15 research outputs found
The cosmological star formation history from the Local Volume of galaxies and constraints on the matter homogeneity
The Lilly-Madau plot is commonly interpreted as the history of the cosmic
star formation of the Universe by showing the co-moving star formation rate
density (SFRD) over cosmic time. Therefore, the Lilly-Madau plot is not only
sensitive to the star formation history (SFH) but also to the number density of
galaxies. Assessing the Catalogue of Neighbouring Galaxies, we reconstruct the
SFHs of galaxies located in the Local Volume (LV) based on delayed- and
power-law SFH models. Galaxies with stellar masses of typically evolve according to the delayed- model
by having first increasing followed by exponentially declining SFRs, while the
majority of less massive star-forming galaxies has an almost constant or
increasing SFH. Deducing the cosmic SFRD evolution of the LV reveals that the
SFHs of local galaxies are inconsistent with the Lilly-Madau plot. The SFRDs of
the LV are significantly lower at redshifts of underestimating
the Lilly-Madau peak at by a factor of
(delayed-) and (power-law model). Assuming the
delayed- model for galaxies with and
a power-law model for less massive galaxies, the SFRD is lower
than measured at . This inconsistency between the evolution of the
local and global SFRD has cosmological implications. Since the Lilly-Madau plot
also constrains the cosmological matter field, the near-constancy of SFHs of LV
galaxies could imply that the peak of the Lilly-Madau plot at is the
imprint of a Gpc-scale inhomogeneity.Comment: Accepted for publication in the Monthly Notices of the Royal
Astronomical Society (MNRAS), 12 pages, 5 figure
The KBC void and Hubble tension contradict ΛCDM on a Gpc scale - Milgromian dynamics as a possible solution
Funding Information: IB is supported by an Alexander von Humboldt Foundation postdoctoral research fellowship.The KBC void is a local underdensity with the observed relative density contrast δ 1 - ρ/ρ0 = 0.46 ± 0.06 between 40 and 300 Mpc around the Local Group. If mass is conserved in the Universe, such a void could explain the 5.3σ Hubble tension. However, the MXXL simulation shows that the KBC void causes 6.04σ tension with standard cosmology (ΛCDM). Combined with the Hubble tension, ΛCDM is ruled out at 7.09σ confidence. Consequently, the density and velocity distribution on Gpc scales suggest a long-range modification to gravity. In this context, we consider a cosmological MOND model supplemented with 11eV/c2 sterile neutrinos. We explain why this νHDM model has a nearly standard expansion history, primordial abundances of light elements, and cosmic microwave background (CMB) anisotropies. In MOND, structure growth is self-regulated by external fields from surrounding structures. We constrain our model parameters with the KBC void density profile, the local Hubble and deceleration parameters derived jointly from supernovae at redshifts 0.023-0.15, time delays in strong lensing systems, and the Local Group velocity relative to the CMB. Our best-fitting model simultaneously explains these observables at the 1.14 per cent confidence level (2.53σ tension) if the void is embedded in a time-independent external field of 0.055 a0. Thus, we show for the first time that the KBC void can naturally resolve the Hubble tension in Milgromian dynamics. Given the many successful a priori MOND predictions on galaxy scales that are difficult to reconcile with ΛCDM, Milgromian dynamics supplemented by 11eV/c2 sterile neutrinos may provide a more holistic explanation for astronomical observations across all scales.Publisher PDFPeer reviewe
The ultra-diffuse dwarf galaxies NGC 1052-DF2 and 1052-DF4 are in conflict with standard cosmology
