The Supersonic Project: SIGOs, A Proposed Progenitor to Globular Clusters, and Their Connections to Gravitational-wave Anisotropies

Abstract Supersonically induced gas objects (SIGOs), are structures with little to no dark-matter component predicted to exist in regions of the universe with large relative velocities between baryons and dark matter at the time of recombination. They have been suggested to be the progenitors of present-day globular clusters. Using simulations, SIGOs have been studied on small scales (around 2 Mpc) where these relative velocities are coherent. However, it is challenging to study SIGOs using simulations on large scales due to the varying relative velocities at scales larger than a few Mpc. Here, we study SIGO abundances semi-analytically: using perturbation theory, we predict the number density of SIGOs analytically, and compare these results to small-box numerical simulations. We use the agreement between the numerical and analytic calculations to extrapolate the large-scale variation of SIGO abundances over different stream velocities. As a result, we predict similar large-scale variations of objects with high gas densities before reionization that could possibly be observed by JWST. If indeed SIGOs are progenitors of globular clusters, then we expect a similar variation of globular cluster abundances over large scales. Significantly, we find that the expected number density of SIGOs is consistent with observed globular cluster number densities. As a proof-of-concept, and because globular clusters were proposed to be natural formation sites for gravitational wave sources from binary black-hole mergers, we show that SIGOs should imprint an anisotropy on the gravitational wave signal on the sky, consistent with their distribution.

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Large-Scale Structure in the Universe: Spatial Distribution and Peculiar Velocities

Symposium - International Astronomical Union ◽

10.1017/s0074180900159303 ◽

1987 ◽

Vol 124 ◽

pp. 335-348

Author(s):

Neta A. Bahcall

Keyword(s):

Dark Matter ◽

Spatial Distribution ◽

Large Scale ◽

Large Scale Structure ◽

Scale Structure ◽

Clusters Of Galaxies ◽

Large Scale Structures ◽

Peculiar Velocities ◽

Scale Structures ◽

The Universe

The evidence for the existence of very large scale structures, ∼ 100h−1Mpc in size, as derived from the spatial distribution of clusters of galaxies is summarized. Detection of a ∼ 2000 kms−1 elongation in the redshift direction in the distribution of the clusters is also described. Possible causes of the effect are peculiar velocities of clusters on scales of 10–100h−1Mpc and geometrical elongation of superclusters. If the effect is entirely due to the peculiar velocities of clusters, then superclusters have masses of order 1016.5M⊙ and may contain a larger amount of dark matter than previously anticipated.

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Observational constraints of a new unified dark fluid and the H0 tension

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz2753 ◽

2019 ◽

Vol 490 (2) ◽

pp. 2071-2085 ◽

Cited By ~ 10

Author(s):

Weiqiang Yang ◽

Supriya Pan ◽

Andronikos Paliathanasis ◽

Subir Ghosh ◽

Yabo Wu

Keyword(s):

Dark Matter ◽

Dark Energy ◽

Large Scale ◽

Cold Dark Matter ◽

Early Time ◽

Observational Constraints ◽

Minimal Extension ◽

Energy Evolution ◽

The Universe ◽

Different Sources

ABSTRACT Unified cosmological models have received a lot of attention in astrophysics community for explaining both the dark matter and dark energy evolution. The Chaplygin cosmologies, a well-known name in this group have been investigated matched with observations from different sources. Obviously, Chaplygin cosmologies have to obey restrictions in order to be consistent with the observational data. As a consequence, alternative unified models, differing from Chaplygin model, are of special interest. In the present work, we consider a specific example of such a unified cosmological model, that is quantified by only a single parameter μ, that can be considered as a minimal extension of the Λ-cold dark matter cosmology. We investigate its observational boundaries together with an analysis of the universe at large scale. Our study shows that at early time the model behaves like a dust, and as time evolves, it mimics a dark energy fluid depicting a clear transition from the early decelerating phase to the late cosmic accelerating phase. Finally, the model approaches the cosmological constant boundary in an asymptotic manner. We remark that for the present unified model, the estimations of H0 are slightly higher than its local estimation and thus alleviating the H0 tension.

