Ue-Li Pen - 21cm Cosmology
-
Upload
cosmoaims-bassett -
Category
Technology
-
view
1.238 -
download
0
description
Transcript of Ue-Li Pen - 21cm Cosmology
![Page 1: Ue-Li Pen - 21cm Cosmology](https://reader034.fdocuments.us/reader034/viewer/2022051611/54ba277b4a79591f4f8b4592/html5/thumbnails/1.jpg)
21cm cosmology Ue-‐Li Pen
K. Masui, E. Switzer, R. Shaw, L. Cailin, G. Paciga, K. Bandura, J. Peterson, T.
Chang, Y. Liao, X. Chen, Y. Li, T. Voytek, A. Natarajan, M. Dobbs, M. Halpern,
J.R. Bond, G. Hinshaw, J. Roy, Y. Gupta, R. Nityananda, and many more
![Page 2: Ue-Li Pen - 21cm Cosmology](https://reader034.fdocuments.us/reader034/viewer/2022051611/54ba277b4a79591f4f8b4592/html5/thumbnails/2.jpg)
Overview
21cm physics Theory: dark energy, gravity waves, neutrinos, enhanced 21cm pre-‐reionizaTon structures.
ObservaTons: first detecTons and upper bounds (GBT, GMRT)
Future: dedicated surveys (CRT, CHIME, etc )
![Page 3: Ue-Li Pen - 21cm Cosmology](https://reader034.fdocuments.us/reader034/viewer/2022051611/54ba277b4a79591f4f8b4592/html5/thumbnails/3.jpg)
21cm: HI hyperfine transiTon
• Hyperfine transiTon when electron and proton spins flip: change in magneTc moment
• h ν =α4 me c2 (me/mp) • ν=1420.40575 MHz • Highly forbidden, lifeTme t~107 years • Astronomical Tme scales T>>t
![Page 4: Ue-Li Pen - 21cm Cosmology](https://reader034.fdocuments.us/reader034/viewer/2022051611/54ba277b4a79591f4f8b4592/html5/thumbnails/4.jpg)
ApplicaTons
Hydrogen Maser Clock Milky way mapping Nearby redshif surveys (HIPASS, ALFALFA) Cosmological redshif surveys (GBT, CHIME/CRT/Tianlai)
High redshif universe (GMRT/LOFAR/MWA/PAPER)
![Page 5: Ue-Li Pen - 21cm Cosmology](https://reader034.fdocuments.us/reader034/viewer/2022051611/54ba277b4a79591f4f8b4592/html5/thumbnails/5.jpg)
Kalberla et al 2005, from WMAP LAMBDA
21cm sky at z=0
![Page 6: Ue-Li Pen - 21cm Cosmology](https://reader034.fdocuments.us/reader034/viewer/2022051611/54ba277b4a79591f4f8b4592/html5/thumbnails/6.jpg)
Image courtesy of NRAO/AUI and Chung et al., Columbia University
![Page 7: Ue-Li Pen - 21cm Cosmology](https://reader034.fdocuments.us/reader034/viewer/2022051611/54ba277b4a79591f4f8b4592/html5/thumbnails/7.jpg)
Atomic physics
-‐-‐ energy splihng=0.068K<<TCMB. -‐-‐ Emission/absorpTon depends on spin temperature TS -‐-‐ Typically collisionally/uv excited. -‐-‐ for TS >> TCMB, emissivity independent of TS: measure hydrogen (HI) mass robustly.
![Page 8: Ue-Li Pen - 21cm Cosmology](https://reader034.fdocuments.us/reader034/viewer/2022051611/54ba277b4a79591f4f8b4592/html5/thumbnails/8.jpg)
21cm: emission
δ Tb=τ TS = const
![Page 9: Ue-Li Pen - 21cm Cosmology](https://reader034.fdocuments.us/reader034/viewer/2022051611/54ba277b4a79591f4f8b4592/html5/thumbnails/9.jpg)
Spin evoluTon
Furlanetto Oh & Briggs, 2006
![Page 10: Ue-Li Pen - 21cm Cosmology](https://reader034.fdocuments.us/reader034/viewer/2022051611/54ba277b4a79591f4f8b4592/html5/thumbnails/10.jpg)
21cm: observaTons
• Hydrogen is the most abundant element in the universe
• 21cm line opTcally thin from the ground over most lines of sight to very high z (~100)
![Page 11: Ue-Li Pen - 21cm Cosmology](https://reader034.fdocuments.us/reader034/viewer/2022051611/54ba277b4a79591f4f8b4592/html5/thumbnails/11.jpg)
21cm: observaTonal challenges • Inverse square law: required collecTng area proporTonal to distance2.
• Highest redshif direct galaxy detecTons at z~0.2 using 2000 hours of WSRT (5000m2)
• For cosmological interests (1<z<100) and wide sky maps needs km2 array: SKA
![Page 12: Ue-Li Pen - 21cm Cosmology](https://reader034.fdocuments.us/reader034/viewer/2022051611/54ba277b4a79591f4f8b4592/html5/thumbnails/12.jpg)
Technical challenges
• SensiTvity: bigger telescopes? • Foreground contaminaTon: design/analysis? • Target: Galaxies, Intensity Mapping/BAO, EoR?
