Proper motions with Subaru II. A sample in the Subaru/XMM-Newton Deep Survey field

We search for stars with proper motions in a set of deep Subaru images, covering about 0.48 square degrees to a depth of $i' \simeq 26$, taken over a span of five and a half years. We follow the methods described in \citet{Richmond2009} to reduce and analyze this dataset. We present a sample of 69 stars with motions of high significance, and discuss briefly the populations from which they are likely drawn. Based on photometry and motions alone, we expect that 14 of the candidates may be white dwarfs. Our candidate with the largest proper motion is surprisingly faint and likely to prove interesting: its colors and motions suggest that it might be an M dwarf moving at over 500 km/sec or an L dwarf in the halo.Comment: 10 pages, 5 figures. Accepted by Publications of the Astronomical Society of Japan, to appear in volume 62, February 2010. Revised version: removed PASJ LaTeX tutorial which was mistakenly appended to pape

Proper motions with Subaru I. Methods and a first sample in the Subaru Deep Field

We search for stars with proper motions in a set of twenty deep Subaru images, covering about 0.28 square degrees to a depth of i ~ 25, taken over a span of six years. In this paper, we describe in detail our reduction and techniques to identify moving objects. We present a first sample of 99 stars with motions of high significance, and discuss briefly the populations from which they are likely drawn. Based on photometry and motions alone, we expect that 9 of the candidates may be white dwarfs. We also find a group of stars which may be extremely metal-poor subdwarfs in the halo.Comment: 12 pages, 8 figures, submitted to PAS

TASS Mark IV Photometric Survey of the Northern Sky

The Amateur Sky Survey (TASS) is a loose confederation of amateur and professional astronomers. We describe the design and construction of our Mark IV systems, a set of wide-field telescopes with CCD cameras which take simultaneous images in the $V$ and $I_C$ passbands. We explain our observational procedures and the pipeline which processes and reduces the images into lists of stellar positions and magnitudes. We have compiled a large database of measurements for stars in the northern celestial hemisphere with $V$-band magnitudes in the range 7 < V < 13. This paper describes data taken over the four-year period starting November, 2001. One of our results is a catalog of repeated measurements on the Johnson-Cousins system for over 4.3 million stars.Comment: Accepted for publication in December, 2006, issue of PASP. 44 pages including 20 figures. Patches catalog available at http://spiff.rit.edu/tass/patches

A Measurement of the Rate of Type Ia Supernovae at Redshift z ≈ 0.1 from the First Season of the SDSS-II Supernova Survey

We present a measurement of the rate of type Ia supernovae (SNe Ia) from the first of three seasons of data from the SDSS-II Supernova Survey. For this measurement, we include 17 SNe Ia at redshift z ≤ 0.12. Assuming a flat cosmology with m = 0.3 = 1 − , we find a volumetric SN Ia rate of [2.93+0.17 −0.04(systematic)+0.90 −0.71(statistical)]×10−5 SNe Mpc−3 h3 70 year−1, at a volumeweighted mean redshift of 0.09. This result is consistent with previous measurements of the SN Ia rate in a similar redshift range. The systematic errors are well controlled, resulting in the most precise measurement of the SN Ia rate in this redshift range. We use a maximum likelihood method to fit SN rate models to the SDSS-II Supernova Survey data in combination with other rate measurements, thereby constraining models for the redshift-evolution of the SN Ia rate. Fitting the combined data to a simple power-law evolution of the volumetric SN Ia rate, rV ∝ (1 + z) , we obtain a value of β = 1.5 ± 0.6, i.e. the SN Ia rate is determined to be an increasing function of redshift at the ∼ 2.5σ level. Fitting the results to a model in which the volumetric SN rate, rV = Aρ(t) + Bρ˙(t), where ρ(t) is the stellar mass density and ρ˙(t) is the star formation rate, we find A = (2.8 ± 1.2) × 10−14 SNe M−1 ⊙ year−1, B = (9.3+3.4 −3.1) × 10−4 SNe M−1 ⊙

Detection of the Baryon Acoustic Peak in the Large-Scale Correlation Function of SDSS Luminous Red Galaxies

We present the large-scale correlation function measured from a spectroscopic sample of 46,748 luminous red galaxies from the Sloan Digital Sky Survey. The survey region covers 0.72h−3Gpc3 over 3816 square degrees and 0.16 \u3c z \u3c 0.47, making it the best sample yet for the study of large-scale structure. We find a well-detected peak in the correlation function at 100h−1Mpc separation that is an excellent match to the predicted shape and location of the imprint of the recombination-epoch acoustic oscillations on the low-redshift clustering of matter. This detection demonstrates the linear growth of structure by gravitational instability between z ≈ 1000 and the present and confirms a firm prediction of the standard cosmological theory. The acoustic peak provides a standard ruler by which we can measure the ratio of the distances to z = 0.35 and z = 1089 to 4% fractional accuracy and the absolute distance to z = 0.35 to 5% accuracy. From the overall shape of the correlation function, we measure the matter density mh2 to 8% and find agreement with the value from cosmic microwave background (CMB) anisotropies. Independent of the constraints provided by the CMB acoustic scale, we find m = 0.273±0.025+0.123(1+w0)+0.137 K. Including the CMB acoustic scale, we find that the spatial curvature is K = −0.010± 0.009 if the dark energy is a cosmological constant. More generally, our results provide a measurement of cosmological distance, and hence an argument for dark energy, based on a geometric method with the same simple physics as the microwave background anisotropies. The standard cosmological model convincingly passes these new and robust tests of its fundamental properties. (Refer to PDF file for exact formulas)