DOCSLIB.ORG

Origin and Evolution of the Universe Structure Formation

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Origin and Evolution of the Universe Structure Formation Astro/Phys 224 Spring 2014 Origin and Evolution of the Universe Week 5 ! Structure Formation Joel Primack University of California, Santa Cruz Physics 224 - Spring 2014 – Tentative Term Project Topics ! ! Adam Coogan – The BICEP2 Result and Its Implications for In=lationary Cosmology ! Devon Hollowood – Some Aspect of the Dark Energy Survey ! Caitlin Johnson – Observing Plan for ACTs to Constrain the Long-Wavelength EBL ! Thomas Kelly – Various Methods of Testing Modi=ied Newtonian Dynamics (MOND) ! Tanmai Sai – Shapes of Simulated Galaxies ! Vivian Tang – Studying Galaxy Evolution by Comparing Simulations and Observations ! Determination of σ8 and ΩM from CMB+ WMAP9+SN+Clusters Planck+WP+HighL+BAO WP = WMAP l<23 Polarization Data ! Cluster Observations HighL= ACT + SPT Planck ● ●WMAP9 WMAP7 WMAP5 ● ● ● BOSS Power Spectrum Normalization Spectrum Power Cosmic Dark Matter Fraction Planck Clusters vs. CMB? Planck 2013 results. XX. Cosmology from Sunyaev–Zeldovich cluster counts - arXiv:1303.5080 Assuming a bias between the X-ray determined mass and the true mass of 20%, motivated by comparison of the Planck cluster masses 3 observed mass scaling relations to those from a set of numerical simulations, we find that ... σ8 = 0.77 ± 0.02 and The systematic uncertainty quoted here expresses the systematic Ωm = 0.29 ± 0.02. The values of the cosmological parameters are degenerate with the massuncertainty bias, on and the weak-lensing it is masses,found i.e. it includesthat all entries in Table 4 of Applegate et al. (2014) with the exception of the scat- the larger values of σ8 and Ωm preferred by the Planck’s measurements of the primary CMBter anisotropies due to triaxiality, which is accountedcan be for here in the statistical uncertainty. Extending the sample to all 38 clusters yields a consis- accommodated by a mass bias of about 45%. Alternatively, consistency with the primary CMBtent result: constraints can be +0.039 βall = 0.698 0.037 (stat) 0.049 (syst) . achieved by inclusion of processes that suppress power on small scales, such as a component of massive− neutrinos.± The weak-lensing masses are expected to yield the true cluster mass on average, and thereby enable a robust calibration of other mass proxies (see discussion in von der Linden et al. 2014; Apple- This has led to papers proposing ∑mν > 0.23 eV such as Hamann & Hasenkampgate etJCAP al. 2014). Therefore,2013 by identifying β = (1 b), these re- − sults suggest that the mass calibration adopted by the Planck team, (1 b) 0.8, underestimates the true cluster masses by between 5 − ⌘ Relative cluster masses can be determined accurately cluster-by-clusterand 25using per cent on average. X-rays as was done by Vikhlinin+09, Mantz+10, and Planck paper XX, but the absolute masses should3.2 Evidence be for a mass-dependentcalibrated calibration problem using gravitational lensing, say Rozo+13,14 and van der Linden+14. The Arnaud+07,10By eye, Fig. X-ray 1 suggests thatcluster the ratio between masses the WtG weak- lensing and Planck mass estimates depends on the cluster mass: at masses . 6 1014 M , the mass estimates roughly agree, whereas ⇥ used in Planck paper XX are the lowest of all. Using gravitational lensing mass calibrationthe discrepancy appears significant raises for more massivethe clusters. To Figure 1. The ratio of cluster masses measured by Planck and by WtG, for quantify the evidence for such a mass-dependent bias, we use the cluster masses and thus predicts fewer expectedthe clusters commonclusters. to both projects. Solid symbolsThis denote clusterslessens which Bayesian the linear regressiontension method developed between by Kelly (2007) to fit were included in the Planck cluster