star formation rate but by the fact that the Universe occupied a smaller volume in previous epochs. The decline of the luminosity density at high $z$ originates in the opacity of the Universe. The calculated bolometric EBL ranges from 100 to 200 $\mathrm{n W m}^{-2}\mathrm{sr}^{-1}$ and is within the limits of 40 and 200 $\mathrm{n W m}^{-2}\mathrm{sr}^{-1}$ of current EBL observations. The model predicts 98\% of the EBL coming from radiation of galaxies at $z<3.5$. Accounting for light extinction by intergalactic dust implies that the Universe was probably more opaque than dark for $z>3.5$.

Galaxy and Mass Assembly (GAMA): maximum-likelihood determination of the luminosity function and its evolution

We describe modifications to the joint stepwise maximum-likelihood method of Cole in order to simultaneously fit the Galaxy and Mass Assembly II galaxy luminosity function (LF), corrected for radial density variations, and its evolution with redshift. The whole sample is reasonably well fitted with luminosity (Qe) and density (Pe) evolution parameters Qe, Pe ≈ 1.0, 1.0 but with significant degeneracies characterized by Qe ≈ 1.4 − 0.4Pe. Blue galaxies exhibit larger luminosity density evolution than red galaxies, as expected. We present the evolution-corrected r-band LF for the whole sample and for blue and red subsamples, using both Petrosian and Sérsic magnitudes. Petrosian magnitudes miss a substantial fraction of the flux of de Vaucouleurs profile galaxies: the Sérsic LF is substantially higher than the Petrosian LF at the bright end.

Faint-end quasar luminosity functions from cosmological hydrodynamic simulations

We investigate the predictions for the faint-end quasar luminosity function (QLF) and its evolution using fully cosmological hydrodynamic simulations which self-consistently follow star formation, black hole growth and associated feedback processes. We find remarkably good agreement between predicted and observed faint end of the optical and X-ray QLFs (the bright end is not accessible in our simulated volumes) at z < 2. At higher redshifts our simulations tend to overestimate the QLF at the faintest luminosities. We show that although the low (high) luminosity ranges of the faint-end QLF are dominated by low (high) mass black holes, a wide range of black hole masses still contributes to any given luminosity range. This is consistent with the complex lightcurves of black holes resulting from the detailed hydrodynamics followed in the simulations. Consistent with the results on the QLFs, we find good agreement for the evolution of the comoving number density (in optical, soft and hard X-ray bands) of AGN for luminosities above 10^43 erg/s. However, the luminosity density evolution from the simulation appears to imply a peak at higher redshift than constrained from hard X-ray data (but not in optical). Our predicted excess at the faintest fluxes at z >= 2 does not lead to an overestimate to the total X-ray background and its contribution is at most a factor of two larger than the unresolved fraction of the 2-8 keV background. Even though this could be explained by some yet undetected, perhaps heavily obscured faint quasar population, we show that our predictions for the faint sources at high redshifts (which are dominated by the low mass black holes) in the simulations are likely affected by resolution effects.

MID-INFRARED GALAXY LUMINOSITY FUNCTIONS FROM THE AGN AND GALAXY EVOLUTION SURVEY

We present galaxy luminosity functions at 3.6, 4.5, 5.8, and 8.0 micron measured by combining photometry from the IRAC Shallow Survey with redshifts from the AGN and Galaxy Evolution Survey of the NOAO Deep Wide-Field Survey Bootes field. The well-defined IRAC samples contain 3800-5800 galaxies for the 3.6-8.0 micron bands with spectroscopic redshifts and z < 0.6. We obtained relatively complete luminosity functions in the local redshift bin of z < 0.2 for all four IRAC channels that are well fit by Schechter functions. We found significant evolution in the luminosity functions for all four IRAC channels that can be fit as an evolution in M* with redshift, \Delta M* = Qz. While we measured Q=1.2\pm0.4 and 1.1\pm0.4 in the 3.6 and 4.5 micron bands consistent with the predictions from a passively evolving population, we obtained Q=1.8\pm1.1 in the 8.0 micron band consistent with other evolving star formation rate estimates. We compared our LFs with the predictions of semi-analytical galaxy formation and found the best agreement at 3.6 and 4.5 micron, rough agreement at 8.0 micron, and a large mismatch at 5.8 micron. These models also predicted a comparable Q value to our luminosity functions at 8.0 micron, but predicted smaller values at 3.6 and 4.5 micron. We also measured the luminosity functions separately for early and late-type galaxies. While the luminosity functions of late-type galaxies resemble those for the total population, the luminosity functions of early-type galaxies in the 3.6 and 4.5 micron bands indicate deviations from the passive evolution model, especially from the measured flat luminosity density evolution. Combining our estimates with other measurements in the literature, we found (53\pm18)% of the present stellar mass of early-type galaxies has been assembled at z=0.7.

