Cosmic Time Research Articles

Different higher order kinematics between star-forming and quiescent galaxies based on the SAMI, MAGPI, and LEGA-C surveys

ABSTRACT We present the first statistical study of spatially integrated non-Gaussian stellar kinematics spanning 7 Gyr in cosmic time. We use deep, rest-frame optical spectroscopy of massive galaxies (stellar mass $M_\star \gt 10^{10.5} \, \mathrm{M_\odot }$) at redshifts z = 0.05, 0.3, and 0.8 from the SAMI, MAGPI, and LEGA-C surveys, to measure the excess kurtosis h4 of the stellar velocity distribution, the latter parametrized as a Gauss–Hermite series. We find that at all redshifts where we have large enough samples, h4 anticorrelates with the ratio between rotation and dispersion, highlighting the physical connection between these two kinematic observables. In addition, and independently from the anticorrelation with rotation-to-dispersion ratio, we also find a correlation between h4 and M⋆, potentially connected to the assembly history of galaxies. In contrast, after controlling for mass, we find no evidence of independent correlation between h4 and aperture velocity dispersion or galaxy size. These results hold for both star-forming and quiescent galaxies. For quiescent galaxies, h4 also correlates with projected shape, even after controlling for the rotation-to-dispersion ratio. At any given redshift, star-forming galaxies have lower h4 compared to quiescent galaxies, highlighting the link between kinematic structure and star-forming activity.

On the origin of the evolution of the halo occupation distribution

ABSTRACT We use the TNG300 magnetohydrodynamic simulation and mock catalogues built using subhalo abundance matching (SHAM) to study the origin of the redshift evolution of the halo occupation distribution (HOD). We analyse stellar-mass selected galaxy samples with fixed number densities, spanning the redshift range 0 ≤ z ≤ 3. We measure their halo occupation functions and fit the HOD parameters to study their evolution over cosmic time. The TNG300 galaxy population strongly depends on the baryonic physics implemented in the simulation. In contrast, the galaxy population predicted by a basic SHAM model without scatter is a direct result of the cosmology of the dark matter simulation. We find that the HOD evolution is similar for both models and is consistent with a previous study of the HOD evolution in semi-analytical models. Specifically, this is the case for the ratio between the characteristic halo masses for hosting central and satellite galaxies. The only HOD parameter whose evolution varies across models is σlogM, which contains information about the stellar mass–halo mass relation of the galaxies but does not strongly impact galaxy clustering. We also demonstrate that the dependence on the specific values of the cosmological parameters is small. We conclude that the cosmology of the galaxy sample, i.e. the cosmological hierarchical growth of structure, and not the baryonic physics prescriptions, governs the evolution of the HOD for stellar mass-selected samples. These results have important implications for populating simulated light-cones with galaxies and can facilitate the interpretation of clustering data at different redshifts.

The chaos – the violin – the Сosmos in the I. Kalynets’s poem “Great-grandfather”

In modern Ukrainian literary studies, the problem of researching intermedial relations in the artistic works of the Sixtiers, in particular, Ihor Kalynets, is relevant. At the same time, there is a lack of studies devoted to the analysis of separate texts. In our opinion, the poem ‘Great-grandfather’ from the collection ‘Kupala Fire’ demonstrates a harmonious interaction of the text levels, from the level of plot to the phonetic one. Therefore, the purpose of this article is a holistic study of the poem. A structuralist approach was used to achieve the mentioned goal. The poem ‘Great-grandfather’ contains the signs of cinematography, and it is based on an external plot. The clipped image of the great-grandfather playing the violin is subtly nuanced and dynamic. The image of the violin, as an ancient sophisticated instrument symbolizing the soul of the great-grandfather, is analyzed. The examination of the dedication in the poetry (to ‘Oleg Krysa’ who is a world-famous Ukrainian violinist) gives reasons to assume that the great-grandfather was a virtuoso violinist. The images of a bow and rosin were analyzed as the attributes of a specific prayer-playing. The meaning of the violin playing is to help the nature and people to by pass the time of twilight with the minimum losses, to turn the chaos of dusk into the cosmic time of a starry night. At this point the great-grandfather becomes the centre of interaction, the final (the fifth) element which enables the transformation. During the study of the colouring of the poem, we managed to conclude that the poetry was not so much of interest because of the colours, but because of their brightness. A noticeable development of brightness to the climax point was followed by a sinusoidal downturn. The last counterpoint in the colour chart is the image of the lemkas-‘soniakhs’ (sunflowers) who are under the influence of the maestro’s playing. The soundcode confirms the expressed ideas and demonstrates I. Kalynets’ virtuoso mastery of phonics. It is concluded that the great-grandfather, who is a violinist, becomes the mediator of the cosmic processes at the moment when he loses the boundaries of his own personality and dissolves in art. The great-grandfather, turning the chaos of twilight into the Cosmos, opens up new spiritual perspectives for his fellow Lemks. It is about a mystical art that unites the day and the night, the heaven and the earth, the man and the God.

