〔Major achievements〕Effects of knowledge improvement on scientific literacy in natural science liberal arts　　　　　　　　　　　　　　　
Dai G. Yamazaki, Lead
Journal of Liberal Arts Education, Mar. 2024, [Reviewed]

〔Major achievements〕Examination of learning effectiveness of video teaching materials for on-demand classes and,consideration of how to appropriately use the video teaching materials　　　　　　　　　　　　　　　
Dai G. Yamazaki, Lead
Journal of Liberal Arts Education, Mar. 2024, [Reviewed]

〔Major achievements〕Guidelines for how to teach and creating teaching materials, and time required learning other than that during class hours in classes using On-demand video materials　　　　　　　　　　　　　　　
Dai G. Yamazaki, Lead
Journal of Liberal Arts Education, Mar. 2023, [Reviewed]

〔Major achievements〕An examination for the online education　　　　　　　　　　　　　　　
Dai. G. Yamazaki, Lead, 茨城大学全学教育機構
茨城大学全学教育機構論集. 大学教育研究, Mar. 2021

Cosmological solutions of the lithium problem　　　　　　　　　　　　　　　
Mathews; G. J.; Kedia; A.; Sasankan; N.; Kusakabe; M.; Luo; Y.; Kajino; T.; Yamazaki; D.; Makki; T.; El Eid; M.
Memorie della Societa Astronomica Italiana, Jun. 2020, [Reviewed]

Cosmological Solutions to the Lithium Problem　　　　　　　　　　　　　　　
Mathews; G. J.; Kedia; A.; Sasankan; N.; Kusakabe; M.; Luo; Y.; Kajino; T.; Yamazaki; D. G.; Makki; T.; El Eid; M.
JPS Conf. Proc., Mar. 2020, [Reviewed]

Verification and problem of learning effect of group work in basic physics education
Dai. G. Yamazaki, 茨城大学全学教育機構
茨城大学全学教育機構論集. 大学教育研究, Mar. 2019

CMB weak lensing with the primordial,magnetic field　　　　　　　　　　　　　　　
Dai G. Yamazaki
Proceedings of the IAU Focus Meeting 8: New Insights in Extragalactic Magnetic Fields, XXXth IAU General Assembly, Nov. 2018

Impact of a primordial magnetic field on cosmic microwave background B modes with weak lensing
Dai G. Yamazaki, We discuss the manner in which the primordial magnetic field (PMF) suppresses the cosmic microwave background (CMB) B mode due to the weak-lensing (WL) effect. The WL effect depends on the lensing potential (LP) caused by matter perturbations, the distribution of which at cosmological scales is given by the matter power spectrum (MPS). Therefore, the WL effect on the CMB B mode is affected by the MPS. Considering the effect of the ensemble average energy density of the PMF, which we call "the background PMF," on the MPS, the amplitude of MPS is suppressed in the wave number range of k>
0.01h Mpc-1. The MPS affects the LP and the WL effect in the CMB B mode
however, the PMF can damp this effect. Previous studies of the CMB B mode with the PMF have only considered the vector and tensor modes. These modes boost the CMB B mode in the multipole range of >
1000, whereas the background PMF damps the CMB B mode owing to the WL effect in the entire multipole range. The matter density in the Universe controls the WL effect. Therefore, when we constrain the PMF and the matter density parameters from cosmological observational data sets, including the CMB B mode, we expect degeneracy between these parameters. The CMB B mode also provides important information on the background gravitational waves, inflation theory, matter density fluctuations, and the structure formations at the cosmological scale through the cosmological parameter search. If we study these topics and correctly constrain the cosmological parameters from cosmological observations, including the CMB B mode, we need to correctly consider the background PMF., American Physical Society
Physical Review D, 15 May 2018, [Reviewed]

Educational Practice Report on Peer Support for Basic Science Class at Ibaraki University in 2016
Dai. G. Yamazaki, 茨城大学全学教育機構
茨城大学全学教育機構論集. 大学教育研究, Mar. 2018

Cosmic magnetism in centimeter- and meter-wavelength radio astronomy
Takuya Kahori; Hiroyuki Nakanishi; Yoshiaki Sofue; Yutaka Fujita; Kiyotomo Ichiki; Shinsuke Ideguchi; Osamu Kameya; Takahiro Kudoh; Yuki Kudoh; Mami Machida; Yoshimitsu Miyashita; Hiroshi Ohno; Takeaki Ozawa; Keitaro Takahashi; Motokazu Takizawa; Dai G. Yamazaki, © The Author(s) 2018. The magnetic field is ubiquitous in the universe. Though it plays an essential role in various astrophysical phenomena, its real origin and evolution are poorly known. This article reviews the understanding of the latest research concerning magnetic fields in the interstellarmedium, the Milky Way Galaxy, external galaxies, active galactic nuclei, clusters of galaxies, and the cosmic web. Particularly, the review is concentrated in the achievements that have been provided by centimeter- and meter-wavelength radio observations. The article also introduces various methods for analyzing linear polarization data, including synchrotron radiation, Faraday rotation, depolarization, and Faraday tomography.
Publications of the Astronomical Society of Japan, 01 Jan. 2018, [Reviewed], [Invited]

The new hybrid BBN model with the photon cooling, X particle, and the primordial magnetic field
Dai G. Yamazaki; Motohiko Kusakabe; Toshitaka Kajino; Grant J. Mathews; Myung-Ki Cheoun, The Big Bang Nucleosynthesis theory accurately reproduces the abundances of light elements in the universes, except for the Li-7 abundance. The calculated Li-7 abundance with the baryon-to-photon ratio fixed by the observations of the cosmic microwave background (CMB) is inconsistent with the observed lithium abundances on the surface of metal-poor halo stars, and this problem is called "Li-7 problem". Previous studies proposed to resolve this Li-7 problem include photon cooling (possibly via the Bose-Einstein condensation of a scalar particle), the decay of a long-lived X particle (possibly the nextto-lightest supersymmetric particle), or an energy density of a primordial magnetic field (PMF). We review and analyze the results of these solutions both separately and in concert, and the constraint on the X particles and the PMF parameters from observed light-element abundances with a likelihood analysis. We can discover parameter ranges of the X particles which can solve the Li-7 problem and constrain the energy density of the PMF., WORLD SCIENTIFIC PUBL CO PTE LTD
INTERNATIONAL JOURNAL OF MODERN PHYSICS E-NUCLEAR PHYSICS, Aug. 2017, [Reviewed], [Invited]

The new BBN model with the photon cooling, X particle, and the primordial magnetic field
D. G. Yamazaki; M. Kusakabe; T. Kajino; G. J. Mathews; and M. K. Cheoun, The Big Bang Nucleosynthesis theory accurately reproduces the abundances of light elements in the universes, except for the Li-7 abundance. The calculated Li-7 abundance with the baryon-to-photon ratio fixed by the observations of the cosmic microwave background (CMB) is inconsistent with the observed lithium abundances on the surface of metal-poor halo stars, and this problem is called "Li-7 problem". Previous studies proposed to resolve this Li-7 problem include photon cooling (possibly via the Bose-Einstein condensation of a scalar particle), the decay of a long-lived X particle (possibly the nextto-lightest supersymmetric particle), or an energy density of a primordial magnetic field (PMF). We review and analyze the results of these solutions both separately and in concert, and the constraint on the X particles and the PMF parameters from observed light-element abundances with a likelihood analysis. We can discover parameter ranges of the X particles which can solve the Li-7 problem and constrain the energy density of the PMF., WORLD SCIENTIFIC PUBL CO PTE LTD
JPS Conference Proceedings, Aug. 2017, [Reviewed]

