scholarly journals 21 cm radiation: A new probe of fundamental physics

2009 ◽  
Vol 5 (H15) ◽  
pp. 312-313
Author(s):  
Rishi Khatri ◽  
Benjamin D. Wandelt
Keyword(s):  
Early Universe ◽  
Finite Thickness ◽  
Low Frequency ◽  
Structure Constant ◽  
Neutral Hydrogen ◽  
Fine Structure Constant ◽  
Radio Telescopes ◽  
Fundamental Physics ◽  
Proton Mass ◽  
Dark Ages

AbstractNew low frequency radio telescopes currently being built open up the possibility of observing the 21 cm radiation from redshifts 200 > z > 30, also known as the dark ages, see Furlanetto, Oh, & Briggs(2006) for a review. At these high redshifts, Cosmic Microwave Background (CMB) radiation is absorbed by neutral hydrogen at its 21 cm hyperfine transition. This redshifted 21 cm signal thus carries information about the state of the early Universe and can be used to test fundamental physics. The 21 cm radiation probes a volume of the early Universe on kpc scales in contrast with CMB which probes a surface (of some finite thickness) on Mpc scales. Thus there is many orders of more information available, in principle, from the 21 cm observations of dark ages. We have studied the constraints these observations can put on the variation of fundamental constants (Khatri & Wandelt(2007)). Since the 21 cm signal depends on atomic physics it is very sensitive to the variations in the fine structure constant and can place constraints comparable to or better than the other astrophysical experiments (Δα/α= < 10−5) as shown in Figure 1. Making such observations will require radio telescopes of collecting area 10 - 106 km2 compared to ~ 1 km2 of current telescopes, for example LOFAR. We should also expect similar sensitivity to the electron to proton mass ratio. One of the challenges in observing this 21 cm cosmological signal is the presence of the synchrotron foregrounds which is many orders of magnitude larger than the cosmological signal but the two can be separated because of their different statistical nature (Zaldarriaga, Furlanetto, & Hernquist(2004)). Terrestrial EM interference from radio/TV etc. and Earth&s ionosphere poses problems for telescopes on ground which may be solved by going to the Moon and there are proposals for doing so, one of which is the Dark Ages Lunar Interferometer (DALI). In conclusion 21 cm cosmology promises a large wealth of data and provides the only way to observe the redshift range between recombination and reionization.

scholarly journals Peering into the dark (ages) with low-frequency space interferometers

2021 ◽  
Author(s):  
Léon V. E. Koopmans ◽  
Rennan Barkana ◽  
Mark Bentum ◽  
Gianni Bernardi ◽  
Albert-Jan Boonstra ◽  
...  
Keyword(s):  
Radio Telescope ◽  
High Redshift ◽  
Low Frequency ◽  
Neutral Hydrogen ◽  
Mission Design ◽  
Radio Frequency Interference ◽  
Fundamental Physics ◽  
Frequency Space ◽  
Dark Ages ◽  
Insight Into

AbstractThe Dark Ages and Cosmic Dawn are largely unexplored windows on the infant Universe (z ~ 200–10). Observations of the redshifted 21-cm line of neutral hydrogen can provide valuable new insight into fundamental physics and astrophysics during these eras that no other probe can provide, and drives the design of many future ground-based instruments such as the Square Kilometre Array (SKA) and the Hydrogen Epoch of Reionization Array (HERA). We review progress in the field of high-redshift 21-cm Cosmology, in particular focussing on what questions can be addressed by probing the Dark Ages at z > 30. We conclude that only a space- or lunar-based radio telescope, shielded from the Earth’s radio-frequency interference (RFI) signals and its ionosphere, enable the 21-cm signal from the Dark Ages to be detected. We suggest a generic mission design concept, CoDEX, that will enable this in the coming decades.

scholarly journals Fundamental physics and the fine-structure constant

2017 ◽  
Vol 5 (2) ◽  
pp. 46 ◽  
Author(s):  
Michael Sherbon
Keyword(s):  
Fine Structure ◽  
Structure Constant ◽  
Fine Structure Constant ◽  
Electron Mass ◽  
Fundamental Constants ◽  
Mass Ratio ◽  
Fundamental Physics ◽  
Weak Force ◽  
Strong Force ◽  
Symmetry Principles

From the exponential function of Euler’s equation to the geometry of a fundamental form, a calculation of the fine-structure constant and its relationship to the proton-electron mass ratio is given. Equations are found for the fundamental constants of the four forces of nature: electromagnetism, the weak force, the strong force and the force of gravitation. Symmetry principles are then associated with traditional physical measures.

scholarly journals Early-universe constraints on a time-varying fine structure constant

