Arman Shafieloo

The clustering of the SDSS-IV extended Baryon Oscillation Spectroscopic Survey DR14 quasar sample: a tomographic measurement of cosmic structure growth and expansion rate based on optimal redshift wei

Publisher: Oxford University Press (OUP)

Date: 26-10-2018

DOI: 10.1093/MNRAS/STY2845

Dynamical dark energy in light of the latest observations

Publisher: Springer Science and Business Media LLC

Date: 28-08-2017

DOI: 10.1038/S41550-017-0216-Z

Using variability and VLBI to measure cosmological distances

Publisher: Oxford University Press (OUP)

Date: 04-2020

DOI: 10.1093/MNRASL/SLAA051

Abstract: In this paper, we propose a new approach to determining cosmological distances to active Galactic nuclei (AGNs) via light travel-time arguments, which can be extended from nearby sources to very high redshift sources. The key assumption is that the variability seen in AGNs is constrained by the speed of light and therefore provides an estimate of the linear size of an emitting region. This can then be compared with the angular size measured with very long baseline interferometryer to derive a distance. We demonstrate this approach on a specific well-studied low-redshift (z = 0.0178) source 3C 84 (NGC 1275), which is the bright radio core of the Perseus Cluster. We derive an angular diameter distance including statistical errors of $D_{\\mathrm{ A}} = 72^{+5}_{-6}$ Mpc for this source, which is consistent with other distance measurements at this redshift. Possible sources of systematic errors and ways to correct for them are discussed.

Institute For The Early Universe (IEU)

Location: Korea, Republic of

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Asia Pacific Center For Theoretical Physics (APCTP)

Location: Korea, Republic of

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Korea Astronomy And Space Science Institute

Location: Korea, Republic of

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IUCAA

Location: India

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University Of Oxford

Location: United Kingdom of Great Britain and Northern Ireland

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Sharif University Of Technology

Location: Iran (Islamic Republic of)

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