![Page 13: Ue-Li Pen - 21cm Cosmology](https://reader034.fdocuments.us/reader034/viewer/2022051611/54ba277b4a79591f4f8b4592/html5/thumbnails/13.jpg)
The 21 cm universe • Cosmological LSS
treasure trove (UP04, Loeb&Zaldarriaga 04, Lewis&Challinor 07, etc)
• Up to 1018 modes: (Jeans/Hubble)3
• Physics: Lensing, gravity waves, primordial NG, BAO, AP
• GW to r ~ 10-‐8
• fNL~ 10-‐4
• Astrophysics: EoR, galaxy evoluTon
• Experiments NOW Tegmark & Zaldarriaga 08
EoR: GMRT/ LOFAR MWA Paper
CHIME/GBT
SDSS
![Page 14: Ue-Li Pen - 21cm Cosmology](https://reader034.fdocuments.us/reader034/viewer/2022051611/54ba277b4a79591f4f8b4592/html5/thumbnails/14.jpg)
Fundamental Physics
• 0<z<2: dark energy, BAO, w-‐w' • z>2: Large angle lensing: modified gravity (Lu & UP 2009, Masui et al 2010)
• z>10: gravitaTonal waves
![Page 15: Ue-Li Pen - 21cm Cosmology](https://reader034.fdocuments.us/reader034/viewer/2022051611/54ba277b4a79591f4f8b4592/html5/thumbnails/15.jpg)
Intensity Mapping • Stars get fainter with distance: hard to see individually at cosmological distance. Galaxies sTll visible.
• Galaxies get fainter with distance: hard to see in HI. Large scale structure sTll visible?
• Large scale structure is LARGE: degree scale. High resoluTon not needed.
• Modest size, monolithic radio telescopes needed. (CPPM 2008, Wyithe&Loeb 2008)
![Page 16: Ue-Li Pen - 21cm Cosmology](https://reader034.fdocuments.us/reader034/viewer/2022051611/54ba277b4a79591f4f8b4592/html5/thumbnails/16.jpg)
From: talk by O. Lahav
![Page 17: Ue-Li Pen - 21cm Cosmology](https://reader034.fdocuments.us/reader034/viewer/2022051611/54ba277b4a79591f4f8b4592/html5/thumbnails/17.jpg)
Foreground: GalacTc Synchrotron
Haslam 408 MHz Much brighter than signal, but no spectral structure
![Page 18: Ue-Li Pen - 21cm Cosmology](https://reader034.fdocuments.us/reader034/viewer/2022051611/54ba277b4a79591f4f8b4592/html5/thumbnails/18.jpg)
Robert C Byrd Telescope: 100m
![Page 19: Ue-Li Pen - 21cm Cosmology](https://reader034.fdocuments.us/reader034/viewer/2022051611/54ba277b4a79591f4f8b4592/html5/thumbnails/19.jpg)
HI content at z=0.8 Cross-‐correlaTng GBT HI & DEEP2 opTcal galaxies at
z ~ 0.7-‐1.1 (Chang et al, Nature 2010) GBT radio continuum
sources + HI
GBT HI
DEEP2 density
![Page 20: Ue-Li Pen - 21cm Cosmology](https://reader034.fdocuments.us/reader034/viewer/2022051611/54ba277b4a79591f4f8b4592/html5/thumbnails/20.jpg)
Chang, Pen, Bandura, Peterson, Nature, 2010
• Measure HI & optical cross-correlation on 9 Mpc (spatial) x 2 Mpc (redshift) comoving scales
• HI brightness temperature on these scales at z=0.8:
•
• Highest-redshift detection of HI in emission at 4-sigma statistical significance.
![Page 21: Ue-Li Pen - 21cm Cosmology](https://reader034.fdocuments.us/reader034/viewer/2022051611/54ba277b4a79591f4f8b4592/html5/thumbnails/21.jpg)
![Page 22: Ue-Li Pen - 21cm Cosmology](https://reader034.fdocuments.us/reader034/viewer/2022051611/54ba277b4a79591f4f8b4592/html5/thumbnails/22.jpg)
GBT 15h auto power
![Page 23: Ue-Li Pen - 21cm Cosmology](https://reader034.fdocuments.us/reader034/viewer/2022051611/54ba277b4a79591f4f8b4592/html5/thumbnails/23.jpg)
IniTal Intensity Mapping
• Detected collecTve large scale structure with 100h of GBT Tme: first demonstraTon of distant IM. No individual galaxies detected, many galaxies per resoluTon element
• Proposal submited for z=1 BAO survey on 4 pixel array at GBT
![Page 24: Ue-Li Pen - 21cm Cosmology](https://reader034.fdocuments.us/reader034/viewer/2022051611/54ba277b4a79591f4f8b4592/html5/thumbnails/24.jpg)
Baryon AcousTc OscillaTons – Dark Energy Probe
• CMB acousTc oscillaTons: imprinted standard ruler, 100 Mpc.