DETECTABILITY OF COSMIC DARK FLOW IN THE TYPE IA SUPERNOVA REDSHIFT-DISTANCE RELATION
G. J. Mathews; B. M. Rose; P. M. Garnavich; D. G. Yamazaki; T. Kajino, We reanalyze the detectability of large-scale dark flow (or local bulk flow) with respect to the CMB background based upon the redshift-distance relation for SN Ia. We made two independent analyses: one based upon identifying the three Cartesian velocity components; and the other based upon the cosine dependence of the deviation from Hubble flow on the sky. We apply these analyses to the Union2.1 SN Ia data and to the SDSS-II supernova survey. For both methods, results for low redshift, z < 0.05, are consistent with previous searches. We find a local bulk flow of v(bf) similar to 300 km s(-1) in the direction of (l, b) similar to (270, 35)degrees. However, the search for a dark flow at z > 0.05 is inconclusive. Based upon simulated data sets, we deduce that the difficulty in detecting a dark flow at high redshifts arises mostly from the observational error in the distance modulus. Thus, even if it exists, a dark flow is not detectable at large redshift with current SN Ia data sets. We estimate that a detection would require both significant sky coverage of SN Ia out to z = 0.3 and a reduction in the effective distance modulus error from 0.2 mag to less than or similar to 0.02 mag. We estimate that a greatly expanded data sample of similar to 10(4) SN Ia might detect a dark flow as small as 300 km s(-1) out to z = 0.3 even with a distance modulus error of 0.2 mag. This may be achievable in a next generation large survey like LSST., IOP PUBLISHING LTD
ASTROPHYSICAL JOURNAL, Aug. 2016, [Reviewed]

Evolution of the cosmic matter density field with a primordial magnetic field
Dai G. Yamazaki, A cosmological magnetic field affects the time evolution of the cosmic matter density field. The squared Alfven velocity of the cosmic fluid is proportional to an ensemble average energy density of a primordial magnetic field (PMF), and it prevents the matter density field from collapsing in the horizon scale. The matter-radiation equality time also is delayed by the presence of the ensemble average energy density of the PMF. The ensemble average energy density of the PMF also affects the matter power spectrum (MPS) through the Meszaros effect and the potential decay. Since the ensemble average energy density of the PMF is not a first order perturbation but a zero order source in the linear perturbation equations for the cosmology, to correctly understand the overall effect of the PMF on the MPS, we should significantly revise previous approaches to research for the MPS with the PMF by considering both the effects of the zero and first order sources from the PMF in the linear perturbation theory. We apply the effects of the zero order sources from the PMF to theoretical computations of the MPS for the first time. We also analyze the overall PMF effect on the MPS. The CMB polarization is affected by the weak lensing. The weak lensing is determined by the MPS. Therefore, we have to consider the zero order sources of the PMF to gain a correct understanding not only of the MPS but also the CMB polarization., AMER PHYSICAL SOC
PHYSICAL REVIEW D, Feb. 2016, [Reviewed]

Constraints on the birth of the universe and origin of cosmic dark flow
G. J. Mathews; M. R. Gangopadhyay; P. Garnavich; B. Rose; K. Ichiki; T. Kajino; Dai Yamazaki, We summarize three recent efforts to constrain the first few moments of cosmic creation before and during the epoch of inflation. We consider two means to explain a slight dip in the power spectrum of the cosmic microwave background for multipoles in the range of l = 10-30 from both the Planck and WMAP data. We show that such a dip could be the result of resonant creation of a massive particle that couples to the inflaton field. For best-fit models, the epoch of resonant particle creation reenters the horizon at wave numbers of k* similar to 0.00011 +/- 0.0004 (h Mpc(-1)). The amplitude and location of these features correspond to the creation of a number of degenerate fermion species of mass similar to 15/lambda(3/2)m(pl) during inflation where lambda is the coupling constant between the inflaton field and the created fermion species. Alternatively, one can explain the existence of such a dip as due to a jump in the inflation generating potential. We show that such a jump can also resolve the excessively large dark flow predicted from the M-theory landscape. Finally, we summarize our efforts to quantify constraints on the cosmic dark flow from a new analysis of the Type Ia supernova distance-redshift relation., WORLD SCIENTIFIC PUBL CO PTE LTD
INTERNATIONAL JOURNAL OF MODERN PHYSICS A, Oct. 2015, [Reviewed]

Cosmological solutions to the lithium problem: Big-bang nucleosynthesis with photon cooling, X -particle decay and a primordial magnetic field
Dai G. Yamazaki; Motohiko Kusakabe; Toshitaka Kajino; Grant. J. Mathews; Myung-Ki Cheoun, The Li7 abundance calculated in BBN with the baryon-to-photon ratio fixed from fits to the CMB power spectrum is inconsistent with the observed lithium abundances on the surface of metal-poor halo stars. Previous cosmological solutions proposed to resolve this Li7 problem include photon cooling (possibly via the Bose-Einstein condensation of a scalar particle) or the decay of a long-lived X particle (possibly the next-to-lightest supersymmetric particle). In this paper we reanalyze these solutions, both separately and in concert. We also introduce the possibility of a primordial magnetic field (PMF) into these models. We constrain the X particles and the PMF parameters by the observed light element abundances using a likelihood analysis to show that the inclusion of all three possibilities leads to an optimum solution to the lithium problem. We deduce allowed ranges for the X particle parameters and energy density in the PMF that can solve Li7 problem. © 2014 American Physical Society., American Physical Society
Physical Review D - Particles, Fields, Gravitation and Cosmology, 01 Jul. 2014, [Reviewed]

Cosmological solutions to the lithium problem: Big-bang nucleosynthesis with photon cooling, X-particle decay and a primordial magnetic field
Dai G. Yamazaki; Motohiko Kusakabe; Toshitaka Kajino; Grant. J. Mathews; Myung-Ki Cheoun, The Li-7 abundance calculated in BBN with the baryon-to-photon ratio fixed from fits to the CMB power spectrum is inconsistent with the observed lithium abundances on the surface of metal-poor halo stars. Previous cosmological solutions proposed to resolve this Li-7 problem include photon cooling (possibly via the Bose-Einstein condensation of a scalar particle) or the decay of a long-lived X particle (possibly the next-to-lightest supersymmetric particle). In this paper we reanalyze these solutions, both separately and in concert. We also introduce the possibility of a primordial magnetic field (PMF) into these models. We constrain the X particles and the PMF parameters by the observed light element abundances using a likelihood analysis to show that the inclusion of all three possibilities leads to an optimum solution to the lithium problem. We deduce allowed ranges for the X particle parameters and energy density in the PMF that can solve Li-7 problem., AMER PHYSICAL SOC
PHYSICAL REVIEW D, Jul. 2014, [Reviewed]

CMB with the background primordial magnetic field
Dai G. Yamazaki, We investigate the effects of the background primordial magnetic field (PMF) on the cosmic microwave background (CMB). The sound speed of the tightly coupled photon-baryon fluid is increased by the background PMF. The increased sound speed causes the odd peaks of the CMB temperature fluctuations to be suppressed and the CMB peak positions to be shifted to a larger scale. The background PMF causes a stronger decaying potential and increases the amplitude of the CMB. These two effects of the background PMF on a smaller scale cancel out, and the overall effects of the background PMF are the suppression of the CMB around the first peak and the shifting of peaks to a larger scale. We also discuss obtaining information about the PMF generation mechanisms, and we examine the nonlinear evolution of the PMF by the constraint on the maximum scale for the PMF distributions. Finally, we discuss degeneracies between the PMF parameters and the standard cosmological parameters., AMER PHYSICAL SOC
PHYSICAL REVIEW D, Apr. 2014, [Reviewed]