The evolution of the luminosity functions in the FORS deep field from low to high redshift

Received -; accepted - Abstract. We present the redshift evolution of the restframe galaxy luminosity function (LF) in the red r', i', and z' bands as derived from the FORS Deep Field (FDF), thus extending the results published in Gabasch et al. (2004a) to longer wavelengths. Using the deep and homogeneous I-band selected dataset of the FDF we are able to follow the red LFs over the redshift range 0.5 < z < 3.5. The results are based on photometric redshifts for 5558 galaxies derived from the photometry in 9 filters achieving an accuracy ofz/(zspec + 1) ≤ 0.03 with only ∼ 1% outliers. A comparison with results from the literature shows the reliability of the derived LFs. Because of the depth of the FDF we can give relatively tight constraints on the faint-end slopeof the LF: The faint-end of the red LFs does not show a large redshift evolution and is compatible within 1� to 2� with a constant slope over the redshift range 0.5 ∼ < z ∼ < 2.0. Moreover, the slopes in r', i', and z' are very similar with a best fitting value of � = −1.33 ± 0.03 for the combined bands. There is a clear trend ofto steepen with increasing wavelength: �UV &u' = −1.07 ± 0.04 → �g'&B = −1.25 ± 0.03 → �r'&i'&z' = −1.33 ± 0.03. We subdivide our galaxy sample into four SED types and determine the contribution of a typical SED type to the overall LF. We show that the wavelength dependence of the LF slope can be explained by the relative contribution of different SED-type LFs to the overall LF, as different SED types dominate the LF in the blue and red bands. Furthermore we also derive and analyze the luminosity density evolution of the different SED types up to z ∼ 2. We investigate the evolution of Mand � � by means of the redshift parametrization M � (z) = M �

The Ultraviolet Luminosity Function of GALEX Galaxies at Photometric Redshifts between 0.07 and 0.25

We present measurements of the UV galaxy luminosity function and the evolution of luminosity density from Galaxy Evolution Explorer (GALEX) observations matched to the Sloan Digital Sky Survey (SDSS). We analyze galaxies in the Medium Imaging Survey overlapping the SDSS First Data Release, with a total coverage of 44 deg2. Using the combined GALEX + SDSS photometry, we compute photometric redshifts and study the luminosity function in three redshift shells between z = 0.07 and 0.25. The Schechter function fits indicate that the faint-end slope α is consistent with -1.1 at all redshifts, but the characteristic UV luminosity M* brightens by 0.2 mag from z = 0.07 to 0.25. In the lowest redshift bin, early- and late-type galaxies are studied separately, and we confirm that red galaxies tend to be brighter and have a shallower slope α than blue ones. The derived luminosity densities are consistent with other GALEX results based on a local spectroscopic sample from the Two-Degree Field, and the evolution follows the trend reported by deeper studies.

The evolution of the luminosity functions in the FORS Deep Field from low to high redshift