cosmology analysis (22 clusters) and log(MWtG) as function of log(MPlanck) (fitting the masses directly open symbols additional clusters in the Planck cluster catalog (16 clusters). avoids the correlated errors in the mass ratios one would have to the CMB and cluster observations. The red, solid line indicates a ratio of unity (no bias). The dashed red line account for if fitting the data as shown in Fig. 1). While we show indicates (1 b) = 0.8, the default value assumed throughout most of P16. − MPlanck as function of MWtG in Fig. 2 to reflect that the weak-lensing The blue line and shaded regions show our best-fit mass ratio along with masses are our proxy for true cluster masses, we assign the Planck the 1- and 2-σ confidence intervals. Since the weak-lensing masses are mass estimates to be the independent variable to reduce the e↵ects Closing the loop: self-consistent ... scaling relationsexpected to be unbiased foron average clusters, the ratio of Planck masses of to weak- Galaxies - Rozo+14 MNRAS lensing masses is a measure of the bias (1 b) = M /M of the of Malmquist bias: MPlanck scales with the survey observable, and − Planck true Planck cluster masses as used in P20. by choosing it as the independent variable, we provide a mass esti- Robust weak-lensing mass calibration of Planck galaxy cluster massesmate - forvon each datader point Linden+14 which is to first order independent of other Planck cluster masses 3 selection e↵ects (as X-ray selection to first order does not correlate with SZ selection biases, and the lensing data are a subsample of MPlanck/MWtG vs. MPlanck MPlanckan X-ray selectedvs. M catalog).WtG The Kelly (2007) method accounts for The systematic uncertainty quoted here expresses the systematic measurement errors in both variables, as well as for intrinsic scat- uncertainty on the weak-lensing masses, i.e. it includes all entries ter in the dependent variable. Rephrasing the results as a power-law, The ratio of in Table 4 of Applegate et al. (2014) with the exception of the scat- the best-fit relation for the 22 clusters in the cosmology sample is: Noter due Bias to triaxiality, which is accounted for here in the statistical Best Fit cluster 0.76+0.39 uncertainty. Extending the sample to all 38 clusters yields a consis- 0.20 MPlanck +0.077 MWtG − tent result: = 0.697 0.095 , 1015 M − ⇥ 1015 M masses ! ! +0.039 ⇣ ⌘ βall = 0.698 0.037 (stat) 0.049 (syst) . where theThis systematic decreases uncertainty on the weak-lensing the mass cali-# − ± measured by The weak-lensing masses are expected to yield the true cluster bration is accounted for in the uncertainty on the coefficient. In 24 mass on average, and thereby enable a robust calibration of other per centtension of the Monte Carlo samples, between the slope (of log(M #Planck) vs. Planck and by mass proxies (see discussion in von der Linden et al. 2014; Apple- log(MWtG)) is unity or larger; i.e. the evidence for a mass-dependent gate et al. 2014). Therefore, by identifying β = (1 b), these re- bias is at the 1σ level for these 22 clusters. Best Fit − clusters⇠ and CMB # Weighing the sults suggest that the mass calibration adopted by the Planck team, To further test for a mass-dependent bias, it is instructive to # include the additional 16 clusters in common between Planck and (1 b) 0.8, underestimates⦿ the true cluster masses by between 5 − ⌘ Giants (WtG). and 25 per cent on average. WtG thatand are not used the in the Planck motivationcluster cosmology analysis, # as /M these slightly extend the mass range probed. For all 38 clusters, we find a consistentfor and! morem precise" > result: 0.23 eV. 3.2 Evidence for500 a mass-dependent calibration problem . +0.15 0 68 0.11 MPlanck +0.059 MWtG − Planck By eye, Fig. 1 suggestsM that the ratio between the WtG weak- = 0.699 0.060 . 1015 M − ⇥ 1015 M lensing and Planck mass estimates depends MText on500 the/M cluster Text⦿ mass:WtG ! ⇣ ⌘ ! at masses . 