We use gravitational lensing of the cosmic microwave background (CMB) to measure the mass of the most distant blindly selected sample of galaxy clusters on which a lensing measurement has been ...performed to date. In CMB data from the the Atacama Cosmology Telescope and the Planck satellite, we detect the stacked lensing effect from 677 near-infrared-selected galaxy clusters from the Massive and Distant Clusters of WISE Survey (MaDCoWS), which have a mean redshift of . There are currently no representative optical weak lensing measurements of clusters that match the distance and average mass of this sample. We detect the lensing signal with a significance of . We model the signal with a halo model framework to find the mean mass of the population from which these clusters are drawn. Assuming that the clusters follow Navarro-Frenk-White (NFW) density profiles, we infer a mean mass of . We consider systematic uncertainties from cluster redshift errors, centering errors, and the shape of the NFW profile. These are all smaller than 30% of our reported uncertainty. This work highlights the potential of CMB lensing to enable cosmological constraints from the abundance of distant clusters populating ever larger volumes of the observable universe, beyond the capabilities of optical weak lensing measurements.
As requirements for satellite on-board processing throughput continue to increase, users of radiation tolerant electronics are driven to ever decreasing feature sizes. As device feature sizes drop ...below the current radiation hardened capabilities of 130 nm one should include more of the high-energy space environment in the analysis of the potential effects. The effects due to particle showers produced by very high-energy celestial gamma-rays and charged particles have been neglected to date because of their low numbers, but small feature size large area devices may have susceptibilities. Above an energy of 30 MeV, the primary photon interaction with matter is pair production. These particles in turn interact producing an electromagnetic shower. The result of such an interaction is that many charged particles will pass through the system at one time. The integrated flux is approximately 10 photons/cm 2 /day with each photon producing two or more charged daughter particles. Since the incident particles are photons they are not affected by the Earth's magnetic field and the integrated rate will be approximately the same for any orbit. An interaction anywhere on the space vehicle, primary structure, subsystem enclosures, or actual electronic parts will produce a shower that can affect any components downstream of it. There is a definite need to study this problem. The NASA gamma-ray large area space telescope, to be launched in the spring of 2008, will be the most sophisticated Gamma- ray telescope ever flown. GLAST is a pair conversion telescope which measures the direction and energy of the daughter products of the incident photon using a silicon strip tracker and CsI calorimeter. It will provide detailed information on both celestial and Earth albedo Gamma-rays as well as providing additional detail on the charged particle environment in low Earth orbit through its on-board and ground segment charged particle rejection capabilities.
Two recent large data releases for the Atacama Cosmology Telescope (ACT), called DR4 and DR5, are available for public access. These data include temperature and polarization maps that cover nearly ...half the sky at arcminute resolution in three frequency bands; lensing maps and component-separated maps covering ~ 2,100 deg2 of sky; derived power spectra and cosmological likelihoods; a catalog of over 4,000 galaxy clusters; and supporting ancillary products including beam functions and masks. The data and products are described in a suite of ACT papers; here we provide a summary. In order to facilitate ease of access to these data we present a set of Jupyter IPython notebooks developed to introduce users to DR4, DR5, and the tools needed to analyze these data. The data products (excluding simulations) and the set of notebooks are publicly available on the NASA Legacy Archive for Microwave Background Data Analysis (LAMBDA); simulation products are available on the National Energy Research Scientific Computing Center (NERSC).
Abstract
We measure the projected number density profiles of galaxies and the splashback feature in clusters selected by the Sunyaev–Zel’dovich effect from the Advanced Atacama Cosmology Telescope ...(AdvACT) survey using galaxies observed by the Dark Energy Survey (DES). The splashback radius is consistent with CDM-only simulations and is located at
2.4
−
0.4
+
0.3
Mpc
h
−
1
. We split the galaxies on color and find significant differences in their profile shapes. Red and green-valley galaxies show a splashback-like minimum in their slope profile consistent with theory, while the bluest galaxies show a weak feature at a smaller radius. We develop a mapping of galaxies to subhalos in simulations and assign colors based on infall time onto their hosts. We find that the shift in location of the steepest slope and different profile shapes can be mapped to the average time of infall of galaxies of different colors. The steepest slope traces a discontinuity in the phase space of dark matter halos. By relating spatial profiles to infall time, we can use splashback as a clock to understand galaxy quenching. We find that red galaxies have on average been in clusters over 3.2 Gyr, green galaxies about 2.2 Gyr, while blue galaxies have been accreted most recently and have not reached apocenter. Using the full radial profiles, we fit a simple quenching model and find that the onset of galaxy quenching occurs after a delay of about a gigayear and that galaxies quench rapidly thereafter with an exponential timescale of 0.6 Gyr.
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