“Luminosity function” papers

The discordant results reached by Hubble (1936 a)and Zwicky (1957) on the form of the galaxian luminosity function are shown to be due to observational selection. In a sample of some 600 field galaxies , regarded as coming from a selection according to the apparent magnitude, the distribution of the residuals from the redshift-magnitude relation is shown to be consistent with a luminosity function that varies as x3 (the cubic ) for 0 < x < 3, and as 10 0.2 x (the exponential ) for 2.5 < x < 8, x being the magnitude from the brightest limit M0 . The cubic law is also found to hold among bright cluster galaxies from analyses of “mean clusters” and on the magnitude differences among the 10 brightest members in each of 18 clusters; while the exponential law, originally suggested by Zwicky, is re-affirmed among faint cluster galaxies .

Cited by 41Open access

Luminosity function of stars

R. A. Bartaya, E. K. Kharadze · Astrophysics · 1977

Cited by 7

Luminosity function of GRBs

Luis Juracy Rangel Lemos, C. L. Bianco, R. Ruffini et al. · arXiv (Cornell University) · 2013

The luminosity function (LF) statistics applied to the BATSE GRBs (sources of GUSBAD catalog) is the theme approached in this work. The LF is a strong statistical tool to extract useful information from astrophysical samples, where the key point of this statistical analysis is in the detector sensitivity, where we have performed careful analysis. We applied the tool of the LF statistics to three GRB classes predicted by the Fireshell model. One of the main differences between the Fireshell and Fireball models is the explanation of the GRB prompt emission, where the first claims that it is divided in two physical processes: 1) transparency of a optically thick Freshell producing the P-GRB emission and 2) interaction of a relativistic shell (composed by baryons electron-positron-photon) against the CBM (circumburst medium), producing the emission so-called extended afterglow peak (EAP). However, the Fireball model, the most quoted one, claims that the prompt emission is caused by interactions among several relativistic shells (composed by electron-positron-photon) with different Lorentz factors, a process called internal shocks. The transparency produces a strong short emission in the beginning, called P-GRB. Thus, to the Fireshell model, the prompt emission is P-GRB plus EAP. We produced, by LF statistics, predicted distributions of: peak flux, redshift and peak luminosity for the three GRB classes predicted by Fireshell model, we also used three GRB rates. We looked for differences among the distributions, and in fact we found. We performed a comparison between the distributions predicted and observed (with and without redshifts), where we had to build a list with 220 GRBs with known redshifts. We also estimated the effects of the Malmquist bias in all samples, and we looked for a correlation between the isotropic luminosity and the Band peak spectral energy.

Cited by 0Open access

The pulsar luminosity function

O. H. Guseinov, E. Yazgan, S. O. Tagieva · CERN Bulletin · 2003

We construct and examine the pulsar luminosity function using the new list which includes data for 1328 radio pulsars. In this work, the luminosity function for 1400 MHz is constructed for the first time. We also present an improved luminosity function for 400 MHz. The luminosity functions at 400 and 1400 MHz are compared. Also, the luminosity functions excluding the binary millisecond pulsars and the pulsars with low magnetic fields are constructed. It is found that the new luminosity function is considerably flatter in the low luminosity part for 400 MHz. 1400 HMz luminosity values of radio pulsars together with upper limits of 1400 MHz luminosity for anomalous X-ray pulsars and dim radio quiet neutron stars are presented as a function of both characteristic age and magnetic field. The implications of the pulsar luminosity function for these new kinds of neutron star are discussed.

Cited by 1

The Quasar Luminosity Function

P. C. Hewett · 1996

Cited by 0

The Subdwarf Luminosity Function

Andrew Digby, N. C. Hambly, J. A. Cooke et al. · arXiv (Cornell University) · 2003

Using data from the Sloan Digital Sky Survey Early Data Release and SuperCOSMOS Sky Survey scans of POSS-I plates we identify a sample of 2600 subdwarfs using reduced proper motion methods and strict selection criteria. This forms one of the largest and most reliable samples of candidate subdwarfs known, and enables us to determine accurate luminosity functions along many different lines of sight. We derive the subdwarf luminosity function with unprecedented accuracy to M_V <= 12.5, finding good agreement with recent local estimates but discrepancy with results for the more distant spheroid. This provides further evidence that the inner and outer parts of the stellar halo cannot be described by a single density distribution. We also find that the form of the inner spheroid density profile within heliocentric distances of 2.5 kpc is closely matched by a power law with an index of -3.15 +/- 0.3.