6 1014 M , the mass estimates roughly agree, whereas In 4.9 per cent of the Monte Carlo samples, the slope is unity or ⇥ Figure 2. The direct comparison between M500 cluster masses measured by larger; i.e. the confidence level for a slope less than unity is 95 per the discrepancyPlanck appearsand significant by WtG. The for symbols more massive are the same clusters. as in Fig. To 1. The green line cent3. Figure 1. The ratio of cluster masses measured by Planck and by WtG, for quantify the evidenceand shaded for such regions a mass-dependentshow the best-fit linear bias, relation we use between the the logarithmic the clusters common to both projects. Solid symbols denote clusters which Bayesian linear regressionmasses and methodits 1- and developed 2-σ confidence by Kelly intervals (2007) (the to fit fit was performed with were included in the Planck cluster cosmology analysis (22 clusters) and log(MWtG) as functionlog(MWtG of) as log( functionMPlanck of) log( (fittingMPlanck the)). masses directly 3 We note that when using bootstrap realizations of an unweighted simple open symbols additional clusters in the Planck cluster catalog (16 clusters). avoids the correlated errors in the mass ratios one would have to linear regression as a more agnostic fit statistic, we recover the same slope, The red, solid line indicates a ratio of unity (no bias). The dashed red line account for if fitting the data as shown in Fig. 1). While we show indicates (1 b) = 0.8, the default value assumed throughout most of P16. − MPlanck as functionc 2014 of M RAS,WtG in MNRAS Fig. 2 to000 reflect, 1–5 that the weak-lensing The blue line and shaded regions show our best-fit mass ratio along with masses are our proxy for true cluster masses, we assign the Planck the 1- and 2-σ confidence intervals. Since the weak-lensing masses are mass estimates to be the independent variable to reduce the e↵ects expected to be unbiased on average, the ratio of Planck masses to weak- lensing masses is a measure of the bias (1 b) = M /M of the of Malmquist bias: MPlanck scales with the survey observable, and − Planck true Planck cluster masses as used in P20.
Load more

Recommended publications
  • Birth of De Sitter Universe from a Time Crystal Universe
    PHYSICAL REVIEW D 100, 123531 (2019) Birth of de Sitter universe from a time crystal universe † Daisuke Yoshida * and Jiro Soda Department of Physics, Kobe University, Kobe 657-8501, Japan (Received 30 September 2019; published 18 December 2019) We show that a simple subclass of Horndeski theory can describe a time crystal universe. The time crystal universe can be regarded as a baby universe nucleated from a flat space, which is mediated by an extension of Giddings-Strominger instanton in a 2-form theory dual to the Horndeski theory. Remarkably, when a cosmological constant is included, de Sitter universe can be created by tunneling from the time crystal universe. It gives rise to a past completion of an inflationary universe. DOI: 10.1103/PhysRevD.100.123531 I. INTRODUCTION Euler-Lagrange equations of motion contain up to second order derivatives. Actually, bouncing cosmology in the Inflation has succeeded in explaining current observa- Horndeski theory has been intensively investigated so far tions of the large scale structure of the Universe [1,2]. [23–29]. These analyses show the presence of gradient However, inflation has a past boundary [3], which could be instability [30,31] and finally no-go theorem for stable a true initial singularity or just a coordinate singularity bouncing cosmology in Horndeski theory was found for the depending on how much the Universe deviates from the spatially flat universe [32]. However, it was shown that the exact de Sitter [4], or depending on the topology of the no-go theorem does not hold when the spatial curvature is Universe [5].
