Dark matter-deficient dwarf galaxies form via tidal stripping of dark matter in interactions with massive companions

ABSTRACT In the standard ΛCDM (Lambda cold dark matter) paradigm, dwarf galaxies are expected to be dark matter-rich, as baryonic feedback is thought to quickly drive gas out of their shallow potential wells and quench star formation at early epochs. Recent observations of local dwarfs with extremely low dark matter content appear to contradict this picture, potentially bringing the validity of the standard model into question. We use NewHorizon, a high-resolution cosmological simulation, to demonstrate that sustained stripping of dark matter, in tidal interactions between a massive galaxy and a dwarf satellite, naturally produces dwarfs that are dark matter-deficient, even though their initial dark matter fractions are normal. The process of dark matter stripping is responsible for the large scatter in the halo-to-stellar mass relation in the dwarf regime. The degree of stripping is driven by the closeness of the orbit of the dwarf around its massive companion and, in extreme cases, produces dwarfs with halo-to-stellar mass ratios as low as unity, consistent with the findings of recent observational studies. ∼30 per cent of dwarfs show some deviation from normal dark matter fractions due to dark matter stripping, with 10 per cent showing high levels of dark matter deficiency (Mhalo/M⋆ < 10). Given their close orbits, a significant fraction of dark matter-deficient dwarfs merge with their massive companions (e.g. ∼70 per cent merge over time-scales of ∼3.5 Gyr), with the dark matter-deficient population being constantly replenished by new interactions between dwarfs and massive companions. The creation of these galaxies is therefore a natural by-product of galaxy evolution and their existence is not in tension with the standard paradigm.

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Aging haloes: implications of the magnitude gap on conditional statistics of stellar and gas properties of massive haloes

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa291 ◽

2020 ◽

Vol 493 (1) ◽

pp. 1361-1374 ◽

Cited By ~ 2

Author(s):

Arya Farahi ◽

Matthew Ho ◽

Hy Trac

Keyword(s):

Dark Matter ◽

Galaxy Formation ◽

Large Scale ◽

Cold Dark Matter ◽

Stellar Mass ◽

Formation Time ◽

Gas Content ◽

Mass Relation ◽

Cold Dark Matter Model ◽

Conditional Statistics

ABSTRACT Cold dark matter model predicts that the large-scale structure grows hierarchically. Small dark matter haloes form first. Then, they grow gradually via continuous merger and accretion. These haloes host the majority of baryonic matter in the Universe in the form of hot gas and cold stellar phase. Determining how baryons are partitioned into these phases requires detailed modelling of galaxy formation and their assembly history. It is speculated that formation time of the same mass haloes might be correlated with their baryonic content. To evaluate this hypothesis, we employ haloes of mass above $10^{14}\, \mathrm{M}_{\odot }$ realized by TNG300 solution of the IllustrisTNG project. Formation time is not directly observable. Hence, we rely on the magnitude gap between the brightest and the fourth brightest halo galaxy member, which is shown that traces formation time of the host halo. We compute the conditional statistics of the stellar and gas content of haloes conditioned on their total mass and magnitude gap. We find a strong correlation between magnitude gap and gas mass, BCG stellar mass, and satellite galaxies stellar mass, but not the total stellar mass of halo. Conditioning on the magnitude gap can reduce the scatter about halo property–halo mass relation and has a significant impact on the conditional covariance. Reduction in the scatter can be as significant as 30 per cent, which implies more accurate halo mass prediction. Incorporating the magnitude gap has a potential to improve cosmological constraints using halo abundance and allows us to gain insight into the baryon evolution within these systems.

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The Future of Dwarf Galaxy Research: What Simulations will Predict?

