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About iCosmos
An interactive cosmology calculator developed at the University of Oxford and recognised with an OxTALENT Award.
Developed at the University of Oxford
iCosmos was developed by Mihran Vardanyan during his research years at Oxford Astrophysics, University of Oxford, where he completed his DPhil in cosmology under the supervision of Joseph Silk and Roberto Trotta. It first went online in 2008. Its purpose was educational: it let students choose their own cosmological parameters and immediately see how distances, volumes, the age of the universe and the growth of structure respond.
Recognition
In 2012 iCosmos was recognised in the University of Oxford's OxTALENT awards, which recognise innovative uses of digital technology at the University, in the IT innovation category.
Referenced in research and teaching
Research that used iCosmos
- Astropy Collaboration (2013) — Astropy: A Community Python Package for Astronomy. Astronomy & Astrophysics 558, A33. The cosmology code of Astropy, the standard Python package for astronomy, was tested against iCosmos and two other widely used calculators (described in the paper’s cosmology section).
- Kahniashvili et al. (2013) — Constraining Primordial Magnetic Fields through Large-scale Structure. The Astrophysical Journal 770, 47. Computed the growth factors used to convert Lyman-α measurements from z = 2.72 to z = 0 with the iCosmos calculator.
- Taylor et al. (2014) — The Core Collapse Supernova Rate from the SDSS-II Supernova Survey. The Astrophysical Journal 792, 135. Used the iCosmos calculator to examine how cosmological parameters affect comoving volume; cites Vardanyan in the references.
- Diemer (2018) — COLOSSUS: A Python Toolkit for Cosmology, Large-scale Structure, and Dark Matter Halos. The Astrophysical Journal Supplement Series 239, 35. Tested the growth factor of the widely used COLOSSUS code against the iCosmos calculator, finding agreement to much better than a percent at low redshift for ΛCDM.
- Coe, Bradley & Zitrin (2015) — Frontier Fields: High-Redshift Predictions and Early Results. The Astrophysical Journal 800, 84. The Hubble Frontier Fields team at the Space Telescope Science Institute recommends “online calculators such as iCosmos” for cosmological distances.
- Jo et al. (2021) — Star formation rate density across the cosmic time. Astrophysics and Space Science 366, 18. References the iCosmos calculator (icosmos.co.uk).
- Martocchia & Polcaro (2010) — GRB 080319b and SN1054. Memorie della Società Astronomica Italiana Supplementi 14, 242–245. Credits Mihran Vardanyan’s iCosmos calculator in a footnote for its cosmological distance estimate.
- Bilton (2016) — Tracing Star Formation around Quasars with Polycyclic Aromatic Hydrocarbons. MPhil thesis, The Open University. Computed the angular diameter distances of its quasar sample with the iCosmos calculator.
Teaching and reference resources
- NASA/IPAC Extragalactic Database (NED) — Extragalactic Articles. Caltech / IPAC. Lists iCosmos among its cosmology calculators, alongside Ned Wright’s calculator.
- Hubble Frontier Fields — Strong Gravitational Lensing Primer (Coe, 2013). Space Telescope Science Institute. Recommends iCosmos for computing angular diameter distances.
- Wikipedia — Distance measure. External links. Links iCosmos as a calculator of cosmological distance measures, with graph generation.
- Wikipedia — Shape of the universe. External links. Links “Geometry of the Universe at icosmos.co.uk”.
- Wikipedia (Italian) — Distanza di diametro angolare. Collegamenti esterni. Links “iCosmos: Cosmology Calculator (With Graph Generation)” in the angular diameter distance article.
- Case Western Reserve University — Cosmology and the Structure of the Universe (Fall 2020). Stacy McGaugh, ASTR/PHYS 328/428. Links iCosmos among the course’s cosmology calculators.
- University of Sydney — Senior Astrophysics, Lecture 5 (2011). Scott Croom, Distances and the CMB. Lists iCosmos as a useful calculator with a graphing facility.
- University of Sydney — Senior Astrophysics, Lecture 6 (2011). Scott Croom. Lists iCosmos with Ned Wright’s calculator under “Useful calculators”.
- Centro de Astrobiología (CSIC-INTA) — Astrofísica Extragaláctica y Cosmología. Tema 11: Cosmología relativista. Links iCosmos in its distances-versus-redshift teaching material.
- Spectroscopic Determination of Cosmological Distances and Parameters (Walker, 2022). Monograph, v2.0. Cites “M. Vardanyan, iCosmos” among its cosmology calculators.
- Cosmology Resource Materials. Curated list on GitHub. Lists iCosmos with the ICRAR and Ned Wright calculators.
Citing iCosmos
Vardanyan, Mihran. iCosmos V4: Cosmology Calculator. https://icosmos.co.uk/. Include your access date, model parameters and exported data when reporting calculations.
Frequently asked questions
What is iCosmos?
iCosmos is a free online cosmology calculator. For any universe you choose (matter, dark energy, radiation, curvature, w0–wa dark energy and the Hubble constant) it computes the comoving, angular diameter and luminosity distances, comoving volume, lookback time, the age of the universe and the linear growth factor at any redshift, and plots how they change.
Who created iCosmos?
iCosmos was created by Mihran Vardanyan, who developed it during his DPhil research in cosmology at Oxford Astrophysics, University of Oxford, supervised by Joseph Silk and Roberto Trotta. It first went online in 2008 and was recognised in the University of Oxford’s OxTALENT awards in 2012.
How accurate is iCosmos?
Every number is checked automatically against independent calculations. On the published benchmark of 21 universes, distances and ages agree with SciPy and mpmath reference values to about 1 part in 10¹⁴ and the growth factor to about 2 × 10⁻⁹; in stress tests over 400 random matter + Λ + curvature universes (H₀ = 70, Ωm 0.005–3, ΩΛ −1 to 3.5, including near-loitering and very low-density open models), the growth factor agrees with the exact Heath integral to better than 10⁻⁹. A further 200 random evolving-dark-energy universes are checked for finite or explained results, not for accuracy. Where a quantity cannot be computed reliably, the calculator says so instead of showing a number. The validation tables are on the Reference page.
Who uses iCosmos?
iCosmos was one of the calculators used to test the cosmology code of Astropy, the standard Python package for astronomy, and the growth factor of the COLOSSUS toolkit. It has been used in research published in The Astrophysical Journal, in theses and in university cosmology courses, and is listed by the NASA/IPAC Extragalactic Database and Wikipedia among cosmology calculators.
How do I cite iCosmos?
Vardanyan, Mihran. iCosmos V4: Cosmology Calculator. https://icosmos.co.uk/. Include your access date, model parameters and exported data when reporting calculations.
Open the iCosmos cosmology calculator
iCosmos 4.5.0 · updated