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Improved constraints on the expansion rate of the Universe up to z~1.1 from the spectroscopic evolution of cosmic chronometers | M. Moresco
; A. Cimatti
; Raul Jimenez
; L. Pozzetti
; G. Zamorani
; M. Bolzonella
; J. Dunlop
; F. Lamareille
; M. Mignoli
; H. Pearce
; P. Rosati
; D. Stern
; L. Verde
; E. Zucca
; C. M. Carollo
; T. Contini
; J.-P. Kneib
; O. Le Fevre
; S. J. Lilly
; V. Mainieri
; A. Renzini
; M. Scodeggio
; I. Balestra
; R. Gobat
; R. McLure
; S. Bardelli
; A. Bongiorno
; K. Caputi
; O. Cucciati
; S. de la Torre
; L. de Ravel
; P. Franzetti
; B. Garilli
; A. Iovino
; P. Kampczyk
; C. Knobel
; K. Kovac
; J.-F. Le Borgne
; V. Le Brun
; C. Maier
; R. Pelló
; Y. Peng
; E. Perez-Montero
; V. Presotto
; J. D. Silverman
; M. Tanaka
; L. A. M. Tasca
; L. Tresse
; D. Vergani
; O. Almaini
; L. Barnes
; R. Bordoloi
; E. Bradshaw
; A. Cappi
; R. Chuter
; M. Cirasuolo
; G. Coppa
; C. Diener
; S. Foucaud
; W. Hartley
; M. Kamionkowski
; A. M. Koekemoer
; C. López-Sanjuan
; H. J. McCracken
; P. Nair
; P. Oesch
; A. Stanford
; N. Welikala
; | Date: |
17 Jan 2012 | Abstract: | 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, whose differential age evolution as a function of
cosmic time directly probes H(z). We analyze the 4000 {AA} 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
eq
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 Lambda CDM 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. | Source: | arXiv, 1201.3609 | Services: | Forum | Review | PDF | Favorites |
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