Primordial nucleosynthesis: A cosmological point of view
G. J. Mathews; T. Kajino; D. Yamazaki; M. Kusakabe; M. -K. Cheoun, Primordial nucleosynthesis remains as one of the pillars of modern cosmology. It is the test- ing ground upon which all cosmological models must ultimately rest. It is our only probe of the universe during the first few minutes of cosmic expansion and in particular during the important radiation-dominated epoch. These lectures review the basic equations of space-time, cosmology, and big bang nucleosynthesis. We will then review the current state of observational constraints on primordial abundances along with the key nuclear reactions and their uncertainties. We summarize which nuclear measurements are most crucial during the big bang. We also review various cosmological models and their constraints. In particular, we summarize the constraints that big bang nucleosynthesis places upon the possible time variation of fundamental constants, along with constraints on the nature and origin of dark matter and dark energy, long-lived supersymmetric particles, gravity waves, and the primordial magnetic field., AMER INST PHYSICS
SEVENTH EUROPEAN SUMMER SCHOOL ON EXPERIMENTAL NUCLEAR ASTROPHYSICS, 2014, [Reviewed]

Origin of Matter and Space-time in the Big Bang
G. J. Mathews; T. Kajino; D. Yamazaki; M. Kusakabe; M. -K. Cheoun, We review the case for and against a bulk cosmic motion resulting from the quantum entanglement of our universe with the multiverse beyond our horizon. Within the current theory or the selection of the initial state of the universe from the landscape multiverse there is a generic prediction that pre-inflation quantum entanglement with other universes should give rise to a cosmic bulk flow with a correlation length of order horizon size and a velocity field relative to the expansion frame of the universe. Indeed, the parameters of this motion are are tightly constrained. A robust prediction can be deduced indicating that there should be an overall motion of of about 800 km/s relative to the background space time as defined by the cosmic microwave background (CMB). This talk will summarize the underlying theoretical motivation for this hypothesis. Of course our motion relative to the background space time (CMB dipole) has been known for decades and is generally attributed to the gravitational pull of the local super cluster. However, this cosmic peculiar velocity field has been recently deduced out to very large distances well beyond that of the local super cluster by using X-ray galaxy clusters as tracers of matter motion. This is achieved via the kinematic component of the Sunyaev-Zeldovich (KSZ) effect produced by Compton scattering of cosmic microwave background photons from the local hot intracluster gas. As such, this method measures peculiar velocity directly in the frame of the cluster. Similar attempts by our group and others have attempted to independently assess this bulk flow via Type Ia supernova redshifts. In this talk we will review the observation case for and against the existence of this bulk flow based upon the observations and predictions of the theory. If this interpretation is correct it has profound implications in that we may be observing for the first time both the physics that occurred before the big bang and the existence of the multiverse beyond our horizon., AMER INST PHYSICS
ORIGIN OF MATTER AND EVOLUTION OF GALAXIES 2013, 2014, [Reviewed]

Constraints on the multi-lognormal magnetic fields from the observations of the cosmic microwave background and the matter power spectrum
Dai G. Yamazaki; Kiyotomo Ichiki; Keitaro Takahashi, Primordial magnetic fields (PMFs), which were generated in the early Universe before recombination, affect the motion of plasma and then the cosmic microwave background and the matter power spectrum. We consider constraints on PMFs with a characteristic correlation length from the observations of the anisotropies of the cosmic microwave background and matter power spectrum. The spectrum of PMFs is modeled with multi-lognormal distributions rather than power-law distribution, and we derive constraints on the strength |B k| at each wave number k along with the standard cosmological parameters in the flat Universe and the foreground sources. We obtain upper bounds on the field strengths at k=10-1, 10-2, 10 -4 and 10-5 Mpc-1 as 4.7 nG, 2.1 nG, 5.3 nG, and 10.9 nG (2σ C.L.) respectively, while the field strength at k=10 -3 Mpc-1 turns out to have a finite value as |B k=10-3|=6.2±1.3 nG (1σ C.L.). This finite value is attributed to the finite values of the polarization with negative parity (BB mode) data at ℓ>300 obtained from the QUAD experiment. If we do not include the BB mode data, we obtain only the upper bound on B k=10-3. © 2013 American Physical Society.
Physical Review D - Particles, Fields, Gravitation and Cosmology, 26 Nov. 2013, [Reviewed]

Constraints on the multi-lognormal magnetic fields from the observations of the cosmic microwave background and the matter power spectrum
Dai G. Yamazaki; Kiyotomo Ichiki; Keitaro Takahashi, Primordial magnetic fields (PMFs), which were generated in the early Universe before recombination, affect the motion of plasma and then the cosmic microwave background and the matter power spectrum. We consider constraints on PMFs with a characteristic correlation length from the observations of the anisotropies of the cosmic microwave background and matter power spectrum. The spectrum of PMFs is modeled with multi-lognormal distributions rather than power-law distribution, and we derive constraints on the strength jBkj at each wave number k along with the standard cosmological parameters in the flat Universe and the foreground sources. We obtain upper bounds on the field strengths at k=10(-1,) 10(-2), 10(-4) and 10(-5) Mpc(-1) as 4.7 nG, 2.1 nG, 5.3 nG, and 10.9 nG (2 sigma C. L.) respectively, while the field strength at k-10-3 Mpc-1 turns out to have a finite value as |Bk=10-3|=6.2 +/- 1.3 nG (1 sigma C.L.). This finite value is attributed to the finite values of the polarization with negative parity (BB mode) data at l > 300 obtained from the QUAD experiment. If we do not include the BB mode data, we obtain only the upper bound on Bk=10-3., AMER PHYSICAL SOC
PHYSICAL REVIEW D, Nov. 2013, [Reviewed]

SUPERNOVA NUCLEOSYNTHESIS, NEUTRINO MASS AND OSCILLATION, AND NUCLEAR WEAK INTERACTIONS
T. Kajino; K. Nakamura; K. Sato; K. Shaku; T. Yoshida; T. Hayakawa; S. Chiba; D. Yamazaki; M. -K. Cheoun; G. J. Mathews, We here discuss how to determine the total neutrino mass and oscillation parameters from supernova nucleosynthesis, the Galactic chemical evolution, and the CMB anisotropies. Neutrinos play the critical roles in nucleosynthesis of light-to-heavy mass nuclei in core-collapse supernovae. We study the nucleosynthesis induced by neutrino interactions and find suitable average neutrino temperatures in order to explain the observed solar system abundances of several isotopes Li-7, B-11, La-138 and Ta-180. These isotopes are predominantly synthesized by the supernova nu-process. We also study the neutrino oscillation effects on their abundances and propose an astrophysical method to determine the unknown neutrino oscillation parameters theta(13) and mass hierarchy., WORLD SCIENTIFIC PUBL CO PTE LTD
FRENCH-JAPANESE SYMPOSIUM ON NUCLEAR STRUCTURE PROBLEMS: ORGANIZED IN THE FRAMEWORK OF FJNSP LIA AND EFES, 2013, [Reviewed]

Effects of power law primordial magnetic field on big bang nucleosynthesis
Dai G. Yamazaki; Motohiko Kusakabe, Big bang nucleosynthesis (BBN) is affected by the energy density of a primordial magnetic field (PMF). For an easy derivation of constraints on models for PMF generations, we assume a PMF with a power law (PL) distribution in wave number defined with a field strength, a PL index, and maximum and minimum scales at a generation epoch. We then show a relation between PL-PMF parameters and the scale invariant (SI) strength of PMF for the first time. We perform a BBN calculation including PMF effects, and show abundances as a function of baryon to photon ratio eta. The SI strength of the PMF is constrained from observational constraints on abundances of He-4 and D. The minimum abundance of Li-7/H as a function of eta slightly moves to a higher Li-7/H value at a larger eta value when a PMF exists during BBN. We then discuss degeneracies between the PL-PMF parameters in the PMF effect. In addition, we assume a general case in which both the existence and the dissipation of PMF are possible. It is then found that an upper limit on the SI strength of the PMF can be derived from a constraint on He-4 abundance, and that a lower limit on the allowed Li-7 abundance is significantly higher than those observed in metal-poor stars. DOI: 10.1103/PhysRevD.86.123006, AMER PHYSICAL SOC
PHYSICAL REVIEW D, Dec. 2012, [Reviewed]

