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DOE OSTI2023

Finding Peas in the Early Universe with JWST

The Early Release Observations (EROs) of JWST beautifully demonstrate the promise of JWST in characterizing the universe at Cosmic Dawn. We analyze the Near Infrared Spectrograph ERO spectra of three z ~ 8 galaxies to determine their metallicities, gas temperatures, and ionization. These galaxies offer the first opportunity to understand the physical properties of Epoch-of-Reionization galaxies through detailed rest-optical emission-line spectroscopy. We show that these objects have metal abundances $12+\mathrm{log}[{\rm{O}}/{\rm{H}}]\,\approx$ 6.9–8.3, based on both the T e method and on a recent calibration of the R 23 metallicity indicator. Since the spectra are some of the earliest science data from JWST, we compare several line ratios with values expected from robust physics, to validate our measurement procedures. We compare the abundances and emission-line ratios to a nearby sample of Green Pea galaxies—a population of nearby emission-line galaxies whose UV properties resemble Epoch-of-Reionization galaxies, and which often have large Lyman continuum escape fractions. The JWST data show striking further similarities between these high-redshift galaxies and nearby Green Peas. The z ~ 8 galaxies span the metallicity range covered by Green Peas. They also show the compact morphology that is typical of emission-line-dominated galaxies at all redshifts. Based on these similarities with Green Peas, it is likely that these are the first rest-optical spectra of galaxies that are actively driving cosmological reionization.

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2023

Dark matter and dark radiation from the early universe with a modulus coupled to the PQMSSM

The supersymmetrized DFSZ axion model is especially compelling in that it contains 1. the SUSY solution to the gauge hierarchy problem, 2. the Peccei-Quinn (PQ) solution to the strong CP problem and 3. the Kim-Nilles solution to the SUSY μ problem. In a string setting, where a discrete R-symmetry ($Z$$^{R}_{24}$ for example) may emerge from the compactification process, a high-quality accidental axion (accion) can emerge from the accidental, approximate remnant global U(1) PQ symmetry where the decay constant f a is linked to the SUSY breaking scale, and is within the cosmological sweet zone. In this setup, one also expects the presence of stringy remnant moduli fields Φ i . Here, we consider the situation of a single light modulus Φ coupled to the PQMSSM in the early universe, with mixed axion plus higgsino-like WIMP dark matter. We evaluate dark matter and dark radiation production via nine coupled Boltzmann equations and assess the severity of the cosmological moduli problem (CMP) along with dark matter and dark radiation production rates. We find that typically the light modulus mass should be m Φ ≳ 10 4 TeV to avoid the moduli-induced dark matter overproduction problem. If one is able to (anthropically) tune the modulus field amplitude, we find a value of Φ 0 ≲ 10 –7 m P would be required to solve the overall CMP.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

NASA NTRS2010

The Origin of Dust in the Early Universe

In this talk I will describe the origin of dust in the early universe. I will be presenting observations of the spectral energy distribution of the galaxy J1148+5251, and present estimates of the dust mass in this high redshift (z=6.4) object. I will then discuss the origin of this dust, and the role of SN and AGB stars as dust sources, and the effect of SNRs on the destruction of dust in the interstellar medium of this galaxy.

Dwek, Eliahu↗

NASA NTRS2011

The Origin of Dust in the Early Universe

Dwek, Eli↗

DOE OSTI2022

Detection of early-universe gravitational-wave signatures and fundamental physics

Detection of a gravitational-wave signal of non-astrophysical origin would be a landmark discovery, potentially providing a significant clue to some of our most basic, big-picture scientific questions about the Universe. In this white paper, we survey the leading early-Universe mechanisms that may produce a detectable signal—including inflation, phase transitions, topological defects, as well as primordial black holes—and highlight the connections to fundamental physics. We review the complementarity with collider searches for new physics, and multimessenger probes of the large-scale structure of the Universe.