2001 ◽  
Vol 64 (10) ◽  
Author(s):  
P. P. Avelino ◽  
S. Esposito ◽  
G. Mangano ◽  
C. J. A. P. Martins ◽  
A. Melchiorri ◽  
...  
Keyword(s):  
Fine Structure ◽  
Early Universe ◽  
Structure Constant ◽  
Fine Structure Constant ◽  
Time Varying

scholarly journals Variation of the fundamental constants over the cosmological time: veracity of Dirac’s intriguing hypothesis

2016 ◽  
Vol 94 (1) ◽  
pp. 89-94 ◽  
Author(s):  
Cláudio Nassif ◽  
A.C. Amaro de Faria
Keyword(s):  
Fine Structure ◽  
Early Universe ◽  
Early Period ◽  
Planck Scale ◽  
Structure Constant ◽  
Energy Scale ◽  
Fine Structure Constant ◽  
Cosmological Time ◽  
Age Of The Universe ◽  
The Universe

We investigate how the universal constants, including the fine structure constant, have varied since the early universe close to the Planck energy scale (EP ∼ 1019 GeV) and, thus, how they have evolved over the cosmological time related to the temperature of the expanding universe. According to a previous paper (Nassif and Amaro de Faria, Jr. Phys. Rev. D, 86, 027703 (2012). doi:10.1103/PhysRevD.86.027703), we have shown that the speed of light was much higher close to the Planck scale. In the present work, we will go further, first by showing that both the Planck constant and the electron charge were also too large in the early universe. However, we conclude that the fine structure constant (α ≅ 1/137) has remained invariant with the age and temperature of the universe, which is in agreement with laboratory tests and some observational data. Furthermore, we will obtain the divergence of the electron (or proton) mass and also the gravitational constant (G) at the Planck scale. Thus, we will be able to verify the veracity of Dirac’s belief about the existence of “coincidences” between dimensionless ratios of subatomic and cosmological quantities, leading to a variation of G with time, that is, the ratio of the electrostatic to gravitational forces between an electron and a proton (∼1041) is roughly equal to the age of the universe divided by an elementary time constant, so that the strength of gravity, as determined by G, must vary inversely with time in the approximation of lower temperature or for times very far from the early period, to compensate for the time-variation of the Hubble parameter (H ∼ t−1). In short, we will show the validity of Dirac’s hypothesis only for times very far from the early period or T ≪ TP (∼1032 K).

scholarly journals Implications and Applications of Fermi Scale Quantum Gravity

2019 ◽  
Author(s):  
U.V.S. Seshavatharam ◽  
S. Lakshminarayana
Keyword(s):  
Binding Energy ◽  
Structure Constant ◽  
Physical Constant ◽  
Fine Structure Constant ◽  
Electron Mass ◽  
New Approach ◽  
Quark Masses ◽  
Proton Mass ◽  
Nuclear Stability ◽  
Elementary Charge

To understand the mystery of final unification, in our earlier publications, we proposed two bold concepts: 1) There exist three atomic gravitational constants associated with electroweak, strong and electromagnetic interactions. 2) There exists a strong elementary charge in such a way that its squared ratio with normal elementary charge is close to reciprocal of the strong coupling constant. In this paper we propose that, can be considered as a compound physical constant associated with proton mass, electron mass and the three atomic gravitational constants. With these ideas, an attempt is made to understand nuclear stability and binding energy. In this new approach, nuclear binding energy can be fitted with four simple terms having one unique energy coefficient with a formula, where is an estimated mean stable mass number. With this new approach, Newtonian gravitational constant can be estimated in a verifiable approach with a model relation of the form, where is the Fine structure constant. Estimated and is 62 ppm higher than the CODATA recommended It needs further investigation. Proceeding further, an attempt is made to fit the recommended quark masses.

scholarly journals WMAP 5-year constraints on α and me

2009 ◽  
Vol 5 (H15) ◽  
pp. 307-307 ◽  
Author(s):  
Claudia G. Scóccola ◽  
Susana J. Landau ◽  
Héctor Vucetich
Keyword(s):  
Statistical Analysis ◽  
Power Spectrum ◽  
Fundamental Constant ◽  
Structure Constant ◽  
Neutral Hydrogen ◽  
Fine Structure Constant ◽  
Electron Mass ◽  
Fundamental Constants ◽  
Escape Probability ◽  
Data Set

