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"Cosmic background radiation."
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Lepton Asymmetries in Cosmology
The cosmological lepton asymmetry, i.e., an excess of leptons over antileptons, is still only loosely constrained, and might be much larger than its tiny baryonic counterpart. If this is the case, charge neutrality requires the lepton asymmetries to be confined in the neutrino sector. We recall the observational effects of neutrino asymmetries on the abundance of light elements produced during Big Bang Nucleosynthesis and on the pattern of cosmic microwave background anisotropies. We point to the necessity of solving the neutrino transport equations, taking into account the effect of flavour oscillation, to derive general and robust constraints on lepton asymmetries. We review the current bounds and briefly discuss prospects for next-generation CMB experiments.
Journal Article
Optical Follow-up of Planck Cluster Candidates with Small Instruments
We report on the search for optical counterparts of Planck Sunyaev-Zel'dovich (SZ) cluster candidates using a 0.6 m non-professional telescope. Among the observed sources, an unconfirmed candidate, PSZ2 G156.24+22.32, is found to be associated with a region of more than 100 galaxies within a 3 arcminute radius around the Sunyaev-Zel'dovich maximum signal coordinates. Using 14 hours of cumulated exposure over the Sloan color filters g′, r′, i′, and z′, we estimate the photometric redshift of these galaxies at zphot = 0.29 0.08. Using the red-sequence galaxy method gives a photometric redshift of 0.30 − 0.05 + 0.03 . Combined with the Planck SZ proxy mass function, this would favor a cluster of 4.4 × 1014 solar masses. This result suggests that a dedicated pool of observatories equipped with such instruments could collectively contribute to optical follow-up programs of massive cluster candidates at moderate redshifts.
Journal Article
The Galactic Interstellar Medium Has a Preferred Handedness of Magnetic Misalignment
The Planck mission detected a positive correlation between the intensity (T) and B-mode polarization of the Galactic thermal dust emission. The TB correlation is a parity-odd signal, whose statistical mean vanishes in models with mirror symmetry. Recent work has shown, with strong evidence, that local handedness of the misalignment between the dust filaments and the sky-projected magnetic field produces TB signals. However, it remains unclear whether the observed global TB signal is caused by statistical fluctuations of magnetic misalignment angles or whether some parity-violating physics in the interstellar medium sets a preferred misalignment handedness. The present work aims to make a quantitative statement about how confidently the statistical fluctuation interpretation is ruled out by filament-based simulations of polarized dust emission. We use the publicly available DUSTFILAMENTS code to simulate the dust emission from filaments whose magnetic misalignment angles are symmetrically randomized and construct the probability density function of ξp, a weighted sum of the TB power spectrum. We find that the Planck data have a ≳10σ tension with the simulated ξp distribution. Our results strongly support the idea that the Galactic filament misalignment has a preferred handedness, whose physical origin is yet to be identified.
Journal Article
Baryogenesis in Formula omitted gravity
The article communicates exploration of gravitational baryogenesis in presence of [Formula omitted] gravity where Q denote the nonmetricity and [Formula omitted] the trace of the energy momentum tensor. We study various baryogenesis interactions proportional to [Formula omitted] and [Formula omitted] for the [Formula omitted] gravity model [Formula omitted], where [Formula omitted], [Formula omitted] and n are model parameters. Additionally we report the viable parameter spaces for which an observationally consistent baryon-to-entropy can be generated. Our results indicate that [Formula omitted] gravity can contribute significantly and consistently to the phenomenon of gravitational baryognesis.
Journal Article
Probing chiral and flavored Formula omitted from cosmic bursts through neutrino interactions
The origin of tiny neutrino mass is an unsolved puzzle leading to a variety of phenomenological aspects beyond the Standard Model (BSM). We consider U(1) gauge extension of the Standard Model (SM) where so-called seesaw mechanism is incarnated with the help of thee generations of Majorana type right-handed neutrinos followed by the breaking of U(1) and electroweak gauge symmetries providing anomaly free structure. In this framework, a neutral BSM gauge boson [Formula omitted] is evolved. To explore the properties of its interactions we consider chiral (flavored) frameworks where [Formula omitted] interactions depend on the handedness (generations) of the fermions. In this paper we focus on [Formula omitted]-neutrino interactions which could be probed from cosmic explosions. We consider [Formula omitted] process which can energize gamma-ray burst (GRB221009A, so far the highest energy) through energy deposition. Hence estimating these rates we constrain U(1) gauge coupling [Formula omitted] and [Formula omitted] mass [Formula omitted] under Schwarzchild (Sc) and Hartle-Thorne (HT) scenarios. We also study [Formula omitted]-DM scattering through [Formula omitted] to constrain [Formula omitted] plane using IceCube data considering high energy neutrinos from cosmic blazar (TXS0506+056), active galaxy (NGC1068), the Cosmic Microwave Background (CMB) and the Lyman- [Formula omitted] data, respectively. Finally highlighting complementarity we compare our results with current and prospective bounds on [Formula omitted] plane from scattering, beam-dump and [Formula omitted] experiments. [PICS code].