Cited by 0Open access

The Protostellar Luminosity Function

Offner, Stella S. R., McKee, Christopher F. · arXiv (Cornell University) · 2011

The protostellar luminosity function (PLF) is the present-day luminosity function of the protostars in a region of star formation. It is determined using the protostellar mass function (PMF) in combination with a stellar evolutionary model that provides the luminosity as a function of instantaneous and final stellar mass. As in McKee & Offner (2010), we consider three main accretion models: the Isothermal Sphere model, the Turbulent Core model, and an approximation of the Competitive Accretion model. We also consider the effect of an accretion rate that tapers off linearly in time and an accelerating star formation rate. For each model, we characterize the luminosity distribution using the mean, median, maximum, ratio of the median to the mean, standard deviation of the logarithm of the luminosity, and the fraction of very low luminosity objects. We compare the models with bolometric luminosities observed in local star forming regions and find that models with an approximately constant accretion time, such as the Turbulent Core and Competitive Accretion models, appear to agree better with observation than those with a constant accretion rate, such as the Isothermal Sphere model. We show that observations of the mean protostellar luminosity in these nearby regions of low-mass star formation suggest a mean star formation time of 0.3$\pm$0.1 Myr. Such a timescale, together with some accretion that occurs non-radiatively and some that occurs in high-accretion, episodic bursts, resolves the classical "luminosity problem" in low-mass star formation, in which observed protostellar luminosities are significantly less than predicted. An accelerating star formation rate is one possible way of reconciling the observed star formation time and mean luminosity.

Cited by 0Open access

of the Luminosity Function

Stefano Zibetti, Simon D. M. White · 2005

Cited by 0

10keV AGN luminosity function

1997

The ROSAT mission has provided us with a significant advance in our knowledge regarding the nature of the faint X-ray source population at soft 0.5-2 keV energies. Deep ROSAT pointings have resolved over half of the soft X-ray

Cited by 0

Luminosity function of GRBs

S. K. Sethi, S. G. Bhargavi · Astronomy and Astrophysics · 2001

We attempt to constrain the luminosity function of Gamma Ray Bursts (GRBs) from the observed number count-flux relation and the afterglow redshift data. We assume three classes of luminosity functions for our analysis: (a) Log-normal distribution, (b) Schechter distribution, and (c) Scale-free distribution. We assume several models of the evolution of the GRB population for each luminosity function. Our analysis shows that: (a) log-normal is the only luminosity function that is compatible with both the observations. This result is independent of the GRB evolution model, (b) for log-normal function, the average photon luminosity L0 and the width of the luminosity function σ that are compatible with both the observations fall in the range: and , (c) the agreement of observations with other luminosity functions requires the GRB population to evolve more strongly than the evolution of the star-formation rate of the universe.

Cited by 17Open access

The CNOC2 Field Galaxy Luminosity Function; 1, A Description of Luminosity Function Evolution

Lin, H, Yee, H K C, Carlberg, R G et al. · CERN Bulletin · 1999

We examine the evolution of the galaxy luminosity function (LF) using a sample of over 2000 galaxies, with 0.12 < z < 0.55 and 17.0 < Rc < 21.5, drawn from the Canadian Network for Observational Cosmology Field Galaxy Redshift Survey (CNOC2), at present the largest such sample at intermediate redshifts. We use UBVRcIc photometry to classify our galaxies into early, intermediate, and late types, for which we compute luminosity functions in the rest-frame B, Rc, and U bandpasses. In particular, we adopt a parameterization of LF evolution including luminosity and number density evolution, and take care to quantify correlations among our LF evolution parameters. Our principal result is a clear quantitative separation of luminosity and density evolution for different galaxy populations, and the finding that the character of the LF evolution is strongly dependent on galaxy type. Specifically, the early- and intermediate-type LF's show primarily brightening at higher redshifts and only modest density evolution, while the late-type LF is best fit by strong number density increases at higher z, with little luminosity evolution. We also carefully measure and account for sample selection effects as functions of galaxy magnitude and color, and show that our results are not significantly affected by potential systematic effects, such as surface brightness selection, photometric errors, or redshift incompleteness. (abstract abridged)

Cited by 0

The PEP HerMES Luminosity Function 1 The Herschel? PEP/HerMES Luminosity Function – I:

2016

Cited by 0

The CNOC2 Field Galaxy Luminosity Function. I. A Description of Luminosity Function Evolution

H. Lin, H. K. C. Yee, R. G. Carlberg et al. · The Astrophysical Journal · 1999

We examine the evolution of the galaxy luminosity function (LF) using a sample of over 2000 galaxies, with 0.12 < z < 0.55 and 17.0 < Rc < 21.5, drawn from the Canadian Network for Observational Cosmology Field Galaxy Redshift Survey (CNOC2), at present the largest such sample at intermediate redshifts. We use UBVRcIc photometry to classify our galaxies into early, intermediate, and late types, for which we compute luminosity functions in the rest-frame B, Rc, and U bandpasses. In particular, we adopt a parameterization of LF evolution including luminosity and number density evolution, and take care to quantify correlations among our LF evolution parameters. Our principal result is a clear quantitative separation of luminosity and density evolution for different galaxy populations, and the finding that the character of the LF evolution is strongly dependent on galaxy type. Specifically, the early- and intermediate-type LF's show primarily brightening at higher redshifts and only modest density evolution, while the late-type LF is best fit by strong number density increases at higher z, with little luminosity evolution. We also carefully measure and account for sample selection effects as functions of galaxy magnitude and color, and show that our results are not significantly affected by potential systematic effects, such as surface brightness selection, photometric errors, or redshift incompleteness. (abstract abridged)

Cited by 220Open access

Search 250 million research papers