arXiv subjects

J. Richard Bond

Publications and source records attributed to J. Richard Bond.

At least 91 records · Page 5Linked to original sources

arXiv2019

Cross-correlating Carbon Monoxide Line-intensity Maps with Spectroscopic and Photometric Galaxy Surveys

Line-intensity mapping (LIM or IM) is an emerging field of observational work, with strong potential to fit into a larger effort to probe large-scale structure and small-scale astrophysical phenomena using multiple complementary tracers. Taking full advantage of such complementarity means, in part, undertaking line-intensity surveys with galaxy surveys in mind. We consider the potential for detection of a cross-correlation signal between COMAP and blind surveys based on photometric redshifts (as in COSMOS) or based on spectroscopic data (as with the HETDEX survey of Lyman-$α$ emitters). We find that obtaining $σ_z/(1+z)\lesssim0.003$ accuracy in redshifts and $\gtrsim10^{-4}$ sources per Mpc$^3$ with spectroscopic redshift determination should enable a CO-galaxy cross spectrum detection significance at least twice that of the CO auto spectrum. Either a future targeted spectroscopic survey or a blind survey like HETDEX may be able to meet both of these requirements.

astro-ph.GA↗

arXiv2018

The mass-Peak Patch algorithm for fast generation of deep all-sky dark matter halo catalogues and its N-Body validation

We present a detailed description and validation of our massively-parallel update to the mass-Peak Patch method, a fully predictive initial-space algorithm to quickly generate dark matter halo catalogues in very large cosmological volumes. We perform an extensive systematic comparison to a suite of N-body simulations covering a broad range of redshifts and simulation resolutions, and find that, without any parameter fitting, our method is able to generally reproduce N-body results while typically using over 3 orders of magnitude less CPU time, and a fraction of the memory cost. Instead of calculating the full non-linear gravitational collapse determined by an N-body simulation, the mass-Peak Patch method finds an overcomplete set of just-collapsed structures around a hierarchy of density-peak points by coarse-grained (homogeneous) ellipsoidal dynamics. A complete set of mass-peaks, or halos, is then determined by exclusion of overlapping patches, and second order Lagrangian displacements are used to move the halos to their final positions and to give their flow velocities. Our results show that the mass-Peak Patch method is well-suited for creating large ensembles of halo catalogues to mock cosmological surveys, and to aid in complex statistical interpretations of cosmological models.

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arXiv2018

BFORE: A CMB Balloon Payload to Measure Reionization, Neutrino Mass, and Cosmic Inflation

BFORE is a high-altitude ultra-long-duration balloon mission to map the cosmic microwave background (CMB). During a 28-day mid-latitude flight launched from Wanaka, New Zealand, the instrument will map half the sky to improve measurements of the optical depth to reionization tau. This will break parameter degeneracies needed to detect neutrino mass. BFORE will also hunt for the gravitational wave B-mode signal, and map Galactic dust foregrounds. The mission will be the first near-space use of TES/mSQUID multichroic detectors (150/217 GHz and 280/353 GHz bands) with low-power readout electronics.

astro-ph.IM↗

arXiv2018

Weak-Lensing Mass Calibration of ACTPol Sunyaev-Zel'dovich Clusters with the Hyper Suprime-Cam Survey

We present weak-lensing measurements using the first-year data from the Hyper Suprime-Cam Strategic Survey Program on the Subaru telescope for eight galaxy clusters selected through their thermal Sunyaev-Zel'dovich (SZ) signal measured at 148 GHz with the Atacama Cosmology Telescope Polarimeter experiment. The overlap between the two surveys in this work is 33.8 square degrees, before masking bright stars. The signal-to-noise ratio of individual cluster lensing measurements ranges from 2.2 to 8.7, with a total of 11.1 for the stacked cluster weak-lensing signal. We fit for an average weak-lensing mass distribution using three different profiles, a Navarro-Frenk-White profile, a dark-matter-only emulated profile, and a full cosmological hydrodynamic emulated profile. We interpret the differences among the masses inferred by these models as a systematic error of 10\%, which is currently smaller than the statistical error. We obtain the ratio of the SZ-estimated mass to the lensing-estimated mass (the so-called hydrostatic mass bias $1-b$) of $0.74^{+0.13}_{-0.12}$, which is comparable to previous SZ-selected clusters from the Atacama Cosmology Telescope and from the {\sl Planck} Satellite. We conclude with a discussion of the implications for cosmological parameters inferred from cluster abundances compared to cosmic microwave background primary anisotropy measurements.

