skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Spherical collapse and virialization in f ( T ) gravities

Abstract

Using the classical top-hat profile, we study the non-linear growth of spherically symmetric density perturbation and structure formation in f ( T ) gravities. In particular, three concrete models, which have been tested against the observation of large-scale evolution and linear perturbation of the universe in the cosmological scenario, are investigated in this framework, covering both minimal and nonminimal coupling cases of f ( T ) gravities. Moreover, we consider the virialization of the overdense region in the models after they detach from the background expanding universe and turn around to collapse. We find that there are constraints in the magnitude and occurring epoch of the initial perturbation. The existence of these constraints indicates that a perturbation that is too weak or occurs too late will not be able to stop the expanding of the overdense region. The illustration of the evolution of the perturbation shows that in f ( T ) gravities, the initial perturbation within the constraints can eventually lead to clustering and form structure. The evolution also shows that nonminimal coupling models collapse slower than the minimal coupling one.

Authors:
; ;  [1]
  1. Shanghai United Center for Astrophysics (SUCA), Shanghai Normal University, 100 Guilin Road, Shanghai 200234 (China)
Publication Date:
OSTI Identifier:
22679964
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Cosmology and Astroparticle Physics; Journal Volume: 2017; Journal Issue: 03; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; COUPLING; COVERINGS; DENSITY; DISTURBANCES; GRAVITATION; NONLINEAR PROBLEMS; PERTURBATION THEORY; QUANTUM GRAVITY; SIMULATION; SPHERICAL CONFIGURATION; SYMMETRY; UNIVERSE

Citation Formats

Lin, Rui-Hui, Zhai, Xiang-Hua, and Li, Xin-Zhou, E-mail: 1000379711@smail.shnu.edu.cn, E-mail: zhaixh@shnu.edu.cn, E-mail: kychz@shnu.edu.cn. Spherical collapse and virialization in f ( T ) gravities. United States: N. p., 2017. Web. doi:10.1088/1475-7516/2017/03/040.
Lin, Rui-Hui, Zhai, Xiang-Hua, & Li, Xin-Zhou, E-mail: 1000379711@smail.shnu.edu.cn, E-mail: zhaixh@shnu.edu.cn, E-mail: kychz@shnu.edu.cn. Spherical collapse and virialization in f ( T ) gravities. United States. doi:10.1088/1475-7516/2017/03/040.
Lin, Rui-Hui, Zhai, Xiang-Hua, and Li, Xin-Zhou, E-mail: 1000379711@smail.shnu.edu.cn, E-mail: zhaixh@shnu.edu.cn, E-mail: kychz@shnu.edu.cn. Wed . "Spherical collapse and virialization in f ( T ) gravities". United States. doi:10.1088/1475-7516/2017/03/040.
@article{osti_22679964,
title = {Spherical collapse and virialization in f ( T ) gravities},
author = {Lin, Rui-Hui and Zhai, Xiang-Hua and Li, Xin-Zhou, E-mail: 1000379711@smail.shnu.edu.cn, E-mail: zhaixh@shnu.edu.cn, E-mail: kychz@shnu.edu.cn},
abstractNote = {Using the classical top-hat profile, we study the non-linear growth of spherically symmetric density perturbation and structure formation in f ( T ) gravities. In particular, three concrete models, which have been tested against the observation of large-scale evolution and linear perturbation of the universe in the cosmological scenario, are investigated in this framework, covering both minimal and nonminimal coupling cases of f ( T ) gravities. Moreover, we consider the virialization of the overdense region in the models after they detach from the background expanding universe and turn around to collapse. We find that there are constraints in the magnitude and occurring epoch of the initial perturbation. The existence of these constraints indicates that a perturbation that is too weak or occurs too late will not be able to stop the expanding of the overdense region. The illustration of the evolution of the perturbation shows that in f ( T ) gravities, the initial perturbation within the constraints can eventually lead to clustering and form structure. The evolution also shows that nonminimal coupling models collapse slower than the minimal coupling one.},
doi = {10.1088/1475-7516/2017/03/040},
journal = {Journal of Cosmology and Astroparticle Physics},
number = 03,
volume = 2017,
place = {United States},
year = {Wed Mar 01 00:00:00 EST 2017},
month = {Wed Mar 01 00:00:00 EST 2017}
}
  • We calculate the non-linear virialization density, Δ{sub c}, of halos under spherical collapse from peaks with an arbitrary initial and final density profile. This is in contrast to the standard calculation of Δ{sub c} which assumes top-hat profiles. Given our formalism, the non-linear halo density can be calculated once the shape of the initial peak's density profile and the shape of the virialized halo's profile are provided. We solve for Δ{sub c} for halos in an Einstein de-Sitter and a ΛCDM universe. As examples, we consider power-law initial profiles as well as spherically averaged peak profiles calculated from the statisticsmore » of a Gaussian random field. We find that, depending on the profiles used, Δ{sub c} is smaller by a factor of a few to as much as a factor of 10 as compared to the density given by the standard calculation ( ≈ 200). Using our results, we show that, for halo finding algorithms that identify halos through an over-density threshold, the halo mass function measured from cosmological simulations can be enhanced at all halo masses by a factor of a few. This difference could be important when using numerical simulations to assess the validity of analytic models of the halo mass function.« less
  • The Gamow-Teller strength distribution in f-p shell nuclei is important in determining {ital e}{sup {minus}}-capture and {beta}-decay rates on neutron rich nuclei in presupernova and collapsing cores of massive stars. We use the recently available data for p-n and n-p reactions on some of these nuclei to generate a generalized relation for the centroid (in energy) of the G-T distribution in terms of nuclear mass number and neutron excess. We then calculate the energy spectrum of the electron-capture neutrinos which stream freely out of the collapsing star {ital without} {ital further} {ital interactions} (i.e., the pre-trapping neutrinos). The number andmore » spectra of such neutrinos detectable through the charged current reaction on Deuterium in the Sudbury Neutrino Observatory has been computed to be {congruent}50 for a supernova explosion at 500 pc. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.« less