Funding Information: IB is supported by an Alexander von Humboldt postdoctoral research fellowship. KG was supported by the German-Russian Interdisciplinary Science Center funded by the German Federal Foreign Office via the German Academic Exchange Service.Recently van Dokkum et al. reported that the galaxy NGC 1052-DF2 (DF2) lacks dark matter if located at 20 Mpc from Earth. In contrast,DF2 is a dark-matter-dominated dwarf galaxy with a normal globular cluster population if it has a much shorter distance near 10 Mpc. However, DF2 then has a high peculiar velocity wrt. the cosmic microwave background of 886 km s-1, which differs from that of the Local Group (LG) velocity vector by 1298 km s-1 with an angle of 117°.Taking into account the dynamical M/L ratio, the stellar mass, half-light radius, peculiar velocity, motion relative to the LG, and the luminosities of the globular clusters, we show that the probability of finding DF2-like galaxies in the lambda cold dark matter (CDM) TNG100-1 simulation is at most 1.0 × 10-4 at 11.5 Mpc and is 4.8 × 10-7 at 20.0 Mpc. At 11.5 Mpc, the peculiar velocity is in significant tension in the TNG100-1, TNG300-1, and Millennium simulations, but naturally in a Milgromian cosmology. At 20.0 Mpc, the unusual globular cluster population would challenge any cosmological model. Estimating that precise measurements of the internal velocity dispersion, stellar mass, and distance exist for 100 galaxies, DF2 is in 2.6σ (11.5 Mpc) and 4.1σ (20.0 Mpc) tension with standard cosmology. Adopting the former distance for DF2 and assuming that NGC 1052-DF4 is at 20.0 Mpc, the existence of both is in tension at ≥4.8σ with the ΛCDM model. If both galaxies are at 20.0 Mpc the ΛCDM cosmology has to be rejected by ≥5.8σ.Publisher PDFPeer reviewe
A simultaneous solution to the Hubble tension and observed bulk flow within 250 h−1 Mpc
Funding: IB was supported by Science and Technology Facilities Council grant ST/V000861/1. PK thanks the Deutscher Akademischer Austauschdienst-Eastern European exchange programme for support.The Λ cold dark matter (ΛCDM) standard cosmological model is in severe tension with several cosmological observations. Foremost is the Hubble tension, which exceeds 5σ confidence. Galaxy number counts show the Keenan–Barger–Cowie (KBC) supervoid, a significant underdensity out to 300 Mpc that cannot be reconciled with ΛCDM cosmology. Haslbauer et al. previously showed that a high local Hubble constant arises naturally due to gravitationally driven outflows from the observed KBC supervoid. The main prediction of this model is that peculiar velocities are typically much larger than expected in the ΛCDM framework. This agrees with the recent discovery by Watkins et al. that galaxies in the CosmicFlows-4 catalogue have significantly faster bulk flows than expected in the ΛCDM model on scales of 100-250 h-1 Mpc. The rising bulk flow curve is unexpected in standard cosmology, causing 4.8σ tension at 200 h-1 Mpc. In this work, we determine what the semi-analytic void model of Haslbauer et al. predicts for the bulk flows on these scales. We find qualitative agreement with the observations, especially if our vantage point is chosen to match the observed bulk flow on a scale of 50 h-1 Mpc. This represents a highly non-trivial success of a previously published model that was not constrained by bulk flow measurements, but which was shown to solve the Hubble tension and explain the KBC void consistently with the peculiar velocity of the Local Group. Our results suggest that several cosmological tensions can be simultaneously resolved if structure grows more efficiently than in the ΛCDM paradigm on scales of tens to hundreds of Mpc.Publisher PDFPeer reviewe
The high fraction of thin disk galaxies continues to challenge ΛCDM cosmology
Funding: I.B. is supported by Science and Technology Facilities Council grant ST/V000861/1. He acknowledges support from an Alexander von Humboldt Foundation postdoctoral research fellowship (2018–2020) and the University of Bonn "Pathways to Research" program.Any viable cosmological framework has to match the observed proportion of early- and late-type galaxies. In this contribution, we focus on the distribution of galaxy morphological types in the standard model of cosmology (Lambda cold dark matter, ΛCDM). Using the latest state-of-the-art cosmological ΛCDM simulations known as Illustris, IllustrisTNG, and EAGLE, we calculate the intrinsic and sky-projected aspect ratio distribution of the stars in subhalos with stellar mass M* > 1010 M⊙ at redshift z = 0. There is a significant deficit of intrinsically thin disk galaxies, which however comprise most of the locally observed galaxy population. Consequently, the