Proceedings of the International Astronomical Union ◽

10.1017/s1743921318007391 ◽

2018 ◽

Vol 14 (S344) ◽

pp. 17-26

Author(s):

Laura V. Sales

Keyword(s):

Dark Matter ◽

Galaxy Formation ◽

Cold Dark Matter ◽

Dwarf Galaxies ◽

Dwarf Galaxy ◽

Matter Content ◽

Dark Matter Halos ◽

Matter Distribution ◽

The Future ◽

Dark Matter Distribution

AbstractWe present a summary of the predictions from numerical simulations to our understanding of dwarf galaxies. It centers the discussion around the Λ Cold Dark Matter scenario (ΛCDM) but discusses also implications for alternative dark matter models. Four key predictions are identified: the abundance of dwarf galaxies, their dark matter content, their relation with environment and the existence of dwarf satellites orbiting dwarf field galaxies. We discuss tensions with observations and identify the most exciting predictions expected from simulations in the future, including i) the existence of “dark galaxies” (dark matter halos without stars), ii) the ability to resolve the structure (size, morphology, dark matter distribution) in dwarfs and iii) the number of ultra-faint satellites around dwarf galaxies. All of these predictions shall inform future observations, not only the faintest galaxies to be discovered within the Local Volume but also distant dwarfs driving galaxy formation in the early universe.

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The Dwarfs Beyond: Relating Stellar and Halo Mass in Dwarf Galaxies to z ~ 1

Proceedings of the International Astronomical Union ◽

10.1017/s1743921315003579 ◽

2014 ◽

Vol 10 (S311) ◽

pp. 150-153

Author(s):

Sarah H. Miller

Keyword(s):

Dark Matter ◽

Cold Dark Matter ◽

Dwarf Galaxies ◽

Stellar Mass ◽

Rotation Curves ◽

Star Forming ◽

Fundamental Challenge ◽

Fisher Relation ◽

Intermediate Redshift ◽

Local Work

AbstractDo the kinematics and mass profiles of dwarf galaxies present a fundamental challenge to standard cold dark matter (CDM) models? New, deep spectroscopy using DEIMOS on Keck for hundreds of low stellar mass (107-109 M⊙ star-forming galaxies at intermediate redshift (0.2 < z < 1) addresses this inquiry in a way that is less subject to cosmic variance and environmental bias than previous, more local work. Half of this sample reveals resolved, doppler-shifted nebular emission, used to constrain rotation curves. From these we can construct the stellar mass Tully-Fisher relation to masses as low as ~107 M⊙, and a persistent discrepancy is found between predictions from simulations and models compared to our observations. We suggest on-going and future tests that will be more effective in distinguishing between the effects of baryonic feedback and alternative models of dark matter in this remarkable regime.

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Creating a galaxy lacking dark matter in a dark matter-dominated universe

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa3716 ◽

2020 ◽

Vol 501 (1) ◽

pp. 693-700

Author(s):

Andrea V Macciò ◽

Daniel Huterer Prats ◽

Keri L Dixon ◽

Tobias Buck ◽

Stefan Waterval ◽

...

Keyword(s):

Dark Matter ◽

Cold Dark Matter ◽

Dwarf Galaxies ◽

Initial Conditions ◽

Radial Component ◽

Tidal Interactions ◽

A Value ◽

Cold Dark Matter Model ◽

Stellar Velocity ◽

Matching Techniques

ABSTRACT We use hydrodynamical cosmological simulations to show that it is possible to create, via tidal interactions, galaxies lacking dark matter (DM) in a DM-dominated universe. We select dwarf galaxies from the NIHAO project, obtained in the standard cold dark matter model and use them as initial conditions for simulations of satellite–central interactions. After just one pericentric passage on an orbit with a strong radial component, NIHAO dwarf galaxies can lose up to 80 per cent of their DM content, but, most interestingly, their central (≈8 kpc) DM-to-stellar mass ratio changes from a value of ∼25, as expected from numerical simulations and abundance matching techniques, to roughly unity as reported for NGC 1052-DF2 and NGC 1054-DF4. The stellar velocity dispersion drops from ∼30 $\, \rm km\, s^{-1}$ before infall to values as low as 6 ± 2 $\, \rm km\, s^{-1}$. These, and the half-light radius around 3 kpc, are in good agreement with observations from van Dokkum and collaborators. Our study shows that it is possible to create a galaxy without DM starting from typical dwarf galaxies formed in a DM-dominated universe, provided they live in a dense environment.