The Star Formation Across Cosmic Time (SFACT) Survey. II. The First Catalog from a New Narrowband Survey for Emission-line Objects

Star Formation Across Cosmic Time (SFACT) is a new narrowband (NB) survey designed to detect faint emission-line galaxies (ELGs) and QSOs over a broad range of redshifts. Here we present the first list of SFACT candidates from our pilot-study fields. Using the WIYN 3.5 m telescope, we are able to achieve good image quality with excellent depth and routinely detect ELGs to r = 25.0. The limiting line flux of the survey is ∼1.0 × 10−16 erg s−1 cm−2. SFACT targets three primary emission lines: Hα, [O iii] λ5007, and [O ii] λ3727. The corresponding redshift windows allow for the detection of objects at z ∼ 0–1. With a coverage of 1.50 deg2 in our three pilot-study fields, a total of 533 SFACT candidates have been detected (355 candidates deg−2). We detail the process by which these candidates are selected in an efficient and primarily automated manner, then tabulate accurate coordinates, broadband photometry, and NB fluxes for each source.

The Star Formation Across Cosmic Time (SFACT) Survey. III. Spectroscopy of the Initial Catalog of Emission-line Objects

The Star Formation Across Cosmic Time (SFACT) survey is a new narrowband survey designed to detect emission-line galaxies (ELGs) and quasi-stellar objects (QSOs) over a wide range of redshifts in discrete redshift windows. The survey utilizes the WIYN 3.5 m telescope and the Hydra multifiber positioner to perform efficient follow-up spectroscopy on galaxies identified in the imaging part of the survey. Because the objects in the SFACT survey are selected by their strong emission lines, it is possible to obtain useful spectra for even the faintest of our sources (r ∼ 25). Here, we present the 453 objects that have spectroscopic data from the three SFACT pilot-study fields, 415 of which are confirmed ELGs. The methodology for processing and measuring these data is outlined in this paper, and example spectra are displayed for each of the three primary emission lines used to detect objects in the survey (Hα, [O III]λ5007, and [O II]λ3727). Spectra of additional QSOs and nonprimary-emission-line detections are also shown as examples. The redshift distribution of the pilot-study sample is examined, and the ELGs are placed in different emission-line diagnostic diagrams in order to distinguish the star-forming galaxies from the active galactic nuclei.

The timeless timing argument and the total mass of the Local Group

ABSTRACT The timing argument connects the motion of a two-body system to its mass in an expanding Universe with a finite age, under the assumption that it has evolved on a self-gravitating orbit. It is commonly applied to the present-day Milky Way (MW)–M31 system in order to infer its unknown mass from the measured kinematics. We use a set of Local Group analogues from the uchuu simulation to investigate the timing argument over cosmic time. We find that the median inferred mass remains almost constant over the past 12 Gyr, even while the haloes themselves grew in mass by more than an order of magnitude. By contrast, we find a closer, and nearly time-invariant agreement between the timing argument value and the mass within a sphere of radius equal to the MW–M31 separation, and we identify this as the total mass of the system. We conclude that the comparatively close present-day agreement between the timing argument and the sum of the halo masses reflects no underlying relation, but merely echoes the fact that the MW and M31 now contain most (but not all) of the mass of the Local Group system.

