Mock Catalogs for UHECR Studies

We provide realistic mock-catalogs of cosmic rays above 40 EeV, for a pure proton composition, assuming their sources are a random subset of ordinary galaxies in a simulated, volume-limited survey, for various choices of source density: 10^-3.5 Mpc^-3, 10^-4.0 Mpc^-3 and 10^-4.5 Mpc^-3. The spectrum at the source is taken to be E^-2.3 and the effects of cosmological redshifting as well as photo-pion and e^+ e^- energy losses are included.Comment: 7 pages, 4 figure

The Dark Side of Galaxy Color: evidence from new SDSS measurements of galaxy clustering and lensing

The age matching model has recently been shown to predict correctly the luminosity L and g-r color of galaxies residing within dark matter halos. The central tenet of the model is intuitive: older halos tend to host galaxies with older stellar populations. In this paper, we demonstrate that age matching also correctly predicts the g-r color trends exhibited in a wide variety of statistics of the galaxy distribution for stellar mass M* threshold samples. In particular, we present new measurements of the galaxy two-point correlation function and the galaxy-galaxy lensing signal as a function of M* and g-r color from the Sloan Digital Sky Survey, and show that age matching exhibits remarkable agreement with these and other statistics of low-redshift galaxies. In so doing, we also demonstrate good agreement between the galaxy-galaxy lensing observed by SDSS and the signal predicted by abundance matching, a new success of this model. We describe how age matching is a specific example of a larger class of Conditional Abundance Matching models (CAM), a theoretical framework we introduce here for the first time. CAM provides a general formalism to study correlations at fixed mass between any galaxy property and any halo property. The striking success of our simple implementation of CAM provides compelling evidence that this technique has the potential to describe the same set of data as alternative models, but with a dramatic reduction in the required number of parameters. CAM achieves this reduction by exploiting the capability of contemporary N-body simulations to determine dark matter halo properties other than mass alone, which distinguishes our model from conventional approaches to the galaxy-halo connection.Comment: references added, minor adjustments to text and notatio

Mind the Gap: Tightening the Mass-Richness Relation with Magnitude Gaps

We investigate the potential to improve optical tracers of cluster mass by exploiting measurements of the magnitude gap, m12, defined as the difference between the r-band absolute magnitude of the two brightest cluster members. We find that in a mock sample of galaxy groups and clusters constructed from the Bolshoi simulation, the scatter about the mass-richness relation decreases by 15-20% when magnitude gap information is included. A similar trend is evident in a volume-limited, spectroscopic sample of galaxy groups observed in the Sloan Digital Sky Survey (SDSS). We find that SDSS groups with small magnitude gaps are richer than large-gap groups at fixed values of the one-dimensional velocity dispersion among group members sigma_v, which we use as a mass proxy. We demonstrate explicitly that m12 contains information about cluster mass that supplements the information provided by group richness and the luminosity of the brightest cluster galaxy, L_bcg. In so doing, we show that the luminosities of the members of a group with richness N are inconsistent with the distribution of luminosities that results from N random draws from the global galaxy luminosity function. As the cosmological constraining power of galaxy clusters is limited by the precision in cluster mass determination, our findings suggest a new way to improve the cosmological constraints derived from galaxy clusters.Comment: references adde

Systematic Effects on Determination of the Growth Factor from Redshift-space Distortions

The linear growth factor of density perturbations is believed to be a powerful observable of future redshift surveys to probe physical properties of dark energy and to distinguish among gravity theories. We investigate systematic effects on determination of the growth factor f from a measurement of redshift-space distortions. Using N-body simulations we identify dark matter halos over a broad mass range. We compute the power spectra and correlation functions for the halos and then examine how well the redshift distortion parameter beta=f/b can be reconstructed as a function of halo mass. We find that beta measured for a fixed halo mass is generally a function of scale even on large scales, in contrast with the common expectation that beta approaches a constant described by Kaiser's formula on such scales. The scale dependence depends on the halo mass, being stronger for smaller halos. It also cannot be easily explained with the well-known distribution function of the halo peculiar velocities. We demonstrate that the biasing for smaller halos has larger nonlinearity and stochasticity, thus the linear bias assumption becomes worse for smaller halos. Only for massive halos with b>1.5, beta approaches the linear theory prediction on scales of r or pi/k>30Mpc/h. Luminous red galaxies (LRG), targeted by the SDSS-III's BOSS survey, tend to reside in very massive halos. Our results indicate that if the LRG is used for the measurement of redshift distortions, f can be measured unbiasedly. On the other hand, if one considers to use emission line galaxies, which are targeted by the BigBOSS survey and inhabited in halos of a broad mass range, the scale dependence of beta must be taken into account carefully; otherwise one might give incorrect constraints on dark energy or modified gravity theories. We also find that beta reconstructed in Fourier space behaves better than that in configuration space.Comment: 12 pages, 9 figures, submitted to ApJ, revised according to referee repor

Type II Supernova Light Curves and Spectra From the CfA

We present multiband photometry of 60 spectroscopically-confirmed supernovae (SN): 39 SN II/IIP, 19 IIn, one IIb and one that was originally classified as a IIn but later as a Ibn. Forty-six have only optical photometry, six have only near infrared (NIR) photometry and eight have both optical and NIR. The median redshift of the sample is 0.016. We also present 192 optical spectra for 47 of the 60 SN. All data are publicly available. There are 26 optical and two NIR light curves of SN II/IIP with redshifts z > 0.01, some of which may give rise to useful distances for cosmological applications. All photometry was obtained between 2000 and 2011 at the Fred Lawrence Whipple Observatory (FLWO), via the 1.2m and 1.3m PAIRITEL telescopes for the optical and NIR, respectively. Each SN was observed in a subset of the $u'UBVRIr'i'JHK_s$ bands. There are a total of 2932 optical and 816 NIR light curve points. Optical spectra were obtained using the FLWO 1.5m Tillinghast telescope with the FAST spectrograph and the MMT Telescope with the Blue Channel Spectrograph. Our photometry is in reasonable agreement with other samples from the literature. Comparison with Pan-STARRS shows that two-thirds of our individual star sequences have weighted-mean V offsets within $\pm$0.02 mag. In comparing our standard-system SN light curves with common Carnegie Supernova Project objects using their color terms, we found that roughly three-quarters have average differences within $\pm$0.04 mag. The data from this work and the literature will provide insight into SN II explosions, help with developing methods for photometric SN classification, and contribute to their use as cosmological distance indicators.Comment: Accepted to ApJS. TAR of light curves and star sequences here: https://www.cfa.harvard.edu/supernova/fmalcolm2017/cfa_snII_lightcurvesndstars.june2017.tar ... Spectra can be found here: https://www.cfa.harvard.edu/supernova/fmalcolm2017/cfaspec_snII.tar.gz ... Passbands and plot of spectra can be found here: https://www.cfa.harvard.edu/supernova/SNarchive.htm