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2022

Light Relics of the Early Universe (Final Technical Report)

The research supported by this award invested two types of signals left over of the early universe that might be observed in maps of the universe: (i) particles produced (thermal relics) during the hot big bang and (ii) signals left in the seeds of structure left from from an inflationary epoch prior to the hot big bang (inflationary relics). The research into thermal relics exposed new signatures of the cosmic neutrino background in the distribution of galaxies, culminating in the first measurement of the neutrino induced phase shift of the baryon acoustic oscillations. Subsequent research explored implications of constraints on hot light particles from the cosmic microwave background and the large scale structure for the physics of dark matter. Green and collaborations also investigated cosmological signatures from the inflationary epoch, including the best constraint to date on oscillatory features in seeds of structure and the first viable proposal to test the quantum origin of structure in the universe.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2026

Extremely Metal-poor Galaxies in DESI DR1: Connections to Galaxies in the Early Universe

Extremely metal-poor galaxies (XMPGs), defined as having metallicities below 10% of the solar value, are considered possible local analogs to primordial systems and offer a unique window into early galaxy evolution. This study presents a large-scale search for XMPGs using data from the Dark Energy Spectroscopic Instrument Data Release 1, systematically evaluating their resemblance to high-redshift galaxies. From a parent sample of more than 14 million galaxies, we identify 662 (556 new) confirmed XMPGs and 763 (666 new) high-quality candidates via the direct T$_{e}$ method. Our results reveal that XMPGs follow a distinct star-forming main sequence (SFMS) that is elevated and shallower than that of the comparing star-forming galaxies. Notably, at higher stellar masses (M$_{⋆}$ > 10$^{7.5}$M$_{⊙}$), the XMPG SFMS converges with the sequence observed in high-redshift galaxies by the James Webb Space Telescope, indicating that mature XMPGs sustain star formation rates comparable to their primordial counterparts. Furthermore, XMPGs consistently deviate below the local fundamental metallicity relation, mirroring high-redshift galaxy behavior. These findings demonstrate that XMPGs not only exhibit low metallicities but also preserve scaling relations characteristic of the early Universe, confirming their potential value as local laboratories for studying early galaxy formation processes.

Sui, Jipeng [Beijing Observ.; Beijing, GUCAS] (ORC↗

NASA NTRS1994

Squeezed states and graviton-entropy production in the early universe

Squeezed states are a very useful framework for the quantum treatment of tensor perturbations (i.e. gravitons production) in the early universe. In particular, the non equilibrium entropy growth in a cosmological process of pair production is completely determined by the associated squeezing parameter and is insensitive to the number of particles in the initial state. The total produced entropy may represent a significant fraction of the entropy stored today in the cosmic blackbody radiation, provided pair production originates from a change in the background metric at a curvature scale of the Planck order. Within the formalism of squeezed thermal states it is also possible to discuss the stimulated emission of gravitons from an initial thermal bath, under the action of the cosmic gravitational background field. We find that at low energy the graviton production is enhanced, if compared with spontaneous creation from the vacuum; as a consequence, the inflation scale must be lowered, in order not to exceed the observed CMB quadrupole anisotropy. This effect is important, in particular, for models based on a symmetry-breaking transition which require, as initial condition, a state of thermal equilibrium at temperatures higher than the inflation scale and in which inflation has a minimal duration.

Giovannini, Massimo↗

NASA NTRS1976

Inhomogeneities in the early universe

The paper investigates certain nonlinear processes that are viable candidates for the mechanisms which produced large-scale inhomogeneities in the early Universe. Several nonlinear Lagrangians are presented for matter, the Korteweg-de Vries equation is analyzed, and the existence of solitons among its solutions is noted. A model based on the possibility of generating a cascade of solitons from an initial perturbation is proposed, and it is shown how large-scale inhomogeneities can be generated when an initial soliton fragments into many others through the nonlinear action of the terms in the Korteweg-de Vries equation. A second model is examined which is based on the interaction of matter with a strong radiation field (an almost monochromatic photon gas) and which involves changes in the refractive index of the vacuum. It is found that matter and radiation will not mix if the radiation field has a nonuniform intensity and that the matter will separate into dense portions or 'cosmological protogalaxies'. The evolution of these portions of matter is studied, and it is found that conditions would be appropriate for the interface between them and the surrounding radiation field to become unstable, giving rise to a turbulent layer.

