Far-infrared Luminosity Function Research Articles

The extended 12 micron galaxy sample

We have selected an all-sky (absolute value of b greater than or equal to 25 deg) 12 micron flux-limited sample of 893 galaxies from the IRAS Faint Source Catalog, Version 2 (FSC-2). We have obtained accurate total fluxes in the IRAS wavebands by using the ADDSCAN procedure for all objects with FSC-2 12 micron fluxes greater than 0.15 Jy and increasing flux densities from 12 to 60 microns, and defined the sample by imposing a survey limit of 0.22 Jy on the total 12 micron flux. Its completeness is verified, by means of the classical log N - log S and V/V(sub max) tests, down to 0.30 Jy, below which we have measured the incompleteness down to the survey limit, using the log N - log S plot, for our statistical analysis. We have obtained redshifts (mostly from catalogs) for virtually all (98.4%) the galaxies in the sample. Using existing catalogs of active galaxies, we defined a subsample of 118 objects consisting of 53 Seyfert 1s and quasars, 63 Seyfert 2s, and two blazars (approximately 13% of the full sample), which is the largest unbiased sample of Seyfert galaxies ever assembled. Since the 12 micron flux has been shown to be about one-fifth of the bolometric flux for Seyfert galaxies and quasars, the subsample of Seyferts (including quasars and blazars) is complete not only to 0.30 Jy at 12 microns but also with respect to a bolometric flux limit of approximately 2.0 x 10(exp -10) ergs/s/sq cm. The average value of V/V(sub max) for the full sample, corrected for incompleteness at low fluxes, is 0.51 +/- 0.04, expected for a complete sample of uniformly distributed galaxies, while the value for the Seyfert galaxy subsample is 0.46 +/- 0.10. We have derived 12 microns and far-infrared luminosity functions for the AGNs, as well as for the entire sample. We extracted from our sample a complete subsample of 235 galaxies flux-limited (8.3 Jy) at 60 microns. The 60 micron luminosity function computed for this subsample is in satisfactory agreement with the ones derived from the bright galaxy sample (BGS) and the deep high-galactic latitude sample, both selected at 60 microns.

Galaxies with spectral energy distributions peaking near 60 micrometers. 1: Optical spectroscopy, infrared photometry, and radio continuum data

We present and discuss broadband infrared photometry in the 1-100 micrometer wavelength range, optical spectroscopy, and radio continuum observations of a sample of IRAS galaxies with unusual spectral energy distributions that peak near 60 micrometers. For inclusion in this sample of '60 PKs', the galaxies must have satisfied the following criteria: IRAS flux ratios f(sub 60)/f(sub 100) greater than 1 and 1 less than f(sub 60)/f(sub 25) less than 4, and galactic latitude absolute value of b greater than 10 deg. In this paper, which is the first of a series, we show that the 60PKs are relatively scarce objects that represent about 2% of the spatial density of 60 micrometer-selected galaxies in the range L(60 micrometers) = 10(exp 9) to 10(exp 12) solar luminosity, but have a far-infrared luminosity function of nearly identical shape. They are detected up to redshifts of 0.2. Besides having the usual high percentage of active galaxies (approximately 30% H II-region like, 50% Seyfert 2, 10% Seyfert 1, 10% unknown) associated with a flat 25 to 60 micrometer spectral index, the sample also includes most of the galaxies that have been found to have a dust-obscured broadline region. We show that the additional f(sub 60)/f(sub 100) greater than 1 constraint selects galaxies with dust that is more centrally concentrated and exposed to a more intense radiation field than in most other IRAS galaxies. In particular, the cirrus component of the far-infrared radiation, which is typically the dominant contributor to the 100 micrometer emission from spiral galaxies, is negligible or missing. This is consistent with the fact that the most distinctive optical signature of 60PKs is the absence of spiral structure: they tend to be peculiar and/or amorphous objects.

Evolution of the blue and far-infrared galaxy luminosity functions

view Abstract Citations (25) References (31) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Evolution of the Blue and Far-Infrared Galaxy Luminosity Functions Lonsdale, Carol J. ; Chokshi, Arati Abstract We construct a blue band luminosity function from published spectroscopic surveys of faint field galaxies (b_j_ > 20) and compare it to three recent determinations of the blue-selected field galaxy luminosity function in the local universe. We find evidence for density evolution for moderate luminosity galaxies (-17.5 > M_b_ > -21.5; h = 0.5) at a rate of (1+z)delta^, with a best fit of δ = 4+/-2, between the current epoch and z >~ 0.1. At M_b_ < -22 we find evidence for about 0.5- 1.5 mag of luminosity evolution in addition to the density evolution, corresponding to an evolutionary rate of L ~ (1+z)gamma^, γ = 0.5-2.5, by a redshift of about 0.4, when the data are compared to the local luminosity function of de Lapparent et al. [ApJ, 343, 1(1989)]. However, in the presence of the above mentioned density evolution, no additional luminosity evolution is required to fit the M_b_ <-22 data if the local luminosity functions of either Efstathiou et al. [MNRAS, 232,431, (1988)] or Loveday et al. [ApJ, 390, 338 (1992)] are used instead. Assuming a steeper faint end slope of α = - 1.3, similar to that observed in the Virgo cluster, could explain the data with a luminosity evolution rate γ = 1-2, without need for any density evolution. We compare the best-fitting composite density and luminosity evolution models to faint IRAS 60 micron source counts. The fits are quite acceptable, implying that the blue and far-infrared evolutionary rates may be similar. Publication: The Astronomical Journal Pub Date: April 1993 DOI: 10.1086/116513 Bibcode: 1993AJ....105.1333L Keywords: Faint Objects; Far Infrared Radiation; Galactic Evolution; Luminosity; Space Density; Blue Stars; Red Shift; Sky Surveys (Astronomy); Stellar Magnitude; Astrophysics; INFRARED: GALAXIES; GALAXIES: EVOLUTION; GALAXIES: LUMINOSITY FUNCTION full text sources ADS |