• Present in current mater distribuTon
• KinemaTc metric of universe
WMAP5 and other, Nolta et al (2008)
![Page 25: Ue-Li Pen - 21cm Cosmology](https://reader034.fdocuments.us/reader034/viewer/2022051611/54ba277b4a79591f4f8b4592/html5/thumbnails/25.jpg)
Present LSS BAO DetecTons
• Percival et al 2007
Percival et al 2007
Eisenstein et al 2005
![Page 26: Ue-Li Pen - 21cm Cosmology](https://reader034.fdocuments.us/reader034/viewer/2022051611/54ba277b4a79591f4f8b4592/html5/thumbnails/26.jpg)
Blake et al 2011: WiggleZ, z~0.6 Masui et al: GBT-BAO proposal 2012, z~1
![Page 27: Ue-Li Pen - 21cm Cosmology](https://reader034.fdocuments.us/reader034/viewer/2022051611/54ba277b4a79591f4f8b4592/html5/thumbnails/27.jpg)
Dedicated Survey Experiment
• Low frequency technology cheap, modest size: (100 m)2 to z<2
• Large field of view: receiver arrays • High surface brightness sensiTvity: compact arrays
• Stable, reliable: no moving parts • Technologies: aperture arrays (Wyithe, Loeb, Geil 2008), cylinders (Peterson et al)
![Page 28: Ue-Li Pen - 21cm Cosmology](https://reader034.fdocuments.us/reader034/viewer/2022051611/54ba277b4a79591f4f8b4592/html5/thumbnails/28.jpg)
Molonglo
Molonglo
AUSTRALIA Brisbane
Darwin
Perth Canberra
Hobart
Adelaide Melbourne
Sydney
+ Northern
Cross
Cambridge
Pushchino
Ooty
![Page 29: Ue-Li Pen - 21cm Cosmology](https://reader034.fdocuments.us/reader034/viewer/2022051611/54ba277b4a79591f4f8b4592/html5/thumbnails/29.jpg)
CMU cylinder in operaTon: J. Peterson, U. Pen, U. Seljak, K. Bandura, K. Sigurdson
![Page 30: Ue-Li Pen - 21cm Cosmology](https://reader034.fdocuments.us/reader034/viewer/2022051611/54ba277b4a79591f4f8b4592/html5/thumbnails/30.jpg)
CHIME, Tianlai, CRT, etc
Fast Fourier Transform Telescope
![Page 31: Ue-Li Pen - 21cm Cosmology](https://reader034.fdocuments.us/reader034/viewer/2022051611/54ba277b4a79591f4f8b4592/html5/thumbnails/31.jpg)
New Cylinder Radio Telescopes
Canada, US, China, France, Morocco Map the Hubble volume to 0.8<z<2.5 Most sensiTve BAO, RSD, lensing survey Ancillary science: 21cm absorbers, radio transients, pulsar search/monitoring, magneTc fields
Scalable to z~20: tens of square kilometers
![Page 32: Ue-Li Pen - 21cm Cosmology](https://reader034.fdocuments.us/reader034/viewer/2022051611/54ba277b4a79591f4f8b4592/html5/thumbnails/32.jpg)
Gravity Waves
• Masui & Pen 2010 (PRL 105, 161302) • Analogous to lensing: shearing of cosmic structure. • Fossil memory effect: h~10-‐6 (inflaTon) • Measure r,nT at z~15 • Requires 1/h2 modes • Separates from lensing: transverse traceless • Structures available to k~10-‐3-‐103:horizon to Jeans scale, ~1018 modes, peaks at z~15
![Page 33: Ue-Li Pen - 21cm Cosmology](https://reader034.fdocuments.us/reader034/viewer/2022051611/54ba277b4a79591f4f8b4592/html5/thumbnails/33.jpg)
Linear gravity wave memory • GW in iniTal condiTon, then redshifs away
![Page 34: Ue-Li Pen - 21cm Cosmology](https://reader034.fdocuments.us/reader034/viewer/2022051611/54ba277b4a79591f4f8b4592/html5/thumbnails/34.jpg)
Detectability
![Page 35: Ue-Li Pen - 21cm Cosmology](https://reader034.fdocuments.us/reader034/viewer/2022051611/54ba277b4a79591f4f8b4592/html5/thumbnails/35.jpg)
Conclusions • 21cm cosmology: probes of dark energy (BAO), modified gravity (lensing), InflaTon (tensor modes), etc. Beyond intrinsic power spectrum. PotenTal measure of gravity waves.
• Intensity Mapping: 21cm unresolved galaxies, accessible in redshif desert z=1-‐3, iniTal HI detecTon and surveys with GBT at z~1. Upper bounds at z=9.
• Prototypes and observaTons under way. Cylinder telescopes a promising technology for fast, large, economic surveys. OpTmal calibraTon and dynamic range.