Radio Sky Surveys for Cosmology for FutureGeneration Radio

Radio Sky Surveys for Cosmology for Future-Generation Radio Facilities Steven T. Myers National Radio Astronomy Observatory Socorro NM Atacama Large Millimeter/submillimeter Array Expanded Very Large Array Robert C. Byrd Green Bank Telescope Very Long Baseline Array

Launchpoint • With new observational facilities, instruments and surveys coming online this decade and next, we will observe galaxies & environments near and far – galaxies are full of incendiary gas, abrasive dust grains, noxious chemicals, and nuclear waste… • But, we want to use them as a force for good –COSMOLOGY!!! • I will describe opportunities in the radio to sub-mm part of the spectrum Radio Futures, Dec 2015 2

Astro 2010: A Game of Questions Astro 2010 Decadal Survey: • Themes One of the worst Massively – Cosmic Dawn Multiplayer Online (MMO) games – Physics of the Universe ever! Co$ting = World of Spreadsheets! – Discovery, Origins, Cosmic Order, Frontiers of Knowledge • The Questions – How do cosmic structures form and evolve? – Why is the universe accelerating? – What is the fossil record of galaxy assembly and evolution from the first stars to the present? – How do baryons cycle in and out of galaxies and what do they do while they are there? Radio Surveys can play a role in all these key problems Many of these are cosmological in nature Most of these have barely started this decade… Radio Futures, Dec 2015 3

Disclaimer (the fine print) • • • This will not be a review talk, I will leave stuff out I don’t discuss mm/sub-mm nearly enough – sorry! There will be little detail of the physics behind the effects and techniques What I will not talk about … – Cosmic Microwave Background – Sunyaev-Zeldovich Effect – Pulsars as probes of long-wavelength Gravity Waves – Tomography of the Hydrogen Epoch of Reionization e. g. the stuff cosmologists are usually keen on (others will discuss these during workshop) I steal stuff from others, like – SKA Science Book https: //www. skatelescope. org/books/ – NGVLA Science White Papers https: //science. nrao. edu/futures/ngvla/documents-publications – my brain (highly biased with information retrieval issues) … side effects may include: brain fog, Bayesian fever, stringy theory, cosmic variance, mid-scale enervation Radio Futures, Dec 2015 4

I. Radio Sky Surveys from a radio survey of the sky… … to a survey of the Universe Radio Futures, Dec 2015 5

Radio Sky Surveys: What are they? • Imaging the sky (continuum, spectral cube, polarimetry) detecting and measuring properties of objects or emission • Classic Sky Survey – cover an area of sky to some depth and angular resolution finding and measuring objects. Useful for multiple astrophysical studies, large discovery space! • “Intensity Mapping” – a low-resolution deeply confused Direct Imaging Survey unable to distinguish objects but able to detect and measure statistics of aggregate emission, usually in a spectral cube • Targeted Survey – observations of a specific set of targets, usually a statistical sample, probably defined and selected in a different waveband or at a different angular Radio Futures, Dec 2015 6 resolution

Classic Radio Sky Surveys • 56 years since 3 C and 32 years since 3 CRR • 20 years since NVSS and FIRST! • Science based on surveys comprise a steadily increasing fraction of VLA publications • New capabilities Pan-STARRS – OTF mosaics, wide fractional bandwidths for increased continuum sensitivity, instantaneous spectral index determination, polarization • New scientific opportunities – reach cosmic (z>1) depths and source densities (comparable to O/IR) – multi-messenger surveys can approach cosmology with different systematic errors 7

Tiered Survey Constructon: Deep and Wide From a survey of the Sky to a survey of the Universe! • Survey representative volumes of the Universe – Local Universe: ALL-SKY • Includes Galaxy & Zone of Avoidance – Distant Universe: Deep Fields • Reach key sensitivity levels – Example: Deep Fields 1. 5 m. Jy = L* radio continuum at z=2 • Metric: Survey Speed – SS = Area/Time at some defined depth (e. g. 0. 1 m. Jy/beam) – scaling: Radio Futures, Dec 2015 8

1 I. Radio Sky Survey Science Examples Charting the Cosmos Radio Futures, Dec 2015 9

Radio Continuum Surveys • sensitive to AGN (dominant >> 1 m. Jy) and star-forming galaxies (<1 m. Jy) – now reaching depths able to see not just AGN • example surveys: – radio galaxy continuum surveys (& ISW, &Non-Gauss) – dusty star-forming galaxies in mm/sub-mm – polarimetric surveys and cosmic magnetism – radio weak lensing Hubble Deep Field – radio strong lensing – cluster plasma physics ALMA Simulated Wootten & Gallimore Radio Futures, Dec 2015 10

