scholarly journals How low does it go? Too few Galactic satellites with standard reionization quenching

2019 ◽  
Vol 488 (4) ◽  
pp. 4585-4595 ◽  
Author(s):  
Andrew S Graus ◽  
James S Bullock ◽  
Tyler Kelley ◽  
Michael Boylan-Kolchin ◽  
Shea Garrison-Kimmel ◽  
...  
Keyword(s):  
Galaxy Formation ◽  
Atomic Hydrogen ◽  
Milky Way ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Formation Theory ◽  
Disc Galaxy ◽  
Galactic Satellites ◽  
Hydrogen Cooling ◽  
The Relationship

ABSTRACT A standard prediction of galaxy formation theory is that the ionizing background suppresses galaxy formation in haloes with peak circular velocities smaller than $V_{\rm peak}\simeq 20 \, \rm km \, s^{-1}$, rendering the majority of haloes below this scale completely dark. We use a suite of cosmological zoom simulations of Milky Way-like haloes that include central Milky Way disc galaxy potentials to investigate the relationship between subhaloes and ultrafaint galaxies. We find that there are far too few subhaloes within 50 kpc of the Milky Way that had $V_{\rm peak}\gtrsim 20\, \rm km \, s^{-1}$ to account for the number of ultrafaint galaxies already known within that volume today. In order to match the observed count, we must populate subhaloes down to $V_{\rm peak}\simeq 6\, \rm km \, s^{-1}$ with ultrafaint dwarfs. The required haloes have peak virial temperatures as low as 1500 K, well below the atomic hydrogen cooling limit of 104 K. Allowing for the possibility that the Large Magellanic Cloud contributes several of the satellites within 50 kpc could potentially raise this threshold to $10\, \rm km \, s^{-1}$ (4000 K), still below the atomic cooling limit and far below the nominal reionization threshold.

scholarly journals The interstellar medium of the Magellanic Clouds from absorption lines

1991 ◽  
Vol 148 ◽  
pp. 401-406 ◽  
Author(s):  
Klaas S. De Boer
Keyword(s):  
Interstellar Medium ◽  
Absorption Line ◽  
Milky Way ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Magellanic Clouds ◽  
Absorption Lines ◽  
Small Magellanic Cloud ◽  
General Aspects

General aspects of ISM studies using absorption line studies are given and available data are reviewed. Topics are: galactic foreground gas, individual fields in the Magellanic Clouds (MCs) and MC coronae. Overall investigations are discussed. It is demonstrated that the metals in the gas of the Large Magellanic Cloud (LMC) and Small Magellanic Cloud (SMC) are a factor of 3 and 10, respectively, in abundance below solar levels. The depletion pattern in the LMC is similar to that of the Milky Way.

scholarly journals “2-D Frutti” Spectra of B Supergiants in the Milky Way and the LMC

1988 ◽  
Vol 132 ◽  
pp. 559-562
Author(s):  
Edward L. Fitzpatrick
Keyword(s):  
Milky Way ◽  
Photon Counting ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Image Tube ◽  
Blue Region ◽  
Pattern Noise ◽  
Fixed Pattern Noise ◽  
The Individual ◽  
Type Detector

Digital spectra of 7 B-type supergiants in the Milky Way and 15 B-type supergiants in the Large Magellanic Cloud (LMC) were obtained in December 1986 using the “2-D Frutti” detector (2-DF) and the Carnegie Image Tube Spectrograph on the 1-m telescope at the Cerro Tololo Inter-American Observatory. The 2-DF is a photon counting, 2-dimensional Shechtman-type detector, now available on both the 1-m and 4-m telescopes at CTIO. The detector/spectrograph configuration used for the December observing run yielded spectra covering the classical blue region, 3800-5000 Å, with a resolution of approximately 3 Å. The typical observing procedure was to obtain spectra for each star at several locations along the slit. The individual spectra were then averaged (to reduce the detector fixed pattern noise) resulting in S/N ratios of 50-60 in the 4300 Å region.