    [Show full text]
  • Expanding Space, Quasars and St. Augustine's Fireworks
    Universe 2015, 1, 307-356; doi:10.3390/universe1030307 OPEN ACCESS universe ISSN 2218-1997 www.mdpi.com/journal/universe Article Expanding Space, Quasars and St. Augustine’s Fireworks Olga I. Chashchina 1;2 and Zurab K. Silagadze 2;3;* 1 École Polytechnique, 91128 Palaiseau, France; E-Mail: [email protected] 2 Department of physics, Novosibirsk State University, Novosibirsk 630 090, Russia 3 Budker Institute of Nuclear Physics SB RAS and Novosibirsk State University, Novosibirsk 630 090, Russia * Author to whom correspondence should be addressed; E-Mail: [email protected]. Academic Editors: Lorenzo Iorio and Elias C. Vagenas Received: 5 May 2015 / Accepted: 14 September 2015 / Published: 1 October 2015 Abstract: An attempt is made to explain time non-dilation allegedly observed in quasar light curves. The explanation is based on the assumption that quasar black holes are, in some sense, foreign for our Friedmann-Robertson-Walker universe and do not participate in the Hubble flow. Although at first sight such a weird explanation requires unreasonably fine-tuned Big Bang initial conditions, we find a natural justification for it using the Milne cosmological model as an inspiration. Keywords: quasar light curves; expanding space; Milne cosmological model; Hubble flow; St. Augustine’s objects PACS classifications: 98.80.-k, 98.54.-h You’d think capricious Hebe, feeding the eagle of Zeus, had raised a thunder-foaming goblet, unable to restrain her mirth, and tipped it on the earth. F.I.Tyutchev. A Spring Storm, 1828. Translated by F.Jude [1]. 1. Introduction “Quasar light curves do not show the effects of time dilation”—this result of the paper [2] seems incredible.
    [Show full text]
  • First Year Wilkinson Microwave Anisotropy Probe (WMAP ) Observations: Determination of Cosmological Parameters
    Accepted by the Astrophysical Journal First Year Wilkinson Microwave Anisotropy Probe (WMAP ) Observations: Determination of Cosmological Parameters D. N. Spergel 2, L. Verde 2 3, H. V. Peiris 2, E. Komatsu 2, M. R. Nolta 4, C. L. Bennett 5, M. Halpern 6, G. Hinshaw 5, N. Jarosik 4, A. Kogut 5, M. Limon 5 7, S. S. Meyer 8, L. Page 4, G. S. Tucker 5 7 9, J. L. Weiland 10, E. Wollack 5, & E. L. Wright 11 [email protected] ABSTRACT WMAP precision data enables accurate testing of cosmological models. We find that the emerging standard model of cosmology, a flat ¡ −dominated universe seeded by a nearly scale-invariant adiabatic Gaussian fluctuations, fits the WMAP data. For the WMAP data 2 2 £ ¢ ¤ ¢ £ ¢ ¤ ¢ £ ¢ only, the best fit parameters are h = 0 ¢ 72 0 05, bh = 0 024 0 001, mh = 0 14 0 02, ¥ +0 ¦ 076 ¢ £ ¢ § ¢ £ ¢ = 0 ¢ 166− , n = 0 99 0 04, and = 0 9 0 1. With parameters fixed only by WMAP 0 ¦ 071 s 8 data, we can fit finer scale CMB measurements and measurements of large scale structure (galaxy surveys and the Lyman ¨ forest). This simple model is also consistent with a host of other astronomical measurements: its inferred age of the universe is consistent with stel- lar ages, the baryon/photon ratio is consistent with measurements of the [D]/[H] ratio, and the inferred Hubble constant is consistent with local observations of the expansion rate. We then fit the model parameters to a combination of WMAP data with other finer scale CMB experi- ments (ACBAR and CBI), 2dFGRS measurements and Lyman ¨ forest data to find the model’s 1WMAP is the result of a partnership between Princeton University and NASA's Goddard Space Flight Center.
