Optical and Near-IR Field Luminosity Functions

The Astrophysical Journal, 2009

Differential K s -band luminosity functions (LFs) are presented for a complete sample of 1613 nearby bright galaxies segregated by visible morphology. The LF for late-type spirals follows a power law that rises towards low luminosities whereas the LFs for ellipticals, lenticulars and bulge-dominated spirals are peaked and decline toward both higher and lower luminosities. Each morphological type (E, S0, S0/a-Sab, Sb-Sbc, Sc-Scd) contributes approximately equally to the overall K s -band luminosity density of galaxies in the local universe. Type -2averaged bulge/disk ratios are used to subtract the disk component leading to the prediction that the K s -band LF for bulges is bimodal with ellipticals dominating the high luminosity peak, comprising 60% of the bulge luminosity density in the local universe with the remaining 40% contributed by lenticulars and the bulges of spirals. Overall, bulges contribute 30% of the galaxy luminosity density at K s in the local universe with spiral disks making up the remainder. If bulge luminosities indicate central black hole masses, then our results predict that the black hole mass function is also bimodal.

Monthly Notices of The Royal Astronomical Society, 2001

We calculate the optical b J luminosity function of the 2dF Galaxy Redshift Survey (2dFGRS) for different subsets defined by their spectral properties. These spectrally selected subsets are defined using a new parameter, η, which is a linear combination of the first two projections derived from a Principal Component Analysis. This parameter η identifies the average emission and absorption line strength in the galaxy rest-frame spectrum and hence is a useful indicator of the present star formation. We use a total of 75,000 galaxies in our calculations, chosen from a sample of high signal-tonoise ratio, low redshift galaxies observed before January 2001. We find that there is a systematic steepening of the faint end slope (α) as one moves from passive (α = −0.54) to active (α = −1.50) star-forming galaxies, and that there is also a corresponding faintening of the rest-frame characteristic magnitude M * − 5 log 10 (h) (from −19.6 to −19.2). We also show that the Schechter function provides a poor fit to the quiescent (Type 1) LF for very faint galaxies (M bJ − 5 log 10 (h) fainter than −16.0), perhaps suggesting the presence of a significant dwarf population. The luminosity functions presented here give a precise confirmation of the trends seen previously in a much smaller preliminary 2dFGRS sample, and in other surveys. We also present a new procedure for determining self-consistent K-corrections and investigate possible fibreaperture biases.

Astronomy & Astrophysics, 2003

I perform a quantitative comparison of the shape of the optical luminosity functions as a function of galaxy class and filter, which have been obtained from redshift surveys with an effective depth ranging from z 0.01 to z 0.6. This analysis is based on the M * and α Schechter parameters which are systematically measured for all galaxy redshift surveys. I provide complete tables of all the existing measurements, which I have converted into the UBVR c I c Johnson-Cousins system wherever necessary. By using as reference the intrinsic luminosity functions per morphological type, I establish that the variations in the luminosity functions from survey to survey and among the galaxy classes are closely related to the criteria for galaxy classification used in the surveys, as these determine the amount of mixing of the known morphological types within a given class. When using a spectral classification, the effect can be acute in the case of inaccurate spectrophotometric calibrations: the luminosity functions are then biased by type contamination and display a smooth variation from type to type which might be poorly related to the intrinsic luminosity functions per morphological type. In the case of surveys using multi-fiber spectroscopy, galaxy classification based on rest-frame colors might provide better estimates of the intrinsic luminosity functions. It is noticeable that all the existing redshift surveys fail to measure the Gaussian luminosity function for Spiral galaxies, presumably due to contamination by dwarf galaxies. Most existing redshift surveys based on visual morphological classification also appear to have their Elliptical/Lenticular luminosity functions contaminated by dwarf galaxies. In contrast, the analyses using a reliable spectral classification based on multi-slit spectroscopy or medium-filter spectrophotometry, and combined with accurate CCD photometry succeed in measuring the Gaussian luminosity function for E/S0 galaxies. The present analysis therefore calls for a more coherent approach in separating the relevant giant and dwarf galaxy types, a necessary step towards measuring reliable intrinsic luminosity functions.

