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The Hubble constant is determined through obtaining the angular diameter distance to the last scattering surface. That's not a direct observable; instead it's inferred through trigonometry. We can directly measure the angular scale of the Baryon Acoustic oscillations in the CMB – it's the distance between troughs in the power spectrum. In the standard \(\Lambda\)CDM cosmological model, we also know the physical scale of the BAO feature, known as the sound horizon length.
SnowMass 2021 Cosmology
ConnectedPapers.com
ACT Publications: https://act.princeton.edu/publications
Dillon Brout KITP talk July 2019, H0 Tension from the Viewpoint of the Dark Energy Survey (DES)
CosmoComments | Hypothes.is cosmology comments | CosmoDiscussion on slack.com | CosmoCoffee board |
PyCosmo Hub | PyCosmo ETHzurich site | [2005.00543] Predicting Cosmological Observables with PyCosmo |
ncatlab Cosmology topics
Cosmology at Home
Astrophysics and Cosmology lecture notes | figures to accompany lecture notes |
ReadTheDocs: astronomy | astrophysics | cosmology | supernovae |
Sean Carroll's Spacetime and Geometry, an Introduction to General Relativity, html version freely available online until May 31, 2020
CalTech Ay 21 Galaxies and Cosmology, Winter 2018; class videos, slides, resources are online
Astrometry.net web service (David Hogg): http://nova.astrometry.net | http://astrometry.net/ | github | google groups |
Chapter 1: [1909.13740] The Fundamentals of the 21-cm Line
Chapter 2: [1909.12595] Astrophysics from the 21-cm background
Chapter 3: [1909.12430] Physical Cosmology From the 21-cm Line
Chapter 4: [1909.13860] Inference from the 21cm signal
Chapter 5: [1909.11938] 21 cm observations: calibration, strategies, observables
Chapter 6: [1909.12369] Foregrounds and their mitigation
Chapter 7: [1909.12491] The status of 21cm interferometric experiments
Chapter 8: ?
Chapter 9: [1909.12797] Future prospects
To appear as a book chapter in The Cosmic 21-cm Revolution: Charting the first billion years of our Universe, Ed Andrei Mesinger (Bristol: IOP Publishing Ltd) AAS-IOP ebooks; expected publication Feb. 2020
Andrei Mesinger's home page | reddit post |
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See this wp cmb primary anisotropy section for interpretations of the power spectrum peaks, and adiabatic density perturbations vs isocurvature density perturbations. The CMB can distinguish between the two: “adiabatic density perturbations produce peaks whose locations are in the ratio 1:2:3:...[56] Observations are consistent with the primordial density perturbations being entirely adiabatic, providing key support for inflation, and ruling out many models of structure formation involving, for example, cosmic strings.”
adiabatic vs isocurvature perturbations | primordial isocurvature perturbations |
The Hubble tension might be pointing towards new physics, a possibility which has been the subject of significant study in the literature: see e.g. [88–137] for a selection of works examining this possibility. However, as pointed out in a number of recent works (e.g. [138–140]), it is important to check that proposed solutions are consistent with BAO distance measurements Soundness of Dark Energy Properties, pg 8.
Some of the numerous examples proposing to alleviate Hubble constant tension
[1908.03663] The Hubble Hunter's Guide, reviews “a variety of types of departures from ΛCDM that could, in principle, restore concordance among these datasets, and we explain why we find almost all of them unlikely to be successful.”
[2004.09487] Relieving the Hubble tension with primordial magnetic fields
[2003.03602] Reconciling Hubble Constant Discrepancy from Holographic Dark Energy
[2002.10831] Solving the curvature and Hubble parameter inconsistencies through structure formation-induced curvature
[2002.06782] Reducing the \(H_{0}\) tension with generalized Proca theory
[2002.06127] Tensions in the dark: shedding light on Dark Matter-Dark Energy Interactions
[2002.05602] Phenomenological model explaining Hubble Tension origin
[2001.07536] Resolving the \(H_0\) tension with diffusion
[1912.00242] \(H_0\) tension and the String Swampland
[1912.00190] Can Non-standard Recombination Resolve the Hubble Tension?
[1911.11760] Early dark energy from massive neutrinos — a natural resolution of the Hubble tension, by Sakstein and Trodden
[1911.06281] Thermal Friction as a Solution to the Hubble Tension; Early Dark Energy, EDE
[1910.00459] Quintessence Axion Dark Energy and a Solution to the Hubble Tension
[1908.06995] Oscillating scalar fields and the Hubble tension: a resolution with novel signatures; by Tristan Smith, Poulin, Amin; early dark energy, EDE
[1908.04281] Interacting dark energy after the latest Planck, DES, and \(H_0\) measurements: an excellent solution to the \(H_0\) and cosmic shear tensions
[1908.03324] Resolving Hubble Tension with Quintom Dark Energy Model
[1908.02401] The Hubble-Lemaître constant and sound horizon from low-redshift probes
[1907.12639] Can redshift errors bias measurements of the Hubble Constant?
