[Paper Review] Evidence that Quasars and Related Active Galaxies are Good Radio Standard Candles and that they are Likely to be a Lot Closer than their Redshifts Imply

M. B. Bell|arXiv (Cornell University)|Feb 10, 2006

Astronomy and Astrophysical Research1 references3 citations

TL;DR

This paper presents evidence that quasars and active galaxies are excellent radio standard candles based on VLBA flux density and jet angular motion data, suggesting their redshifts are largely intrinsic rather than cosmological. The analysis reveals these sources are likely much closer than their redshifts imply—mostly within 100 Mpc—supporting a local universe model where radio luminosity is stable and logN-logS slopes match expectations without requiring cosmological evolution.

ABSTRACT

For many years some astronomers have continued to argue, using redshift periodicities and quasar-galaxy associations, that quasars may be closer than their redshifts imply. Here, for the first time using raw radio data, I re-examine this question and find new evidence that supports this argument. Using VLBA flux densities and angular motions in jets, I show that the central engine of quasars and BL Lac objects appears to be a good radio standard candle. Using this information, relative distances are calculated and absolute radio distances are then obtained by referencing to a source whose true distance has been obtained using Cepheid variables. The results reveal that in this model most of the strong radio sources found in early surveys are nearer than 100 Mpc. (abridged)

Motivation & Objective

• To test whether quasars and active galaxies are good radio standard candles using raw radio data, challenging the assumption that their redshifts are cosmological.
• To re-evaluate the distance estimates of strong radio sources by correcting for intrinsic flux density variations due to viewing angle (inclination) effects.
• To determine whether the observed logN-logS slope of -3/2 and source number counts are consistent with a local universe model rather than cosmological evolution.
• To assess whether the apparent luminosity-redshift relationship can be explained by intrinsic redshifts and orientation-dependent beaming, rather than cosmological expansion.
• To provide an alternative explanation for quasar properties that avoids invoking large-scale cosmological evolution and instead relies on intrinsic radio luminosity constancy and inclination corrections.

Proposed method

• Used raw VLBA flux densities and jet angular motions to infer intrinsic radio luminosities of quasars and BL Lac objects.
• Applied a geometric correction to flux densities based on inclination angle (i), assuming a central torus with a hole, using the relation S(i)/S(90°) ∝ [N(i)/sin i]^{2/3} to normalize fluxes to edge-on orientation.
• Corrected observed flux densities to edge-on by removing the intrinsic flux component, which moves sources with low inclination angles (face-on) to the left in flux-distance diagrams.
• Reconstructed source number density distributions after correcting for inclination and detection limits, using bins of 10° in inclination angle.
• Compared corrected number counts and logN-logS slopes to theoretical expectations under both local and cosmological models.
• Used Cepheid variable distances as a reference to derive absolute distances, anchoring the local distance scale for strong radio sources.

Experimental results

Research questions

• RQ1 Are quasars and active galaxies good radio standard candles when corrected for viewing-angle-dependent flux variations?
• RQ2 Does the observed logN-logS slope of -3/2 arise naturally from a local universe model without requiring cosmological evolution?
• RQ3 Can the apparent increase in radio luminosity with redshift be explained by intrinsic redshifts and orientation effects rather than cosmological expansion?
• RQ4 What is the true distance scale of strong radio sources in early surveys, and how does it compare to redshift-based estimates?
• RQ5 To what extent do inclination-corrected flux densities and number counts support a local universe model over the standard cosmological model?

Key findings

• The central engines of quasars and BL Lac objects behave as good radio standard candles when corrected for inclination effects, with flux densities normalized to edge-on orientation.
• After inclination correction, the number density distribution of sources matches the expected distribution for a uniform, isotropic source population, with a peak near face-on (i ≈ 0°).
• The corrected logN-logS slope is consistent with -3/2 over a wide range, supporting a local model without requiring luminosity or density evolution.
• Source number counts increase as the cube of distance, as expected in a local universe, confirming the viability of the local model.
• The data fit the local model perfectly, while fitting the cosmological redshift model requires arbitrary, unphysical assumptions about luminosity and density evolution.
• The observed flux density, not redshift, is the best indicator of distance; most strong radio sources are likely within 100 Mpc, much closer than redshifts suggest.