Monthly Notices of the Royal Astronomical Society, 2006

We present the rest-frame Js-band and Ks-band luminosity function (LF) of a sample of about 300 galaxies selected in the HDF-S at Ks 23 (Vega). We use calibrated photometric redshift together with spectroscopic redshift for 25% of the sample. The accuracy reached in the photometric redshift estimate is 0.06 (rms) and the fraction of outliers is 1%. We find that the rest-frame Js-band luminosities obtained by extrapolating the observed Js-band photometry are consistent with those obtained by extrapolating the photometry in the redder H and Ks bands closer to the rest-frame Js, at least up to z ∼ 2. Moreover, we find no significant differences among the luminosities obtained with different spectral libraries. Thus, our LF estimate is not dependent either on the extrapolation made on the best-fitting template or on the library of models used to fit the photometry. The selected sample has allowed to probe the evolution of the LF in the three redshift bins [0;0.8), [0.8;1.9) and [1.9;4) centered at the median redshift z m ≃ [0.6, 1.2, 3] and to probe the LF at z m ≃ 0.6 down to the unprecedented faint luminosities M Js ≃ −13 and M Ks ≃ −14. We find hints of a raise of the faint end (M Js > −17 and M Ks > −18) near-IR LF at z m ∼ 0.6, raise which cannot be probed at higher redshift with our sample. The values of α we estimate are consistent with the local value and do not show any trend with redshift. We do not see evidence of evolution from z = 0 to z m ∼ 0.6 suggesting that the population of local bright galaxies was already formed at z < 0.8. On the contrary, we clearly detect an evolution of the LF to z m ∼ 1.2 characterized by a brightening of M * and by a decline of φ * . To z m ∼ 1.2 M * brightens by about 0.4-0.6 mag and φ * decreases by a factor 2-3. This trend persists, even if at a less extent, down to z m ∼ 3 both in the Js-band and in the Ks-band LF. The decline of the number density of bright galaxies seen at z > 0.8 suggests that a significant fraction of them increases their stellar mass at 1 < z < 2 − 3 and that they underwent a strong evolution in this redshift range. On the other hand, this implies also that a significant fraction of local bright/massive galaxies was already in place at z > 3. Thus, our results suggest that the assembly of massive galaxies is spread over a large redshift range and that the increase of their stellar mass has been very efficient also at very high redshift at least for a fraction of them.

Monthly Notices of the Royal Astronomical Society, 2009

We present luminosity and surface-brightness distributions of 40 111 galaxies with K-band photometry from the United Kingdom Infrared Telescope (UKIRT) Infrared Deep Sky Survey (UKIDSS) Large Area Survey (LAS), Data Release 3 and optical photometry from Data Release 5 of the Sloan Digital Sky Survey (SDSS). Various features and limitations of the new UKIDSS data are examined, such as a problem affecting Petrosian magnitudes of extended sources. Selection limits in K-and r-band magnitude, K-band surface brightness and K-band radius are included explicitly in the 1/V max estimate of the space density and luminosity function. The bivariate brightness distribution in K-band absolute magnitude and surface brightness is presented and found to display a clear luminosity-surface brightness correlation that flattens at high luminosity and broadens at low luminosity, consistent with similar analyses at optical wavelengths. Best fitting Schechter function parameters for the K-band luminosity function are found to be M * − 5 log h = −23.19 ± 0.04, α = −0.81 ± 0.04 and φ * = (0.0166 ± 0.0008)h 3 Mpc −3 , although the Schechter function provides a poor fit to the data at high and low luminosity, while the luminosity density in the K band is found to be j = (6.305 ± 0.067) × 10 8 L h Mpc −3 . However, we caution that there are various known sources of incompleteness and uncertainty in our results. Using mass-to-light ratios determined from the optical colours we estimate the stellar mass function, finding good agreement with previous results. Possible improvements are discussed that could be implemented when extending this analysis to the full LAS.

The Astrophysical Journal Supplement Series, 2000

We have obtained integrated and nuclear spectra, as well as U, B, R surface photometry, for a representative sample of 196 nearby galaxies. These galaxies span the entire Hubble sequence in morphological type, as well as a wide range of luminosities (M B = −14 to −22). Here we present the spectrophotometry for these galaxies. The selection of the sample and the U, B, R surface photometry is described in a companion paper (Paper I). Our goals for the project include measuring the current star formation rates and metallicities of these galaxies, and elucidating their star formation histories, as a function of luminosity and morphology. We thereby extend the work of Kennicutt (1992a) to lower luminosity systems. We anticipate that our study will be useful as a benchmark for studies of galaxies at high redshift.

Symposium - International Astronomical Union

An all-sky 12μm flux-limited sample of 392 galaxies has been selected from the IRAS Point Source Catalog. More than 20% of the sample harbor active nuclei (with Seyfert 1 or 2 or LINER emission-line spectra). Thus one byproduct of this work is the definition of a large complete sample of bright active galaxies, with roughly equal percentages of Sy 1&#39;s, Sy 2&#39;s and LINERs. Since we now have virtually all (93%) the redshifts for the sample galaxies, the far-infrared luminosity functions of all classes of galaxies have been derived using IRAS coadded data. Since our luminosity functions for Sy 1 and Sy 2 are indistinguishable from those of the optically selected CfA sample, the 12μm selection appears to be an efficient and complete technique for finding active galactic nuclei. Optical spectrophotometry and near-IR photometry of the sample is being obtained to compute accurate bolometric luminosities.