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N-body Simulations of Galaxy Formation

Symposium - International Astronomical Union ◽

10.1017/s0074180900136137 ◽

1988 ◽

Vol 130 ◽

pp. 259-271

Author(s):

Carlos S. Frenk

Keyword(s):

Dark Matter ◽

Galaxy Formation ◽

Large Scale ◽

Cold Dark Matter ◽

Large Scale Structure ◽

High Density ◽

Galactic Halos ◽

Body Techniques ◽

Massive Halos ◽

The Universe

Modern N-body techniques allow the study of galaxy formation in the wider context of the formation of large-scale structure in the Universe. The results of such a study within the cold dark matter cosmogony are described. Dark galactic halos form at relatively recent epochs. Their properties and abundance are similar to those inferred for the halos of real galaxies. Massive halos tend to form preferentially in high density regions and as a result the galaxies that form within them are significantly more clustered than the underlying mass. This natural bias may be strong enough to reconcile the observed clustering of galaxies with the assumption that Ω = 1.

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Large-Scale Structure of the Universe in Unstable Dark Matter Models

Symposium - International Astronomical Union ◽

10.1017/s0074180900136174 ◽

1988 ◽

Vol 130 ◽

pp. 293-300

Author(s):

A.G. Doroshkevich ◽

A.A. Klypin ◽

M.U. Khlopov

Keyword(s):

Dark Matter ◽

Galaxy Formation ◽

Large Scale ◽

Numerical Models ◽

Large Scale Structure ◽

Scale Structure ◽

Microwave Background ◽

Physical Background ◽

The Mean ◽

The Universe

Processes of the formation and the evolution of the large-scale structure are discussed in the framework of unstable dark matter models. Six numerical models are presented. The projected distribution of simulated galaxies on the sky, wedge diagrams, correlation functions and the mean linear scale of voids are presented. Physical background of the hypothesis of unstable particles and possible observational tests are discussed. The level of the microwave background fluctuations is estimated analytically. Special attention is given to late stage of supercluster evolution and galaxy formation.

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Formation Times for Rich Clusters of Galaxies

Publications of the Astronomical Society of Australia ◽

10.1017/s1323358000015113 ◽

1977 ◽

Vol 3 (2) ◽

pp. 140-142 ◽

Cited By ~ 1

Author(s):

B. M. Lewis

Keyword(s):

Gaussian Distribution ◽

Large Scale ◽

Velocity Dispersion ◽

Large Scale Structure ◽

Elliptical Galaxies ◽

Scale Structure ◽

Clusters Of Galaxies ◽

Number Density ◽

Radial Gradient ◽

The Universe

Rich clusters of galaxies are a common feature of the large-scale structure of the Universe. Those studied so far, show striking regularities with (a)a smooth radial gradient of number density.(b)’isothermal’ distributions, which according to Bahcall (1975) have a scatter of only ±15% in the size of their characteristic core radii.(c)their limiting structural diameters are ~50 Mpc (cf. Abell, 1975), if they are identified with superclusters.(d)the magnitude of the velocity dispersion about their centres is generally 600-1000 km s-1, and the velocities are cpnsistent with a gaussian distribution (Yahil and Vidal, 1976; also Faber and Dressier, 1976).(e)The extreme velocities are generally within ±3000 km s-1, and for Coma are ∼2400 km s-1 (Tifft and Gregory, 1976).(f)elliptical galaxies tend to predominate near the centre, spirals in the surrounding loose groups.

