## Yun Wang's Group's Dark Energy Measurements

**Results from Wang, Chuang, & Mukherjee (2012),
arXiv:1109.3172 (Phys. Rev. D 85, 023517 (2012)):**
*Dark energy density as a function of cosmic time, in units of yoctograms [10**(-24) grams] per cubic meter,
measured from the data of 472 SNe compiled by Conley et al. (2011),
with the galaxy clustering measurements from the Sloan Digital Sky Survey data by Chuang & Wang (2011),
the cosmic microwave background anisotropy data from WMAP seven year observations
(Komatsu et al. 2011), model-independent distances measured from 69 gamma-ray bursts (Wang 2008),
and Hubble constant measuement by Riess et al. (2011). The 68% (shaded) and 95%
confidence level regions are shown. The cosmological redshift z is an indicator
of cosmic time; the universe is approximately 14 Giga yrs old today (z=0), and
approximately 6 Giga yrs old at z=1.
A cosmological constant is indicated by the thick dashed black line.
The green contours indicate the matter density.
Thanks to Max Tegmark for suggesting this alternative presentation of the results.
*

**Fig. 15 from Wang, Chuang, & Mukherjee (2012),
arXiv:1109.3172.**
*This is the same as the figure above, but in units of rho_X(0) (the dark energy density today). The errors are not shown for rho_m(z).
*

**Fig. 16 from Wang, Chuang, & Mukherjee (2012),
arXiv:1109.3172.**
*The measured cosmic expansion history H(z) corresponding to
the above measurement of dark energy density function. The error bars represent the 68% confidence level. The lower panel shows [da/dt] divided by the Hubble constant, where a is the cosmic scale factor; this clearly shows that the expansion of the universe began to accelerate recently (at redshift z~0.5). Note that H(z)=[da/dt]/a.
*