SIMBA-C: an updated chemical enrichment model for galactic chemical evolution in the SIMBA simulation

ABSTRACT We introduce a new chemical enrichment and stellar feedback model into GIZMO, using the SIMBA sub-grid models as a base. Based on the state-of-the-art chemical evolution model of Kobayashi et al., SIMBA-C tracks 34 elements from H→Ge and removes SIMBA’s instantaneous recycling approximation. Furthermore, we make some minor improvements to SIMBA’s base feedback models. SIMBA-C provides significant improvements on key diagnostics such as the knee of the z = 0 galaxy stellar mass function, the faint end of the main sequence, and the ability to track black holes in dwarf galaxies. SIMBA-C also matches better with recent observations of the mass–metallicity relation at z = 0, 2. By not assuming instantaneous recycling, SIMBA-C provides a much better match to galactic abundance ratio measures such as [O/Fe] and [N/O]. SIMBA-C thus opens up new avenues to constrain feedback models using detailed chemical abundance measures across cosmic time.

Exorcising the ghost condensate dark energy with a sextic dispersion relation

The universe's current acceleration is a pretty recent phenomenon in cosmological time scales. This means that the modes that have left our horizon since the beginning of the contemporary acceleration phase, have not really reached the exact IR limit. Noting this observation, we reconsider the possibility of having a ghost condensate as dark energy with a sixth-order dispersion relation. Looking at the three-point function of such a theory, we obtain the constraints on the coefficient of the sixth-order dispersion relation to avoid strong coupling. We notice that such a constraint can be easily satisfied, without fine-tuning. Such a ghost condensate, if coupled to the standard model fields, induces a constant Lorentz-violating spin-dependent force, which can gravitate or anti-gravitate. The Newtonian potential is modified with an oscillatory behavior at distance scale MPl/M2 at the time scale MPl2/M3, where M2 is the expectation value of the ghost field velocity, i.e. 〈ϕ˙〉=M2.

AGN’s Deadness Over Cosmic Time: UVJ Diagrams of X-Ray AGN

Over cosmic time, galaxies tend to separate into a bimodal distribution of “red and dead” or blue and star-forming. We examine whether active galaxies evolve in a similar way, and whether this reveals anything about the complexities of the relationship between an AGN and the host galaxy. We use the Stripe82X survey to identify 3940 X-ray AGN spanning z = 0–2.5, and we measure the rest-frame UVJ colors of each galaxy. We classify AGN as star-forming or quiescent based on their location in a UVJ color diagram. We find that there is not a clear bimodal distribution between AGN in star-forming and quiescent galaxies. Furthermore, the most luminous X-ray sources tend to lie in the star-forming region, which may indicate a correlation between central engine activity and increased rates of star formation.

The Star Formation Across Cosmic Time (SFACT) Survey. I. Survey Description and Early Results from a New Narrowband Emission-line Galaxy Survey

We introduce the Star Formation Across Cosmic Time (SFACT) survey. SFACT is a new narrowband survey for emission-line galaxies (ELGs) and QSOs being carried out using the wide-field imager on the WIYN 3.5 m telescope. Because of the superior depth and excellent image quality afforded by WIYN, we routinely detect ELGs to r = 25.0. Our survey observations are made using three custom narrowband filters centered on 6590 Å, 6950 Å, and 7460 Å. Due to the sensitivity of the survey, we are able to simultaneously detect sources via a number of different emission lines over a wide range of redshifts. The principal lines detected in SFACT are Hα (redshifts up to 0.144), [O iii]λ5007 (redshifts up to 0.500), and [O ii]λ3727 (redshifts up to 1.015). In this paper, we detail the properties of the survey as well as present initial results obtained by analyzing our three pilot-study fields. These fields have yielded a total of 533 ELG candidates in an area of 1.50 deg2 (surface density of 355 ELGs deg−2). Follow-up spectra for a subset of the ELG candidates are also presented. One of the key attributes of the SFACT survey is that the ELGs are detected in discrete redshift windows that will allow us to robustly quantify the properties of the star-forming and active galactic nucleus populations as a function of redshift to z = 1 and beyond. The planned acquisition of additional narrowband filters will allow us to expand our survey to substantially higher redshifts.

