Local Luminosity Function Research Articles

Infrared Imaging and Photometry of a Sample of Seyfert Galaxies

It is well know that the determination of the local luminosity function of Seyfert nuclei meets several difficulties produced by: the determination of a suitable sample, the estimation of the nuclear magnitudes biased from the contribution from the host galaxies, which may be dominant if the nucleus is faints and the presumably large errors associated with the estimated magnitudes.

Hot gaseous coronae of early-type galaxies and their radio luminosity function

Recent X-ray observations have revealed that early-type galaxies (which usually produce extended double radio sources) generally have hot gaseous haloes extending up to ∼102kpc1,2. Moreover, much of the cosmic X-ray background radiation is probably due to a hotter, but extremely tenuous, intergalactic medium (IGM)3. We have presented4–7 an analytical model for the propagation of relativistic beams from galactic nuclei, in which the beams' crossing of the pressure-matched interface between the IGM and the gaseous halo, plays an important role. The hotspots at the ends of the beams fade quickly when their advance becomes subsonic with respect to the IGM. This model has successfully predicted (for typical double radio sources) the observed8 current mean linear-size (∼2D≃350 kpc)4,5, the observed8–11 decrease in linear-size with cosmological redshift4–6 and the slope of the linear-size versus radio luminosity10,12–14 relation6. We have also been able to predict the redshift-dependence of observed numbers and radio luminosities of giant radio galaxies7,15. Here, we extend this model to include the propagation of somewhat weaker beams. We show that the observed flattening of the local radio luminosity function (LRLF)16–20 for radio luminosity P≈ 1024 W Hz−1 at 1 GHz can be explained without invoking ad hoc a corresponding break in the beam power function Φ(Lb), because the heads of the beams with Lb < 1025 W Hz−1 are decelerated to sonic velocity within the halo itself, which leads to a rapid decay of radio luminosity and a reduced contribution of these intrinsically weaker sources to the observed LRLF.

Space Distribution of X-Ray Clusters of Galaxies

The Intra-Cluster Plasma constitutes an archive of the past history of all clusters and of many groups of galaxies: statistical observations of their X-ray emission will set significant constraints on the dynamical, thermal and chemical events in these cosmic structures. Data on the local X-ray luminosity function N(L, z ≃ 0) were provided by the 1st generation X-ray surveys. HEAO II provided an integral of N(L, z) out to z ≃ 0.4, the counts from a subsample of the MSS (Gioia et al. 1984, Ap.J. 283, 495): these counts result very flat, cf. Fig. 2.

Estimates of a nuclear luminosity function of Seyfert galaxies

Nuclear magnitudes of Seyfert galaxies, determined from two-dimensional photometric data, are used to make an estimate of the luminosity function (LF) of Seyfert nuclei. This provides a direct observational check of two indirect determinations of this LF, one of which is favoured by the present result. Comparisons with the Seyfert LF for integrated magnitudes, the local quasar LF, and the LF of field galaxies, are discussed.

Quasars: Their Evolution, Absorption Lines and the Intergalactic Gas

For many years now it has been known that the number vs. magnitude counts of quasars is the prima facie evidence of a cosmological evolution of this class of objects. Down to an apparent magnitude B - 19 the number of quasars increases by almost a factor 8 per magnitude Interval, compared to a factor 4 obtained in an Euclidean universe filled with a uniform distribution of sources, and correspondingly less for the classical Friedmann models of Gen. Relativity due to the red-shift effects. This strong evolution has been recently questioned because of several biases which may artificially steepen the slope of the counts in the optical surveys. Deep surveys of quasars selected via multi-colour techniques down to B - 23 have confirmed the long standing inference that the number count relationship must flatten beyond B - 20. As a consequence, pure density evolution models, where only the number density of quasars increases with the redshift z, leaving unchanged the shape of the local luminosity function, are ruled out, since too many quasars are predicted at faint magnitudes compared to the dramatic flattening of the counts (see, e.g., ref. 4).