The search for a primordial magnetic field
Dai G. Yamazaki; Toshitaka Kajino; Grant J. Mathews; Kiyotomo Ichiki, Magnetic fields appear wherever plasma and currents can be found. As such, they thread through all scales in Nature. It is natural, therefore, to suppose that magnetic fields might have been formed within the high temperature environments of the big bang. Such a primordial magnetic field (PMF) would be expected to arise from and/or influence a variety of cosmological phenomena such as inflation, cosmic phase transitions, big bang nucleosynthesis, the cosmic microwave background (CMB) temperature and polarization anisotropies, the cosmic gravity wave background, and the formation of large-scale structure. In this review, we summarize the development of theoretical models for analyzing the observational consequences of a PMF. We also summarize the current state of the art in the search for observational evidence of a PMF. In particular, we review the framework needed to calculate the effects of a PMF power spectrum on the CMB and the development of large scale structure. We summarize the current constraints on the PMF amplitude B lambda and the power spectral index n(B) and discuss prospects for better determining these quantities in the near future. (c) 2012 Elsevier B.V. All rights reserved., ELSEVIER SCIENCE BV
PHYSICS REPORTS-REVIEW SECTION OF PHYSICS LETTERS, Aug. 2012, [Reviewed]

Evidence for a Primordial Magnetic Field from the CMB Polarization and Power Spectra
Grant J. Mathews; Dai G. Yamazaki; Kiyotomo Ichiki; Toshitaka Kajino, World Scientific
Proceedings of the MG12 Meeting on General Relativity, Feb. 2012, [Reviewed]

Frontiers of Big Bang Cosmology and Primordial Nucleosynthesis
Grant J. Mathews; Myung-Ki Cheoun; Toshitaka Kajino; Motohiko Kusakabe; Dai G. Yamazaki, We summarize some current research on the formation and evolution of the universe and overview some of the key questions surrounding the the big bang. There are really only two observational cosmological probes of the physics of the early universe. Of those two, the only probe during the relevant radiation dominated epoch is the yield of light elements during the epoch of big bang nucleosynthesis. The synthesis of light elements occurs in the temperature regime from 10(8) to 1010 K and times of about 1 to 10(4) sec into the big bang. The other probe is the spectrum of temperature fluctuations in the CMB which (among other things) contains information of the first quantum fluctuations in the universe, along with details of the distribution and evolution of dark matter, baryonic matter and photons up to the surface of photon last scattering. Here, we emphasize the role of these probes in answering some key questions of the big bang and early universe cosmology., AMER INST PHYSICS
ORIGIN OF MATTER AND EVOLUTION OF GALAXIES 2011, 2012, [Reviewed]

Effects of a primordial magnetic field with log-normal distribution on the cosmic microwave background
Dai G. Yamazaki; Kiyotomo Ichiki; Keitaro Takahashi, We study the effect of primordial magnetic fields (PMFs) on the anisotropies of the cosmic microwave background (CMB). We assume the spectrum of PMFs is described by log-normal distribution which has a characteristic scale, rather than power-law spectrum. This scale is expected to reflect the generation mechanisms and our analysis is complementary to previous studies with power-law spectrum. We calculate power spectra of energy density and Lorentz force of the log-normal PMFs, and then calculate CMB temperature and polarization angular power spectra from scalar, vector, and tensor modes of perturbations generated from such PMFs. By comparing these spectra with WMAP7, QUaD, CBI, Boomerang, and ACBAR data sets, we find that the current CMB data set places the strongest constraint at k10 -2.5Mpc -1 with the upper limit B3nG. © 2011 American Physical Society.
Physical Review D - Particles, Fields, Gravitation and Cosmology, 27 Dec. 2011, [Reviewed]

Effects of a primordial magnetic field with log-normal distribution on the cosmic microwave background
Dai G. Yamazaki; Kiyotomo Ichiki; Keitaro Takahashi, We study the effect of primordial magnetic fields (PMFs) on the anisotropies of the cosmic microwave background (CMB). We assume the spectrum of PMFs is described by log-normal distribution which has a characteristic scale, rather than power-law spectrum. This scale is expected to reflect the generation mechanisms and our analysis is complementary to previous studies with power-law spectrum. We calculate power spectra of energy density and Lorentz force of the log-normal PMFs, and then calculate CMB temperature and polarization angular power spectra from scalar, vector, and tensor modes of perturbations generated from such PMFs. By comparing these spectra with WMAP7, QUaD, CBI, Boomerang, and ACBAR data sets, we find that the current CMB data set places the strongest constraint at k similar or equal to 10(-2.5) Mpc(-1) with the upper limit B less than or similar to 3 nG., AMER PHYSICAL SOC
PHYSICAL REVIEW D, Dec. 2011, [Reviewed]

Constraints on the neutrino mass and the primordial magnetic field　　　　　　　　　　　　　　　
Dai G. Yamazaki; Kiyotomo Ichiki; Toshitaka Kajino; Grant J. Mathews
Annual Report of the National Astronomical Observatory of Japan, Dec. 2011

Primordial Magnetic Field Effects on the CMB and Large-Scale Structure
Dai G. Yamazaki; Kiyotomo Ichiki; Toshitaka Kajino; Grant J. Mathews, Magnetic fields are everywhere in nature, and they play an important role in every astronomical environment which involves the formation of plasma and currents. It is natural therefore to suppose that magnetic fields could be present in the turbulent high-temperature environment of the big bang. Such a primordial magnetic field (PMF) would be expected to manifest itself in the cosmic microwave background (CMB) temperature and polarization anisotropies, and also in the formation of large-scale structure. In this paper, we summarize the theoretical framework which we have developed to calculate the PMF power spectrum to high precision. Using this formulation, we summarize calculations of the effects of a PMF which take accurate quantitative account of the time evolution of the cutoff scale. We review the constructed numerical program, which is without approximation, and an improvement over the approach used in a number of previous works for studying the effect of the PMF on the cosmological perturbations. We demonstrate how the PMF is an important cosmological physical process on small scales. We also summarize the current constraints on the PMF amplitude B. and the power spectral index n(B) which have been deduced from the available CMB observational data by using our computational framework., HINDAWI PUBLISHING CORP
Advances in Astronomy, 03 Dec. 2010, [Reviewed]

Magnetic Field Effects on the CMB and Large-Scale Structure
Dai G. Yamazaki; Kiyotomo Ichiki; Toshitaka Kajino; Grant. J. Mathews, A primordial magnetic field (PMF) would be expected to manifest itself in the cosmic microwave background (CMB) temperature and polarization anisotropies, and also in the formation of large scale structure(LSS). In this article, we demonstrate how the PMF is an important cosmological physical process on small scales as follows, We also report the newest constraints on the PMF amplitude B-lambda and the power spectral index n(B) which have been deduced from the available CMB observational data by using our computational framework and the Markov chain Monte Carlo method. In particular we find that vertical bar B lambda vertical bar < 2.10(68%CL) nG and < 2.98(95%CL) nG and n(B)< -1.19(68%CL) and < -0.25(95%CL) at a present scale of I Mpc., AMER INST PHYSICS
AIP Conference Proceedings, 16 Aug. 2010, [Reviewed]

Constraints on the neutrino mass and the primordial magnetic field from the matter density fluctuation parameter sigma(8)
Dai G. Yamazaki; Kiyotomo Ichiki; Toshitaka Kajino; Grant J. Mathews, We have made an analysis of limits on the neutrino mass based upon the formation of large-scale structure in the presence of a primordial magnetic field. We find that a new upper bound on the neutrino mass is possible based upon fits to the cosmic microwave background and matter power spectrum when the existing independent constraints on the matter density fluctuation parameter sigma(8) and the primordial magnetic field are taken into account., AMER PHYSICAL SOC
PHYSICAL REVIEW D, May 2010, [Reviewed]