    [Show full text]
  • On Asymptotically De Sitter Space: Entropy & Moduli Dynamics
    On Asymptotically de Sitter Space: Entropy & Moduli Dynamics To Appear... [1206.nnnn] Mahdi Torabian International Centre for Theoretical Physics, Trieste String Phenomenology Workshop 2012 Isaac Newton Institute , CAMBRIDGE 1 Tuesday, June 26, 12 WMAP 7-year Cosmological Interpretation 3 TABLE 1 The state of Summarythe ofart the cosmological of Observational parameters of ΛCDM modela Cosmology b c Class Parameter WMAP 7-year ML WMAP+BAO+H0 ML WMAP 7-year Mean WMAP+BAO+H0 Mean 2 +0.056 Primary 100Ωbh 2.227 2.253 2.249−0.057 2.255 ± 0.054 2 Ωch 0.1116 0.1122 0.1120 ± 0.0056 0.1126 ± 0.0036 +0.030 ΩΛ 0.729 0.728 0.727−0.029 0.725 ± 0.016 ns 0.966 0.967 0.967 ± 0.014 0.968 ± 0.012 τ 0.085 0.085 0.088 ± 0.015 0.088 ± 0.014 2 d −9 −9 −9 −9 ∆R(k0) 2.42 × 10 2.42 × 10 (2.43 ± 0.11) × 10 (2.430 ± 0.091) × 10 +0.030 Derived σ8 0.809 0.810 0.811−0.031 0.816 ± 0.024 H0 70.3km/s/Mpc 70.4km/s/Mpc 70.4 ± 2.5km/s/Mpc 70.2 ± 1.4km/s/Mpc Ωb 0.0451 0.0455 0.0455 ± 0.0028 0.0458 ± 0.0016 Ωc 0.226 0.226 0.228 ± 0.027 0.229 ± 0.015 2 +0.0056 Ωmh 0.1338 0.1347 0.1345−0.0055 0.1352 ± 0.0036 e zreion 10.4 10.3 10.6 ± 1.210.6 ± 1.2 f t0 13.79 Gyr 13.76 Gyr 13.77 ± 0.13 Gyr 13.76 ± 0.11 Gyr a The parameters listed here are derived using the RECFAST 1.5 and version 4.1 of the WMAP[WMAP-7likelihood 1001.4538] code.
    [Show full text]
  • FIRST-YEAR WILKINSON MICROWAVE ANISOTROPY PROBE (WMAP) 1 OBSERVATIONS: DETERMINATION of COSMOLOGICAL PARAMETERS D. N. Spergel,2
    The Astrophysical Journal Supplement Series, 148:175–194, 2003 September E # 2003. The American Astronomical Society. All rights reserved. Printed in U.S.A. FIRST-YEAR WILKINSON MICROWAVE ANISOTROPY PROBE (WMAP)1 OBSERVATIONS: DETERMINATION OF COSMOLOGICAL PARAMETERS D. N. Spergel,2 L. Verde,2,3 H. V. Peiris,2 E. Komatsu,2 M. R. Nolta,4 C. L. Bennett,5 M. Halpern,6 G. Hinshaw,5 N. Jarosik,4 A. Kogut,5 M. Limon,5,7 S. S. Meyer,8 L. Page,4 G. S. Tucker,5,7,9 J. L. Weiland,10 E. Wollack,5 and E. L. Wright11 Received 2003 February 11; accepted 2003 May 20 ABSTRACT WMAP precision data enable accurate testing of cosmological models. We find that the emerging standard model of cosmology, a flat Ã-dominated universe seeded by a nearly scale-invariant adiabatic Gaussian fluctuations, fits the WMAP data. For the WMAP data only, the best-fit parameters are h ¼ 0:72 Æ 0:05, 2 2 þ0:076 bh ¼ 0:024 Æ 0:001, mh ¼ 0:14 Æ 0:02, ¼ 0:166À0:071, ns ¼ 0:99 Æ 0:04, and 8 ¼ 0:9 Æ 0:1. With parameters fixed only by WMAP data, we can fit finer scale cosmic microwave background (CMB) measure- ments and measurements of large-scale structure (galaxy surveys and the Ly forest). This simple model is also consistent with a host of other astronomical measurements: its inferred age of the universe is consistent with stellar ages, the baryon/photon ratio is consistent with measurements of the [D/H] ratio, and the inferred Hubble constant is consistent with local observations of the expansion rate.
