Author Topic: SDSS's BOSS, QSO's and Dark Energy  (Read 1469 times)

paulrogers

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JeanTate

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Re: SDSS's BOSS, QSO's and Dark Energy
« Reply #1 on: November 14, 2012, 07:51:12 pm »
"Baryon Acoustic Oscillations in the Ly-α forest of BOSS quasars", by Busca et al. (Schlegel is one of the "et al."s  ;) as is a certain Anze Slosar, a.k.a. zookeeper_anze) is an astro-ph preprint (arXiv:1211.2616, link is to abstract). Here's the abstract:

Quote from: Busca et al.
We report a detection of the baryon acoustic oscillation (BAO) feature in the three-dimensional correlation function of the transmitted flux fraction in the \Lya forest of high-redshift quasars. The study uses 48,640 quasars in the redshift range $2.1\le z \le 3.5$ from the Baryon Oscillation Spectroscopic Survey (BOSS) of the third generation of the Sloan Digital Sky Survey (SDSS-III). At a mean redshift $z=2.3$, we measure the monopole and quadrupole components of the correlation function for separations in the range $20\hMpc<r<200\hMpc$. A peak in the correlation function is seen at a separation equal to $(1.01\pm0.03)$ times the distance expected for the BAO peak within a concordance $\Lambda$CDM cosmology. This first detection of the BAO peak at high redshift, when the universe was strongly matter dominated, results in constraints on the angular diameter distance $\da$ and the expansion rate $H$ at $z=2.3$ that, by themselves, require the existence of dark energy. Combined with constraints derived from Cosmic Microwave Background (CMB) observations, this result implies $H(z=2.3)=(224\pm8){\rm km s^{-1}Mpc^{-1}}$, indicating that the time derivative of the cosmological scale parameter $\dot{a}=H(z=2.3)/(1+z)$ is significantly greater than that measured with BAO at $z\sim0.5$. This demonstrates that the expansion was decelerating in the range $0.7<z<2.3$, as expected from the matter domination during this epoch. Combined with measurements of $H_0$, one sees the pattern of deceleration followed by acceleration characteristic of a dark-energy dominated universe.

axxo1

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Re: SDSS's BOSS, QSO's and Dark Energy
« Reply #2 on: August 25, 2013, 12:25:00 pm »
great article for a layman like me.
It sure makes me crave to know more on the subject.