Energy distributions of radio galaxies

Far-infrared observations of 140 radio galaxies which span a range of over four orders of magnitude in radio power, (from weak nuclear sources in nearby galaxies, to powerful FR II doubled lobed sources at moderate redshift) are presented. The strength of the far-infrared emission is more closely correlated with core than total radio emission. Far-infrared emission in radio galaxies represents star formation that is more closely tied to the active nucleus than to the global properties of the galaxy. The far-infrared luminosity function shows good continuity between radio galaxies and radio loud quasars.

Far-infrared luminosity functions of normal galaxies

A volume-limited sample (&lt;1400 km s^-1^ corrected for local motion) is constructed from the Zwicky catalog and IRAS data base to examine the far-infrared (FIR) luminosity functions of normal galaxies, and to investigate possible relationships between FIR emission and galaxy morphology. Quantitative and unbiased treatment is provided by "survival analysis" statistical methods. We find that the FIR distributions of normal galaxies are better fit by lognormal than Schechter functions. The total FIR emissivity (8 to 115 microns) of normal galaxies is approximately equal to half their emission in the B plus V optical bands. Normal galaxy FIR emission is uncorrelated with the basic S0-Sm Hubble sequence of spiral galaxy morphology, but appears to be affected by de Vaucouleurs' revised morphological classifications based on inner rings and S-shaped arms. Spirals with bars and inner rings are systematically fainter than unbarred spirals. We suggest that bars and rings reduce the amount or spatially confine the dust in spiral disks, resulting in lower efficiency conversion of optical and UV photons into the infrared.

The 12 micron galaxy sample. I - Luminosity functions and a new complete active galaxy sample

view Abstract Citations (140) References (19) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The 12 Micron Galaxy Sample. I. Luminosity Functions and a New Complete Active Galaxy Sample Spinoglio, Luigi ; Malkan, Matthew A. Abstract For all types of active galaxies, the most representative measure of total flux is the mid-infrared flux. The 12 micron flux is about one-fifth of the bolometric flux for Seyfert 2 galaxies, Seyfert 1 galaxies, and quasars. Therefore, we selected from the IRAS Point Source Catalog (PSC-2), an all-sky 12 micron flux-limited sample. To obtain a sample of 390 galaxies, a flux limit of 0.3 Jy was required. The incompleteness at low fluxes of the PSC-2 was determined by several techniques, all of which gave consistent results. Most of the sample galaxies are in existing catalogs, and 99% have measured redshifts. The 12 micron and the far-infrared luminosity functions of active and normal galaxies, corrected for incompleteness, have been derived using IRAS co-added data. Twenty-two percent of the sample galaxies harbor active nuclei. This new, large, and complete sample of bright active galaxies consists almost equally of Seyfert 1, Seyfert 2, and LINER nuclei. Our luminosity functions for Seyfert 1 and Seyfert 2 galaxies are indistinguishable from those of the optically selected CfA sample. Thus 12 micron selection is the most efficient available technique for finding complete active galaxy samples. Publication: The Astrophysical Journal Pub Date: July 1989 DOI: 10.1086/167577 Bibcode: 1989ApJ...342...83S Keywords: Active Galactic Nuclei; Infrared Sources (Astronomy); Seyfert Galaxies; Astronomical Catalogs; Color-Color Diagram; Far Infrared Radiation; Infrared Astronomy Satellite; Luminosity; Red Shift; Astrophysics; GALAXIES: NUCLEI; GALAXIES: SEYFERT; INFRARED: SOURCES; LUMINOSITY FUNCTION; QUASARS full text sources ADS | data products SIMBAD (403) NED (372)

A 12μm Flux Limited Sample of Galaxies: Preliminary Results on the IR Luminosity Function

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's, Sy 2'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.

Analysis of a complete sample of galaxies at Formula: the optical, radio and far-infrared luminosity functions

Les donnees du satellite IRAS et d'Arecibo a 2.4 GHz sur un echantillon de 1671 galaxies sont traitees statistiquement pour etudier l'evolution de la fonction de luminosite du visible au domaine radio en passant par l'IR lointain