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arXiv2018

The LABOCA/ACT Survey of Clusters at All Redshifts: multi-wavelength analysis of background submillimeter galaxies

We present a multi-wavelength analysis of 48 submillimeter galaxies (SMGs) detected in the LABOCA/ACT Survey of Clusters at All Redshifts, LASCAR, which acquired new 870 $μ$m and ATCA 2.1 GHz observations of ten galaxy clusters detected through their Sunyaev-Zel'dovich effect (SZE) signal by the Atacama Cosmology Telescope. Far-infrared observations were also conducted with the PACS (100/160 $μ$m) and SPIRE (250/350/500 $μ$m) instruments on $Herschel$ for sample subsets of five and six clusters. LASCAR 870 $μ$m, maps were reduced using a multi-scale iterative pipeline that removes the SZE increment signal, yielding point-source sensitivities of $σ\sim2\rm{\,mJy\,beam}^{-1}$. We detect in total 49 sources at the $4σ$ level, and conduct a detailed multi-wavelength analysis considering our new radio and far-IR observations plus existing near-IR and optical data. One source is identified as a foreground galaxy, 28 SMGs are matched to single radio sources, 4 have double radio counterparts, and 16 are undetected at 2.1 GHz but tentatively associated in some cases to near-IR/optical sources. We estimate photometric redshifts for 34 sources with secure (25) and tentative (9) matches at different wavelengths, obtaining a median $z=2.8^{+2.1}_{-1.7}$. Compared to previous results for single-dish surveys, our redshift distribution has a comparatively larger fraction of sources at $z>3$ and the high-redshift tail is more extended. This is consistent with millimeter spectroscopic confirmation of a growing number of high-$z$ SMGs and relevant for testing of cosmological models. Analytical lens modeling is applied to estimate magnification factors for 42 SMGs at cluster-centric radii $>1.2$'; with the demagnified flux densities and source-plane areas, we obtain integral number counts that agree with previous submillimeter surveys.

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arXiv2018

The Atacama Cosmology Telescope: The Two-Season ACTPol Sunyaev-Zel'dovich Effect Selected Cluster Catalog

We present a catalog of 182 galaxy clusters detected through the Sunyaev-Zel'dovich effect by the Atacama Cosmology Telescope in a contiguous 987.5 deg$^{2}$ field. The clusters were detected as SZ decrements by applying a matched filter to 148 GHz maps that combine the original ACT equatorial survey with data from the first two observing seasons using the ACTPol receiver. Optical/IR confirmation and redshift measurements come from a combination of large public surveys and our own follow-up observations. Where necessary, we measured photometric redshifts for clusters using a pipeline that achieves accuracy $Δz/(1 + z)=0.015$ when tested on SDSS data. Under the assumption that clusters can be described by the so-called Universal Pressure Profile and its associated mass-scaling law, the full signal-to-noise > 4 sample spans the mass range $1.6 < M^{\rm UPP}_{\rm 500c}/10^{14}{\rm M}_{\odot}<9.1$, with median $M^{\rm UPP}_{\rm 500c}=3.1 \times 10^{14}$ M$_{\odot}$. The sample covers the redshift range $0.1 < z < 1.4$ (median $z = 0.49$) and 28 clusters are new discoveries (median $z = 0.80$). We compare our catalog with other overlapping cluster samples selected using the SZ, optical,and X-ray wavelengths. We find the ratio of the UPP-based SZ mass to richness-based weak-lensing mass is $\langle M^{\rm UPP}_{\rm 500c} \rangle / \langle M^{\rm λWL}_{\rm 500c} \rangle = 0.68 \pm 0.11$. After applying this calibration, the mass distribution for clusters with $M_{\rm 500c} > 4 \times 10^{14}$ M$_{\odot}$ is consistent with the number of such clusters found in the South Pole Telescope SZ survey.

