Advances in Astrophysics

Download PDF (393.8 KB) PP. 135 - 137 Pub. Date: November 1, 2016

DOI: 10.22606/adap.2016.13001

• Paul Halpern^*
  Dept. of Math, Physics, and Statistics, University of the Sciences in Philadelphia, 600 S. 43rd St., Philadelphia, PA, United States
• Nick Tomasello^*
  Dept. of Math, Physics, and Statistics, University of the Sciences in Philadelphia, 600 S. 43rd St., Philadelphia, PA, United States

Because of the expansion of space and the finite age of the cosmos, there exists a horizon beyond which the light emitted by objects will never be able to reach us, marking the bounds of the observable universe. One can calculate the current distance to the horizon by tracing the amount of time it would have taken a photon starting from an object currently there to have reached us. In a 2005 paper, Gott et al. derived this distance using first year CMB data from the WMAP survey. However, more recent CMB data collected by the Planck satellite and published in 2013 have since yielded different values of cosmological parameters. In this paper, we have applied these updated parameters to refine the distance to the edge of the observable universe. We have determined a revised value for the radius of the observable universe that is 0.7% smaller than the previous estimate.

Hubble radius; particle horizon; conformal time

[1] A. G. Riess, et. al., “Observational Evidence from Supernovae for an Accelerating Universe and a Cosmological Constant,” Astronomical Journal, vol. 116, pp. 1009–1038, 1998.

[2] S. Perlmutter, et. al., “Measurements of Omega and Lambda from 42 High-Redshift Supernovae,” Astrophysical Journal, vol. 517, pp. 565–586, 1999.

[3] T. M. Davis and C. H. Lineweaver, “Expanding Confusion: Common Misconceptions of Cosmological Horizons and the Superluminal Expansion of the Universe,” Publications of the Astronomical Society of Australia, vol. 21, pp. 97–109, 2004.

[4] J. R. Gott III, et. al., “A Map of the Universe,” Astronomical Journal, vol. 624, pp. 463–484, 2005.

[5] D. N. Spergel, et. al., “First year Wilkinson Microwave Anisotropy Probe (WMAP) observations: determination of cosmological parameters,” Astronomical Journal Supplement, vol. 148, pp. 175–194, 2003.

[6] P. A. R. Ade, et. al., “Planck 2013 results. XVI. Cosmological Parameters ,” Astronomy and Astrophysics, vol. 571, no. A16, pp. 1–66, 2014. 7. P. A. R. Ade, et. al., “Planck 2015 results. XIII. Cosmological parameters,” ArXiv:1502.01589. Accepted for publication in Astronomical Journal, 2016.