Canuto, V.↗

DOE OSTI2025

Lepton flavor asymmetries: from the early Universe to BBN

Large primordial lepton flavor asymmetries with almost vanishing total baryon-minus-lepton number can evade the usual BBN and CMB constraints if neutrino oscillations lead to perfect flavor equilibration. Solving the momentum averaged quantum kinetic equations (QKEs) describing neutrino oscillations and interactions, we perform the first systematic investigation of this scenario, uncovering a rich flavor structure in stark contradiction to the assumption of simple flavor equilibration. We find (i) a particular direction in flavor space, ∆ne ≃ – 2/3 (– 1)∆n μ for normal (inverted) neutrino mass hierarchy, in which the flavor equilibration is efficient and primordial asymmetries are essentially unconstrained, (ii) a minimal washout factor, ∆$n_{e}^{2}$| BBN ≤ 0.03 (0.016) ∑ α ∆$n_{α}^{2}$| ini yielding a conservative estimate for the allowed primordial asymmetries in a generic flavor direction, and (iii) particularly strong or weak washout if one of the initial flavor asymmetries vanishes due to non-adiabatic muon- or electron-driven MSW transitions. These results open up the possibility of a first-order QCD phase transition facilitated by large lepton asymmetries as well as baryogenesis from large and compensated ∆n e = ∆n μ asymmetries. Our systematic approach of deriving momentum averaged QKEs includes collision terms beyond the damping approximation, energy transfer between the neutrino and electron-photon plasma, and provides a fast and reliable way to investigate the impact of primordial lepton asymmetries at the time of BBN. We publicly release the Mathematica code COFLASY-M on https://github.com/mariofnavarro/COFLASY which solves the QKEs numerically.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

NASA NTRS2001

Probing the Early Universe with the SZ Effect

The Cosmic Microwave Background Radiation (CMBR) which we observe today is relic radiation which last interacted with matter more than 10 billion years ago, when the expanding universe cooled to the point that free electrons and ionized nuclei recombined to form atoms. Prior to recombination, scattering between photons and free electrons was a very frequent occurrence, and the distance light could penetrate was small; afterwards, with free electrons out of circulation, the universe became largely transparent to light. Thus, the CMBR photons we observe today give us a clear view of the state of the early universe. Measured deviations in the intensity of the CMBR trace the small perturbations in the primordial matter density, which have been amplified by gravitational forces to form the magnificent, complex structures which comprise the present-day universe.

Joy, M. K.↗

NASA NTRS1968

Baryon inhomogeneity in the early universe.

Matter excess over antimatter in early high density high temperature universe, discussing baryon inhomogeneity

Harrison, E. R.↗

NASA NTRS2011

First Detections of the [NII] 122 Micrometer Line at High Redshift: Demonstrating the Utility of the Line for Studying Galaxies in the Early Universe

We report the first detections of the [NIl] 122 {\mu} m line from a high redshift galaxy. The line was strongly (> 6{\sigma}) detected from SMMJ02399-0136, and HI413+ 117 (the Cloverleaf QSO) using the Redshift(z) and Early Universe Spectrometer (ZEUS) on the CSO. The lines from both sources are quite bright with line-to-FIR continuum luminosity ratios that are approx.7.0x10(exp -4) (Cloverleaf) and 2.1x10(exp -3) (SMMJ02399). With ratios 2-10 times larger than the average value for nearby galaxies, neither source exhibits the line-to-continuum deficits seen in nearby sources. The line strengths also indicate large ionized gas fractions, approx.8 to 17% of the molecular gas mass. The [OIII]/[NII] line ratio is very sensitive to the effective temperature of ionizing stars and the ionization parameter for emission arising in the narrow-line region (NLR) of an AGN. Using our previous detection of the [01II] 88 {\mu}m line, the [OIII]/ [NIl] line ratio for SMMJ02399-0136 indicates the dominant source of the line emission is either stellar HII regions ionized by 09.5 stars, or the NLR of the AGN with ionization parameter 10g(U) = -3.3 to -4.0. A composite system, where 30 to 50% of the FIR lines arise in the NLR also matches the data. The Cloverleaf is best modeled by a superposition of approx.200 M82like starbursts accounting for all of the FIR emission and 43% of the [NIl] line. The remainder may come from the NLR. This work demonstrates the utility of the [NIl] and [OIII] lines in constraining properties of the ionized medium.

Ferkinhoff, Carl↗

NASA NTRS1988

Magnetically induced neutrino oscillations and neutrino refractive effects in the early universe

The interrelation between hypothetical neutrino magnetic dipole moments (MDMs) and primeval magnetic fields is discussed. The parameter range over which these possibilities are mutually exclusive is determined, taking into account for the first time neutrino refractive effects in the early universe. It is shown that an independent determination of either the neutrino MDMs or the primeval magnetic field strength would set powerful bounds on the other quantity.

