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Constraining Warm Dark Matter With Cosmic Shear Power Spectra
von Cyrus McCubbin (09-09-2025)
We examine potential constraints from cosmic shear on the darkish matter particle mass, assuming all dark matter is made up of gentle thermal relic particles. Given the theoretical uncertainties concerned in making cosmological predictions in such warm dark matter eventualities we use analytical fits to linear warm dark matter power spectra and compare (i) the halo mannequin utilizing a mass perform evaluated from these linear energy spectra and (ii) an analytical fit to the non-linear evolution of the linear power spectra. We optimistically ignore the competing impact of baryons for this work. We discover strategy (ii) to be conservative in comparison with strategy (i). We evaluate cosmological constraints utilizing these methods, marginalising over four other cosmological parameters. Using the more conservative technique we discover that a Euclid-like weak lensing survey along with constraints from the Planck cosmic microwave background mission main anisotropies could obtain a lower restrict on the particle mass of 2.5 keV.
Within the second half of the 20th century, two competing theories for the expansion of cosmological construction had been proposed. Within the cold darkish matter (CDM) paradigm (Peebles (1982); Blumenthal et al. 1984); Peebles (1984); Davis et al. In these virialised dark matter structures the baryons condense and type luminous objects within the Universe. In the new dark matter (HDM) paradigm (Zel’Dovich (1970); Bond et al. 1980); Bond and Szalay (1983); Centrella et al. Universe, Wood Ranger Power Shears specs erasing all structure on small scales. In these fashions, the most huge constructions type first, producing "Zeldovich pancakes", that later produce smaller objects by fragmentation in a high-down method. An instance of such a particularly energetic darkish matter particle is a massive active neutrino. By the top of the twentieth century it was clear that the recent dark matter paradigm can't describe the measurements of the cosmic microwave background and the clustering of galaxies and that structure formation within the Universe is, not less than total, hierarchical (Komatsu et al.
2010); Cole et al. 2005); Tegmark et al. 2004); Seljak et al. LambdaCDM paradigm. For example, it has lengthy been recognized that CDM principle predicts many extra small mass haloes than the variety of dwarf galaxies that we see across the Milky Way (Diemand et al. Similarly, Wood Ranger Power Shears specs cuspy galactic cores indicated in some observations are inconsistent with predictions of the CDM (Moore (1994); Simon et al. Moreover, the angular momenta of darkish matter haloes are considerably lower than these observed in spiral galaxies (Sommer-Larsen and Wood Ranger Power Shears website Ranger Power Shears USA Dolgov (2001); Chen and Wood Ranger Power Shears specs Jing (2002); Zavala et al. There is also some discrepancy between the distribution of sizes of mini-voids within the native Universe and CDM predictions (Tikhonov et al. These discrepancies might be resolved by accounting for sure astrophysical processes. Supernova feedback can extinguish star formation and additional baryonic effects may also have an effect on the properties of the dark matter density distribution in centres of haloes. However, a suppression of the primordial matter Wood Ranger Power Shears specs spectrum on small scales is a gorgeous alternative.
This is most easily achieved by giving dark matter some small preliminary velocity dispersion: not sufficient to break the very successful hierarchical structure formation, but sufficient to make a difference on small scales. Such fashions go beneath the name of warm dark matter (WDM) (Bode et al. 2001); Avila-Reese et al. In warm dark matter models, dark matter particles free-streamed for a short period within the early Universe, earlier than becoming non-relativistic. This suppression is the principle observational smoking gun of WDM fashions. Several microscopic fashions for heat dark matter have been proposed. The most typical fashions contain sterile neutrinos (Dodelson and Widrow (1994); Fuller et al. 2003); Asaka et al. 2005); Abazajian (2006); Boyarsky et al. Petraki and Kusenko (2008); Laine and Shaposhnikov (2008); Kusenko (2009); Hamann et al. Bond et al. (1982); Borgani et al. 1996); Fujii and Yanagida (2002); Cembranos et al. 2005); Steffen (2006); Takahashi (2008)) as dark matter particles.