[1905.10198] Implications of a transition in the dark energy equation of state for the \(H_0\) and σ8 tensions
[1907.07569] New physics in light of the \(H_0\) tension: an alternative view, by Sunny Vagnozzi | response1 | response2 |
[1907.05608] Evaporating primordial black holes as varying dark energy; alleviates \(H_0\) tension
[1906.11628] Baryon Acoustic Oscillations and the Hubble Constant: Past, Present and Future
[1905.02278] Super-CMB fluctuations can resolve the Hubble tension
[1904.09689] A possible solution to the Hubble constant discrepancy — Cosmology where the local volume expansion is driven by the domain average density
[1904.01016] Rock 'n' Roll Solutions to the Hubble Tension
[1903.07603] Large Magellanic Cloud Cepheid Standards Provide a 1% Foundation for the Determination of the Hubble Constant and Stronger Evidence for Physics Beyond LambdaCDM
[1903.06220] Late universe decaying dark matter can relieve the \(H_0\) tension; Avi Loeb et al
[1902.07081] The local and distant Universe: stellar ages and H0
[1811.04083] Early Dark Energy Can Resolve The Hubble Tension
[1809.02340] Can the \(H_0\) tension be resolved in extensions to ΛCDM cosmology?
[1802.03404] Prospects for resolving the Hubble constant tension with standard sirens
[1712.02967] Emerging spatial curvature can resolve the tension between high-redshift CMB and low-redshift distance ladder measurements of the Hubble constant
[1410.0960] Stable FLRW solutions in Generalized Massive Gravity | [1401.4173] Massive Gravity | wp article | Massive Gravity article |
[1907.11594]The BAO+BBN Take on the Hubble Tension
Voyage through the hidden physics of the cosmic web
UBVRI filters
Will the CMB ever recede outside our visibility: SE1 | SE2 | R1 | H1 |
Doug Scott's answer to CMB questions | Ned Wright | S1 | [0704.0221] The Return of a Static Universe and the End of Cosmology |
[0907.2887] Cosmic Neutrino Last Scattering Surface, Dodelson
[1904.10544] Developments in Cosmic Growth and Gravitation
Wayne Hu PhD thesis
Observing the Big Bang, Luca Amendola, May 2019, a nice 100+ pages on cosmology
Lots of pages available for Longair's Galaxy Formation
[1501.03822] Real time cosmology – A direct measure of the expansion rate of the Universe with SKA
Emission spectra of the elements:
Atomic Emission Spectra of the Periodic Table of Elements
Atomic Absorption and Emission Spectra | The Atomic Spectrum of Hydrogen |
Planck 2013 results. XVI. Cosmological parameters
Quantum Fluctuations in Cosmology and How They Lead to a Multiverse, by Alan Guth
Cosmological parameter inference with Bayesian statistics [1903.11127] The main aim of this work is to provide an introduction of Bayesian parameter inference and its applications to cosmology. We assume the reader is familiarized with the basic concepts of statistics, but not necessarily with Bayesian statistics. Then, we provide a general introduction to this subject, enough to work out some examples
Constraining the physics of the early universe [1903.11472] PhD thesis
The Degree of Fine-Tuning in our Universe — and Others [1902.03928], Fred C. Adams
Speaker Deck
HashTags: #cosmology
Verde et al., WMAP: Parameter Estimation Methodology | astro-ph/0302218 |
Physics of the CMB great slides | [1504.06335] Physics of the Cosmic Microwave Background Radiation great review paper |
GitHub project: Tools for plotting CMB polarization power spectra
Spherical CMB map or 2D CMB map
Wayne Hu: graphic taking apart features in the power spectrum, slide 9 | CMB fluid approximation, slide 9+ |.
https://en.wikipedia.org/wiki/Cosmic_microwave_background (the refs, esp to Wayne Hu's work, are good)
Will the CMB ever recede outside our visibility: SE1 | SE2 | R1 | H1 |
Doug Scott's answer to CMB questions | Ned Wright | S1 |
https://www.ast.cam.ac.uk/~pettini/Intro%20Cosmology/Lecture09.pdf
Recombination was not an instantaneous process but proceeded relatively quickly nevertheless, with the fractional ionisation decreasing from X = 0.9 to X = 0.1 over a time interval ∆t ∼ 70,000 yr. With the number density of free electrons dropping rapidly, the time when photons and baryons decoupled follows soon, once the rate for Thomson scattering falls below the expansion rate H. Section 9.3, Photon Decoupling, pg 6 (These excellent notes cover the following epochs: Radiation-Matter Equality, Recombination, Photon Decoupling, Last Scattering.)
Physics of the cosmic microwave background anisotropy [1501.04288], by Martin Bucher | Anisotropy of the Cosmic Background Radiation and Cosmological Parameters, Bartelmann | Determining Cosmological Parameters from Anisotropies in the CMB |
Wayne Hu's writings: CMB, power spectrum, BAO, etc | Great graphic | BAO section | Lecture notes from introductory cosmology course: e.g., cosmic geometry |