Searcharxiv⌕ Search
Home/Archive/arXiv

arXiv · astro-ph/0612018

Radio sources in the 6dFGS: Local luminosity functions at 1.4 GHz for star-forming galaxies and radio-loud AGN

Tom Mauch·Elaine M. Sadler
View original source ↗Read source document ↗Export metadata ↓

Abstract

We have identified 7824 radio sources from the 1.4GHz NRAO VLA Sky Survey (NVSS) with galaxies brighter than K=12.75 mag. in the Second Incremental Data Release of the 6dF Galaxy Survey (6dFGS DR2). The resulting sample of redshifts and optical spectra for radio sources over an effective sky area of 7076 square degrees (about 17% of the celestial sphere) is the largest of its kind ever obtained. NVSS radio sources associated with galaxies in the 6dFGS span a redshift range 0.003<z<0.3 and have median z=0.043. Through visual examination of 6dF spectra we have identified the dominant mechanism for radio emission from each galaxy. 60% are fuelled by star-formation and 40% are fuelled by an active galactic nucleus powered by a supermassive black hole. We have accurately determined the local radio luminosity function at 1.4GHz for both classes of radio source and have found it to agree well with other recent determinations. From the radio luminosity function of star-forming galaxies we derive a local star formation density of 0.022+/-0.001 M_sun/yr/Mpc^3, in broad agreement with recent determinations at radio and other wavelengths. We have split the radio luminosity function of radio-loud AGN into bins of absolute K-band magnitude (M_K) and compared this with the underlying K-band galaxy luminosity function of all 6dFGS galaxies to determine the bivariate radio-$K$-band luminosity function. We verify that radio-loud AGN preferentially inhabit the brightest and hence most massive host galaxies and show that the fraction of all galaxies which host a radio-loud AGN scales as L_K^2.1, indicative of a similarly strong scaling with black hole mass and stellar mass.

Explore related subjects

astro-ph

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Tom Mauch, Elaine M. Sadler. 2006-12-01. Radio sources in the 6dFGS: Local luminosity functions at 1.4 GHz for star-forming galaxies and radio-loud AGN. https://doi.org/10.1111/j.1365-2966.2006.11353.x

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

arXiv2026

Frame covariance of CMBR lensing in the exact 1+3 covariant radiation hierarchy

The exact $1+3$ covariant Boltzmann hierarchy for the cosmic microwave background contains acceleration, shear and vorticity couplings whose coefficients grow linearly in $\ell$. We show that all are the multipole form of the aberration operator in the photon Liouville equation. Under a change of threading, this operator shifts by the along-ray generator of a Lorentz boost. The acceleration coupling of $\ell$ to $\ell\pm1$ and the shear coupling of $\ell$ to $\ell\pm2$ are therefore frame-covariant descriptions of the same operator, related by an algebraic, pointwise relabelling of direction. With emitter and observer frames fixed, the observed sky is independent of the intermediate threading at every $\ell$. We derive this in $1+3$ covariant and gauge-invariant variables without constructing second-order gauge-invariant variables. The $O(ε^2\ell)$ content is gravitational lensing, as known in metric variables. Linearisation about a Friedmann--Lemaître--Robertson--Walker background removes these couplings, requiring lensing to be reinstated from the geodesic equation. Keeping the threading arbitrary makes frame covariance explicit and places observer aberration in the same operator. In the Newtonian threading we compute both halves of the deflection: the equivalence-principle contribution enters through aberration, while the spatial-curvature contribution arises from free streaming on perturbed spatial sections and reduces to the same operator. The lensing efficiency follows from the direction derivative. The angular-power-spectrum contribution is quartic in the potential: for a deflection statistically independent of the source, the two fourth-order terms carrying $\ell^2$ cancel where the spectrum is smooth on the deflection scale, and lensing redistributes power without adding ensemble variance.

astro-ph↗
arXiv2026

Cosmic Conundrums with Quantum Corrections

Darh energy was discovered over 25 years ago and we do not have an explanation of it. Dark matter comprises 95% of matter in the universe and we still don't know what it is. The Webb telescope has been finding fully formed galaxies with massive black holes millions of times the mass of the sun in the early universe and we don't have any explanation. A quantum density limitation will be used to solve these and other outstanding problems.

astro-ph↗
arXiv2026

On binary pulsars and the force of gravity

The energy-momentum budget of the astrophysical systems can be studied by the exact local conservation equation derived by Landau and Lifshitz. We show that a similar equation is valid for the Einstein-Cartan gravity. We reanalyze a binary pulsar system using the Landau-Lifshitz conservation equation and show that the orbital period change rate can be completely understood as a curvature backreaction process. Taking into account the detailed theoretical and observational research of relativistic binary pulsar systems, especially the system of Hulse and Taylor, we conclude that general relativity and astrophysical observations rule out the existence of gravitational radiation. We comment upon the LIGO GW events and their alternative explanation, as well as the recent pulsar timing arrays data.

astro-ph↗