An alternative to inflation? Critical role of neutrino anisotropic stress in CMB
T. Kajino; K. Kojima; D. Yamazaki; K. Ichiki; G. J. Mathews, We study the role of anisotropic stress in the evolution of curvature perturbations and the cosmic microwave background (CMB) power spectrum. We found that if the extra anisotropic stress preexisted before the neutrino decoupling, the cancellation of the anisotropic stress of neutrinos and extra anisotropic stress could lead to a spectrum that could reproduce the observed CMB power spectrum. (C) 2010 Elsevier B.V. All rights reserved., ELSEVIER SCIENCE BV
PROGRESS IN PARTICLE AND NUCLEAR PHYSICS, Apr. 2010, [Reviewed]

New constraints on the primordial magnetic field
Dai G. Yamazaki; Kiyotomo Ichiki; Toshitaka Kajino; Grant J. Mathews, We present the newest statistical and numerical analysis of the matter and cosmic microwave background power spectrum with effects of the primordial magnetic field (PMF) included. New limits to the PMF strength and power spectral index are obtained based upon the accumulated data for both the matter and CMB power spectra on small angular scales. We find that a maximum develops in the probability distribution for a magnitude of the PMF of |Bλ|=0. 85±1.25(±1σ)nG on a comoving scale of at 1 Mpc, corresponding to upper limits of <
2.10nG (68% CL) and <
2.98nG (95% CL). While for the power spectral index we find nB=-2.37-0.73+0.88(±1σ), corresponding to upper limits of <
-1.19 (68% CL) and <
-0.25 (95% CL). This result provides new constraints on models for magnetic field generation and the physics of the early universe. We conclude that future observational programs for the CMB and matter power spectrum will likely provide not only upper limits but also lower limits to the PMF parameters. © 2010 The American Physical Society.
Physical Review D - Particles, Fields, Gravitation and Cosmology, 19 Jan. 2010, [Reviewed]

New constraints on the primordial magnetic field
Dai G. Yamazaki; Kiyotomo Ichiki; Toshitaka Kajino; Grant J. Mathews, We present the newest statistical and numerical analysis of the matter and cosmic microwave background power spectrum with effects of the primordial magnetic field (PMF) included. New limits to the PMF strength and power spectral index are obtained based upon the accumulated data for both the matter and CMB power spectra on small angular scales. We find that a maximum develops in the probability distribution for a magnitude of the PMF of vertical bar B-lambda vertical bar = 0.85 +/- 1.25(+/-1 sigma) nG on a comoving scale of at 1 Mpc, corresponding to upper limits of <2.10 nG (68% CL) and <2.98 nG (95% CL). While for the power spectral index we find n(B) = -2.37(-0.73)(+0.88)(+/-1 sigma), corresponding to upper limits of < - 1.19 (68% CL) and < - 0.25 (95% CL). This result provides new constraints on models for magnetic field generation and the physics of the early universe. We conclude that future observational programs for the CMB and matter power spectrum will likely provide not only upper limits but also lower limits to the PMF parameters., AMER PHYSICAL SOC
PHYSICAL REVIEW D, Jan. 2010, [Reviewed]

Primordial Magnetic Field Effects on the CMB and Large-Scale Structure
Dai G. Yamazaki; Kiyotomo Ichiki; Toshitaka Kajino; Grant J. Mathews, Magnetic fields are everywhere in nature, and they play an important role in every astronomical environment which involves the formation of plasma and currents. It is natural therefore to suppose that magnetic fields could be present in the turbulent high-temperature environment of the big bang. Such a primordial magnetic field (PMF) would be expected to manifest itself in the cosmic microwave background (CMB) temperature and polarization anisotropies, and also in the formation of large-scale structure. In this paper, we summarize the theoretical framework which we have developed to calculate the PMF power spectrum to high precision. Using this formulation, we summarize calculations of the effects of a PMF which take accurate quantitative account of the time evolution of the cutoff scale. We review the constructed numerical program, which is without approximation, and an improvement over the approach used in a number of previous works for studying the effect of the PMF on the cosmological perturbations. We demonstrate how the PMF is an important cosmological physical process on small scales. We also summarize the current constraints on the PMF amplitude B. and the power spectral index n(B) which have been deduced from the available CMB observational data by using our computational framework., HINDAWI PUBLISHING CORP
ADVANCES IN ASTRONOMY, 2010, [Reviewed]

Limit of primordial magnetic field from the matter power spectra　　　　　　　　　　　　　　　
Dai G. Yamazaki; Kiyotomo Ichiki; Toshitaka Kajino; Grant J. Mathews
Annual Report of the National Astronomical Observatory of Japan, Dec. 2009

Constraints on the primordial magnetic field from σ8
Dai G. Yamazaki; Kiyotomo Ichiki; Toshitaka Kajino; Grant J. Mathews, A primordial magnetic field (PMF) can affect the evolution of density-field fluctuations in the early universe. In this paper we constrain the PMF amplitude Bλ and power spectral index nB by comparing calculated density-field fluctuations with observational data, i.e. the number density fluctuation of galaxies. We show that the observational constraints on cosmological density fluctuations, as parametrized by σ8, lead to strong constraints on the amplitude and spectral index of the PMF. © 2008 The American Physical Society.
Physical Review D - Particles, Fields, Gravitation and Cosmology, 02 Dec. 2008, [Reviewed]

Constraints on the primordial magnetic field from sigma(8)
Dai G. Yamazaki; Kiyotomo Ichiki; Toshitaka Kajino; Grant J. Mathews, A primordial magnetic field (PMF) can affect the evolution of density-field fluctuations in the early universe. In this paper we constrain the PMF amplitude B-lambda and power spectral index n(B) by comparing calculated density-field fluctuations with observational data, i.e. the number density fluctuation of galaxies. We show that the observational constraints on cosmological density fluctuations, as parametrized by sigma(8), lead to strong constraints on the amplitude and spectral index of the PMF., AMER PHYSICAL SOC
PHYSICAL REVIEW D, Dec. 2008, [Reviewed]

A Strong Constraint on the Neutrino Mass from the Formation of Large Scale Structure in the Presence of the Primordial Magnetic Field　　　　　　　　　　　　　　　
Dai G. Yamazaki; Kiyotomo Ichiki; Toshitaka Kajino; Grant J. Mathews
Proceedings of the 10th Symposium on Nuclei in the Cosmos (NIC X), Dec. 2008, [Reviewed]

Effects of primordial magnetic field and background gravitational wave on low and high multipoles of the cosmic microwave background　　　　　　　　　　　　　　　
Dai G. Yamazaki; Kiyotomo Ichiki; Toshitaka Kajino; Grant J. Mathews
Annual Report of the National Astronomical Observatory of Japan, Dec. 2008

NEUTRINO MASS AND COLD DARK MATTER PARTICLES IN BIG-BANG NUCLEO SYNTHESIS
Toshitaka Kajino; Motohiko Kusakabe; Kazuhiko Kojima; Takashi Yoshida; Dai G. Yamazaki; Kiyotomo Ichiki; Grant J. Mathews, Neutrino is a tiny weakly interacting massive particle, but it has strong impacts on various cosmological and astrophysical phenomena. Neutrinos play a critical role in nucleosynthesis of light-to-heavy mass elements in core-collapse supernovae. The light element synthesis is particularly affected by neutrino oscillation (MSW) effect through the vprocess. We propose first that precise determination of sin(2) 2 theta(13) and mass hierarchy can be made by a theoretical study of the observed Li-7/B-11 ratio in stars and presolar grains which are produced from SN ejecta. Theoretical sensitivity in our proposed method is shown to be superior to ongoing long-baseline neutrino experiments for the parameter region 10(-4) <= Sin(2)2 theta(13) <= 10(-2). We secondly discuss how to constrain the neutrino mass Sigma mv from precise analysis of cosmic microwave background anisotropies in the presence of primordial magnetic field. We obtain an upper limit Sigma m(v) < 1.3eV(2 sigma). Thirdly, we discuss decaying dark-matter particle model in order to solve the primordial lithium problems that the standard Big-Bang nucleosynthesis theory predicts extremely different Li-6 and Li-7 abundances from observations., WORLD SCIENTIFIC PUBL CO PTE LTD
MODERN PHYSICS LETTERS A, Sep. 2008, [Reviewed]