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arXiv2017

The Impact of baryonic physics on the kinetic Sunyaev-Zel'dovich Effect

Poorly understood "baryonic physics" impacts our ability to predict the power spectrum of the kinetic Sunyaev-Zel'dovich (kSZ) effect. We study this in one sample high resolution simulation of galaxy formation and feedback, Illustris. The high resolution of Illustris allows us to probe the kSZ power spectrum on multipoles $\ell =10^3-3\times 10^4$. Strong AGN feedback in Illustris nearly wipes out gas fluctuations at $k\gtrsim1~h~\rm{Mpc}^{-1}$ and at late times, likely somewhat under predicting the kSZ power generated at $z\lesssim 1$. The post-reionization kSZ power spectrum for Illustris is well-fit by $\mathcal{D}^{z<6}_{\ell} = 1.38[\ell/3000]^{0.21}~μK^2$ over $3000\lesssim\ell\lesssim10000$, somewhat lower than most other reported values but consistent with the analysis of Shaw et al. Our analysis of the bias of free electrons reveals subtle effects associated with the multi-phase gas physics and stellar fractions that affect even linear scales. In particular there are fewer electrons in biased galaxies, due to gas cooling and star formation, and this leads to an electron bias less than one even at low wavenumbers. The combination of bias and electron fraction that determines the overall suppression is relatively constant, $f_e^2b^2_{e0} \sim 0.7$, but more simulations are needed to see if this is Illustris-specific. By separating the kSZ power into different terms, we find at least $6\, (10)\%$ of the signal at $\ell=3000\, (10000)$ comes from non-Gaussian connected four-point density and velocity correlations, $\left<δv δv\right>_{c}$, even without correcting for the Illustris simulation box size. A challenge going forward will be to accurately model long-wave velocity modes simultaneously with Illustris-like high resolution to capture the complexities of galaxy formation and its correlations with large scale flows.

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arXiv2017

Line-Intensity Mapping: 2017 Status Report

Following the first two annual intensity mapping workshops at Stanford in March 2016 and Johns Hopkins in June 2017, we report on the recent advances in theory, instrumentation and observation that were presented in these meetings and some of the opportunities and challenges that were identified looking forward. With preliminary detections of CO, [CII], Lya and low-redshift 21cm, and a host of experiments set to go online in the next few years, the field is rapidly progressing on all fronts, with great anticipation for a flood of new exciting results. This current snapshot provides an efficient reference for experts in related fields and a useful resource for nonspecialists. We begin by introducing the concept of line-intensity mapping and then discuss the broad array of science goals that will be enabled, ranging from the history of star formation, reionization and galaxy evolution to measuring baryon acoustic oscillations at high redshift and constraining theories of dark matter, modified gravity and dark energy. After reviewing the first detections reported to date, we survey the experimental landscape, presenting the parameters and capabilities of relevant instruments such as COMAP, mmIMe, AIM-CO, CCAT-p, TIME, CONCERTO, CHIME, HIRAX, HERA, STARFIRE, MeerKAT/SKA and SPHEREx. Finally, we describe recent theoretical advances: different approaches to modeling line luminosity functions, several techniques to separate the desired signal from foregrounds, statistical methods to analyze the data, and frameworks to generate realistic intensity map simulations.

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arXiv2017

Measuring Reionization, Neutrino Mass, and Cosmic Inflation with BFORE

BFORE is a NASA high-altitude ultra-long-duration balloon mission proposed to measure the cosmic microwave background (CMB) across half the sky during a 28-day mid-latitude flight launched from Wanaka, New Zealand. With the unique access to large angular scales and high frequencies provided by the balloon platform, BFORE will significantly improve measurements of the optical depth to reionization tau, breaking parameter degeneracies needed for a measurement of neutrino mass with the CMB. The large angular scale data will enable BFORE to hunt for the large-scale gravitational wave B-mode signal, as well as the degree-scale signal, each at the r~0.01 level. The balloon platform allows BFORE to map Galactic dust foregrounds at frequencies where they dominate, in order to robustly separate them from CMB signals measured by BFORE, in addition to complementing data from ground-based telescopes. The combination of frequencies will also lead to velocity measurements for thousands of galaxy clusters, as well as probing how star-forming galaxies populate dark matter halos. The mission will be the first near-space use of TES multichroic detectors (150/217 GHz and 280/353 GHz bands) using highly-multiplexed mSQUID microwave readout, raising the technical readiness level of both technologies.