Interpretation of deep counts of radio sources

view Abstract Citations (86) References (28) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Interpretation of Deep Counts of Radio Sources Danese, L. ; de Zotti, G. ; Franceschini, A. ; Toffolatti, L. Abstract A new determination of the local radio luminosity function of galaxies allows it to be concluded that unevolving low-luminosity sources cannot account for the observed flattening of the normalized differential source counts below mJy levels. Nor can this feature be produced by the evolving populations that dominate the counts at higher flux densities. The local radio luminosities of spiral galaxies are too low to contribute significantly to the counts above 1 mJy, even in the presence of evolution consistent with the observational constraints; thus the blue galaxy population observed by Kron, Koo, and Windhorst (1985) up to greater than or equal to 10 mJy can hardly be identified with normal spiral galaxies. On the other hand, it is shown that evolving starburst/interacting galaxies can easily account for all the data available so far. The inferred evolution time scale (about 20-25 percent of the Hubble time) is within the expected range for gas consumption in starburst galaxies. Publication: The Astrophysical Journal Pub Date: July 1987 DOI: 10.1086/184928 Bibcode: 1987ApJ...318L..15D Keywords: Galactic Evolution; Luminosity; Radiant Flux Density; Radio Sources (Astronomy); Spiral Galaxies; Astronomical Spectroscopy; Hubble Constant; Interacting Galaxies; Radio Galaxies; Starburst Galaxies; Astrophysics; COSMOLOGY; GALAXIES: EVOLUTION; LUMINOSITY FUNCTION; RADIO SOURCES: GALAXIES full text sources ADS |

The local radio luminosity function of galaxies at 843 MHz

Following the investigation of the radio luminosity function by Harnett, two samples of galaxies have been observed with the Molonglo Observatory Synthesis Telescope at 843 MHz. These comprise 176 E and S0 galaxies from the sample by Sadler, and 21 galaxies with δ ≤ -45°, a subset of Harnett's sample. The resulting local radio luminosity function (LRLF) has been extended to radio powers of ~10 18 W Hz -1 sr -1 . At such low luminosities, the irregular galaxies apparently begin to dominate the LRLF. Spirals on the other hand, continue to be confined to radio powers in the range 10 19-22 WHz -1 sr -1 . The radio properties of S0 galaxies depend on their absolute optical luminosities and hence their masses. The most massive appear similar to radio ellipticals, but at lower optical luminosities comparable to those of spirals, S0 galaxies resemble early-type spirals closely both in their detection rate and correlation between radio and optical luminosities.

Three-dimensional luminosity function of type 1 Seyfert galaxies

Two-dimensional (radio, x-ray) and three-dimensional (radio, x-ray, optical) local luminosity functions of type 1 Seyfert galaxies are constructed. The partial rank correlation coefficients show that there is a true correlation between the radio and x-ray emission of Sy 1 galaxies.

Photometric parallaxes for selected stars of color class M from the NLTT catalog. II - The declination zone 0 deg to +20 deg

view Abstract Citations (42) References (16) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Photometric parallaxes for selected stars of color class M from the NLTT catalog. II. The declination zone 0 to +20. Weis, E. W. Abstract VRI photometry and photometric parallaxes are presented for a sample of 702 stars of color class m in the NLTT catalog for which no trigonometric parallaxes have been measured. Additional VRI photometry of stars with trigonometric parallaxes is also presented. For the program stars, 97 have πph ≥ 0arcsec.040 but only four stars are found to have πph ≥ 0arcsec.100. These nearby stars have no significant effect on the local stellar luminosity function of Wielen. Publication: The Astronomical Journal Pub Date: March 1986 DOI: 10.1086/114045 Bibcode: 1986AJ.....91..626W Keywords: Stellar Color; Stellar Parallax; Stellar Spectrophotometry; Astronomical Catalogs; Northern Sky; Stellar Luminosity; Tables (Data); Astronomy full text sources ADS | data products SIMBAD (761) ARI (1) Related Materials (3) Part 1: 1984ApJS...55..289W Part 3: 1987AJ.....93..451W Part 4: 1988AJ.....96.1710W

From local active galactic nuclei to early quasars

To close the gap between the local luminosity function of the optically selected active galactic nuclei and the population properties of distant (z 2 to cover the beginning of the quasar era.