    [Show full text]
  • CMBEASY:: an Object Oriented Code for the Cosmic Microwave
    www.cmbeasy.org CMBEASY:: an Object Oriented Code for the Cosmic Microwave Background Michael Doran∗ Department of Physics & Astronomy, HB 6127 Wilder Laboratory, Dartmouth College, Hanover, NH 03755, USA and Institut f¨ur Theoretische Physik der Universit¨at Heidelberg, Philosophenweg 16, 69120 Heidelberg, Germany We have ported the cmbfast package to the C++ programming language to produce cmbeasy, an object oriented code for the cosmic microwave background. The code is available at www.cmbeasy.org. We sketch the design of the new code, emphasizing the benefits of object orienta- tion in cosmology, which allow for simple substitution of different cosmological models and gauges. Both gauge invariant perturbations and quintessence support has been added to the code. For ease of use, as well as for instruction, a graphical user interface is available. I. INTRODUCTION energy, dark matter, baryons and neutrinos. The dark energy can be a cosmological constant or quintessence. The cmbfast computer program for calculating cos- There are three scalar field field models implemented, or mic microwave background (CMB) temperature and po- alternatively one may specify an equation-of-state his- larization anisotropy spectra, implementing the fast line- tory. Furthermore, the modular code is easily adapted of-sight integration method, has been publicly available to new problems in cosmology. since 1996 [1]. It has been widely used to calculate spec- In the next section IIA we explain object oriented pro- cm- tra for open, closed, and flat cosmological models con- gramming and its use in cosmology. The design of beasy taining baryons and photons, cold dark matter, massless is presented in section II B, while the graphical and massive neutrinos, and a cosmological constant.
    [Show full text]
  • The Effects of the Small-Scale Behaviour of Dark Matter Power Spectrum on CMB Spectral Distortion
    Prepared for submission to JCAP The effects of the small-scale behaviour of dark matter power spectrum on CMB spectral distortion Abir Sarkar,1,2 Shiv.K.Sethi,1 Subinoy Das3 1Raman Research Institute, CV Raman Ave Sadashivnagar, Bengaluru, Karnataka 560080, India 2Indian Institute of Science,CV Raman Ave, Devasandra Layout, Bengaluru, Karnataka 560012, India 3Indian Institute of Astrophysics,100 Feet Rd, Madiwala, 2nd Block, Koramangala, Bengaluru, Karnataka 560034, India E-mail: [email protected], [email protected], [email protected] Abstract. After numerous astronomical and experimental searches, the precise particle nature of dark matter is still unknown. The standard Weakly Interacting Massive Particle(WIMP) dark mat- ter, despite successfully explaining the large-scale features of the universe, has long-standing small- scale issues. The spectral distortion in the Cosmic Microwave Background(CMB) caused by Silk damping in the pre-recombination era allows one to access information on a range of small scales 0.3Mpc <k< 104 Mpc−1, whose dynamics can be precisely described using linear theory. In this paper, we investigate the possibility of using the Silk damping induced CMB spectral distortion as a probe of the small-scale power. We consider four suggested alternative dark matter candidates— Warm Dark Matter (WDM), Late Forming Dark Matter (LFDM), Ultra Light Axion (ULA) dark matter and Charged Decaying Dark Matter (CHDM); the matter power in all these models deviate significantly from the ΛCDM model at small scales. We compute the spectral distortion of CMB for these alternative models and compare our results with the ΛCDM model. We show that the main arXiv:1701.07273v3 [astro-ph.CO] 7 Jul 2017 impact of alternative models is to alter the sub-horizon evolution of the Newtonian potential which affects the late-time behaviour of spectral distortion of CMB.
