اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدCan the CIB constrain the dark energy?
290
0
0.0
(
0
)
اسأل ChatGPT حول البحث
ﻻ يوجد ملخص باللغة العربية
Galaxies are often used as tracers of the large scale structure (LSS) to measure the Integrated Sachs-Wolfe effect (ISW) by cross-correlating the galaxy survey maps with the Cosmic Microwave Background (CMB) map. We use the Cosmic Infrared Background (CIB) as a tracer of the LSS to perform a theoretical CIB-CMB cross-correlation to measure the ISW for different Planck HFI frequencies. We discuss the detectability of this ISW signal using a Signal-to-noise ratio analysis and find that the ISW detected this way can provide us with the highest SNR for a single tracer ranging from 5 to 6.7 (maximum being for 857 GHz) with the CIB and CMB maps extracted over the whole sky. A Fisher matrix analysis showed that this measurement of the ISW can improve the constraints on the cosmological parameters; especially the equation of state of the dark energy $w$ by $sim 47%$. Performing a more realistic analysis including the galactic dust residuals in the CIB maps over realistic sky fractions shows that the dust power spectra dominate over the CIB power spectra at $ell < 100$ and ISW cant be detected with high SNR. We perform the cross-correlation on the existing CIB-CMB maps over $sim 11%$ of the sky in the southern hemisphere and find that the ISW is not detected with the existing CIB maps over such small sky fractions.
قيم البحث
اقرأ أيضاً
We propose a new scheme for constraining the dark energy equation of state parameter/parameters based on the study of the evolution of the configuration entropy. We analyze a set of one parameter and two parameter dynamical dark energy models and fin
d that the derivative of the configuration entropy in all the dynamical dark energy models exhibit a minimum. The magnitude of the minimum of the entropy rate is decided by both the parametrization of the equation of state as well as the associated parameters. The location of the minimum of the entropy rate is less sensitive to the form of the parametrization but depends on the associated parameters. We determine the best fit equations for the location and magnitude of the minimum of the entropy rate in terms of the parameter/parameters of the dark energy equation of state. These relations would allow us to constrain the dark energy equation of state parameter/parameters for any given parametrization provided the evolution of the configuration entropy in the Universe is known from observations.
We discuss the ratio of the angular diameter distances from the source to the lens, $D_{ds}$, and to the observer at present, $D_{s}$, for various dark energy models. It is well known that the difference of $D_s$s between the models is apparent and t
his quantity is used for the analysis of Type Ia supernovae. However we investigate the difference between the ratio of the angular diameter distances for a cosmological constant, $(D_{ds}/D_{s})^{Lambda}$ and that for other dark energy models, $(D_{ds}/D_{s})^{rm{other}}$ in this paper. It has been known that there is lens model degeneracy in using strong gravitational lensing. Thus, we investigate the model independent observable quantity, Einstein radius ($theta_E$), which is proportional to both $D_{ds}/D_s$ and velocity dispersion squared, $sigma_v^2$. $D_{ds}/D_s$ values depend on the parameters of each dark energy model individually. However, $(D_{ds}/D_s)^{Lambda} - (D_{ds}/D_{s})^{rm{other}}$ for the various dark energy models, is well within the error of $sigma_v$ for most of the parameter spaces of the dark energy models. Thus, a single strong gravitational lensing by use of the Einstein radius may not be a proper method to investigate the property of dark energy. However, better understanding to the mass profile of clusters in the future or other methods related to arc statistics rather than the distances may be used for constraints on dark energy.
We argue that observations of old neutron stars can impose constraints on dark matter candidates even with very small elastic or inelastic cross section, and self-annihilation cross section. We find that old neutron stars close to the galactic center
or in globular clusters can maintain a surface temperature that could in principle be detected. Due to their compactness, neutron stars can acrete WIMPs efficiently even if the WIMP-to-nucleon cross section obeys the current limits from direct dark matter searches, and therefore they could constrain a wide range of dark matter candidates.
This overview article describes the legacy prospect and discovery potential of the Dark Energy Survey (DES) beyond cosmological studies, illustrating it with examples from the DES early data. DES is using a wide-field camera (DECam) on the 4m Blanco
Telescope in Chile to image 5000 sq deg of the sky in five filters (grizY). By its completion the survey is expected to have generated a catalogue of 300 million galaxies with photometric redshifts and 100 million stars. In addition, a time-domain survey search over 27 sq deg is expected to yield a sample of thousands of Type Ia supernovae and other transients. The main goals of DES are to characterise dark energy and dark matter, and to test alternative models of gravity; these goals will be pursued by studying large scale structure, cluster counts, weak gravitational lensing and Type Ia supernovae. However, DES also provides a rich data set which allows us to study many other aspects of astrophysics. In this paper we focus on additional science with DES, emphasizing areas where the survey makes a difference with respect to other current surveys. The paper illustrates, using early data (from `Science Verification, and from the first, second and third seasons of observations), what DES can tell us about the solar system, the Milky Way, galaxy evolution, quasars, and other topics. In addition, we show that if the cosmological model is assumed to be Lambda+ Cold Dark Matter (LCDM) then important astrophysics can be deduced from the primary DES probes. Highlights from DES early data include the discovery of 34 Trans Neptunian Objects, 17 dwarf satellites of the Milky Way, one published z > 6 quasar (and more confirmed) and two published superluminous supernovae (and more confirmed).
The use of standard rulers, such as the scale of the Baryonic Acoustic oscillations (BAO), has become one of the more powerful techniques employed in cosmology to probe the entity driving the accelerating expansion of the Universe. In this paper, the
topology of large scale structure (LSS) is used as one such standard ruler to study this mysterious `dark energy. By following the redshift evolution of the clustering of luminous red galaxies (LRGs) as measured by their 3D topology (counting structures in the cosmic web), we can chart the expansion rate and extract information about the equation of state of dark energy. Using the technique first introduced in (Park & Kim, 2009), we evaluate the constraints that can be achieved using 3D topology measurements from next-generation LSS surveys such as the Baryonic Oscillation Spectroscopic Survey (BOSS). In conjunction with the information that will be available from the Planck satellite, we find a single topology measurement on 3 different scales is capable of constraining a single dark energy parameter to within 5% and 10% when dynamics are permitted. This offers an alternative use of the data available from redshift surveys and serves as a cross-check for BAO studies.
سجل دخول لتتمكن من نشر تعليقات
التعليقات
جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