Neutrino mass effects on vector and tensor CMB anisotropies in the presence of a primordial magnetic field
Kazuhiko Kojima; Kiyotomo Ichiki; Dai G. Yamazaki; Toshitaka Kajino; Grant J. Mathews, If a primordial magnetic field (PMF) is present during photon decoupling and afterward, a finite neutrino mass can affect all modes of the CMB. In this work, we expand on earlier studies of the scalar mode effects by constructing the vector and tensor-mode equations in the presence of massive neutrinos and a PMF. We compute the power spectrum of the various modes in an illustrative example and find that the neutrino mass can significantly affect the vector and tensor modes when a PMF exists, while the effects are negligible for no PMF. The most prominent result of the present analysis is the behavior of the EE (grad-like polarization power spectrum) component of the tensor mode at low multipoles. For massive neutrinos the EE mode can become comparable to the observed primary anisotropy. Therefore, if and when the EE mode power spectrum is measured at low multipoles the possibility exists to place a strong constraint on the sum of the neutrino masses. © 2008 The American Physical Society.
Physical Review D, 14 Aug. 2008, [Reviewed]

Neutrino mass effects on vector and tensor CMB anisotropies in the presence of a primordial magnetic field
Kazuhiko Kojima; Kiyotomo Ichiki; Dai G. Yamazaki; Toshitaka Kajino; Grant J. Mathews, If a primordial magnetic field (PMF) is present during photon decoupling and afterward, a finite neutrino mass can affect all modes of the CMB. In this work. we expand on earlier studies of the scalar mode effects by constructing the vector and tensor-mode equations in the presence of massive neutrinos and a PMF. We compute the power spectrum of the various modes in an illustrative example and find that the neutrino mass can significantly affect the vector and tensor modes when a PMF exists. while the effects are negligible for no PMF The most prominent result of the present analysis is the behavior of the EE (grad-like polarization power spectrum) component of the tensor mode at low multipoles. For massive neutrinos the EE mode can become comparable to the observed primary anisotropy. Therefore, if and when the EE mode power spectrum is measured at low multipoles the possibility exists to place a strong constraint on the SUM of the neutrino masses., AMER PHYSICAL SOC
PHYSICAL REVIEW D, Aug. 2008, [Reviewed]

Effects of primordial magnetic field on early universe
Dai G. Yamazaki; Kiyotomo Ichiki; Kajino Toshitaka; Grant J. Mathews, The existence of a primordial magnetic field (PMF) would affect both the temperature and polarization anisotropies of the cosmic microwave background (CMB) and the formation of the large scale structure(LSS). It also provides a plausible explanation for the disparity between observations and theoretical fits to the CMB power spectrum and the LSS. Here we report on calculations of not only the numerical power spectrum of the PMF, but also the correlations between the PMF power spectrum and the primary curvature perturbations., WORLD SCIENTIFIC PUBL CO PTE LTD
MODERN PHYSICS LETTERS A, Jun. 2008, [Reviewed]

Neutrino‐Mass Effects on the CMB Anisotropies in a Cosmological Model with a Primordial Magnetic Field
Kazuhiko Kojima; Dai G. Yamazaki; Toshitaka Kajino, In recent years neutrino oscillation experiments have showed that neutrinos have finite mass. One can determine the neutrino mass from neutrinoless double-beta decay experiments, but the exact mass of neutrinos is still unknown, However, we can also constrain the neutrino mass from a precise analysis of the CMB data, which constrains the mass to be smaller than 2 eV (2 sigma) in a standard Lambda CDM model [1]. In recent studies it has beddn shown that a primordial magnetic field (PMF) exists, and it makes important effects on the CMB anisotropies. In this work, we constrain the total neutrino mass from the CMB anisotropies with the PMF effect. We thus a obtained a smaller upper limit on the neutrino mass, i.e. < 1.3eV(2 sigma). We will also discuss the dependence on the power law spectral index of the PMF and on the vector CMB anisotropies., AMER INST PHYSICS
AIP Conference Proceedings, 30 May 2008, [Reviewed]

Cosmological Constraint on "Neutrino Mass" from CMB Anisotropies with Primordial Magnetic Field
Kazuhiko Kojima; Dai G. Yamazaki; Toshitaka Kajino, World Scientific Publishing Co. Pte. Ltd.
Dark Matter in Astroparticle and Particle Physics,Proceedings of the 6th International Heidelberg Conference, May 2008, [Reviewed]

Effects of Primordial Magnetic Field on CMB and Matter Power Spectrum
Dai G. Yamazaki; Kiyotomo Ichiki; Toshitaka Kajino; Grant J. Mathews, World Scientific Publishing Co. Pte. Ltd.
Dark Matter in Astroparticle and Particle Physics,Proceedings of the 6th International Heidelberg Conference, May 2008, [Reviewed]

Effects of a primordial magnetic field on low and high multipoles of the cosmic microwave background
Dai G. Yamazaki; Kiyotomo Ichiki; Toshitaka Kajino; Grant J. Mathews, The existence of a primordial magnetic field (PMF) would affect both the temperature and polarization anisotropies of the cosmic microwave background (CMB). It also provides a plausible explanation for the possible disparity between observations and theoretical fits to the CMB power spectrum. Here we report on calculations of not only the numerical CMB power spectrum from the PMF, but also the correlations between the CMB power spectrum from the PMF and the primary curvature perturbations. We then deduce a precise estimate of the PMF effect on all modes of perturbations. We find that the PMF affects not only the CMB TT (temperature fluctuation), TE (cross correlation as temperature-E-type polarization) modes on small angular scales, but also on large angular scales. The introduction of a PMF leads to a better fit to the CMB power spectrum for the higher multipoles, and the fit at lowest multipoles can be used to constrain the correlation of the PMF with the density fluctuations for large negative values of the spectral index. Our prediction for the BB (B-type polarization) mode for a PMF average field strength vertical bar B-lambda vertical bar=4.0 nG is consistent with the upper limit on the BB mode deduced from the latest CMB observations. We find that the BB mode is dominated by the vector mode of the PMF for higher multipoles. We also show that by fitting the complete power spectrum one can break the degeneracy between the PMF amplitude and its power spectral index., AMER PHYSICAL SOC
PHYSICAL REVIEW D, Feb. 2008, [Reviewed]

Effects of The Primordial Magnetic Field on The CMB
Dai G. Yamazaki; Kiyotomo Ichiki; Toshitaka Kajino; Grant. J. Mathews, The existence of a primordial magnetic field (PMF) would affect both the temperature and polarization anisotropies of the cosmic microwave background (CMB). It also provides a plausible explanation for the disparity between observations and theoretical fits to the CMB power spectrum. Here we report on calculations of not only the numerical power spectrum of the PMF, but also the correlations between the PMF power spectrum and the primary curvature perturbations., AMER INST PHYSICS
AIP Conference Proceedings, 26 Nov. 2007

The effect of primordial magnetic field on the early universe　　　　　　　　　　　　　　　
Dai G. Yamazaki, University of Tokyo
Mar. 2007, [Reviewed]

