Search

We search for the signature of cosmological shocks in stacked gas pressure profiles of galaxy clusters using data from the South Pole Telescope (SPT). Specifically, we stack the latest Compton-y maps from the 2500 deg2 SPT-SZ survey on the locations of clusters identified in that same data set. The sample contains 516 clusters with mean mass 〈 M 200m〉 = 1014.9\, M⊙ and redshift z= 0.55. We analyse in parallel a set of zoom-in hydrodynamical simulations from the three hundred project. The SPT-SZ data show two features: (i) a pressure deficit at R/R200m = 1.08 ± 0.09, measured at 3.1σ significance and not observed in the simulations, and; (ii) a sharp decrease in pressure at R/R200m = 4.58 ± 1.24 at 2.0σ significance. The pressure deficit is qualitatively consistent with a shock-induced thermal non-equilibrium between electrons and ions, and the second feature is consistent with accretion shocks seen in previous studies. We split the cluster sample by redshift and mass, and find both features exist in all cases. There are also no significant differences in features along and across the cluster major axis, whose orientation roughly points towards filamentary structure. As a consistency test, we also analyse clusters from the Planck and Atacama Cosmology Telescope Polarimeter surveys and find quantitatively similar features in the pressure profiles. Finally, we compare the accretion shock radius (R sh,\, acc) with existing measurements of the splashback radius (Rsp) for SPT-SZ and constrain the lower limit of the ratio, R sh,\, acc/R sp\> 2.16\± 0.59.

CMB-HD is a proposed ultra-deep (0.5 uk-arcmin), high-resolution (15arcseconds) millimeter-wave survey over half the sky that would answer manyoutstanding questions in both fundamental physics of the Universe andastrophysics. This survey would be delivered in 7.5 years of observing 20,000square degrees, using two new 30-meter-class off-axis cross-Dragone telescopesto be located at Cerro Toco in the Atacama Desert. Each telescope would field800,000 detectors (200,000 pixels), for a total of 1.6 million detectors.

A millimeter-wave survey over half the sky, that spans frequencies in therange of 30 to 350 GHz, and that is both an order of magnitude deeper and ofhigher-resolution than currently funded surveys would yield an enormous gain inunderstanding of both fundamental physics and astrophysics. By providing such adeep, high-resolution millimeter-wave survey (about 0.5 uK-arcmin noise and 15arcsecond resolution at 150 GHz), CMB-HD will enable major advances. It willallow 1) the use of gravitational lensing of the primordial microwavebackground to map the distribution of matter on small scales (k~10/hMpc), whichprobes dark matter particle properties. It will also allow 2) measurements ofthe thermal and kinetic Sunyaev-Zel'dovich effects on small scales to map thegas density and gas pressure profiles of halos over a wide field, which probesgalaxy evolution and cluster astrophysics. In addition, CMB-HD would allow usto cross critical thresholds in fundamental physics: 3) ruling out or detectingany new, light (< 0.1eV), thermal particles, which could potentially be thedark matter, and 4) testing a wide class of multi-field models that couldexplain an epoch of inflation in the early Universe. Such a survey would also5) monitor the transient sky by mapping the full observing region every fewdays, which opens a new window on gamma-ray bursts, novae, fast radio bursts,and variable active galactic nuclei. Moreover, CMB-HD would 6) provide a censusof planets, dwarf planets, and asteroids in the outer Solar System, and 7)enable the detection of exo-Oort clouds around other solar systems, sheddinglight on planet formation. CMB-HD will deliver this survey in 5 years ofobserving half the sky, using two new 30-meter-class off-axis cross-Dragonetelescopes to be located at Cerro Toco in the Atacama Desert. The telescopeswill field about 2.4 million detectors (600,000 pixels) in total.

Opening up a new window of millimeter-wave observations that span frequencybands in the range of 30 to 500 GHz, survey half the sky, and are both an orderof magnitude deeper (about 0.5 uK-arcmin) and of higher-resolution (about 10arcseconds) than currently funded surveys would yield an enormous gain inunderstanding of both fundamental physics and astrophysics. In particular, sucha survey would allow for major advances in measuring the distribution of darkmatter and gas on small-scales, and yield needed insight on 1.) dark matterparticle properties, 2.) the evolution of gas and galaxies, 3.) new lightparticle species, 4.) the epoch of inflation, and 5.) the census of bodiesorbiting in the outer Solar System.

Opening up a new window of millimeter-wave observations that span frequencybands in the range of 30 to 500 GHz, survey half the sky, and are both an orderof magnitude deeper (about 0.5 uK-arcmin) and of higher-resolution (about 10arcseconds) than currently funded surveys would yield an enormous gain inunderstanding of both fundamental physics and astrophysics. In particular, sucha survey would allow for major advances in measuring the distribution of darkmatter and gas on small-scales, and yield needed insight on 1.) dark matterparticle properties, 2.) the evolution of gas and galaxies, 3.) new lightparticle species, 4.) the epoch of inflation, and 5.) the census of bodiesorbiting in the outer Solar System.

Distance estimation has been used extensively in the investigation of cognitive maps, yet it is not well understood as a cognitive process in its own right and, as a result, has been viewed as a simple read-out from a spatial representation. In contrast, this paper considers distance estimation to be a complex mental process in which heuristics guide the choice of strategies. Specifically, verbal protocols were collected on a distance estimation task for 20 undergraduates using a variety of city pairs in U.S. and Canada. On the basis of these data, distance estimation is shown to be a constructive process, using a relatively limited number of heuristics, such as addition, hedges and ratios. The choice of heuristics and the time to make a judgment are shown to be related to variables such as the familiarity of locations and the distance to be judged. The advantage of viewing distance estimation as a constructive process rather than a passive readout off an intemal map is argued.