Cosmic Lab: Late Integrated Sachs-Wolfe • Decay of potentials in LCDM cause signature in CMB – Cross correlate CMB with large-scale structure tracers – WMAP and Planck (2013 Paper 19) used NVSS (3 -5 s) – radio N(z) is broad, probe to high redshift Radio Futures, Dec 2015 11

Headline Science: Faraday Tomography • Science: – map our Galactic B – B through the cosmic web – evolution with z • NVSS+: Taylor, Stil, Sundstrom 2009 – 3 x 104 sources, ~1/deg 2 • VLASS (2016 -2024): – conservative estimate – 2 x 105 sources, ~ 6/deg 2 • Future surveys (SKA) – 1000/deg 2 for cosmic web – sky area limited (10 deg 2 10 n. Jy rms) Radio Futures, Dec 2015 12

Radio Gravitational Lensing • Measure gravitational potentials through lensing distortion – strong lensing multiple images and high magnification – weak lensing distortions of shapes of sources • Weak Lensing – Dark Energy evolution – cluster DM halos – need high source density • Strong Lensing – galaxy & group DM halos – microlensing – very model dependent Radio Futures, Dec 2015 13

Radio Weak Lensing • High enough source density of galaxies for weak lensing studies – Probe higher z than optical lensing surveys. – Different systematics than optical (PSF known) – direct measurement of shapes in uv plane – Polarization can help identify intrinsic position angles From Williamson et al. 2007 Core of mass profile produces strong lensing arcs (Einstein radius) Tangential shear (stretch) in outer weakly lensed regions c/o M. Brown Ø Forecasted constrains on cosmic shear power spectrum with a 3 GHz 1. 5 m. Jy 10 deg 2 DEEP survey Ø first deep radio data set that can obtain a statistically significant weak-lensing signal. ~3 sources / arcmin 2 Look for presence of coherent shear signal above (random? ) intrinsic shapes Radio Futures, Dec 2015 14

Radio Weak Lensing • Early steps! This year on Ar. Xiv: 1507. 05977 Cross-correlation cosmic shear with the SDSS High enough source density of galaxies for weak and VLA FIRST surveys lensing studies Demetroullas, Michael L. Brown – Probe higher z than optical lensing. Constantinos surveys. – Different systematics than optical (PSF known) – direct measurement of shapes in uv plane – Polarization can help identify intrinsic position angles From Williamson et al. 2007 Core of mass profile produces strong lensing arcs (Einstein radius) Tangential shear (stretch) in outer weakly lensed regions c/o M. Brown Ø Forecasted constrains on cosmic shear power spectrum with a 3 GHz 1. 5 m. Jy 10 deg 2 DEEP survey Ø first deep radio data set that can obtain a statistically significant weak-lensing signal. ~3 sources / arcmin 2 Look for presence of coherent shear signal above (random? ) intrinsic shapes Radio Futures, Dec 2015 15

Radio Strong Lensing • Find, measure, monitor multiple image (or arc) systems – in cm wavelength for radio continuum emission – in mm/sub-mm for dust continuum (U/LIRGS) • What you can measure – lens model: DM halo shape and profile (cuspy? ) – time delays: can extract H 0 measurement, model dep. • What you need – large samples, go deep • mm/sub-mm is very promising due to LF – accurate imaging and monitoring Futures, Dec 2015 Credit: ALMA (NRAO/ESO/NAOJ)/Y. Tamura (The University of Tokyo)/Mark Radio Swinbank (Durham University). 16

Cluster Lab: Role of B fields in the ICM Deep ignorance on origin and evolution of cosmic B fields – Affects cosmic ray transport – Role in cluster gas heating? – Trace galaxy/cluster interactions The AGN ICM connection – feedback on galaxy formation – affects use of SZE for cosmology? Hercules-A X-ray cavities correspond to radio lobes = feedback? Baum et al. , NASA, ESA, HHT Radio Futures, Dec 2015 17