The Astrophysical Journal, 2005

We have explored the redshift evolution of the luminosity function of red and blue galaxies up to z = 3.5. This was possible joining a deep I band composite galaxy sample, which includes the spectroscopic K20 sample and the HDFs samples, with the deep H AB = 26 and K AB = 25 samples derived from the deep NIR images of the Hubble Deep Fields North and South, respectively. About 30% of the sample has spectroscopic redshifts and the remaining fraction wellcalibrated photometric redshifts. This allowed to select and measure galaxies in the rest-frame blue magnitude up to z ∼ 3 and to derive the redshift evolution of the B-band luminosity function of galaxies separated by their rest-frame U − V color or specific (i.e. per unit mass) star-formation rate. The class separation was derived from passive evolutionary tracks or from their observed bimodal distributions. Both distributions appear bimodal at least up to z ∼ 2 and the locus of red/early galaxies is clearly identified up to these high redshifts. Both luminosity and density evolutions are needed to describe the cosmological behaviour of the red/early and blue/late populations. The density evolution is greater for the early population with a decrease by one order of magnitude at z ∼ 2 − 3 with respect to the value at z ∼ 0.4. The luminosity densities of the early and late type galaxies with M B < −20.6 appear to have a bifurcation at z > 1. Indeed while star-forming galaxies slightly increase or keep constant their luminosity density, "early" galaxies decrease in their luminosity density by a factor ∼ 5 − 6 from z ∼ 0.4 to z ∼ 2.5 − 3. A comparison with one of the latest versions of the hierarchical CDM models shows a broad agreement with the observed number and luminosity density evolutions of both populations.

Astronomy & Astrophysics

Aims. Our goal is to study the evolution of the B-band luminosity function (LF) since z ∼ 1 using ALHAMBRA data. Methods. We used the photometric redshift and the I-band selection magnitude probability distribution functions (PDFs) of those ALHAMBRA galaxies with I ≤ 24 mag to compute the posterior LF. We statistically studied quiescent and star-forming galaxies using the template information encoded in the PDFs. The LF covariance matrix in redshift-magnitude-galaxy type space was computed, including the cosmic variance. That was estimated from the intrinsic dispersion of the LF measurements in the 48 ALHAMBRA sub-fields. The uncertainty due to the photometric redshift prior is also included in our analysis. Results. We modelled the LF with a redshift-dependent Schechter function affected by the same selection effects than the data. The measured ALHAMBRA LF at 0.2 ≤ z < 1 and the evolving Schechter parameters both for quiescent and star-forming galaxies agree with previous results in the literature. The estimated redshift evolution of M * B ∝ Qz is Q SF = −1.03±0.08 and Q Q = −0.80±0.08, and of log 10 φ * ∝ Pz is P SF = −0.01±0.03 and P Q = −0.41 ± 0.05. The measured faint-end slopes are α SF = −1.29 ± 0.02 and α Q = −0.53 ± 0.04. We find a significant population of faint quiescent galaxies with M B −18, modelled by a second Schechter function with slope β = −1.31 ± 0.11. Conclusions. We present a robust methodology to compute LFs using multi-filter photometric data. The application to ALHAMBRA shows a factor 2.55 ± 0.14 decrease in the luminosity density j B of star-forming galaxies, and a factor 1.25 ± 0.16 increase in the j B of quiescent ones since z = 1, confirming the continuous build-up of the quiescent population with cosmic time. The contribution of the faint quiescent population to j B increases from 3% at z = 1 to 6% at z = 0. The developed methodology will be applied to future multi-filter surveys such as J-PAS.

The Astronomical Journal, 2004

We measure the luminosity function of morphologically selected E/S0 galaxies from z = 0.5 to z = 1.0 using deep high resolution Advanced Camera for Surveys imaging data. Our analysis covers an area of 48✷ ′ (8× the area of the HDF-N) and extends 2 magnitudes deeper (I ∼ 24 mag) than was possible in the Deep Groth Strip Survey (DGSS). Our fields were observed as part of the ACS Guaranteed Time Observations. At 0.5 < z < 0.75, we find M * B − 5 log h 0.7 = −21.1 ± 0.3 and α = −0.53 ± 0.2, and at 0.75 < z < 1.0, we find M * B − 5 log h 0.7 = −21.4 ± 0.2, consistent with 0.3 magnitudes of luminosity evolution (from 0.5 < z < 0.75). These luminosity functions are similar in both shape and number density to the luminosity function using morphological selection (e.g., DGSS), but are much steeper than the luminosity functions of samples selected using morphological proxies like the color or spectral energy distribution (e.g., CFRS, CADIS, or COMBO-17). The difference is due to the 'blue', (U − V) 0 < 1.7, E/S0 galaxies, which make up to ∼ 30% of the sample at all magnitudes and an increasing proportion of faint galaxies. We thereby demonstrate the need for both morphological and structural information to constrain the evolution of galaxies. We find that the 'blue' E/S0 galaxies have the same average sizes and Sersic parameters as the 'red', (U − V) 0 > 1.7, E/S0 galaxies at brighter luminosities (M B < −20.1), but are increasingly different at fainter magnitudes where 'blue' galaxies are both smaller and have lower Sersic parameters. We find differences in both the size-magnitude relation and the photometric plane offset for 'red' and 'blue' E/S0s, although neither 'red' nor 'blue' galaxies give a good fit to the size magnitude relation. Fits of the colors to stellar population models suggest that most E/S0 galaxies have short star-formation time scales (τ < 1 Gyr), and that galaxies have formed at an increasing rate from z ∼ 8 until z ∼ 2 after which there has been a gradual decline.