We present the redshift evolution of the restframe galaxy luminosity function (LF) in the red r � , i � ,a ndzbands, as derived from the FORS Deep Field (FDF), thus extending our earlier results to longer wavelengths. Using the deep and homogeneous I-band selected dataset of the FDF, we were able to follow the red LFs over the redshift range 0.5 < z < 3.5. The results are based on photometric redshifts for 5558 galaxies derived from the photometry in 9 filters and achieving an accuracy of ∆z/(zspec + 1) ≤ 0.03 with only ∼1% outliers. A comparison with results from the literature shows the reliability of the derived LFs. Because of the depth of the FDF, we can give relatively tight constraints on the faint-end slope α of the LF; the faint-end of the red LFs does not show a large redshift evolution and is compatible within 1σ to 2σ with a constant slope over the redshift range 0.5 < z < 2.0. Moreover, the slopes in r � , i � ,a ndzare very similar to a best-fitting value of α = −1.33 ± 0.03 for the combined bands. There is a clear trend of α to steepen with increasing wavelength: αUV&u� = −1.07 ± 0.04 → αg� &B = −1.25 ± 0.03 → αr� &i� &z� = −1.33 ± 0.03. We subdivided our galaxy sample into four SED types and determined the contribution of a typical SED type to the overall LF. We show that the wavelength dependence of the LF slope can be explained by the relative contribution of different SED-type LFs to the overall LF, as different SED types dominate the LF in the blue and red bands. Furthermore we also derived and analyzed the luminosity density evolution of the different SED types up to z ∼ 2. We investigated the evolution of M ∗ and φ ∗ by means of the redshift parametrization M ∗ (z) = M ∗ + a ln (1 + z )a ndφ ∗ (z) = φ ∗ (1 + z) b . Based on the FDF data, we found only a mild brightening of M ∗ (ar� ∼− 0.8, and ai� ,z� ∼− 0.4) and a decreasing φ ∗ (br� ,i� ,z� ∼− 0.6) with increasing redshift. Therefore, fromz �∼ 0. 5t oz �∼ 3 the characteristic luminosity increases by ∼0.8, ∼0.4, and ∼0.4 mag in the r � , i � ,a ndzbands, respectively. Simultaneously the characteristic density decreases by about 40% in all analyzed wavebands. A comparison of the LFs with semi- analytical galaxy formation models by Kauffmann et al. (1999) shows a similar result to the blue bands: the semi-analytical models predict LFs that describe the data at low redshift very well, but show growing disagreement with increasing redshifts.

Star Formation History since [ITAL][CLC]z[/CLC][/ITAL] = 1.5 as Inferred from Rest-Frame Ultraviolet Luminosity Density Evolution

We investigate the evolution of the universal rest-frame ultraviolet luminosity density from z = 1.5 to the present. We analyze an extensive sample of multicolor data (U, BAB, VAB = 24.5) plus spectroscopic redshifts from the Hawaii Survey Fields and the Hubble Deep Field. Our multicolor data allow us to select our sample in the rest-frame ultraviolet (2500 A) over the entire redshift range to z = 1.5. We conclude that the evolution in the luminosity density is a function of the form (1 + z)1.7 ± 1.0 for a flat lambda (Ωm0 = 0.3, Ωλ0 = 0.7) cosmology and (1 + z)2.4 ± 1.0 for an Einstein–de Sitter cosmology.

Luminosity Density Evolution in the Universe and Cosmological Parameters

Star formation history in galaxies is strongly correlated to their present-day colors and the Hubble sequence can be considered as a sequence of different star formation history. Therefore we can model the cosmic star formation history based on the colors of local galaxies, and comparison to direct observations of luminosity density evolution at high redshift gives a new test for the cosmological parameters which is insensitive to merger history of galaxies. The luminosity density evolution in 0 &lt; z &lt; 1 observed by the Canada-France Redshift Survey in three wavebands of 2800Å, 4400Å, and 1μm indicates that the Λ-dominated flat universe with λ0 ∼ 0.8 (&gt; 0.53 at 95%CL) is strongly favored.The cosmic star formation rate (SFR) at z &gt; 2 is also compared to the latest data of the Hubble Deep Field including new data which were not incorporated in the previous work of Totani, Yoshii, &amp; Sato (1997), and our model of the luminosity density of spiral galaxies taking account of gas infall is consistent with the observations. Starbursts in elliptical galaxies, which are expected from the galactic wind model, however overproduce SFRs and hence they should be formed at z ≳ 5 or their UV emission has to be hidden by dust extinction. The amount of metals in galactic winds and escaping ionizing photons are enough to contaminate the Lyα forests or to reionize the universe.

Luminosity evolution, extragalactic background light and the opacity of the Universe

Recent observations of the evolution of the luminosity density of the Universe with look-back time and measurements of the extragalactic background light (EBL) can be used to constrain the apparent redshift of the peak in the luminosity density at optical, near-infrared (NIR) and far-infrared (FIR) wavelengths. The optical (450 nm) luminosity density is found to peak in the interval 1.0<z<1.8, the NIR (1000 nm) in 1.0<z<4.4 and the FIR (240-1000 μm) in 0.25<z<∞. From the observed spectral energy distribution in the FIR, we conclude that the EBL in the FIR is significantly affected by emission from sources at high redshift (z~4). The determined peaks in the luminosity density are difficult to reconcile with standard models of galaxy evolution. We suggest that the observations in the optical and the NIR may be affected by optical depth effects. Given the apparent evolution of the FIR luminosity density we conclude that the Universe becomes opaque at redshifts of z=1-3.