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NIHAO – XXV. Convergence in the cusp-core transformation of cold dark matter haloes at high star formation thresholds

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa3028 ◽

2020 ◽

Vol 499 (2) ◽

pp. 2648-2661

Author(s):

Aaron A Dutton ◽

Tobias Buck ◽

Andrea V Macciò ◽

Keri L Dixon ◽

Marvin Blank ◽

...

Keyword(s):

Dark Matter ◽

Star Formation ◽

Galaxy Formation ◽

Cold Dark Matter ◽

Dwarf Galaxies ◽

Dwarf Galaxy ◽

Good Description ◽

Good Match ◽

Virial Mass ◽

Density Threshold

ABSTRACT We use cosmological hydrodynamical galaxy formation simulations from the NIHAO project to investigate the response of cold dark matter (CDM) haloes to baryonic processes. Previous work has shown that the halo response is primarily a function of the ratio between galaxy stellar mass and total virial mass, and the density threshold above which gas is eligible to form stars, n[cm−3]. At low n all simulations in the literature agree that dwarf galaxy haloes are cuspy, but at high n ≳ 100 there is no consensus. We trace halo contraction in dwarf galaxies with n ≳ 100 reported in some previous simulations to insufficient spatial resolution. Provided the adopted star formation threshold is appropriate for the resolution of the simulation, we show that the halo response is remarkably stable for n ≳ 5, up to the highest star formation threshold that we test, n = 500. This free parameter can be calibrated using the observed clustering of young stars. Simulations with low thresholds n ≤ 1 predict clustering that is too weak, while simulations with high star formation thresholds n ≳ 5, are consistent with the observed clustering. Finally, we test the CDM predictions against the circular velocities of nearby dwarf galaxies. Low thresholds predict velocities that are too high, while simulations with n ∼ 10 provide a good match to the observations. We thus conclude that the CDM model provides a good description of the structure of galaxies on kpc scales provided the effects of baryons are properly captured.

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Clustering dependence of Chandra COSMOS Legacy AGN on host galaxy properties

Proceedings of the International Astronomical Union ◽

10.1017/s1743921320002987 ◽

2019 ◽

Vol 15 (S356) ◽

pp. 226-226

Author(s):

Viola Allevato

Keyword(s):

Dark Matter ◽

Formation Rate ◽

Stellar Mass ◽

Active Galaxies ◽

Host Galaxy ◽

Mass Star ◽

Mass Relation ◽

Dark Matter Halos ◽

X Ray

AbstractThe presence of a super massive BH in almost all galaxies in the Universe is an accepted paradigm in astronomy. How these BHs form and how they co-evolve with the host galaxy is one of the most intriguing unanswered problems in modern Cosmology and of extreme relevance to understand the issue of galaxy formation. Clustering measurements can powerfully test theoretical model predictions of BH triggering scenarios and put constraints on the typical environment where AGN live in, through the connection with their host dark matter halos. In this talk, I will present some recent results on the AGN clustering dependence on host galaxy properties, such as galaxy stellar mass, star formation rate and specific BH accretion rate, based on X-ray selected Chandra COSMOS Legacy Type 2 AGN. We found no significant AGN clustering dependence on galaxy stellar mass and specif BHAR for Type 2 COSMOS AGN at mean z ∼ 1.1, with a stellar - halo mass relation flatter than predicted for non active galaxies in the Mstar range probed by our sample. We also observed a negative clustering dependence on SFR, with AGN hosting halo mass increasing with decreasing SFR. Mock catalogs of active galaxies in hosting dark matter halos with logMh[Msun] > 12.5, matched to have the same X-ray luminosity, stellar mass and BHAR of COSMOS AGN predict the observed Mstar - Mh, BHAR - Mh and SFR-Mh relations, at z ∼ 1.

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The formation of ultradiffuse galaxies in the RomulusC galaxy cluster simulation

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa2015 ◽

2020 ◽

Vol 497 (3) ◽

pp. 2786-2810 ◽

Cited By ~ 2

Author(s):

M Tremmel ◽

A C Wright ◽

A M Brooks ◽

F Munshi ◽

D Nagai ◽

...