astro-ph.IM↗

arXiv2017

Limits on the ultra-bright Fast Radio Burst population from the CHIME Pathfinder

We present results from a new incoherent-beam Fast Radio Burst (FRB) search on the Canadian Hydrogen Intensity Mapping Experiment (CHIME) Pathfinder. Its large instantaneous field of view (FoV) and relative thermal insensitivity allow us to probe the ultra-bright tail of the FRB distribution, and to test a recent claim that this distribution's slope, $α\equiv-\frac{\partial \log N}{\partial \log S}$, is quite small. A 256-input incoherent beamformer was deployed on the CHIME Pathfinder for this purpose. If the FRB distribution were described by a single power-law with $α=0.7$, we would expect an FRB detection every few days, making this the fastest survey on sky at present. We collected 1268 hours of data, amounting to one of the largest exposures of any FRB survey, with over 2.4\,$\times$\,10$^5$\,deg$^2$\,hrs. Having seen no bursts, we have constrained the rate of extremely bright events to $<\!13$\,sky$^{-1}$\,day$^{-1}$ above $\sim$\,220$\sqrt{(τ/\rm ms)}$ Jy\,ms for $τ$ between 1.3 and 100\,ms, at 400--800\,MHz. The non-detection also allows us to rule out $α\lesssim0.9$ with 95$\%$ confidence, after marginalizing over uncertainties in the GBT rate at 700--900\,MHz, though we show that for a cosmological population and a large dynamic range in flux density, $α$ is brightness-dependent. Since FRBs now extend to large enough distances that non-Euclidean effects are significant, there is still expected to be a dearth of faint events and relative excess of bright events. Nevertheless we have constrained the allowed number of ultra-intense FRBs. While this does not have significant implications for deeper, large-FoV surveys like full CHIME and APERTIF, it does have important consequences for other wide-field, small dish experiments.

astro-ph.HE↗

arXiv2017

Cosmological Parameters from pre-Planck CMB Measurements: a 2017 Update

We present cosmological constraints from the combination of the full mission 9-year WMAP release and small-scale temperature data from the pre-Planck ACT and SPT generation of instruments. This is an update of the analysis presented in Calabrese et al. 2013 and highlights the impact on $Λ$CDM cosmology of a 0.06 eV massive neutrino - which was assumed in the Planck analysis but not in the ACT/SPT analyses - and a Planck-cleaned measurement of the optical depth to reionization. We show that cosmological constraints are now strong enough that small differences in assumptions about reionization and neutrino mass give systematic differences which are clearly detectable in the data. We recommend that these updated results be used when comparing cosmological constraints from WMAP, ACT and SPT with other surveys or with current and future full-mission Planck cosmology. Cosmological parameter chains are publicly available on the NASA's LAMBDA data archive.

astro-ph.CO↗

arXiv2016

The Atacama Cosmology Telescope: Two-Season ACTPol Lensing Power Spectrum

We report a measurement of the power spectrum of cosmic microwave background (CMB) lensing from two seasons of Atacama Cosmology Telescope Polarimeter (ACTPol) CMB data. The CMB lensing power spectrum is extracted from both temperature and polarization data using quadratic estimators. We obtain results that are consistent with the expectation from the best-fit Planck LCDM model over a range of multipoles L=80-2100, with an amplitude of lensing A_lens = 1.06 +/- 0.15 (stat.) +/- 0.06 (sys.) relative to Planck. Our measurement of the CMB lensing power spectrum gives sigma_8 Omega_m^0.25 = 0.643 +/- 0.054; including baryon acoustic oscillation scale data, we constrain the amplitude of density fluctuations to be sigma_8 = 0.831 +/- 0.053. We also update constraints on the neutrino mass sum. We verify our lensing measurement with a number of null tests and systematic checks, finding no evidence of significant systematic errors. This measurement relies on a small fraction of the ACTPol data already taken; more precise lensing results can therefore be expected from the full ACTPol dataset.