    [Show full text]
  • Galaxy Formation Within the Classical Big Bang Cosmology
    Galaxy formation within the classical Big Bang Cosmology Bernd Vollmer CDS, Observatoire astronomique de Strasbourg Outline • some basics of astronomy small structure • galaxies, AGNs, and quasars • from galaxies to the large scale structure of the universe large • the theory of cosmology structure • measuring cosmological parameters • structure formation • galaxy formation in the cosmological framework • open questions small structure The architecture of the universe • Earth (~10-9 ly) • solar system (~6 10-4 ly) • nearby stars (> 5 ly) • Milky Way (~6 104 ly) • Galaxies (>2 106 ly) • large scale structure (> 50 106 ly) How can we investigate the universe Astronomical objects emit elctromagnetic waves which we can use to study them. BUT The earth’s atmosphere blocks a part of the electromagnetic spectrum. need for satellites Back body radiation • Opaque isolated body at a constant temperature Wien’s law: sun/star (5500 K): 0.5 µm visible human being (310 K): 9 µm infrared molecular cloud (15 K): 200 µm radio The structure of an atom Components: nucleus (protons, neutrons) + electrons Bohr’s model: the electrons orbit around the nucleus, the orbits are discrete Bohr’s model is too simplistic quantum mechanical description The emission of an astronomical object has 2 components: (i) continuum emission + (ii) line emission Stellar spectra Observing in colors Usage of filters (Johnson): U (UV), B (blue), V (visible), R (red), I (infrared) The Doppler effect • Is the apparent change in frequency and wavelength of a wave which is emitted by
    [Show full text]
  • The Optical Depth to Reionization As a Probe of Cosmological and Astrophysical Parameters Aparna Venkatesan University of San Francisco, [email protected]
    The University of San Francisco USF Scholarship: a digital repository @ Gleeson Library | Geschke Center Physics and Astronomy College of Arts and Sciences 2000 The Optical Depth to Reionization as a Probe of Cosmological and Astrophysical Parameters Aparna Venkatesan University of San Francisco, [email protected] Follow this and additional works at: http://repository.usfca.edu/phys Part of the Astrophysics and Astronomy Commons, and the Physics Commons Recommended Citation Aparna Venkatesan. The Optical Depth to Reionization as a Probe of Cosmological and Astrophysical Parameters. The Astrophysical Journal, 537:55-64, 2000 July 1. http://dx.doi.org/10.1086/309033 This Article is brought to you for free and open access by the College of Arts and Sciences at USF Scholarship: a digital repository @ Gleeson Library | Geschke Center. It has been accepted for inclusion in Physics and Astronomy by an authorized administrator of USF Scholarship: a digital repository @ Gleeson Library | Geschke Center. For more information, please contact [email protected]. THE ASTROPHYSICAL JOURNAL, 537:55È64, 2000 July 1 ( 2000. The American Astronomical Society. All rights reserved. Printed in U.S.A. THE OPTICAL DEPTH TO REIONIZATION AS A PROBE OF COSMOLOGICAL AND ASTROPHYSICAL PARAMETERS APARNA VENKATESAN Department of Astronomy and Astrophysics, 5640 South Ellis Avenue, University of Chicago, Chicago, IL 60637; aparna=oddjob.uchicago.edu Received 1999 December 17; accepted 2000 February 8 ABSTRACT Current data of high-redshift absorption-line systems imply that hydrogen reionization occurred before redshifts of about 5. Previous works on reionization by the Ðrst stars or quasars have shown that such scenarios are described by a large number of cosmological and astrophysical parameters.
    [Show full text]
  • FRW Cosmology
    17/11/2016 Cosmology 13.8 Gyrs of Big Bang History Gravity Ruler of the Universe 1 17/11/2016 Strong Nuclear Force Responsible for holding particles together inside the nucleus. The nuclear strong force carrier particle is called the gluon. The nuclear strong interaction has a range of 10‐15 m (diameter of a proton). Electromagnetic Force Responsible for electric and magnetic interactions, and determines structure of atoms and molecules. The electromagnetic force carrier particle is the photon (quantum of light) The electromagnetic interaction range is infinite. Weak Force Responsible for (beta) radioactivity. The weak force carrier particles are called weak gauge bosons (Z,W+,W‐). The nuclear weak interaction has a range of 10‐17 m (1% of proton diameter). Gravity Responsible for the attraction between masses. Although the gravitational force carrier The hypothetical (carrier) particle is the graviton. The gravitational interaction range is infinite. By far the weakest force of nature. 2 17/11/2016 The weakest force, by far, rules the Universe … Gravity has dominated its evolution, and determines its fate … Grand Unified Theories (GUT) Grand Unified Theories * describe how ∑ Strong ∑ Weak ∑ Electromagnetic Forces are manifestations of the same underlying GUT force … * This implies the strength of the forces to diverge from their uniform GUT strength * Interesting to see whether gravity at some very early instant unifies with these forces ??? 3 17/11/2016 Newton’s Static Universe ∑ In two thousand years of astronomy, no one ever guessed that the universe might be expanding. ∑ To ancient Greek astronomers and philosophers, the universe was seen as the embodiment of perfection, the heavens were truly heavenly: – unchanging, permanent, and geometrically perfect.