Effect of primordial magnetic field on seeds for large scale structure
Dai Great Yamazaki; Kiyotomo Ichiki; Ken-ichi Umezu; Hidekazu Hanayama, Magnetic field plays a very important role in many astronomical phenomena at various scales of the universe. It is no exception in the early universe. Since the energy density, pressure, and tension of the primordial magnetic field affect gravitational collapses of plasma, the formation of seeds for large-scale structures should be influenced by them. Here we numerically investigate the effects of stochastic primordial magnetic field on the seeds of large-scale structures in the universe in detail. We found that the amplitude ratio between the density spectra with and without PMF (vertical bar P(k)/P-0(k)vertical bar at k > 0.2 Mpc(-1)) lies between 75% and 130% at present for the range of PMF strengths 0.5nG < B-lambda < 1.0nG, depending on the spectral index of PMF and the correlation between the matter density and the PMF distributions., AMER PHYSICAL SOC
PHYSICAL REVIEW D, Dec. 2006, [Reviewed]

Constraints on the evolution of the primordial magnetic field from the small-scale cosmic microwave background angular anisotropy
D. G. Yamazaki; K. Ichiki; T. Kajino; G. J. Mathews, Recent observations of the cosmic microwave background (CMB) have extended the measured power spectrum to higher multipoles l greater than or similar to 1000, and there appears to be possible evidence for excess power on small angular scales. The primordial magnetic field (PMF) can strongly affect the CMB power spectrum and the formation of large-scale structure. In this paper, we calculate the CMB temperature anisotropies generated by including a power-law magnetic field at the photon last-scattering surface (PLSS). We then deduce an upper limit on the PMF based on our theoretical analysis of the power excess on small angular scales. We have taken into account several important effects such as the modified matter sound speed in the presence of a magnetic field. An upper limit to the field strength of vertical bar B lambda vertical bar less than or similar to 4.7 nG at the present scale of 1 Mpc is deduced. This is obtained by comparing the calculated theoretical result including the Sunyaev-Zeldovich (SZ) effect with recent observed data on the small-scale CMB anisotropies from the Wilkinson Microwave Anisotropy Probe (WMAP), the Cosmic Background Imager (CBI), and the Arcminute Cosmology Bolometer Array Receiver (ACBAR). We discuss several possible mechanisms for the generation and evolution of the PMF., UNIV CHICAGO PRESS
ASTROPHYSICAL JOURNAL, Aug. 2006, [Reviewed]

Primordial magnetic field constrained from CMB anisotropies,and its generation and evolution before, during and after the BBN　　　　　　　　　　　　　　　
Dai G. Yamazaki; Kiyotomo Ichiki; Toshitaka Kajino; Grant J. Mathews
Proceedings of the International Symposium on Nuclear Astrophysics - Nuclei in the Cosmos - IX, 2006, [Reviewed]

Constraint of Cosmological Magnetic Field from Likelihood Analysis　　　　　　　　　　　　　　　
D. G. Yamazaki; K. Ichiki; T. Kajino and G. J. Mathews
Inflating horizons of particle astrophysics and cosmology: proceedings of the Yamada Conference LIX, held on June 20-24, 2005 in Tokyo, Japan ,Frontiers Science Series, 2006, [Reviewed]

Primordial magnetic field at the photon last scattering surface
DG Yamazaki; K Ichiki; T Kajino, We construct the original method and numerical code to calculate the effects of magnetic field on CMB at the last scattering surface (LSS). In order to investigate the specific nature of the magnetic field effects on the CMB, we compare our calculated perturbation and the WMAP data., ELSEVIER SCIENCE BV
NUCLEAR PHYSICS A, Jul. 2005, [Reviewed]

Constraining the primordial magnetic field from cosmic microwave background anisotropies at higher multipoles
D. G. Yamazaki; K. Ichiki; T. Kajino, The cosmological magnetic field is one of the important physical quantities that strongly affect the cosmic microwave background (cmb) power spectrum. Recent cmb observations have been extended to higher multipoles (l ≳ 1000), and they resultantly exhibit an excess power that is more than the standard model prediction in cosmological theory that best fits the wilkinson microwave anisotropy probe (wmap) data at lower multipoles (l ≲ 900). We calculate the cmb temperature anisotropies generated by the power-law magnetic field at the last scattering surface in order to remove the tension between theory and observation at higher multipoles and also to place an upper limit on the primordial magnetic field. In our present calculation we take account of the effect of the ionization ratio, without approximation. This effect is very crucial to precisely estimating the effect of the magnetic field on the cmb power spectrum. We consider effects of both the scalar and vector modes of the magnetic field on the cmb anisotropies, for which current data are known to be insensitive to the tensor mode, which we ignore in the present study. In order to constrain the primordial magnetic field, we evaluate the likelihood function of the wmap data in a wide range of parameters of the magnetic field strength |b|λ and the power-law spectral index nb, along with six cosmological parameters in flat universe models, using the technique of the markov chain monte carlo method. We find that the upper limit at the 2 σ confidence level turns out to be |bλ| ≳ 3.9 ng at 1 mpc for any nb-values, which is obtained by comparing the calculated result, including the sunyaev-zeldovich effect, with recent wmap data of the cmb anisotropies. © 2005. The american astronomical society. All rights reserved., Institute of Physics Publishing
Astrophysical Journal, 20 May 2005, [Reviewed]

Effects of magnetic field on cosmic microwave background at the photon's last scattering　　　　　　　　　　　　　　　
Dai G. Yamazaki, University of Tokyo
Mar. 2004, [Reviewed]

シリーズ：ソフトウェア紹介 CosmoMC（Antony Lewis & Sarah Bridle）　　　　　　　　　　　　　　　
山崎 大
2012年10月号, 20 Sep. 2012, [Invited]

〔Major achievements〕大学で学ぶ力学の基礎 数学的基礎から仕事まで　　　　　　　　　　　　　　　
山崎大, Single work
学術図書出版社, May 2024
9784780690286

数理解析への「微分積分の基礎」　　　　　　　　　　　　　　　
数理解析への; 微分積分の基礎; 編集委員会; 月から同委員, Joint editor
学術図書出版社, 20 Dec. 2013

「大学生のための力と運動の基礎」　　　　　　　　　　　　　　　
茨城大学力学教科書; 月から同委員, Joint editor
培風館, 14 Apr. 2011

〔Major achievements〕天文学・宇宙物理学に関するリベラルアーツにおける科学リテラシー知見獲得効果と授業・教材作成指針　　　　　　　　　　　　　　　
山崎大
日本天文学会2024年春季年会, Mar. 2024
20240311, 20240315

天文学・宇宙物理学の自然科学教養授業における科学リテラシーに関する知見獲得効果について　　　　　　　　　　　　　　　
山崎大
日本天文学会2023年秋季年会, Sep. 2023

〔Major achievements〕天文学・宇宙物理学のリベラルアーツ教育の疑似科学に対する知見獲得効果について　　　　　　　　　　　　　　　
山崎大 (茨城大学)
日本天文学会2022年秋季年会, 13 Sep. 2022

〔Major achievements〕Constraints on primordial magnetic fields with energy density　　　　　　　　　　　　　　　
山崎大 (茨城大学)
日本天文学会2021年秋季年会, 15 Sep. 2021

ビッグバンから宇宙の晴れ上がりまでの連続性を考慮したパラメータ制限　　　　　　　　　　　　　　　
山崎大; 国立天文台; 日下部元彦; 梶野敏貴; 北京航空航
日本天文学会2020年秋季年会, 09 Sep. 2020

宇宙論における磁場の制限
山崎 大
日本SKAサイエンス会議「宇宙磁場」2019, 22 Nov. 2019

原初磁場と有質量ニュートリノの弱重力レンズ効果に対する影響の考察　　　　　　　　　　　　　　　
日本天文学会2019年秋季年会, 13 Sep. 2019

宇宙論的観測による原初磁場制限の現状　　　　　　　　　　　　　　　
山崎 大
第７回観測的宇宙論ワークショップ, 13 Nov. 2018

原初磁場の制限における問題点　　　　　　　　　　　　　　　
山崎 大
日本天文学会2018年秋季年会, Sep. 2018

CMB weak lensing with the primordial magnetic field
Dai G. Yamazaki
IAU Focus Meeting FM8: New Insights in Extragalactic Magnetic Fields, 29 Aug. 2018