AbstractWe have studied the role of fundamental constants in an updated recombination scenario. We focus on the time variation of the fine structure constant α, and the electron mass me in the early Universe. In the last years, helium recombination has been studied in great detail revealing the importance of taking new physical processes into account in the calculation of the recombination history. The equations to solve the detailed recombination scenario can be found for example in Wong et al. 2008. In the equation for helium recombination, a term which accounts for the semi-forbidden transition 23p–11s is added. Furthermore, the continuum opacity of HI is taken into account by a modification in the escape probability of the photons that excite helium atoms, with the fitting formulae proposed Kholupenko et al 2007. We have analized the dependences of the quantities involved in the detailed recombination scenario on α and me. We have performed a statistical analysis with COSMOMC to constrain the variation of α and me at the time of neutral hydrogen formation. The observational set used for the analysis was data from the WMAP 5-year temperature and temperature-polarization power spectrum and other CMB experiments such as CBI, ACBAR and BOOMERANG and the power spectrum of the 2dFGRS. Considering the joint variation of α and me we obtain the following bounds: -0.011 < $\frac{&#x0394; &#x03B1;}{&#x03B1;_0}$ < 0.019 and -0.068 < $\frac{&#x0394; m_e}{(m_e)_0$ < 0.030 (68% c.l.). When considering only the variation of one fundamental constant we obtain: -0.010 < $\frac{&#x0394; &#x03B1;}{&#x03B1;_0$ < 0.008 and -0.04 < $\frac{&#x0394; m_e}{(m_e)_0}$ < 0.02 (68% c.l.). We compare these results with the ones presented in Landau et al 2008, which were obtained in the standard recombination scenario and using WMAP 3 year release data. The constraints are tighter in the current analysis, which is an expectable fact since we are working with more accurate data from WMAP. The bounds obtained are consistent with null variation, for both α and me, but in the present analysis, the 68% confidence limits on the variation of both constants have changed. In the case of α, the present limit is more consistent with null variation than the previous one, while in the case of me the single parameters limits have moved toward lower values. To study the origin of this difference, we have performed another statistical analysis, namely the analysis of the standard recombination scenario together with WMAP5 data, the other CMB data sets and the 2dFGRS power spectrum. We see that the change in the obtained results is due to the new WMAP data set, and not to the new recombination scenario. The obtained results for the cosmological parameters are in agreement within 1 σ with the ones obtained by the WMAP collaboration, without considering variation of fundamental constants.

scholarly journals Cosmic magnetic field observations with next generation instrumentation

2009 ◽  
Vol 5 (H15) ◽  
pp. 430-431
Author(s):  
Rainer Beck
Keyword(s):  
Magnetic Fields ◽  
Milky Way ◽  
Low Frequency ◽  
Radio Telescopes ◽  
Radio Waves ◽  
Huge Number ◽  
Fundamental Physics ◽  
New Era ◽  
Weak Magnetic Fields ◽  
The Universe

AbstractThe origin of magnetic fields in the Universe is an open problem in astrophysics and fundamental physics. Forthcoming radio telescopes will open a new era in studying cosmic magnetic fields. Low-frequency radio waves will reveal the structure of weak magnetic fields in the outer regions and halos of galaxies and in intracluster media. At higher frequencies, the EVLA and the SKA will map the structure of magnetic fields in galaxies in unprecedented detail. All-sky surveys of Faraday rotation measures (RM) towards a huge number of polarized background sources with the SKA and its pathfinders will allow us to model the structure and strength of the regular magnetic fields in the Milky Way, the interstellar medium of galaxies, in galaxy clusters and the intergalactic medium.

scholarly journals Multiverse Predictions for Habitability: Number of Potentially Habitable Planets

Universe ◽  
2019 ◽  
Vol 5 (6) ◽  
pp. 157 ◽  
Author(s):  
McCullen Sandora
Keyword(s):  
Fine Structure ◽  
Mass Distribution ◽  
Lower Bounds ◽  
Structure Constant ◽  
Stellar Mass ◽  
Fine Structure Constant ◽  
Mass Ratio ◽  
Habitable Planets ◽  
Hot Jupiters ◽  
Proton Mass

How good is our universe at making habitable planets? The answer to this depends on which factors are important for life: Does a planet need to be Earth mass? Does it need to be inside the temperate zone? are systems with hot Jupiters habitable? Here, we adopt different stances on the importance of each of these criteria to determine their effects on the probabilities of measuring the observed values of several physical constants. We find that the presence of planets is a generic feature throughout the multiverse, and for the most part conditioning on their particular properties does not alter our conclusions much. We find conflict with multiverse expectations if planetary size is important and it is found to be uncorrelated with stellar mass, or the mass distribution is too steep. The existence of a temperate circumstellar zone places tight lower bounds on the fine structure constant and electron to proton mass ratio.

scholarly journals Spectra of Distant Quasars and Verification of Possible Variation of Fundamental Constants over Cosmological Time-Scales

1994 ◽  
Vol 159 ◽  
pp. 361-362
Author(s):  
D.A. Varshalovich ◽  
A.Y. Potekhin
Keyword(s):  
Fine Structure ◽  
Time Scales ◽  
Spectroscopic Data ◽  
Structure Constant ◽  
Fine Structure Constant ◽  
Fundamental Constants ◽  
Mass Ratio ◽  
Cosmological Time ◽  
Proton Mass ◽  
Variation Rate

Constraints on possible variation rate of the fine-structure constant, , and the electron-proton mass ratio , over cosmological time scales are obtained from analyses of quasar spectroscopic data.

Sign in / Sign up

Export Citation Format

Share Document