The gap of stellar mass in galaxy groups: another perspective of the too-big-to-fail problem in the Milky Way

Kang, Xi; Wang, Lei; Luo, Yu

doi:10.1093/mnras/stw1166

Cited by 10 publications

(9 citation statements)

References 53 publications

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“…The Milky Way analogs on average have only 0.3 satellites brighter than these luminosities, versus two for the Milky Way (Liu et al 2011). The distribution of these bright satellites is also remarkably consistent with simulations using fairly straightforward assumptions about the galaxy-halo connection Rodríguez-Puebla et al 2013;Kang et al 2016). It is below these luminosities that the Milky Way's satellite properties diverge from simple galaxy formation predictions.…”

Section: Introductionsupporting

confidence: 69%

The SAGA Survey. I. Satellite Galaxy Populations around Eight Milky Way Analogs

Geha

Wechsler

Mao

et al. 2017

ApJ

242

306

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We present the survey strategy and early results of the "Satellites Around Galactic Analogs" (SAGA) Survey. The SAGA Survey's goal is to measure the distribution of satellite galaxies around 100 systems analogous to the Milky Way down to the luminosity of the Leo I dwarf galaxy (M r < −12.3). We define a Milky Way analog based on K-band luminosity and local environment. Here, we present satellite luminosity functions for 8 Milky Way analog galaxies between 20 to 40 Mpc. These systems have nearly complete spectroscopic coverage of candidate satellites within the projected host virial radius down to r o < 20.75 using low redshift gri color criteria. We have discovered a total of 25 new satellite galaxies: 14 new satellite galaxies meet our formal criteria around our complete host systems, plus 11 additional satellites in either incompletely surveyed hosts or below our formal magnitude limit. Combined with 13 previously known satellites, there are a total of 27 satellites around 8 complete Milky Way analog hosts. We find a wide distribution in the number of satellites per host, from 1 to 9, in the luminosity range for which there are five Milky Way satellites. Standard abundance matching extrapolated from higher luminosities predicts less scatter between hosts and a steeper luminosity function slope than observed. We find that the majority of satellites (26 of 27) are star-forming. These early results indicate that the Milky Way has a different satellite population than typical in our sample, potentially changing the physical interpretation of measurements based only on the Milky Way's satellite galaxies.

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Section: Introductionsupporting

confidence: 69%

The SAGA Survey. I. Satellite Galaxy Populations around Eight Milky Way Analogs

Geha

Wechsler

Mao

et al. 2017

ApJ

242

306

View full text Add to dashboard Cite

show abstract

“…The other problem is that the predicted central mass density is higher than observed (the "too-big-to-fail" problem, Boylan-Kolchin et al (2012). Several solutions have been proposed, such as the possibility that dark matter is not cold (e.g., Lovell et al 2012;Vogelsberger & Zavala 2013), an induced core arising from baryon physics and star formation (e.g., Brooks & Zolotov 2014;Guo et al 2015;Wetzel et al 2016;Brooks et al 2017), the MW having a lower halo mass (e.g., Vera-Ciro et al 2013;Dierickx & Loeb 2017) or the MW having a particular quirk of accreting its subhaloes (Kang et al (2016)).…”

Section: Introductionmentioning

confidence: 99%

The effect of the Large Magellanic Cloud on the satellite galaxy population in Milky Way analogous galaxies

Zhang

Luo

Kang

2019

Monthly Notices of the Royal Astronomical Society

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Observational work have shown that the two brightest satellite galaxies of the Milky Way (MW), the Large Magellanic Cloud (LMC) and the Small Magellanic Cloud (SMC), are rare amongst MW analogues. It is then interesting to know whether the presence of massive satellite has any effect on the whole satellite population in MW analogues. In this article, we investigate this problem using a semi-analytical model combined with the Millennium-II Simulation. MW-analogous galaxies are defined to have similar stellar mass or dark matter halo mass to the MW. We find that, in the first case, the halo mass is larger and there are, on average, twice as many satellites in Milky Way analogs if there is a massive satellite galaxy in the system. This is mainly from the halo formation bias. The difference is smaller if MW analogues are selected using halo mass. We also find that the satellites distribution is slightly asymmetric, being more concentrated on the line connecting the central galaxy and the massive satellite and that, on average, LMC have brought in 14.7 satellite galaxies with M r < 0 at its accretion, among which 4.5 satellites are still within a distance of 50kpc from the LMC. Considering other satellites, we predict that there are 7.8 satellites with 50kpc of the LMC. By comparing our model with the early data of Satellites Around Galactic Analogs (SAGA), a survey to observe satellite galaxies around 100 Milky Way analogues, we find that SAGA has more bright satellites and less faint satellites than our model predictions. A future comparison with the final SAGA data is needed.

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“…Under the current ΛCDM structure formation scenario, the most salient and persistent missmatch with observations occurs at the smallest scales, where models appear to over-predict the number of satellites a large galaxy like the Milky Way should have, e.g. Moore et al (1999), Kang et al (2016). Also, it is at the smallest scales of the dwarf spheroidal systems where tests of the dark matter hypothesis become cleaner and more sensitive, given the absence of gas and the presence of well studied stellar populations, they have been recently used to attempt predicting direct dark matter annihilation signals e.g.…”

Section: Introductionmentioning

confidence: 99%

Theoretical lower limits on sizes of ultrafaint dwarf galaxies from dynamical friction

Hernández

2016

Mon. Not. R. Astron. Soc.

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Dwarf spheroidal galaxies are the smallest known stellar systems where under Newtonian interpretations, a significant amount of dark matter is required to explain observed kinematics. In fact, they are in this sense the most heavily dark matter dominated objects known. That, plus the increasingly small sizes of the newly discovered ultra faint dwarfs, puts these systems in the regime where dynamical friction on individual stars starts to become relevant. We calculate the dynamical friction timescales for pressure supported isotropic spherical dark matter dominated stellar systems, yielding τ DF = 0.93(r h /10pc) 2 (σ/kms −1 )Gyr, where r h is the half-light radius. For a stellar velocity dispersion value of 3km/s, as typical for the smallest of the recently detected ultra faint dwarf spheroidals, dynamical friction timescales becomes smaller than the 10Gyr typical of the stellar ages for these systems, for r h < 19pc. Thus, this becomes a theoretical lower limit below which dark matter dominated stellar systems become unstable to dynamical friction. We present a comparison with structural parameters of the smallest ultra faint dwarf spheroidals known, showing that these are already close to the stability limit derived, any future detection of yet smaller such systems would be inconsistent with a particle dark matter hypothesis.

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The gap of stellar mass in galaxy groups: another perspective of the too-big-to-fail problem in the Milky Way

Cited by 10 publications

References 53 publications

The SAGA Survey. I. Satellite Galaxy Populations around Eight Milky Way Analogs

The SAGA Survey. I. Satellite Galaxy Populations around Eight Milky Way Analogs

The effect of the Large Magellanic Cloud on the satellite galaxy population in Milky Way analogous galaxies

Theoretical lower limits on sizes of ultrafaint dwarf galaxies from dynamical friction

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