CMB weak lensing with a primordial magnetic field　　　　　　　　　　　　　　　
Dai G. Yamazaki
International Symposium on Cosmology and Particle Astrophysics (CosPA) 2017, 14 Dec. 2017

CMB B mode による原初磁場の制限について　　　　　　　　　　　　　　　
山崎 大
日本天文学会2017年秋季年会, Sep. 2017

Weak lensing effect と CMB 偏光揺らぎに対する原初磁場の影響　　　　　　　　　　　　　　　
山崎 大
日本天文学会2017年春季年会, Mar. 2017

宇宙膨張に対する原初磁場の影響を考慮した宇宙背景放射と物質密度進化　　　　　　　　　　　　　　　
山崎 大
新学術領域「なぜ宇宙は加速するのか？- 徹底的究明と将来への挑戦-」シンポジウム, Mar. 2017

The new BBN model with the photon cooling, X particle, and the primordial magnetic field　　　　　　　　　　　　　　　
Dai G. Yamazaki
14th International Symposium on Nuclei in the Cosmos XIV, Jun. 2016

The B mode with a primordial magnetic field　　　　　　　　　　　　　　　
Dai G. Yamazaki
B mode from Space, Dec. 2015

複合ビッグバン元素合成モデルの検証　　　　　　　　　　　　　　　
山崎 大
理論懇シンポジウム2015, Dec. 2015

原初磁場を考慮した大規模構造形成　　　　　　　　　　　　　　　
日本天文学会2015年秋季年会, Sep. 2015

宇宙磁場を考慮した大規模構造形成　　　　　　　　　　　　　　　
山崎 大
SKA-Japanワークショップ2015, Mar. 2015

宇宙背景放射偏光揺らぎと原初磁場　　　　　　　　　　　　　　　
山崎 大
日本天文学会2015年春季年会, Mar. 2015

原初磁場を考慮したビッグバン元素合成　　　　　　　　　　　　　　　
山崎 大
日本天文学会2014年春季年会, Mar. 2014

Multi-lognormal magnetic field limits from the cosmic microwave background　　　　　　　　　　　　　　　
Dai G. Yamazaki
PASCOS2013, 2013

Constraint on the multi lognormal magnetic field from the CMB　　　　　　　　　　　　　　　
Dai G. Yamazaki
CMB2013, 2013

Constraint on the multi lognormal magnetic field　　　　　　　　　　　　　　　
Dai G. Yamazaki
SKA Science Workshop in East Asia 2013, 2013

Magnetic Field Effects on the CMB and Large-Scale Structure　　　　　　　　　　　　　　　
Dai G. Yamazaki
OMEG10, 2010

Dark energy, Finite-mass Neutrino, and Primordial Magnetic Field　　　　　　　　　　　　　　　
Dai G. Yamazaki
IPMU International Conference, dark energy: lighting up the darkness!, 2009

A Strong Constraint on the Neutrino Mass from the Formation of Large Scale Structure in the Presence of the Primordial Magnetic Field　　　　　　　　　　　　　　　
Dai G. Yamazaki
The 10th International Symposium on Nuclei in the Cosmos, 2008

A Strong Constraint on the Neutrino Mass from the Formation of Large Scale Structure in ,the Presence of the Primordial Magnetic Field　　　　　　　　　　　　　　　
Dai G. Yamazaki
The 10th International Symposium on Nuclei in the Cosmos, 2008

Effects of Primordial Magnetic Field on Early Universe　　　　　　　　　　　　　　　
Dai G. Yamazaki
International Symposium on Cosmology and Particle Astrophysics, 2007, [Invited]

Effects of Primordial Magnetic Field on CMB and Density Field　　　　　　　　　　　　　　　
Dai G. Yamazaki
Sixth International Heidelberg conference on DARK MATTER IN ASTRO and ,PARTICLE PHYSICS, 2007

Effects of The Primordial Magnetic Field on The CMB　　　　　　　　　　　　　　　
Dai G. Yamazaki
13th International Symposium on Particle, String and Cosmology, 2007

Primordial magnetic field constrained from CMB anisotropies, and its generation and evolution before, during and after the BBN　　　　　　　　　　　　　　　
Dai G. Yamazaki
The 9th International Symposium on Nuclei in the Cosmos, 2006

Effect of Primordial Magnetic field on Large Scale Structure　　　　　　　　　　　　　　　
Dai G. Yamazaki
East Asian Young Astronomers Meeting 2006, 2006

Primordial magnetic field constrained from CMB anisotropies, and its generation and ,evolution before, during and after the BBN　　　　　　　　　　　　　　　
Dai G. Yamazaki
The 9th International Symposium on Nuclei in the Cosmos, 2006

Constraining Primordial Magnetic Field from CMB　　　　　　　　　　　　　　　
Dai G. Yamazaki
World of year physics 2005 Nonlinear Cosmology: Turbulence and Fields, 2005, [Invited]

The Primordial magnetic field and the Cosmic Microwave Background　　　　　　　　　　　　　　　
Dai G. Yamazaki
COSMO-05 International Workshop on Particle Physics and the Early Universe, 2005

Constraint of Cosmological Magnetic Field from Likelihood Analysis　　　　　　　　　　　　　　　
Dai G. Yamazaki
The 59th Yamada conference, Inflating Horizon of Particle Astrophysics and Cosmology, 2005

Constrains of The Primordial Magnetic Field by CMB for Higher Multipole l　　　　　　　　　　　　　　　
Dai G. Yamazaki
COSMO-04 International Workshop on Particle Physics and the Early Universe, 2004

Primordial Magnetic Field at the Photon Last Scattering Surface　　　　　　　　　　　　　　　
Dai G. Yamazaki
The 8th International Symposium on Nuclei in the Cosmos, 2004

The Primordial Magnetic Field and Cosmic Microwave Background　　　　　　　　　　　　　　　
Dai G. Yamazaki
East Asian Young Astronomers Meeting 2003, 2003

Primordial Magnetic Field and CMB　　　　　　　　　　　　　　　
Dai G. Yamazaki
The 1st Yamada Symposium on Neutrinos and Dark Matter in Nuclear Physics, 2003

Sep. 2010, Japan SKA Consortium

Apr. 2003, The Astronomical Society of Japan

〔Major achievements〕原初磁場を考慮した複合ビッグバン元素合成モデルの展開　　　　　　　　　　　　　　　
若手研究(B)
Apr. 2016 - Mar. 2019

〔Major achievements〕原初磁場を考慮した宇宙論・宇宙物理学の展開　　　　　　　　　　　　　　　
Grant-in-Aid for Young Scientists(B)
Apr. 2013 - Mar. 2016

〔Major achievements〕令和5年度 北関東三大学教育FD～三大学連携教育検討プラットフォーム講演会①「数学・物理学の基礎教育におけるオンライン教材の作成と活用方法」【オンライン教材作成方法紹介】　　　　　　　　　　　　　　
appearance
08 Mar. 2024

〔Major achievements〕令和4年度 北関東三大学教育FD～三大学連携教育検討プラットフォーム講演会①「数学・物理学教育におけるオンライン教材開発の現状と活用」　　　　　　　　　　　　　　
appearance
03 Mar. 2023

宇宙論史I(リカレント教育プログラム)　　　　　　　　　　　　　　
lecturer
Oct. 2022

平成30年度国立大学教養教育実施組織会議 事例報告 「茨城大学 “科学の基礎 質問室”」　　　　　　　　　　　　　　
informant
国立大学教養教育実施組織, 平成30年度国立大学教養教育実施組織会議, 08 Jun. 2018 - 08 Jun. 2018