First Results from the JWST Early Release Science Program Q3D: Benchmark Comparison of Optical and Mid-infrared Tracers of a Dusty, Ionized Red Quasar Wind at z = 0.435

The [O iii] 5007 Å emission line is the most common tracer of warm, ionized outflows in active galactic nuclei across cosmic time. JWST newly allows us to use mid-IR spectral features at both high spatial and spectral resolution to probe these same winds. Here we present a comparison of ground-based, seeing-limited [O iii] and space-based, diffraction-limited [S iv] 10.51 μm maps of the powerful, kiloparsec-scale outflow in the Type 1 red quasar SDSS J110648.32+480712.3. The JWST data are from the Mid-InfraRed Instrument. There is a close match in resolution between the data sets (∼0.″6), in ionization potential of the O+2 and S+3 ions (35 eV) and in line sensitivity (1–2 × 10−17 erg s−1 cm−2 arcsec−2). The [O iii] and [S iv] line shapes match in velocity and line width over much of the 20 kpc outflowing nebula, and [S iv] is the brightest line in the rest-frame 3.5–19.5 μm range, demonstrating its usefulness as a mid-IR probe of quasar outflows. [O iii] is nevertheless intrinsically brighter and provides better contrast with the point-source continuum, which is strong in the mid-IR. There is a strong anticorrelation of [O iii]/[S iv] with average velocity, which is consistent with a scenario of differential obscuration between the approaching (blueshifted) and receding (redshifted) sides of the flow. The dust in the wind may also obscure the central quasar, consistent with models that attribute red quasar extinction to dusty winds.

Sub-millimetre galaxies with Webb

We utilised the unprecedented depth and resolution of recent early-release science (ERS) JWST observations to define the near-infrared counterparts of sub-millimetre galaxies (SMGs). We identified 45 SCUBA-2 SMG positions within the Cosmic Evolution Early Release Science (CEERS) survey JWST/NIRCam fields. Through an analysis of multi-wavelength p-values, NIRCam colours and predicted SCUBA-2 fluxes, we define 43 JWST/NIRCam counterparts to the SCUBA-2 SMGs, finding a 63 per cent agreement with those identified in prior HST studies. Using EaZy-py, we fitted the available HST and JWST observations to quantify the photometric redshifts of the NIRCam-SMGs, establishing a broad range of redshift from z ≈ 0.2–5.4 with a median of z ≈ 2.29, in agreement with other studies of SMGs. We identified significant variations in the morphology of the NIRCam-SMGs from isolated discs and spheroidal galaxies to irregular interacting systems. We analysed their rest-frame optical and near-infrared morphological properties (e.g. effective radius (Re), Sérsic index (n), concentration (C), asymmetry (A), clumpiness (S), as well as the Gini and M20 parameters), finding, on average, late-type disc-like morphologies with large scatter into the intermediate and merger regions of the non-parametric parameter space. For the non-merging galaxies, we find a median rest-frame optical size and Sérsic index (and 1σ scatter) of Re = 3.10 ± 1.67 kpc and n = 0.96 ± 0.66. Whilst in the rest-frame near-infrared, we establish more compact, higher Sérsic index morphologies (Re = 1.64 ± 0.97, n = 1.85 ± 0.63). We further establish that both the rest-frame optical and near-infrared effective radii correlate negatively (at a 2σ level) with redshift, whilst the Sérsic index remains constant with cosmic time. Our results are consistent with the picture of inside-out galaxy evolution, with more centrally concentrated older stellar populations, and more extended, younger star-forming regions whose stellar emission is heavily attenuated in the central regions.

Tacita Dean’s Affective Intermediality: Precarious Visions in-between the Visual Arts, Cinema, and the Gallery Film

Tacita Dean’s art relies on the perception of liminalities, of moving in-between, of one medium unfolding into another through dispersed, “molecular” sensations, either subverting or augmenting impressions of art forms perceived on the level of larger, structural wholes. Arguing against the wide-angle perspective employed by media studies approaches and for a close-up analysis of an “affective intermediality” in Tacita Dean’s art, the author looks at the landmark exhibitions at the National Gallery, the National Portrait Gallery, and the Royal Academy in London organised in 2018. The article singles out some of the individual works in the context of the exhibition as a work of art, and focuses on questions like the cross-media phenomenon of the “cinematic”, the affective performativity of the various dispositifs employed in her installations of celluloid films, the affordances of Dean’s signature aperture-gate masking technique, as well as the relation between narrative cinema experienced in a theatrical space and film as the medium of a visual artist. The essay concludes with a brief analysis of her gallery film, Antigone (2018), unravelling an allegorical journey through cosmic time and atmospheric landscapes, viewed as an ode to the “blind vision” of photochemical film and as a synthesis of key features of her intermediality conceived as a strategy for the re-sensitization of mediums by approaching one art from the point of view of another.