Journal Article
An absorption profile centred at 78 megahertz in the sky-averaged spectrum
The 21-cm absorption profile is detected in the sky-averaged radio spectrum, but is much stronger than predicted, suggesting that the primordial gas might have been cooler than predicted.
An absorption profile in the sky
As the first stars heated hydrogen in the early Universe, the 21-cm hyperfine line—an astronomical standard that represents the spin-flip transition in the ground state of atomic hydrogen—was altered, causing the hydrogen gas to absorb photons from the microwave background. This should produce an observable absorption signal at frequencies of less than 200 megahertz (MHz). Judd Bowman and colleagues report the observation of an absorption profile centred at a frequency of 78 MHz that is about 19 MHz wide and 0.5 kelvin deep. The profile is generally in line with expectations, although it is deeper than predicted. An accompanying paper by Rennan Barkana suggests that baryons were interacting with cold dark-matter particles in the early Universe, cooling the gas more than had been expected.
After stars formed in the early Universe, their ultraviolet light is expected, eventually, to have penetrated the primordial hydrogen gas and altered the excitation state of its 21-centimetre hyperfine line. This alteration would cause the gas to absorb photons from the cosmic microwave background, producing a spectral distortion that should be observable today at radio frequencies of less than 200 megahertz
1
. Here we report the detection of a flattened absorption profile in the sky-averaged radio spectrum, which is centred at a frequency of 78 megahertz and has a best-fitting full-width at half-maximum of 19 megahertz and an amplitude of 0.5 kelvin. The profile is largely consistent with expectations for the 21-centimetre signal induced by early stars; however, the best-fitting amplitude of the profile is more than a factor of two greater than the largest predictions
2
. This discrepancy suggests that either the primordial gas was much colder than expected or the background radiation temperature was hotter than expected. Astrophysical phenomena (such as radiation from stars and stellar remnants) are unlikely to account for this discrepancy; of the proposed extensions to the standard model of cosmology and particle physics, only cooling of the gas as a result of interactions between dark matter and baryons seems to explain the observed amplitude
3
. The low-frequency edge of the observed profile indicates that stars existed and had produced a background of Lyman-α photons by 180 million years after the Big Bang. The high-frequency edge indicates that the gas was heated to above the radiation temperature less than 100 million years later.
Journal Article
Kinetic Axion If/I Gravity Phase Space
In this work, we studied the phase space of f(R) gravity in the presence of a misalignment axion, including parity violating Chern–Simons terms. We construct the autonomous dynamical system by using appropriate dimensionless variables and find the cosmological attractors of the phase space, which are basically the fixed points of the autonomous dynamical system. We focus on the R[sup.2] model and the misalignment axion potential near the minimum. We demonstrate that the Chern–Simons terms have no effect on the phase space. We found four distinct, possibly unstable fixed points with physical significance. Specifically, we found two identical de Sitter fixed points, one radiation domination fixed point, and one dark matter dominated fixed point. Thus, in the presence of a kinetic misalignment axion, the vacuum f(R) gravity contains all of the cosmological fixed points that can characterize all of the known evolution eras of our universe.
Journal Article
Polarization Observations with the Cosmic Background Imager
Polarization observations of the cosmic microwave background with the Cosmic Background Imager from September 2002 to May 2004 provide a significant detection of the f-mode polarization and reveal an angular power spectrum of polarized emission showing peaks and valleys that are shifted in phase by half a cycle relative to those of the total intensity spectrum. This key agreement between the phase of the observed polarization spectrum and that predicted on the basis of the total intensity spectrum provides support for the standard model of cosmology, in which dark matter and dark energy are the dominant constituents, the geometry is close to flat, and primordial density fluctuations are predominantly adiabatic with a matter power spectrum commensurate with inflationary cosmological models.
Journal Article