astro-ph.CO↗

arXiv2016

The Atacama Cosmology Telescope: Two-Season ACTPol Spectra and Parameters

We present the temperature and polarization angular power spectra measured by the Atacama Cosmology Telescope Polarimeter (ACTPol). We analyze night-time data collected during 2013-14 using two detector arrays at 149 GHz, from 548 deg$^2$ of sky on the celestial equator. We use these spectra, and the spectra measured with the MBAC camera on ACT from 2008-10, in combination with Planck and WMAP data to estimate cosmological parameters from the temperature, polarization, and temperature-polarization cross-correlations. We find the new ACTPol data to be consistent with the LCDM model. The ACTPol temperature-polarization cross-spectrum now provides stronger constraints on multiple parameters than the ACTPol temperature spectrum, including the baryon density, the acoustic peak angular scale, and the derived Hubble constant. Adding the new data to planck temperature data tightens the limits on damping tail parameters, for example reducing the joint uncertainty on the number of neutrino species and the primordial helium fraction by 20%.

astro-ph.CO↗

arXiv2016

Design of 280 GHz feedhorn-coupled TES arrays for the balloon-borne polarimeter SPIDER

We describe 280 GHz bolometric detector arrays that instrument the balloon-borne polarimeter SPIDER. A primary science goal of SPIDER is to measure the large-scale B-mode polarization of the cosmic microwave background in search of the cosmic-inflation, gravitational-wave signature. 280 GHz channels aid this science goal by constraining the level of B-mode contamination from galactic dust emission. We present the focal plane unit design, which consists of a 16$\times$16 array of conical, corrugated feedhorns coupled to a monolithic detector array fabricated on a 150 mm diameter silicon wafer. Detector arrays are capable of polarimetric sensing via waveguide probe-coupling to a multiplexed array of transition-edge-sensor (TES) bolometers. The SPIDER receiver has three focal plane units at 280 GHz, which in total contains 765 spatial pixels and 1,530 polarization sensitive bolometers. By fabrication and measurement of single feedhorns, we demonstrate 14.7$^{\circ}$ FHWM Gaussian-shaped beams with $<$1% ellipticity in a 30% fractional bandwidth centered at 280 GHz. We present electromagnetic simulations of the detection circuit, which show 94% band-averaged, single-polarization coupling efficiency, 3% reflection and 3% radiative loss. Lastly, we demonstrate a low thermal conductance bolometer, which is well-described by a simple TES model and exhibits an electrical noise equivalent power (NEP) = 2.6 $\times$ 10$^{-17}$ W/$\sqrt{\mathrm{Hz}}$, consistent with the phonon noise prediction.

astro-ph.IM↗

arXiv2016

A giant radio halo in a low-mass SZ-selected galaxy cluster: ACT-CL J0256.5+0006

We present the detection of a giant radio halo (GRH) in the Sunyaev-Zel'dovich (SZ)-selected merging galaxy cluster ACT-CL J0256.5+0006 ($z = 0.363$), observed with the Giant Metrewave Radio Telescope at 325 MHz and 610 MHz. We find this cluster to host a faint ($S_{610} = 5.6 \pm 1.4$ mJy) radio halo with an angular extent of 2.6 arcmin, corresponding to 0.8 Mpc at the cluster redshift, qualifying it as a GRH. J0256 is one of the lowest-mass systems, $M_{\rm 500,SZ} = (5.0 \pm 1.2) \times 10^{14} M_\odot$, found to host a GRH. We measure the GRH at lower significance at 325 MHz ($S_{325} = 10.3 \pm 5.3$ mJy), obtaining a spectral index measurement of $α^{610}_{325} = 1.0^{+0.7}_{-0.9}$. This result is consistent with the mean spectral index of the population of typical radio halos, $α= 1.2 \pm 0.2$. Adopting the latter value, we determine a 1.4 GHz radio power of $P_{1.4\text{GHz}} = (1.0 \pm 0.3) \times 10^{24}$ W Hz$^{-1}$, placing this cluster within the scatter of known scaling relations. Various lines of evidence, including the ICM morphology, suggest that ACT-CL J0256.5+0006 is composed of two subclusters. We determine a merger mass ratio of 7:4, and a line-of-sight velocity difference of $v_\perp = 1880 \pm 280$ km s$^{-1}$. We construct a simple merger model to infer relevant time-scales in the merger. From its location on the $P_{\rm 1.4GHz}{-}L_{\rm X}$ scaling relation, we infer that we observe ACT-CL J0256.5+0006 approximately 500 Myr before first core crossing.