sky-projected aspect ratio distribution produced by these ΛCDM simulations disagrees with the Galaxy And Mass Assembly (GAMA) survey and Sloan Digital Sky Survey at ≥12.52σ (TNG50-1) and ≥14.82σ (EAGLE50) confidence. The deficit of intrinsically thin galaxies could be due to a much less hierarchical merger-driven build-up of observed galaxies than is given by the ΛCDM framework. It might also arise from the implemented sub-grid models, or from the limited resolution of the above-mentioned hydrodynamical simulations. We estimate that an 85 times better mass resolution realization than TNG50-1 would reduce the tension with GAMA to the 5.58σ level. Finally, we show that galaxies with fewer major mergers have a somewhat thinner aspect ratio distribution. Given also the high expected frequency of minor mergers in ΛCDM, the problem may be due to minor mergers. In this case, the angular momentum problem could be alleviated in Milgromian dynamics because of a reduced merger frequency arising from the absence of dynamical friction between extended dark matter halos.Publisher PDFPeer reviewe
On the absence of backsplash analogues to NGC 3109 in the ΛCDM framework
Funding: IB is supported by an Alexander von Humboldt Foundation postdoctoral research fellowship. MSP and BF thank the Deutscher Akademischer Austauschdienst for PPP grant 57512596 funded by the Bundesministerium für Bildung und Forschung, and the Partenariat Hubert Curien (PHC) for PROCOPE project 44677UE. MSP thanks the Klaus Tschira Stiftung and German Scholars Organization e.V. for support via a Klaus Tschira Boost Fund. BF acknowledges funding from the Agence Nationale de la Recherche (projects ANR-18-CE31-0006 and ANR-19-CE31-0017) and from the European Research Council (ERC) under the European Union’s Horizon 2020 Framework Programme (grant agreement number 834148).The dwarf galaxy NGC 3109 is receding 105 km s−1 faster than expected in a Lambda cold dark matter (ΛCDM) timing argument analysis of the Local Group and external galaxy groups within 8 Mpc. If this few-body model accurately represents long-range interactions in ΛCDM, this high velocity suggests that NGC 3109 is a backsplash galaxy that was once within the virial radius of the Milky Way and was slingshot out of it. Here, we use the Illustris TNG300 cosmological hydrodynamical simulation and its merger tree to identify backsplash galaxies. We find that backsplashers as massive (≥4.0 × 1010 M⊙) and distant (≥1.2 Mpc) as NGC 3109 are extremely rare, with none having also gained energy during the interaction with their previous host. This is likely due to dynamical friction. Since we identified 13 225 host galaxies similar to the Milky Way or M31, we conclude that postulating NGC 3109 to be a backsplash galaxy causes >3.96σ tension with the expected distribution of backsplashers in ΛCDM. We show that the dark matter only version of TNG300 yields much the same result, demonstrating its robustness to how the baryonic physics is modelled. If instead NGC 3109 is not a backsplasher, consistency with ΛCDM would require the 3D timing argument analysis to be off by 105 km s−1 for this rather isolated dwarf, which we argue is unlikely. We discuss a possible alternative scenario for NGC 3109 and the Local Group satellite planes in the context of MOND, where the Milky Way and M31 had a past close flyby 7–10 Gyr ago.Publisher PDFPeer reviewe
The many tensions with dark-matter based models and implications on the nature of the Universe
(Abridged) Fundamental tensions between observations and dark-matter based
cosmological models have emerged. This updated review has two purposes: to
explore new tensions that have arisen in recent years, compounding the
unresolved tensions from previous studies, and to use the shortcomings of the
current theory to guide the development of a successful model. Tensions arise
in view of the profusion of thin disk galaxies, the pronounced symmetrical
structure of the Local Group of Galaxies, the common occurrence of planes of
satellite systems, the El Gordo and Bullet galaxy clusters, significant matter
inhomogeneities on scales much larger than 100 Mpc, and the observed rapid
formation of galaxies and super-massive black holes at redshifts larger than 7.
