Improved constraints on the expansion rate of the Universe up to z ∼ 1.1 from the spectroscopic evolution of cosmic chronometers
- Dipartimento di Astronomia, Università di Bologna, via Ranzani 1, 40127 Bologna (Italy)
- ICREA and ICC, University of Barcelona (IEEC-UB), Barcelona 08028 (Spain)
- INAF — Osservatorio Astronomico di Bologna, via Ranzani 1, 40127 Bologna (Italy)
- SUPA, Institute for Astronomy, The University of Edinburgh, Royal Observatory Edinburgh, EH9 3HJ (United Kingdom)
- Institut de Recherche en Astrophysique et Planétologie, CNRS, 14, avenue Edouard Belin, F-31400 Toulouse (France)
- European Southern Observatory, Karl-Schwarzschild-Straße 2, 85748 Garching bei München (Germany)
- Jet Propulsion Laboratory, California Institute of Technology, Mail Stop 169-221, Pasadena CA-91109 (United States)
- ETH Zurich, Institute of Astronomy, Wolfgang-Pauli-Straße 27, 8093 Zurich (Switzerland)
We present new improved constraints on the Hubble parameter H(z) in the redshift range 0.15 < z < 1.1, obtained from the differential spectroscopic evolution of early-type galaxies as a function of redshift. We extract a large sample of early-type galaxies ( ∼ 11000) from several spectroscopic surveys, spanning almost 8 billion years of cosmic lookback time (0.15 < z < 1.42). We select the most massive, red elliptical galaxies, passively evolving and without signature of ongoing star formation. Those galaxies can be used as standard cosmic chronometers, as firstly proposed by Jimenez and Loeb (2002), whose differential age evolution as a function of cosmic time directly probes H(z). We analyze the 4000 Å break (D4000) as a function of redshift, use stellar population synthesis models to theoretically calibrate the dependence of the differential age evolution on the differential D4000, and estimate the Hubble parameter taking into account both statistical and systematical errors. We provide 8 new measurements of H(z), and determine its change in H(z) to a precision of 5–12% mapping homogeneously the redshift range up to z ∼ 1.1; for the first time, we place a constraint on H(z) at z≠0 with a precision comparable with the one achieved for the Hubble constant (about 5–6% at z ∼ 0.2), and covered a redshift range (0.5 < z < 0.8) which is crucial to distinguish many different quintessence cosmologies. These measurements have been tested to best match a ΛCDM model, clearly providing a statistically robust indication that the Universe is undergoing an accelerated expansion. This method shows the potentiality to open a new avenue in constrain a variety of alternative cosmologies, especially when future surveys (e.g. Euclid) will open the possibility to extend it up to z ∼ 2.
- OSTI ID:
- 22280060
- Journal Information:
- Journal of Cosmology and Astroparticle Physics, Vol. 2012, Issue 08; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 1475-7516
- Country of Publication:
- United States
- Language:
- English
Similar Records
Revisiting dark energy models using differential ages of galaxies
Impact of a Locally Measured H {sub 0} on the Interpretation of Cosmic-chronometer Data