Galaxy Mergers and Active Nuclei - Part Two - Cosmological Evolution

Galaxy mergers may produce active galactic nuclei (AGNs) by repopulating stellar loss-cone orbits around a central black hole. In the companion paper we derived a local bolometric luminosity function of AGNs based on this process. In this paper we interpret the observed cosmological evolution of the luminosity function of AGNs as due to evolution of the merging rate among galaxies after their formation at a redshift of approx.3. An important difference between our model and previous (empirical) models is that the evolution depends on galactic (stellar) luminosity instead of central nonthermal luminosity. The radio counts at 1.4 GHz and optical counts are reproduced by the model if the merging rate of the galaxies at the bright end of the galaxy luminosity function evolves considerably faster than the merging rate of the smaller galaxies. The theoretical and observed luminosity functions at high redshift have similar characteristics: (i) at high luminosity the evolution is best described by luminosity evolution, and (2) the luminosity function has a maximum at approx.10/sup 3/ Gpc/sup -3/, which is the space density of the most massive galaxies. A large fraction of these galaxies are presumably formed in the precursors of rich clusters. Their merger rate is highmore » initially and declines rapidly on a time scale of a few billion years. If the initial density fluctuation spectrum for protoclusters of mass M/sub cl/ has the form deltarho/rhoproportionalM/sup( -1+n//3)/2/sub cl/, then the steep evolution of the most luminous galaxies suggests nroughly-equal-1.3 at a redshift of approx.3, which is consistent with the observed clustering of galaxies.« less

Galaxy mergers and active nuclei. I - The luminosity function. II - Cosmological evolution

view Abstract Citations (36) References (35) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Galaxy mergers and active nuclei. I - The luminosity function. II - Cosmological evolution Roos, N. Abstract Theoretical models of active-galactic-nucleus (AGN) formation in galaxies with massive central black holes by the repopulation of stellar loss-cone orbits during galaxy mergers are investigated. A local AGN bolometric luminosity function is calculated for galaxies with Galaxy-like nuclear density distributions using a merging rate based on the two-point correlation function of galaxies and shown to be qualitatively similar to the observed luminosity functions in the visible, X-ray, and radio bands, with a power-law index of -1.4 at high luminosity and a break at radio luminosity about 10 to the 44th erg/s (corresponding to an interacting-galaxy mass ratio greater than 20). The cosmological evolution of the galaxy merging rate is considered, assuming galaxy formation at z = about 3 and galactic-stellar-luminosity-dependent evolution, and found to be faster at the bright end of the galaxy luminosity function. The merger rate outside rich clusters in an expanding universe is found to vary as the inverse of cosmic time. Publication: The Astrophysical Journal Pub Date: July 1985 DOI: 10.1086/163314 Bibcode: 1985ApJ...294..479R Keywords: Black Holes (Astronomy); Cosmology; Extragalactic Radio Sources; Galactic Clusters; Galactic Evolution; Galactic Nuclei; Interacting Galaxies; Luminosity; Active Galactic Nuclei; Astronomical Models; Bivariate Analysis; Mass Ratios; Quasars; Radio Galaxies; Red Shift; Seyfert Galaxies; Stellar Orbits; Astrophysics full text sources ADS |