astro-ph.GA↗

arXiv2016

The Atacama Cosmology Telescope: Dynamical masses for 44 SZ-selected galaxy clusters over 755 square degrees

We present galaxy velocity dispersions and dynamical mass estimates for 44 galaxy clusters selected via the Sunyaev-Zel'dovich (SZ) effect by the Atacama Cosmology Telescope. Dynamical masses for 18 clusters are reported here for the first time. Using \Nbody\ simulations, we model the different observing strategies used to measure the velocity dispersions and account for systematic effects resulting from these strategies. We find that the galaxy velocity distributions may be treated as isotropic, and that an aperture correction of up to 7 per cent in the velocity dispersion is required if the spectroscopic galaxy sample is sufficiently concentrated towards the cluster centre. Accounting for the radial profile of the velocity dispersion in simulations enables consistent dynamical mass estimates regardless of the observing strategy. Cluster masses $M_{200}$ are in the range $(1-15)\times10^{14}M_\odot$. Comparing with masses estimated from the SZ distortion assuming a gas pressure profile derived from X-ray observations gives a mean SZ-to-dynamical mass ratio of $1.10\pm0.13$, but there is an additional 0.14 systematic uncertainty due to the unknown velocity bias; the statistical uncertainty is dominated by the scatter in the mass-velocity dispersion scaling relation. This ratio is consistent with previous determinations at these mass scales.

astro-ph.CO↗

arXiv2016

Evidence for the Thermal Sunyaev-Zel'dovich Effect Associated with Quasar Feedback

Using a radio-quiet subsample of the Sloan Digital Sky Survey spectroscopic quasar catalogue, spanning redshifts 0.5-3.5, we derive the mean millimetre and far-infrared quasar spectral energy distributions (SEDs) via a stacking analysis of Atacama Cosmology Telescope and Herschel-Spectral and Photometric Imaging REceiver data. We constrain the form of the far-infrared emission and find 3$σ$-4$σ$ evidence for the thermal Sunyaev-Zel'dovich (SZ) effect, characteristic of a hot ionized gas component with thermal energy $(6.2 \pm 1.7)\times 10^{60}$ erg. This amount of thermal energy is greater than expected assuming only hot gas in virial equilibrium with the dark matter haloes of $(1-5)\times 10^{12}h^{-1}$M$_\odot$ that these systems are expected to occupy, though the highest quasar mass estimates found in the literature could explain a large fraction of this energy. Our measurements are consistent with quasars depositing up to $(14.5 \pm 3.3)~τ_8^{-1}$ per cent of their radiative energy into their circumgalactic environment if their typical period of quasar activity is $τ_8\times~10^8$ yr. For high quasar host masses, $\sim10^{13}h^{-1}$M$_\odot$, this percentage will be reduced. Furthermore, the uncertainty on this percentage is only statistical and additional systematic uncertainties enter at the 40 per cent level. The SEDs are dust dominated in all bands and we consider various models for dust emission. While sufficiently complex dust models can obviate the SZ effect, the SZ interpretation remains favoured at the 3$σ$-4$σ$ level for most models.

astro-ph.GA↗

arXiv2016

A cryogenic rotation stage with a large clear aperture for the half-wave plates in the Spider instrument

We describe the cryogenic half-wave plate rotation mechanisms built for and used in Spider, a polarization-sensitive balloon-borne telescope array that observed the Cosmic Microwave Background at 95 GHz and 150 GHz during a stratospheric balloon flight from Antarctica in January 2015. The mechanisms operate at liquid helium temperature in flight. A three-point contact design keeps the mechanical bearings relatively small but allows for a large (305 mm) diameter clear aperture. A worm gear driven by a cryogenic stepper motor allows for precise positioning and prevents undesired rotation when the motors are depowered. A custom-built optical encoder system monitors the bearing angle to an absolute accuracy of +/- 0.1 degrees. The system performed well in Spider during its successful 16 day flight.

astro-ph.IM↗