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Indirect effects of dark matter

International Journal of Modern Physics D ◽

10.1142/s0218271819410116 ◽

2019 ◽

Vol 28 (13) ◽

pp. 1941011 ◽

Cited By ~ 4

Author(s):

K. M. Belotsky ◽

E. A. Esipova ◽

A. Kh. Kamaletdinov ◽

E. S. Shlepkina ◽

M. L. Solovyov

Keyword(s):

Dark Matter ◽

Indirect Effects ◽

Large Scale ◽

Gamma Ray ◽

Space Distribution ◽

Stable Form ◽

Final State ◽

Electron Positron ◽

Text Mode ◽

The Universe

Here, we briefly review possible indirect effects of dark matter (DM) of the universe. It includes effects in cosmic rays (CR): first of all, the positron excess at [Formula: see text]500[Formula: see text]GeV and possible electron–positron excess at 1–1.5[Formula: see text]TeV. We tell that the main and least model-dependent constraint on such possible interpretation of CR effects goes from gamma-ray background. Even ordinary [Formula: see text] mode of DM decay or annihilation produces prompt photons (FSR) so much that it leads to contradiction with data on cosmic gamma-rays. We present our attempts to possibly avoid gamma-ray constraint. They concern with peculiarities of both space distribution of DM and their physics. The latter involves complications of decay/annihilation modes of DM, modifications of Lagrangian of DM-ordinary matter interaction and inclusion of mode with identical fermions in final state. In this way, no possibilities to suppress were found except, possibly, the mode with identical fermions. While the case of spatial distribution variation allows achieving consistency between different data. Also, we consider stable form of DM which can interact with baryons. We show which constraint such DM candidate can get from the damping effect in plasma during large-scale structure (LSS) formation in comparison with other existing constraints.

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Testing Gravity using Void Profiles

Proceedings of the International Astronomical Union ◽

10.1017/s1743921316010577 ◽

2014 ◽

Vol 11 (S308) ◽

pp. 555-560 ◽

Cited By ~ 1

Author(s):

Yan-Chuan Cai ◽

Nelson Padilla ◽

Baojiu Li

Keyword(s):

Dark Matter ◽

Gravitational Lensing ◽

Modified Gravity ◽

Large Scale ◽

Line Of Sight ◽

Number Density ◽

Density Profiles ◽

Photometric Redshift ◽

Redshift Survey ◽

Near Future

AbstractWe investigate void properties inf(R)models using N-body simulations, focusing on their differences from General Relativity (GR) and their detectability. In the Hu-Sawickif(R)modified gravity (MG) models, the halo number density profiles of voids are not distinguishable from GR. In contrast, the samef(R)voids are more empty of dark matter, and their profiles are steeper. This can in principle be observed by weak gravitational lensing of voids, for which the combination of a spectroscopic redshift and a lensing photometric redshift survey over the same sky is required. Neglecting the lensing shape noise, thef(R)model parameter amplitudesfR0=10-5and 10-4may be distinguished from GR using the lensing tangential shear signal around voids by 4 and 8 σ for a volume of 1 (Gpc/h)3. The line-of-sight projection of large-scale structure is the main systematics that limits the significance of this signal for the near future wide angle and deep lensing surveys. For this reason, it is challenging to distinguishfR0=10-6from GR. We expect that this can be overcome with larger volume. The halo void abundance being smaller and the steepening of dark matter void profiles inf(R)models are unique features that can be combined to break the degeneracy betweenfR0and σ8.

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Hipparcos subdwarfs and globular cluster ages: towards reliable absolute ages

Symposium - International Astronomical Union ◽

10.1017/s0074180900116985 ◽

1997 ◽

Vol 189 ◽

pp. 433-438 ◽

Cited By ~ 3

Author(s):

F. Pont ◽

M. Mayor ◽

C. Turon

Keyword(s):