Cluster Lab: Relics and jets in Abell 2256 • • • Owen et al. 2014 (ar. Xiv: 1408. 5931) High-resolution (Aconfiguration) radio X-ray ICM emission in red Filamentary shock region outside core of cluster. Merger? Plasma Weather – connection to ICM and DM halo “climate” evolution? CAUTION: clusters and plasma physics more complicated than we think and are prepared to model! ar. Xiv: 1408. 5931 Radio surveys can provide important indicators on astrophysics of cosmological test objects Radio Futures, Dec 2015 18 18 10

Radio Line Surveys • Detect and measure galaxies in line emission – bulk atomic and molecular gas: HI, CO, CII – masers as signposts • Lines Redshifts – if independent distance indicator peculiar velocities • can probe cosmic flows & large-scale grav. potentials SDSS 0927+2001 z = 5. 8 – w/2 D astrometry 3 D velocities CO 2 -1 at 31 GHz • Example surveys – HI galaxy surveys – CO, CII galaxy surveys 11 kpc – (mega)maser surveys for H 0 and astrometry Wang, Wagg et al. Radio Futures, Dec 2015 19

Radio Line Probes • 1 - Atomic Hydrogen (weak transition) – HI line (rest 1. 42 GHz, z=1. 5 at 568 MHz) – single line in “clean” part of spectrum (easy “z”) • 2 - Molecular CO (strong transition) – CO ladder (1 -0 rest 115. 27 GHz, z=1. 5 at 46. 11 GHz) – whole J ladder of lines (115, 230, 345, 460…) – congested area of spectrum (need to see multiple transitions) • 3 - CII (158 mm, 1. 9 THz) – very bright, redshifted into sub-mm From Myers et al. NAA Astro 2010 white paper Radio Futures, Dec 2015 20

Radio Line Cosmology Approaches • Large HI spectroscopic surveys – intensity mapping – “Billion Galaxy Survey” – non-Gaussianity from HI bi-spectrum – weak lensing of velocity profile (Morales) – peculiar velocities • Large CO spectroscopic surveys – intensity mapping – CO galaxy surveys • can combine with Continuum surveys – weak lensing (& strong) – other continuum probes (ISW) From Bower et al. ar. Xiv: 1510. 06432 Radio Futures, Dec 2015 21

Radio Dark Energy (BAO) • Overview Maartens etal. (ar. Xiv: 1501. 04076) • Eo. R for Low-band array • HI spectroscopic survey – intensity mapping for SKA-1 – Billion Galaxy Survey for SKA-2 • Continuum survey – weak lensing (& strong) Radio Futures, Dec 2015 22

Final Fantasy MMXXX: SKA-2+ • Billion Galaxy HI spectroscopic survey to z > 1. 5 Astro 2010 white paper: Myers et al. ar. Xiv: 0903. 0615 Radio Futures, Dec 2015 23

Ultimate Radio Cosmology • Combine a large HI galaxy survey with a radio weak lensing survey – different systematics to O/IR equivalents (DETF) • A w-machine – 109 galaxy BAO survey – also weak lensing (continuum) – target 0. 01 in w • Design Driver – target precision requires survey speed of 4 x 109 m 4 K 2 deg 2 – a km 2 area w/ 10 deg 2 FOV – would also like to identify individual galaxies (need arcsecond resolution) – survey database for other science Rawlings et al. SKA Science Book Radio Futures, Dec 2015 24

Other Radio Cosmology Surveys • Astrometric Surveys – long baseline techniques have unsurpassed accuracy • mas accuracy or better goals – continuum: AGN proper motions (Darling et al. 2013) • see the Hubble expansion? ? ? – line: megamaser surveys for H 0 and proper motions • And wait, there’s more – absorption line surveys, fundamental constants – Supermassive Black Holes & cosmology? • there must be a connection (beyond galaxy growth) • can we find first SMBH in and beyond the EOR? Radio Futures, Dec 2015 25

IV. Final Thoughts one step beyond … Radio Futures, Dec 2015 26

Upshot • Extremely high discovery potential for radio cosmology surveys – line and continuum surveys complementary (& w/OIR) – tremendous ancillary multi-use survey science – key Dark Energy and Dark Matter cosmology – crosses m/cm/mm/sub-mm wavebands in different tracers – pushes technology to maximize survey speeds (incl. Dn) • Soapbox: If we want >$1 G facilities in 2020+ or 2030+, we should use our new & existing facilities now (and in the future including modest upgrades or retooling) to their practical limits in demonstrating the potential of these key projects, especially for high-risk. Radio high-reward Futures, Dec 2015 27 approaches

The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. www. nrao. edu • science. nrao. edu Radio Futures, Dec 2015 28