Generation of Near-Equipartition Magnetic Fields in Turbulent Collisionless Plasmas.

The mechanisms that generate "seed" magnetic fields in our Universe and that amplify them throughout cosmic time remain poorly understood. By means of fully kinetic particle-in-cell simulations of turbulent, initially unmagnetized plasmas, we study the genesis of magnetic fields via the Weibel instability and follow their dynamo growth up to near-equipartition levels. In the kinematic stage of the dynamo, we find that the rms magnetic field strength grows exponentially with rate γ_{B}≃0.4u_{rms}/L, where L/2π is the driving scale and u_{rms} is the rms turbulent velocity. In the saturated stage, the magnetic field energy reaches about half of the turbulent kinetic energy. Here, magnetic field growth is balanced by dissipation via reconnection, as revealed by the appearance of plasmoid chains. At saturation, the integral-scale wave number of the magnetic spectrum approaches k_{int}≃12π/L. Our results show that turbulence-induced by, e.g., the gravitational buildup of galaxies and galaxy clusters-can magnetize collisionless plasmas with large-scale near-equipartition fields.

Co-Evolution vs. Co-existence: The effect of accretion modelling on the evolution of black holes and host galaxies

ABSTRACT We append two additional black hole (BH) accretion models, namely viscous disc and gravitational torque-driven accretion, into the Numerical Investigation of a Hundred Astrophysical Objects (NIHAO) project of galaxy simulations. We show that these accretion models, characterized by a weaker dependence on the BH mass compared to the commonly used Bondi-Hoyle accretion, naturally create a common evolutionary track (co-existence) between the mass of the BH and the stellar mass of the galaxy, even without any direct coupling via feedback (FB). While FB is indeed required to control the final BH and stellar mass of the galaxies, our results suggest that FB might not be the leading driver of the cosmic co-evolution between these two quantities; in these models, co-evolution is simply determined by the shared central gas supply. Conversely, simulations using Bondi-Hoyle accretion show a two-step evolution, with an early growth of stellar mass followed by exponential growth of the central supermassive black hole (SMBH). Our results show that the modelling of BH accretion (sometimes overlooked) is an extremely important part of BH evolution and can improve our understanding of how scaling relations emerge and evolve, and whether SMBH and stellar mass co-exist or co-evolve through cosmic time.

Missing Giants: Predictions on Dust-obscured Galaxy Stellar Mass Assembly Throughout Cosmic Time

Due to their extremely dust-obscured nature, much uncertainty still exists surrounding the stellar mass growth and content in dusty, star-forming galaxies (DSFGs) at z > 1. In this work, we present a numerical model built using empirical data on DSFGs to estimate their stellar mass contributions across the first ∼10 Gyr of cosmic time. We generate a dust-obscured stellar mass function that extends beyond the mass limit of star-forming stellar mass functions in the literature, and predict that massive DSFGs constitute as much as 50%–100% of all star-forming galaxies with M ≥1011 M ⊙ at z > 1. We predict the number density of massive DSFGs and find general agreement with observations, although more data is needed to narrow wide observational uncertainties. We forward-model mock massive DSFGs to their quiescent descendants and find remarkable agreement with observations from the literature demonstrating that, to first order, massive DSFGs are a sufficient ancestral population to describe the prevalence of massive quiescent galaxies at z > 1. We predict that massive DSFGs and their descendants contribute as much as 25%–60% to the cosmic stellar mass density during the peak of cosmic star formation, and predict an intense epoch of population growth during the ∼1 Gyr from z = 6 to 3 during which the majority of the most massive galaxies at high-z grow and then quench. Future studies seeking to understand massive galaxy growth and evolution in the early universe should strategize synergies with data from the latest observatories (e.g., JWST and the Atacama Large Millimeter/submillimeter Array) to better include the heavily dust-obscured galaxy population.

