scholarly journals DARK MATTER DECAY AND ANNIHILATION IN THE LOCAL UNIVERSE: CLUES FROM FERMI

2010 ◽  
Vol 726 (1) ◽  
pp. L6 ◽  
Author(s):  
A. J. Cuesta ◽  
T. E. Jeltema ◽  
F. Zandanel ◽  
S. Profumo ◽  
F. Prada ◽  
...  
Keyword(s):  
Dark Matter ◽  
Local Universe

scholarly journals A comparative study of satellite galaxies in Milky Way-like galaxies from HSC, DECaLS, and SDSS

2020 ◽  
Vol 500 (3) ◽  
pp. 3776-3801
Author(s):  
Wenting Wang ◽  
Masahiro Takada ◽  
Xiangchong Li ◽  
Scott G Carlsten ◽  
Ting-Wen Lan ◽  
...  
Keyword(s):  
Dark Matter ◽  
Milky Way ◽  
Statistical Study ◽  
Satellite System ◽  
Large Scatter ◽  
Local Universe ◽  
Good Representative ◽  
Luminosity Functions ◽  
Satellite Galaxies ◽  
Good Agreement

ABSTRACT We conduct a comprehensive and statistical study of the luminosity functions (LFs) for satellite galaxies, by counting photometric galaxies from HSC, DECaLS, and SDSS around isolated central galaxies (ICGs) and paired galaxies from the SDSS/DR7 spectroscopic sample. Results of different surveys show very good agreement. The satellite LFs can be measured down to MV ∼ −10, and for central primary galaxies as small as 8.5 < log10M*/M⊙ < 9.2 and 9.2 < log10M*/M⊙ < 9.9, which implies there are on average 3–8 satellites with MV < −10 around LMC-mass ICGs. The bright end cutoff of satellite LFs and the satellite abundance are both sensitive to the magnitude gap between the primary and its companions, indicating galaxy systems with larger magnitude gaps are on average hosted by less massive dark matter haloes. By selecting primaries with stellar mass similar to our Milky Way (MW), we discovered that (i) the averaged satellite LFs of ICGs with different magnitude gaps to their companions and of galaxy pairs with different colour or colour combinations all show steeper slopes than the MW satellite LF; (ii) there are on average more satellites with −15 < MV < −10 than those in our MW; (iii) there are on average 1.5 to 2.5 satellites with MV < −16 around ICGs, consistent with our MW; (iv) even after accounting for the large scatter predicted by numerical simulations, the MW satellite LF is uncommon at MV > −12. Hence, the MW and its satellite system are statistically atypical of our sample of MW-mass systems. In consequence, our MW is not a good representative of other MW-mass galaxies. Strong cosmological implications based on only MW satellites await additional discoveries of fainter satellites in extra-galactic systems. Interestingly, the MW satellite LF is typical among other MW-mass systems within 40 Mpc in the local Universe, perhaps implying the Local Volume is an underdense region.

scholarly journals Dark matter in the Local Universe

2014 ◽  
Vol 58 ◽  
pp. 1-18 ◽  
Author(s):  
Gustavo Yepes ◽  
Stefan Gottlöber ◽  
Yehuda Hoffman
Keyword(s):  
Dark Matter ◽  
Local Universe

scholarly journals Stellar and dark matter density in the Local Universe

2018 ◽  
Vol 339 (7-8) ◽  
pp. 615-622 ◽  
Author(s):  
I. D. Karachentsev ◽  
K. N. Telikova
Keyword(s):  
Dark Matter ◽  
Matter Density ◽  
Local Universe ◽  
Dark Matter Density

scholarly journals Building Galactic Disks in Triaxial Dark Matter Halos

2006 ◽  
Vol 2 (S235) ◽  
pp. 24-28
Author(s):  
Isaac Shlosman
Keyword(s):  
Dark Matter ◽  
Angular Momentum ◽  
Star Formation ◽  
Numerical Simulations ◽  
Recent Work ◽  
Stellar Evolution ◽  
Dark Matter Halos ◽  
Local Universe ◽  
Broad Agreement ◽  
Formation And Evolution

AbstractWe review our recent work on the formation and evolution of disks within triaxial dark matter (DM) halos by means of numerical simulations, including star formation and feedback from stellar evolution. The growing disks are strongly influenced by shapes of DM halos and modify them in turn. Disk parameters are in a broad agreement with those in the local universe. Gas-rich stellar bars grow in tandem with the disk and facilitate the angular momentum redistribution in the system and radial gas inflow. Nested bars appear to form as a by-product. Interactions between various non-axisymmetric components—bars, disks and halos lead to decay of bars or washing out of ellipticity in the inner halo.

scholarly journals Void asymmetries in the cosmic web: a mechanism for bulk flows

2014 ◽  
Vol 11 (S308) ◽  
pp. 561-570
Author(s):  
J. Bland-Hawthorn ◽  
S. Sharma
Keyword(s):  
Dark Matter ◽  
Cosmic Microwave Background ◽  
Large Scale ◽  
Local Group ◽  
3D Structure ◽  
Moving Frame ◽  
Microwave Background ◽  
Local Universe ◽  
Scale Separation