Keyword(s):

Dark Matter ◽

Stellar Evolution ◽

Dwarf Galaxies ◽

Galaxy Cluster ◽

High Mass ◽

Tidal Interactions ◽

Low Surface Brightness ◽

Low Mass ◽

Tidal Heating ◽

Low Surface Brightness Galaxies

ABSTRACT We study the origins of 122 ultradiffuse galaxies (UDGs) in the Romulus c zoom-in cosmological simulation of a galaxy cluster (M200 = 1.15 × 1014 M⊙), one of the only such simulations capable of resolving the evolution and structure of dwarf galaxies (M⋆ < 109 M⊙). We find broad agreement with observed cluster UDGs and predict that they are not separate from the overall cluster dwarf population. UDGs in cluster environments form primarily from dwarf galaxies that experienced early cluster in-fall and subsequent quenching due to ram pressure. The ensuing dimming of these dwarf galaxies due to passive stellar evolution results in a population of very low surface brightness galaxies that are otherwise typical dwarfs. UDGs and non-UDGs alike are affected by tidal interactions with the cluster potential. Tidal stripping of dark matter, as well as mass-loss from stellar evolution, results in the adiabatic expansion of stars, particularly in the lowest mass dwarfs. High-mass dwarf galaxies show signatures of tidal heating while low-mass dwarfs that survive until z = 0 typically have not experienced such impulsive interactions. There is little difference between UDGs and non-UDGs in terms of their dark matter haloes, stellar morphology, colours, and location within the cluster. In most respects cluster UDG and non-UDGs alike are similar to isolated dwarf galaxies, except for the fact that they are typically quenched.

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The weak lensing radial acceleration relation: Constraining modified gravity and cold dark matter theories with KiDS-1000

Astronomy and Astrophysics ◽

10.1051/0004-6361/202040108 ◽

2021 ◽

Vol 650 ◽

pp. A113

Author(s):

Margot M. Brouwer ◽

Kyle A. Oman ◽

Edwin A. Valentijn ◽

Maciej Bilicki ◽

Catherine Heymans ◽

...

Keyword(s):

Dark Matter ◽

Galaxy Formation ◽

Modified Gravity ◽

Cold Dark Matter ◽

Weak Lensing ◽

Mass Relation ◽

Gravitational Acceleration ◽

Radial Acceleration ◽

The Galaxy ◽

The Difference

We present measurements of the radial gravitational acceleration around isolated galaxies, comparing the expected gravitational acceleration given the baryonic matter (gbar) with the observed gravitational acceleration (gobs), using weak lensing measurements from the fourth data release of the Kilo-Degree Survey (KiDS-1000). These measurements extend the radial acceleration relation (RAR), traditionally measured using galaxy rotation curves, by 2 decades in gobs into the low-acceleration regime beyond the outskirts of the observable galaxy. We compare our RAR measurements to the predictions of two modified gravity (MG) theories: modified Newtonian dynamics and Verlinde’s emergent gravity (EG). We find that the measured relation between gobs and gbar agrees well with the MG predictions. In addition, we find a difference of at least 6σ between the RARs of early- and late-type galaxies (split by Sérsic index and u − r colour) with the same stellar mass. Current MG theories involve a gravity modification that is independent of other galaxy properties, which would be unable to explain this behaviour, although the EG theory is still limited to spherically symmetric static mass models. The difference might be explained if only the early-type galaxies have significant (Mgas ≈ M⋆) circumgalactic gaseous haloes. The observed behaviour is also expected in Λ-cold dark matter (ΛCDM) models where the galaxy-to-halo mass relation depends on the galaxy formation history. We find that MICE, a ΛCDM simulation with hybrid halo occupation distribution modelling and abundance matching, reproduces the observed RAR but significantly differs from BAHAMAS, a hydrodynamical cosmological galaxy formation simulation. Our results are sensitive to the amount of circumgalactic gas; current observational constraints indicate that the resulting corrections are likely moderate. Measurements of the lensing RAR with future cosmological surveys (such as Euclid) will be able to further distinguish between MG and ΛCDM models if systematic uncertainties in the baryonic mass distribution around galaxies are reduced.

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