Fukugita, Masataka↗

NASA NTRS2011

First Detections of the [N II] 122 micron Line at High Redshift: Demonstrating the Utility of the Line for Studying Galaxies in the Early Universe

We report the first detections of the [N II] 122 micron line from a high-redshift galaxy. The line was strongly (>6(sigma)) detected from SMMJ02399-0136, and H1413 + 117 (the Cloverleaf QSO) using the Redshift (zeta) and Early Universe Spectrometer on the Caltech Submillimeter Observatory. The lines from both sources are quite bright with line to far-infrared (FIR) continuum luminosity ratios that are approx.7.0 x 10(exp -4) (Cloverleaf) and 2.1 x 10(exo -3) (SMMJ02399). With ratios 2-10 times larger than the average value for nearby galaxies, neither source exhibits the line to continuum deficits seen in nearby sources. The line strengths also indicate large ionized gas fractions, approx.8%-17% of the molecUlar gas mass. The [O III]/[N II] line ratio is very sensitive to the effective temperature of ionizing stars and the ionization parameter for emission arising in the narrow-line region (NLR) of an active galactic nucleus (AGN). Using Our previous detection of the [O III] 88 micron line, the [O III]/[N II]line ratio for SMMJ02399-0136 indicates that the dominant source of the line emission is either stellar H II regions ionized by O9.5 stars, or the NLR of the AGN with ionization parameter log(U) = -3.3 to -4.0. A composite system, where 30%-50% of the FIR lines arise in the NLR also matches the data. The Cloverleaf is best modeled by a superposition of approx.200 M82-like starbursts accounting for all of the FIR emission and 43% of the [N II]line. The remainder may come from the NLR. This war!< demonstrates the utility of the [N II] and [O III] lines in constraining properties of the ionized medium.

Ferkinhoff, Carl↗

NASA NTRS2013

Energy Feedback from X-ray Binaries in the Early Universe

X-ray photons, because of their long mean-free paths, can easily escape the galactic environments where they are produced, and interact at long distances with the intergalactic medium, potentially having a significant contribution to the heating and reionization of the early universe. The two most important sources of X-ray photons in the universe are active galactic nuclei (AGNs) and X-ray binaries (XRBs). In this Letter we use results from detailed, large scale population synthesis simulations to study the energy feedback of XRBs, from the first galaxies (z (redshift) approximately equal to 20) until today.We estimate that X-ray emission from XRBs dominates over AGN at z (redshift) greater than or approximately equal to 6-8. The shape of the spectral energy distribution of the emission from XRBs shows little change with redshift, in contrast to its normalization which evolves by approximately 4 orders of magnitude, primarily due to the evolution of the cosmic star-formation rate. However, the metallicity and the mean stellar age of a given XRB population affect significantly its X-ray output. Specifically, the X-ray luminosity from high-mass XRBs per unit of star-formation rate varies an order of magnitude going from solar metallicity to less than 10% solar, and the X-ray luminosity from low-mass XRBs per unit of stellar mass peaks at an age of approximately 300 Myr (million years) and then decreases gradually at later times, showing little variation for mean stellar ages 3 Gyr (Giga years, or billion years). Finally, we provide analytical and tabulated prescriptions for the energy output of XRBs, that can be directly incorporated in cosmological simulations.

galaxies↗

DOE OSTI2023

Interplay of quantum information, thermodynamics, and gravity in the early Universe

Our interdisciplinary proposal brought together a unique team of researchers to tackle foundational questions on the quantum origins of the Universe and out-of-equilibrium quantum systems in general. The specific goals of our proposal were as follows. First, to develop a self-consistent quantum mechanical framework for the early Universe using an open system approach, with focus on non-Markovian vs. Markovian evolution of system modes and signatures in late-time observables. Second, to explore the use of quantum resource theory and thermodynamics techniques to understand the initial conditions of the Universe. Third, to in vestigate open quantum system dynamics in strongly-coupled qubit and oscillator systems, with focus on non-Markovian evolution, entanglement dynamics, and quantum backaction, including experimental real izations and implications for gravity. And fourth, to establish thermodynamics for chaotic quantum systems, with emphasis on dynamics of information scrambling and implications for black hole solutions in AdS/CFT and quantum gravity.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

NASA NTRS1987

Early-universe thermal production of not-so-invisible axions

It is found that, for Peccei-Quinn symmetry-breaking scales of less than about 4 x 10 to the 8th GeV (corresponding to axion masses of greater than about 0.03 eV) thermal production of axions in the early universe (via the Primakoff and photoproduction processes) dominates coherent production by a factor of about 1200/m sub a/(1 eV)/ exp 2.175. The photon luminosity from the decays of these relic axions leads to an upper limit to the axion mass of order 2-5 eV. If the axion mass saturates this bound, relic axion decays may well be detectable.

Turner, Michael S.↗