Cosmological evolution of radio sources

view Abstract Citations (300) References (63) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Cosmological evolution of radio sources. Condon, J. J. Abstract Data which encompass source counts at five different frequencies, together with redshift distributions of strong sources, spectral index distributions of sources, and the 1.4-GHz local luminosity function, are presently used to constrain the epoch-dependent spectral luminosity function of extragalactic radio sources. A simple evolutionary model is found for the spectral luminosity function which is consistent with these data, as well as the magnitude distribution of galaxies optically identified with faint sources, and with in addition evolves all sources in the same way. This last feature renders the model consistent with physical mechanisms of evolution which do not distinguish between low luminosity and high luminosity sources. The model suggests that the question as to whether the mean spectral index of steep spectrum sources correlates with luminosity or redshift may be decidable on the basis of the spectral index distributions of faint sources, even if no redshifts are available for them. Publication: The Astrophysical Journal Pub Date: December 1984 DOI: 10.1086/162705 Bibcode: 1984ApJ...287..461C Keywords: Cosmology; Extragalactic Radio Sources; Luminosity; Red Shift; Flux Density; Normal Density Functions; Quasars; Astrophysics full text sources ADS |

The NGC 5128 globular-cluster system - Star counts in U, V, and R

view Abstract Citations (49) References (30) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The NGC 5128 globular cluster system : star counts in U, V, and R. Harris, G. L. H. ; Hesser, J. E. ; Harris, H. C. ; Curry, P. J. Abstract Star counts in U, V, and R within about 23 arcmin of the nearby peculiar elliptical galaxy NGC 5128 show 800-900 counted objects in excess of background in the region studied. The cluster system inferred from these data seems to follow an r1/4 law distribution for r greater than or equal to 4 arcmin. Inside this radius it is possible that the clusters are deficient relative to the halo light. Using data from other studies, a cluster-luminosity function over a range of 5 mag has been constructed. It agrees with the Local Group globular-cluster luminosity function over the full range if the distance to NGC 5128 is less than or equal to 4 Mpc. The analysis of the counts suggests total cluster population N t = 1200-1900, specific frequency, S = 3.0-3.2, and distance about 3-4 Mpc. Larger distances are permitted only if the luminosity function is nonstandard; in such a case, then S is much less than 3 or N is much greater than 2000. Publication: The Astrophysical Journal Pub Date: December 1984 DOI: 10.1086/162675 Bibcode: 1984ApJ...287..175H Keywords: Astronomical Photography; Galactic Structure; Globular Clusters; Star Distribution; Density Distribution; Elliptical Galaxies; Luminosity; Peculiar Galaxies; Radial Distribution; Astronomy full text sources ADS | data products SIMBAD (1) NED (1)

Deep Radio Source Counts and Small Scale Fluctuations of the Microwave Background Radiation

Source counts which now extend to surface densities of ∼105 sources/sr make possible a direct evaluation of the radio source contribution to the small-scale fluctuations in the microwave background on scales larger than ∼10′, at wavelengths cm. Comprehensive radio spectral data permit a straightforward and largely model-independent extrapolation of the N(S) relation to shorter wavelengths. On the other hand, Peacock and Gull (1981, hereafter PG) have constructed a set of models which incorporate a wealth of additional data, such as local luminosity functions, luminosity/redshift distributions, luminosity-spectral index correlations; they can therefore be exploited to optimize the extrapolations both to higher frequencies and to fainter flux densities. Only one of these models, however, namely No. 4, is consistent with the recent P(D) results (Wall et al. 1982; Ledden et al. 1980) which provide information on the areal density of sources at s~1mJy; therefore, in the following we shall focus on it.

An outsider's view of the Galaxy - Photometric parameters, scale lengths, and absolute magnitudes of the spheroidal and disk components of our Galaxy