Given the nature of the tensions, the real Universe needs to be described by a
model in which gravitation is effectively stronger than Einsteinian/Newtonian
gravitation at accelerations below Milgrom's acceleration scale. The promising
nuHDM model, anchored on Milgromian dynamics but keeping the standard expansion
history with dark energy, solves many of the above tensions. However galaxy
formation appears to occur too late in this model, model galaxy clusters reach
too large masses, and the mass function of model galaxy clusters is too flat
and thus top-heavy in comparison to the observed mass function. Classes of
models that reassess inflation, dark energy and the role of the CMB should be
explored.Comment: 58 pages, 9 figures, 291 references, based on invited presentation
and to appear in the proceedings of Corfu2022: Workshop on Tensions in
Cosmology, Corfu Sept. 7-12., 2022 (organisers: E. Saridakis, S. Basilakos,
S. Capozziello, E. Di Valentino, O. Mena, S. Pan, J. Levi Said); replaced
version contains updated citation
Erratum:The ultra-diffuse dwarf galaxies NGC 1052-DF2 and 1052-DF4 are in conflict with standard cosmology (Monthly Notices of the Royal Astronomical Society (2019) 489: 2 (2634–2651) DOI: 10.1093/mnras/stz2270)
This is an erratum to the paper ‘The ultra-diffuse dwarf galaxies NGC 1052-DF2 and 1052-DF4 are in conflict with standard cosmology’ published in MNRAS 489 (2), 2634–2651 (2019). Sentence number five in the abstract has been corrected for a small linguistic error which, if uncorrected, may lead to misunderstanding. The complete abstract with the corrected sentence reads as follows: ‘Recently van Dokkum et al. reported that the galaxy NGC 1052-DF2 (DF2) lacks dark matter if located at 20 Mpc from Earth. In contrast, DF2 is a dark-matter-dominated dwarf galaxy with a normal globular cluster population if it has a much shorter distance near 10 Mpc. However, DF2 then has a high peculiar velocity wrt. the cosmic microwave background of 886 km s−1, which differs from that of the Local Group (LG) velocity vector by 1298 km s−1 with an angle of 117. Taking into account the dynamical M/L ratio, the stellar mass, half-light radius, peculiar velocity, motion relative to the LG, and the luminosities of the globular clusters, we show that the probability of finding DF2-like galaxies in the lambda cold dark matter (CDM) TNG100-1 simulation is at most 1.0 × 10−4 at 11.5 Mpc and is 4.8 × 10−7 at 20.0 Mpc. At 11.5 Mpc, the peculiar velocity is in significant tension with the TNG100-1, TNG300-1, and Millennium simulations, but natural in a Milgromian cosmology. At 20.0 Mpc, the unusual globular cluster population would challenge any cosmological model. Estimating that precise measurements of the internal velocity dispersion, stellar mass, and distance exist for 100 galaxies, DF2 is in 2.6σ (11.5 Mpc) and 4.1σ (20.0 Mpc) tension with standard cosmology. Adopting the former distance for DF2 and assuming that NGC 1052-DF4 is at 20.0 Mpc, the existence of both is in tension at ≥4.8σ with the CDM model. If both galaxies are at 20.0 Mpc the∆CDM cosmology has to be rejected by ≥5.8σ.’</p
The ultra-diffuse dwarf galaxies NGC 1052-DF2 and 1052-DF4 are in conflict with standard cosmology
Recently van Dokkum et al. (2018b) reported that the galaxy NGC 1052-DF2
(DF2) lacks dark matter if located at Mpc from Earth. In contrast, DF2 is
a dark-matter-dominated dwarf galaxy with a normal globular cluster population
if it has a much shorter distance near Mpc. However, DF2 then has a high
peculiar velocity wrt. the cosmic microwave background of
, which differs from that of the Local Group (LG) velocity
vector by with an angle of 117 \, ^{\circ}. Taking
into account the dynamical ratio, the stellar mass, half-light radius,
peculiar velocity, motion relative to the LG, and the luminosities of the
globular clusters, we show that the probability of finding DF2-like galaxies in
the lambda cold dark matter (CDM) TNG100-1 simulation is at most
at Mpc and is at Mpc. At
Mpc, the peculiar velocity is in significant tension with the TNG100-1,
TNG300-1, and Millennium simulations, but occurs naturally in a Milgromian
cosmology. At Mpc, the unusual globular cluster population would
challenge any cosmological model. Estimating that precise measurements of the
internal velocity dispersion, stellar mass, and distance exist for
galaxies, DF2 is in ( Mpc) and ( Mpc)
tension with standard cosmology. Adopting the former distance for DF2 and
assuming that NGC 1052-DF4 is at Mpc, the existence of both is in
tension at with the CDM model. If both galaxies are at
Mpc the CDM cosmology has to be rejected by .Comment: Published in the Monthly Notices of the Royal Astronomical Society,
19 pages, 13 figures, 9 table