ترغب بنشر مسار تعليمي؟ اضغط هنا

Measuring redshift through X-ray spectroscopy of galaxy clusters: results from Chandra data and future prospects

203   0   0.0 ( 0 )
 نشر من قبل Yu Heng
 تاريخ النشر 2011
  مجال البحث فيزياء
والبحث باللغة English




اسأل ChatGPT حول البحث

The ubiquitous presence of the Fe line complex in the X-ray spectra of galaxy clusters offers the possibility of measuring their redshift without resorting to spectroscopic follow-up observations. In this paper we assess the accuracy with which the redshift of galaxy clusters can be recovered from an X-ray spectral analysis of Chandra archival data. This study indicates a strategy to build large surveys of clusters whose identification and redshift measurement are both based on X-ray data alone. We apply a blind search for K--shell and L--shell Fe line complex in X-ray cluster spectra using Chandra archival observations of galaxy clusters. The Fe line in the ICM spectra can be detected by simply analyzing the C-statistics variation $Delta C_{stat}$ as a function of the redshift parameter. We repeat the measurement under different conditions, and compare the X-ray derived redshift $z_X$ with the one obtained by means of optical spectroscopy $z_o$. We explore how a number of priors on metallicity and luminosity can be effectively used to reduce catastrophic errors. The $Delta C_{stat}$ provides the most efficient means for discarding wrong redshift measures and to estimate the actual error on $z_X$. We identify a simple and efficient procedure for optimally measuring the redshifts from the X-ray spectral analysis of clusters of galaxies. When this procedure is applied to mock catalogs extracted from high sensitivity, wide-area cluster surveys, such as those proposed with Wide Field X-ray Telescope (WFXT) mission, it is possible to obtain a complete samples of X-ray clusters with reliable redshift measurements, thus avoiding time-consuming optical spectroscopic observations. This methodology will make it possible to trace cosmic growth by studying the evolution of the cluster mass function directly using X-ray data.



قيم البحث

اقرأ أيضاً

406 - Joana S. Santos 2010
In this contribution we trace the evolution of cool-core clusters out to z~1.3 using high-resolution Chandra data of three representative cluster samples spanning different redshift ranges. Our analysis is based on the measurement of the surface brig htness (SB) concentration, c_SB, which strongly anti-correlates with the central cooling time and allows us to characterize the cool-core strength in low S/N data. We confirm a negative evolution in the fraction of cool-core clusters with redshift, in particular for very strong cool-cores. Still, we find evidence for a large population of well formed cool-cores at z ~ 1. This analysis is potentially very effective in constraining the nature and the evolution of the cool-cores, once large samples of high-z clusters will be available. In this respect, we explore the potential of the proposed mission Wide Field X-ray Telescope (WFXT) to address this science case. We conclude that WFXT provides the best trade-off of angular resolution, sensitivity and covered solid angle in order to discover and fully characterize the cool-core cluster population up to z=1.5.
Baryon acoustic oscillations (BAO) at low redshift provide a precise and largely model-independent way to measure the Hubble constant, H0. The 6dF Galaxy Survey measurement of the BAO scale gives a value of H0 = 67 +/- 3.2 km/s/Mpc, achieving a 1-sig ma precision of 5%. With improved analysis techniques, the planned WALLABY (HI) and TAIPAN (optical) redshift surveys are predicted to measure H0 to 1-3% precision.
In a flat universe dominated by dark energy, the Integrated Sachs-Wolfe (ISW) effect can be detected as a large-angle cross-correlation between the CMB and a tracer of large scale structure. We investigate whether the inconclusive ISW signal derived from 2MASS galaxy maps can be improved upon by including photometric redshifts for the 2MASS galaxies. These redshifts are derived by matching the 2MASS data with optical catalogues generated from SuperCOSMOS scans of major photographic sky surveys. We find no significant ISW signal in this analysis; an ISW effect of the form expected in a LambdaCDM universe is only weakly preferred over no correlation, with a likelihood ratio of 1.5:1. We consider ISW detection prospects for future large scale structure surveys with fainter magnitude limits and greater survey depth; even with the best possible data, the ISW cross-correlation signal would be expected to evade detection in >~ 10% of cases.
We present results based on Chandra observations of a large sample of 129 hot galaxy clusters. We measure the concentration parameter c_200, the dark mass M_200 and the baryonic mass content in all the objects of our sample, providing the largest dat aset of mass parameters for galaxy clusters in the redshift range z = 0.01 - 1.4. We confirm a that a tight correlation between c_200 and M_200, c propto M^a_vir /(1+z)^b with a = -0.56 +/- 0.15 and b =0.80 +/- 0.25 (68 per cent confidence limits), is present, in good agreement with the predictions from numerical simulations and previous observations. Fitting the mass profile with a generalized NFW model, we got the inner slope alpha, with alpha = 0.94 +/- 0.13. Finally, we show that the inner slope of the density profile, alpha correlates with the baryonic mass content, M_b : namely alpha is decreasing with increasing baryonic mass content.
236 - Peter R. Young 2021
Future prospects for solar spectroscopy missions operating in the extreme ultraviolet (EUV) and soft X-ray (SXR) wavelength ranges, 1.2-1600 Angstroms, are discussed. NASA is the major funder of Solar Physics missions, and brief summaries of the oppo rtunities for mission development under NASA are given. Upcoming major solar missions from other nations are also described. The methods of observing the Sun in the two wavelength ranges are summarized with a discussion of spectrometer types, imaging techniques and detector options. The major spectral features in the EUV and SXR regions are identified, and then the upcoming instruments and concepts are summarized. The instruments range from large spectrometers on dedicated missions, to tiny, low-cost CubeSats launched through rideshare opportunities.
التعليقات
جاري جلب التعليقات جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
mircosoft-partner

هل ترغب بارسال اشعارات عن اخر التحديثات في شمرا-اكاديميا