    [Show full text]
  • “De Sitter Effect” in the Rise of Modern Relativistic Cosmology
    The role played by the “de Sitter effect” in the rise of modern relativistic cosmology ● Matteo Realdi ● Department of Astronomy, Padova ● Sait 2009. Pisa, 7-5-2009 Table of contents ● Introduction ● 1917: Einstein, de Sitter and the universes of General Relativity ● 1920's: the debates on the “de Sitter effect”. The connection between theory and observation and the rise of scientific cosmology ● 1930: the expanding universe and the decline of the interest in the de Sitter effect ● Conclusion 1 - Introduction ● Modern cosmology: study of the origin, structure and evolution of the universe as a whole, based on the interpretation of astronomical observations at different wave- lengths through the laws of physics ● The early years: 1917-1930. Extremely relevant period, characterized by new ideas, discoveries, controversies, in the light of the first comparison of theoretical world-models with observations at the turning point of relativity revolution ● Particular attention on the interest in the so-called “de Sitter effect”, a theoretical redshift-distance relation which is predicted through the line element of the empty universe of de Sitter ● The de Sitter effect: fundamental influence in contributions that scientists as de Sitter, Eddington, Weyl, Lanczos, Lemaître, Robertson, Tolman, Silberstein, Wirtz, Lundmark, Stromberg, Hubble offered during the 1920's both in theoretical and in observational cosmology (emergence of the modern approach of cosmologists) ➔ Predictions and confirmations of an appropriate redshift- distance relation marked the tortuous process towards the change of viewpoint from the 1917 paradigm of a static universe to the 1930 picture of an expanding universe evolving both in space and in time 2 - 1917: the Universes of General Relativity ● General relativity: a suitable theory in order to describe the whole of space, time and gravitation? ● Two different metrics, i.e.
    [Show full text]
  • Cosmic Microwave Background
    1 29. Cosmic Microwave Background 29. Cosmic Microwave Background Revised August 2019 by D. Scott (U. of British Columbia) and G.F. Smoot (HKUST; Paris U.; UC Berkeley; LBNL). 29.1 Introduction The energy content in electromagnetic radiation from beyond our Galaxy is dominated by the cosmic microwave background (CMB), discovered in 1965 [1]. The spectrum of the CMB is well described by a blackbody function with T = 2.7255 K. This spectral form is a main supporting pillar of the hot Big Bang model for the Universe. The lack of any observed deviations from a 7 blackbody spectrum constrains physical processes over cosmic history at redshifts z ∼< 10 (see earlier versions of this review). Currently the key CMB observable is the angular variation in temperature (or intensity) corre- lations, and to a growing extent polarization [2–4]. Since the first detection of these anisotropies by the Cosmic Background Explorer (COBE) satellite [5], there has been intense activity to map the sky at increasing levels of sensitivity and angular resolution by ground-based and balloon-borne measurements. These were joined in 2003 by the first results from NASA’s Wilkinson Microwave Anisotropy Probe (WMAP)[6], which were improved upon by analyses of data added every 2 years, culminating in the 9-year results [7]. In 2013 we had the first results [8] from the third generation CMB satellite, ESA’s Planck mission [9,10], which were enhanced by results from the 2015 Planck data release [11, 12], and then the final 2018 Planck data release [13, 14]. Additionally, CMB an- isotropies have been extended to smaller angular scales by ground-based experiments, particularly the Atacama Cosmology Telescope (ACT) [15] and the South Pole Telescope (SPT) [16].
    [Show full text]