Globular Cluster ◽

Globular Clusters ◽

Large Fraction ◽

Age Determination ◽

Colour Scale ◽

Minimum Age ◽

Age Of The Universe ◽

Robust Prediction ◽

The Universe ◽

Cluster Age

The maximum age of galactic globular clusters provides the best observational constraint on the minimum age of the Universe. One of the main “missing link” in the globular cluster age determination has been the lack of a precise calibration, with local subdwarfs, of the position of the subdwarf sequence at different [Fe/H].Hipparcos data may change this situation. As many precise parallaxes become available for local subdwarfs, the distance to globular clusters can be estimated directly from ZAMS fitting to the subdwarf locus. The ages can then be inferred from the turnoff luminosity (a robust prediction of stellar evolution models), rather than using secondary indicators such as Horizontal-Branch position, or indicators depending on the uncertain colour scale such as turnoff colour.Combining Hipparcos parallaxes with [Fe/H] values determined with the CORAVEL spectrometer, we are studying the position of the subdwarfs in the Colour-Magnitude Diagram from a sample of more than 900 subdwarf candidates. Preliminary results are presented here. It is shown that the distances of many subdwarfs had been underestimated in previous studies, mainly because a large fraction of them is in fact evolved off the main sequence into the turnoff or the subgiant branch.

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Voronoi volume function: a new probe of cosmology and galaxy evolution

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa1379 ◽

2020 ◽

Vol 495 (3) ◽

pp. 3233-3251 ◽

Cited By ~ 1

Author(s):

Aseem Paranjape ◽

Shadab Alam

Keyword(s):

Dark Matter ◽

Galaxy Evolution ◽

Large Scale ◽

Cold Dark Matter ◽

Voronoi Tessellation ◽

Small Scale ◽

Summary Statistics ◽

Number Density ◽

Volume Function ◽

Space Effects

ABSTRACT We study the Voronoi volume function (VVF) – the distribution of cell volumes (or inverse local number density) in the Voronoi tessellation of any set of cosmological tracers (galaxies/haloes). We show that the shape of the VVF of biased tracers responds sensitively to physical properties such as halo mass, large-scale environment, substructure, and redshift-space effects, making this a hitherto unexplored probe of both primordial cosmology and galaxy evolution. Using convenient summary statistics – the width, median, and a low percentile of the VVF as functions of average tracer number density – we explore these effects for tracer populations in a suite of N-body simulations of a range of dark matter models. Our summary statistics sensitively probe primordial features such as small-scale oscillations in the initial matter power spectrum (as arise in models involving collisional effects in the dark sector), while being largely insensitive to a truncation of initial power (as in warm dark matter models). For vanilla cold dark matter (CDM) cosmologies, the summary statistics display strong evolution and redshift-space effects, and are also sensitive to cosmological parameter values for realistic tracer samples. Comparing the VVF of galaxies in the Galaxies & Mass Assembly (GAMA) survey with that of abundance-matched CDM (sub)haloes tentatively reveals environmental effects in GAMA beyond halo mass (modulo unmodelled satellite properties). Our exploratory analysis thus paves the way for using the VVF as a new probe of galaxy evolution physics as well as the nature of dark matter and dark energy.

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Observational and astrophysical cosmology: 1980–2018

The Oxford Handbook of the History of Modern Cosmology ◽

10.1093/oxfordhb/9780198817666.013.10 ◽

2019 ◽

pp. 375-423

Author(s):

Malcolm S. Longair

Keyword(s):

Dark Matter ◽

Dark Energy ◽

Cosmological Constant ◽

Large Scale ◽

Cosmological Parameters ◽

Semiconductor Detectors ◽

Empirical Knowledge ◽

Global Geometry ◽

The Universe ◽

Large Scale Structure Formation

Since 1980, our empirical knowledge of the universe has advanced tremendously and precision cosmology has become a reality. These developments have been largely technology-driven, the result of increased computer power, new generations of telescopes for all wavebands, new types of semiconductor detectors, such as CCDs, and major investments by many nations in superb observing facilities. The discipline also benefitted from the influx of experimental and theoretical physicists into the cosmological arena. The accuracy and reliability of the values of the cosmological parameters has improved dramatically, many of them now being known to about 1%. The ΛCDM model provides a remarkable fit to all the observational data, demonstrating that the cosmological constant is non-zero and that the global geometry of the universe is flat. The underlying physics of galaxy and large-scale structure formation has advanced dramatically and demonstrated the key roles played by dark matter and dark energy.

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