A two-component model of the Galaxy consisting of (I) an R/sup 1/4/ spheroid of effective radius r/sup I//sub e/=2.67 kpc (for r/sub 0/=8.0 kpc) and peak brightness ..mu../sup I//sub B/(0) =15.11 mag arcsec/sup -2/, and (II) an exponential disk of effective radius r/sup II//sub e/=5.98 kpc and (assumed) peak brightness ..mu../sup II//sub B/(0) =21.65 (after Freeman) is shown to be consistent with the galactic disk brightness inferred from star counts and to give a good representation of new observations of the brightness distribution in the bulge along galactic meridian 0/sup degree/. An ellipsoidal model of the spheroid with a/sup I//sub e/=3.45 kpc and c/a=0.6 is also considered with little change in most results; averages from the two cases are adopted. For an outside observer the face-on total absolute magnitude of the Galaxy (with allowance for uniform internal extinction of total optical depth A/sub B/=0.4 mag) is M/sup 0//sub T/(B) =-20.08 or L/sub T/(B) =1.6 x 10/sup 10/L/sub sun/, of which half is emitted within the effective radius r/sub e/=5.1 kpc. The fraction K/sub I/=L/sup I//L/sub T/=0.34 +- 0.04 contributed by the spheroidal component is in close agreement with corresponding values for several Sbc (T=4) galaxies. The calculated standard face-on isophotalmore » diameter of the Galaxy at the ..mu../sub B/=25.0 level, D/sub 0/=23.0 kpc is in close agreement with three independent estimates (21.4--23.4) from statistical relations for spiral galaxies. The luminosity index ..lambda..= (T+L)/10 of the Galaxy derived by three independent methods is ..lambda..=0.71 +- 0.03, implying a luminosity class L=3 +- 1 (LC=II), if T=4 +- 0.5. The mean intrinsic color (corrected for extinction) of the spheroidal component derived from the observations is /sub I/=0.65 +- 0.05; that of the disk stellar population derived from local luminosity functions is /sub II/=0.40 (after Holmberg, transformed to B,V system).« less

The mass of the galactic halo derived from the luminosity function of high-velocity stars

view Abstract Citations (180) References (35) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The mass of the galactic halo derived from the luminosity function of high-velocity stars. Schmidt, M. Abstract The local luminosity function of high-velocity stars is derived on the basis of a complete sample of stars of large proper motion with trigonometric parallaxes. The fraction of these stars belonging to a roughly spherical galactic halo is deduced by using a kinematical criterion based on space velocities of metal-poor RR Lyrae variables. The local mass density of halo stars is about 1.7 x 10- solar masses per cubic parsec, corresponding to a fractional mass within the Sun's distance from the center of 6 percent, i.e., an order of magnitude lower than that of the massive halo proposed by Ostriker and Peebles. Subject headings: galactic structure - high-velocity stars - luminosity function - proper-motion stars - stellar statistics Publication: The Astrophysical Journal Pub Date: November 1975 DOI: 10.1086/153949 Bibcode: 1975ApJ...202...22S Keywords: Galactic Structure; Stellar Luminosity; Stellar Mass; Velocity Distribution; Astronomical Models; Galactic Radiation; Mass Distribution; Star Distribution; Stellar Evolution; Stellar Motions; Astrophysics full text sources ADS | data products SIMBAD (57)

Solar Neighbourhood as the Local Macroscopic Volume Element Within the Galaxy

The notion of the local Macroscopic Volume Element (MVE) is introduced in order to facilitate the application of hydro-dynamical methods of treating internal motions in stellar systems and in particular in our Galaxy. The MVE must characterize the properties of the stellar system in a given point within the system. Hence the diameter of the MVE must be taken as small as possible; it must, however, contain a sufficiently large number of stars in order that the laws of statistics might be applied. The greater is the local star density the smaller can be made the size of the MVE.Modern catalogues of nearby stars by Gliese (1969) and Woolley et al. (1970) afford a good collection of data for a determination of local characteristics of the Galaxy in the immediate neighbourhood of the Sun. In the first section we discuss such characteristics as the local stellar density, the local luminosity function and the influence of observational selection upon them. In the second section we consider the local solar motion and the effect of the asymmetry of stellar motions. The responsibility for the content of paragraph 1 lies primarily upon T. A. Agekjan while that for paragraph 2 upon K. F. Ogorodnikov. We both are indebted to G. V. Ishkhanov and to L. V. Chuvicova for substantial help in numerical computations.

The Local Luminosity Function and the Secular Evolution of Extragalactic Radio Sources

It is argued that recent criticisms of an earlier paper (Davidson) by Longair & Scheuer are unfounded. The count models of Doroshkevich, Longair & Zeldovich are shown to be based on the wrong luminosity function and an incorrect evolutionary theory for the radio source population.