Randall R. Rojas

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Two key research issues in the field of causal learning are how people acquire causal knowledge when observing data that are presented sequentially, and the level of abstraction at which learning takes place. Does sequential causal learning solely involve the acquisition of specific cause-effect links, or do learners also acquire knowledge about abstract(More)
We study the spectroscopic properties of a sample of 10 void galaxies identified in the Sloan Digital Sky Survey (SDSS) and compare these with the properties of galaxies in higher density regions (wall galaxies). This sample of void galaxies covers the range of absolute magnitude from Mr 1⁄4 13:5 to Mr 1⁄4 22:5 in regions with density contrast / < 0:6. We(More)
Wide-angle, moderately deep redshift surveys such as that conducted as part of the Sloan Digital Sky Survey (SDSS) allow study of the relationship between the structural elements of the large-scale distribution of galaxies – including groups, cluster, superclusters, and voids – and the dependence of galaxy formation and evolution on these enviroments. We(More)
We estimate the Mass Function of void galaxies in the second public data release of the Sloan Digital Sky Survey from a sample of 1000 galaxies with local density contrasts of δv < −0.6. The galaxy sample is split into ellipticals and spirals using a color-Sérsic index criterion. We estimate the virial masses of ellipticals using the measured spectral(More)
The Sloan Digital Sky Survey now extends over a large enough region that galaxies in low density environments can be detected. Rojas et al. have developed a technique to extract more than 1000 void galaxies with δρ/ρ < −0.6 on scales r > 7h−1Mpc from the SDSS. In this paper, we present the luminosity function of these galaxies and compare it to that of(More)
We estimate the mass function of void galaxies in the second public data release of the Sloan Digital Sky Survey from a sample of 1000 galaxies with local density contrasts of v < 0:6. The galaxy sample is split into ellipticals and spirals using a color-Sérsic index criterion. We estimate the virial masses of ellipticals using the measured spectral line(More)
Using a nearest neighbor analysis, we construct a sample of void galaxies from the Sloan Digital Sky Survey (SDSS) and compare the photometric properties of these galaxies to the population of non-void (wall) galaxies. We trace the density field of galaxies using a volume-limited sample with zmax = 0.089. Galaxies from the flux-limited SDSS with z ≤ zmax(More)
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