Improved constraints on modified gravity with eccentric gravitational waves

Recent gravitational wave observations have allowed stringent new constraints on modifications to general relativity (GR) in the extreme gravity regime. Although these observations were consistent with compact binaries with no orbital eccentricity, gravitational waves emitted in mildly eccentric binaries may be observed once detectors reach their design sensitivity. In this paper, we study the effect of eccentricity in gravitational wave constraints of modified gravity, focusing on Jordan-Brans-Dicke-Fierz theory as an example. Using the stationary phase approximation and the postcircular approximation (an expansion in small eccentricity), we first construct an analytical expression for frequency-domain gravitational waveforms produced by inspiraling compact binaries with small eccentricity in this theory. We then calculate the overlap between our approximate analytical waveforms and an eccentric numerical model (TaylorT4) to determine the regime of validity (in eccentricity) of the former. With this at hand, we carry out a Fisher analysis to determine the accuracy to which Jordan-Brans-Dicke-Fierz theory could be constrained given future eccentric detections consistent with general relativity. We find that the constraint on the theory initially deteriorates (due to covariances between the eccentricity and the Brans-Dicke coupling parameter), but then it begins to recover, once the eccentricity is larger than approximately 0.03. We also find that third-generation ground-based detectors and space-based detectors could allow for constraints that are up to an order of magnitude more stringent than current Solar System bounds. Our results suggest that waveforms in modified gravity for systems with moderate eccentricity should be developed to maximize the theoretical physics that can be extracted in the future

Improved constraints on modified gravity with eccentric gravitational waves

Recent gravitational wave observations have allowed stringent new constraints on modifications to general relativity (GR) in the extreme gravity regime. Although these observations were consistent with compact binaries with no orbital eccentricity, gravitational waves emitted in mildly eccentric binaries may be observed once detectors reach their design sensitivity. In this paper, we study the effect of eccentricity in gravitational wave constraints of modified gravity, focusing on Jordan-Brans-Dicke-Fierz theory as an example. Using the stationary phase approximation and the postcircular approximation (an expansion in small eccentricity), we first construct an analytical expression for frequency-domain gravitational waveforms produced by inspiraling compact binaries with small eccentricity in this theory. We then calculate the overlap between our approximate analytical waveforms and an eccentric numerical model (TaylorT4) to determine the regime of validity (in eccentricity) of the former. With this at hand, we carry out a Fisher analysis to determine the accuracy to which Jordan-Brans-Dicke-Fierz theory could be constrained given future eccentric detections consistent with general relativity. We find that the constraint on the theory initially deteriorates (due to covariances between the eccentricity and the Brans-Dicke coupling parameter), but then it begins to recover, once the eccentricity is larger than approximately 0.03. We also find that third-generation ground-based detectors and space-based detectors could allow for constraints that are up to an order of magnitude more stringent than current Solar System bounds. Our results suggest that waveforms in modified gravity for systems with moderate eccentricity should be developed to maximize the theoretical physics that can be extracted in the future

ODF1 modifica sus grupos tioles a lo largo del tránsito epididimario es positiva a monobromobimane y la reacción entre ambos afecta la motilidad espermática

Durante el tránsito epididimario se ha evidenciado una oxidación en proteínas ricas en cisteína, se conoce que esa oxidación de grupos tioles da como consecuencia la estabilización de proteínas en el espermatozoide

The Formation of the First Massive Black Holes

Supermassive black holes (SMBHs) are common in local galactic nuclei, and SMBHs as massive as several billion solar masses already exist at redshift z=6. These earliest SMBHs may grow by the combination of radiation-pressure-limited accretion and mergers of stellar-mass seed BHs, left behind by the first generation of metal-free stars, or may be formed by more rapid direct collapse of gas in rare special environments where dense gas can accumulate without first fragmenting into stars. This chapter offers a review of these two competing scenarios, as well as some more exotic alternative ideas. It also briefly discusses how the different models may be distinguished in the future by observations with JWST, (e)LISA and other instruments.Comment: 47 pages with 306 references; this review is a chapter in "The First Galaxies - Theoretical Predictions and Observational Clues", Springer Astrophysics and Space Science Library, Eds. T. Wiklind, V. Bromm & B. Mobasher, in pres

Sperm from Hyh Mice Carrying a Point Mutation in αSNAP Have a Defect in Acrosome Reaction

Hydrocephalus with hop gait (hyh) is a recessive inheritable disease that arose spontaneously in a mouse strain. A missense mutation in the Napa gene that results in the substitution of a methionine for isoleucine at position 105 (M105I) of αSNAP has been detected in these animals. αSNAP is a ubiquitous protein that plays a key role in membrane fusion and exocytosis. In this study, we found that male hyh mice with a mild phenotype produced morphologically normal and motile sperm, but had a strongly reduced fertility. When stimulated with progesterone or A23187 (a calcium ionophore), sperm from these animals had a defective acrosome reaction. It has been reported that the M105I mutation affects the expression but not the function of the protein. Consistent with an hypomorphic phenotype, the testes and epididymides of hyh mice had low amounts of the mutated protein. In contrast, sperm had αSNAP levels indistinguishable from those found in wild type cells, suggesting that the mutated protein is not fully functional for acrosomal exocytosis. Corroborating this possibility, addition of recombinant wild type αSNAP rescued exocytosis in streptolysin O-permeabilized sperm, while the mutant protein was ineffective. Moreover, addition of recombinant αSNAP. M105I inhibited acrosomal exocytosis in permeabilized human and wild type mouse sperm. We conclude that the M105I mutation affects the expression and also the function of αSNAP, and that a fully functional αSNAP is necessary for acrosomal exocytosis, a key event in fertilization