AbstractBulk flows of galaxies moving with respect to the cosmic microwave background are well established observationally and seen in the most recent ΛCDM simulations. With the aid of an idealised Gadget-2 simulation, we show that void asymmetries in the cosmic web can exacerbate local bulk flows of galaxies. The {\it Cosmicflows-2} survey, which has mapped in detail the 3D structure of the Local Universe, reveals that the Local Group resides in a “local sheet” of galaxies that borders a “local void” with a diameter of about 40 Mpc. The void is emptying out at a rate of 16 km s-1Mpc-1. In a co-moving frame, the Local Sheet is found to be moving away from the Local Void at ∼ 260 km s-1. Our model shows how asymmetric collapse due to unbalanced voids on either side of a developing sheet or wall can lead to a systematic movement of the sheet. We conjectured that asymmetries could lead to a large-scale separation of dark matter and baryons, thereby driving a dependence of galaxy properties with environment, but we do {\it not} find any evidence for this effect.

scholarly journals A young galaxy cluster in the old Universe

2019 ◽  
Vol 489 (2) ◽  
pp. 2014-2029 ◽  
Author(s):  
Tetsuya Hashimoto ◽  
Tomotsugu Goto ◽  
Rieko Momose ◽  
Chien-Chang Ho ◽  
Ryu Makiya ◽  
...  
Keyword(s):  
Dark Matter ◽  
Galaxy Evolution ◽  
Galaxy Formation ◽  
Galaxy Cluster ◽  
Dark Matter Halo ◽  
Current Standard ◽  
Local Universe ◽  
Star Forming ◽  
Blue Star ◽  
Blue Galaxies

ABSTRACT Galaxies evolve from a blue star-forming phase into a red quiescent one by quenching their star formation activity. In high-density environments, this galaxy evolution proceeds earlier and more efficiently. Therefore, local galaxy clusters are dominated by well-evolved red elliptical galaxies. The fraction of blue galaxies in clusters monotonically declines with decreasing redshift, i.e. the Butcher–Oemler effect. In the local Universe, observed blue fractions of massive clusters are as small as ≲0.2. Here we report a discovery of a ‘blue cluster’ that is a local galaxy cluster with an unprecedentedly high fraction of blue star-forming galaxies yet hosted by a massive dark matter halo. The blue fraction is 0.57, which is 4.0σ higher than those of the other comparison clusters under the same selection and identification criteria. The velocity dispersion of the member galaxies is 510 km s−1, which corresponds to a dark matter halo mass of 2.0$^{+1.9}_{-1.0}\times 10^{14}$ M⊙. The blue fraction of the cluster is more than 4.7σ beyond the standard theoretical predictions including semi-analytic models of galaxy formation. The probability to find such a high blue fraction in an individual cluster is only 0.003 per cent, which challenges the current standard frameworks of the galaxy formation and evolution in the ΛCDM universe. The spatial distribution of galaxies around the blue cluster suggests that filamentary cold gas streams can exist in massive haloes even in the local Universe. However these cold streams have already disappeared in the theoretically simulated local universes.

scholarly journals H I Imaging Surveys: Gas and Galaxy Evolution in Different Environments

2010 ◽  
Vol 6 (S277) ◽  
pp. 41-46
Author(s):  
Jacqueline van Gorkom
Keyword(s):  
Dark Matter ◽  
Star Formation ◽  
Galaxy Evolution ◽  
Large Scale ◽  
Large Scale Structure ◽  
Local Universe ◽  
Formation And Evolution ◽  
Gas Accretion ◽  
Optical Surveys ◽  
Matter Component

AbstractOur understanding of the formation and evolution of galaxies and the large scale structure has advanced enormously over the last decade, thanks to an impressive synergy between theoretical and observational efforts. While the growth of the dark matter component seems well understood, the physics of the gas, during its accretion, removal and/or depletion is less well understood. Increasingly large scale optical surveys are tracing out the cosmic web of filaments and voids and mathematical tools have been developed to describe these structures and identify galaxies in specific environments. H I imaging surveys begin to answer the question: how do galaxies get and lose their gas. The best evidence for ongoing gas accretion is found in the lowest density environments, while removal of gas in the highest density environments stops star formation and reddens the galaxies. Although current H I emission surveys are limited to redshifts less than 0.2, this is where the LSS is best defined and much can be learned in the local universe.

scholarly journals Luminosity Bias: From Haloes to Galaxies

2013 ◽  
Vol 30 ◽  
Author(s):  
C. M. Baugh
Keyword(s):  
Dark Matter ◽  
Galaxy Formation ◽  
Large Scale ◽  
Large Scale Structure ◽  
Morphological Type ◽  
Intrinsic Properties ◽  
Matter Distribution ◽  
Local Universe ◽  
Galaxy Bias ◽  
The Universe

AbstractLarge surveys of the local Universe have shown that galaxies with different intrinsic properties such as colour, luminosity and morphological type display a range of clustering amplitudes. Galaxies are therefore not faithful tracers of the underlying matter distribution. This modulation of galaxy clustering, called bias, contains information about the physics behind galaxy formation. It is also a systematic to be overcome before the large-scale structure of the Universe can be used as a cosmological probe. Two types of approaches have been developed to model the clustering of galaxies. The first class is empirical and filters or weights the distribution of dark matter to reproduce the measured clustering. In the second approach, an attempt is made to model the physics which governs the fate of baryons in order to predict the number of galaxies in dark matter haloes. I will review the development of both approaches and summarise what we have learnt about galaxy bias.

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