Using [Ne v]/[Ne iii] to Understand the Nature of Extreme-ionization Galaxies

Spectroscopic studies of extreme-ionization galaxies (EIGs) are critical to our understanding of exotic systems throughout cosmic time. These EIGs exhibit spectral features requiring >54.42 eV photons: the energy needed to ionize helium into He2+ fully and emit He ii recombination lines. Spectroscopic studies of EIGs can probe exotic stellar populations or accretion onto intermediate-mass black holes (∼102–105 M ⊙), which are the possibly key contributors to the reionization of the Universe. To facilitate the use of EIGs as probes of high-ionization systems, we focus on ratios constructed from several rest-frame UV/optical emission lines: [O iii] λ5008, Hβ, [Ne iii] λ3870, [O ii] λ λ3727, 3729, and [Ne v] λ3427. These lines probe the relative intensity at energies of 35.12, 13.62, 40.96, 13.62, and 97.12 eV, respectively, covering a wider range of ionization than traced by other common rest-frame UV/optical techniques. We use the ratios of these lines ([Ne v]/[Ne iii] ≡ Ne53, [O iii]/Hβ, and [Ne iii]/[O ii]), which are nearby in wavelength, mitigating the effects of dust attenuation and uncertainties in flux calibration. We make predictions from photoionization models constructed from Cloudy that use a broad range of stellar populations and black hole accretion models to explore the sensitivity of these line ratios to changes in the ionizing spectrum. We compare our models to observations from the Hubble Space Telescope and JWST of galaxies with strong high-ionization emission lines at z ∼ 0, z ∼ 2, and 5 < z < 8.5. We show that the Ne53 ratio can separate galaxies with ionization from “normal” stellar populations from those with active galactic nuclei and even “exotic” Population III models. We introduce new selection methods to identify galaxies with photoionization driven by Population III stars or intermediate-mass black hole accretion disks that could be identified in upcoming high-redshift spectroscopic surveys.

Dynamic dark energy from the local limit of nonlocal gravity

Nonlocal gravity (NLG), a classical extension of Einstein’s theory of gravitation, has been studied mainly in linearized form. In particular, nonlinearities have thus far prevented the treatment of cosmological models in NLG. In this essay, we discuss the local limit of NLG and apply this limit to the expanding homogenous and isotropic universe. The theory only allows spatially flat cosmological models; furthermore, de Sitter spacetime is forbidden. The components of the model will have different dynamics with respect to cosmic time as compared to the standard [Formula: see text]CDM model; specifically, instead of the cosmological constant, the modified flat model of cosmology involves a dynamic dark energy component in order to account for the accelerated phase of the expansion of the universe.

Carbonaceous dust grains seen in the first billion years of cosmic time

Large dust reservoirs (up to approximately 108 M⊙) have been detected1–3 in galaxies out to redshift z ≃ 8, when the age of the Universe was only about 600 Myr. Generating substantial amounts of dust within such a short timescale has proven challenging for theories of dust formation4,5 and has prompted the revision of the modelling of potential sites of dust production6–8, such as the atmospheres of asymptotic giant branch stars in low-metallicity environments, supernova ejecta and the accelerated growth of grains in the interstellar medium. However, degeneracies between different evolutionary pathways remain when the total dust mass of galaxies is the only available observable. Here we report observations of the 2,175 Å dust attenuation feature, which is well known in the Milky Way and galaxies at z ≲ 3 (refs. 9–11), in the near-infrared spectra of galaxies up to z ≃ 7, corresponding to the first billion years of cosmic time. The relatively short timescale implied for the formation of carbonaceous grains giving rise to this feature12 suggests a rapid production process, possibly in Wolf–Rayet stars or supernova ejecta.

Classification of exact Bianchi type V cosmological solutions via conformal vector fields admitting energy conditions in [formula omitted] gravity

The aim of this paper is to discuss exact Bianchi-type V cosmological solutions via conformal vector fields (CVFs) admitting energy conditions within the framework of f(T) gravity. For this study, we first derive the Einstein field equations (EFEs) by considering the Bianchi type V space–times in f(T) gravity. We formulate the exact Bianchi type V metrics in f(T) gravity by imposing certain constraints on space–time components. In particular, we emphasize extracting the power law, exponential, and singular solutions. We plot the dynamical parameters of the obtained solutions versus cosmic time t to observe their behavior graphically. We analyze the metrics via CVFs in order to sort out conservation laws. We also discuss several cosmological constraints for each of the obtained solutions. Furthermore, to check the physical soundness of the resultant metrics, we find several constraints under which the solutions admit energy conditions.