scholarly journals Blue Straggler Stars Beyond the Milky Way. III. Detection of Evolved Blue Straggler Candidates in Large Magellanic Cloud Clusters

2018 ◽  
Vol 156 (3) ◽  
pp. 110 ◽  
Author(s):  
Chengyuan Li ◽  
Licai Deng ◽  
Kenji Bekki ◽  
Jongsuk Hong ◽  
Richard de Grijs ◽  
...  
Keyword(s):  
Milky Way ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Cloud Clusters ◽  
Blue Straggler

scholarly journals The Large Magellanic Cloud PN population

2015 ◽  
Vol 11 (A29B) ◽  
Author(s):  
Warren A. Reid
Keyword(s):  
Milky Way ◽  
Central Star ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Parent Population ◽  
The Past ◽  
Standard Candle ◽  
Evolutionary Paths ◽  
Stellar Density

AbstractThe Large Magellanic Cloud (LMC) and Small Magellanic Cloud (SMC) allow us to study late stellar evolution in environments that are respectively about a half and a quarter the metallicity of the Milky Way. With a known distance and low reddening, the LMC is an excellent environment to study PNe and conduct multiple studies. Over the past twelve months we have used the UKST Hα survey to complete our search for faint PNe in the outer most LMC beyond the 64 deg2area previously covered. Follow-up spectroscopy using AAOmega on the AAT and the 2.3-m telescope at Siding Spring Observatory have yielded a further 22 new LMC PNe while confirming the 8 previously known in the outer LMC. Medium- and high-resolution spectra have been used to measure fluxes and derive densities, mass and central star temperatures. A strong correlation is found between PNe and stellar density. This is visually displayed and given an empirical value of α = 1 PN / 2.5 × 106L⊙. The current [Oiii]-based PNLF, apart from providing an excellent standard candle, contains information about the parent population. The new PNLF, which extends down nine magnitudes, permits investigation of the faint end, the overall effects of internal extinction and provides clues to explain the insensitivity of the PNLF cutoff. When compared to the ionised density and mass of LMC PNe, the PNLF reveals it’s bimodal characteristics. Two separate evolutionary paths are evident for young, evolving PNe.

scholarly journals Equilibrium models of the Milky Way mass are biased high by the LMC

2020 ◽  
Vol 498 (4) ◽  
pp. 5574-5580 ◽  
Author(s):  
Denis Erkal ◽  
Vasily A Belokurov ◽  
Daniel L Parkin
Keyword(s):  
Milky Way ◽  
Large Magellanic Cloud ◽  
Substantial Effect ◽  
Magellanic Cloud ◽  
Equilibrium Models ◽  
Simple Modification ◽  
Bulk Motion ◽  
Stellar Halo ◽  
Large Satellite

ABSTRACT Recent measurements suggest that the Large Magellanic Cloud (LMC) may weigh as much as 25 per cent of the Milky Way (MW). In this work, we explore how such a large satellite affects mass estimates of the MW based on equilibrium modelling of the stellar halo or other tracers. In particular, we show that if the LMC is ignored, the MW mass within 200 kpc is overestimated by as much as 50 per cent. This bias is due to the bulk motion in the outskirts of the Galaxy’s halo and can be, at least in part, accounted for with a simple modification to the equilibrium modelling. Finally, we show that the LMC has a substantial effect on the orbit Leo I which acts to increase its present-day speed relative to the MW. We estimate that accounting for a $1.5\times 10^{11} \, \mathrm{M}_\odot$ LMC would lower the inferred MW mass to $\sim 10^{12} \, \mathrm{M}_\odot$.

scholarly journals Ram-Pressure Induced Star Formation in the LMC

2008 ◽  
Vol 25 (3) ◽  
pp. 138-148 ◽  
Author(s):  
Chiara Mastropietro ◽  
Andreas Burkert ◽  
Ben Moore
Keyword(s):  
Star Formation ◽  
High Resolution ◽  
Milky Way ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Gaseous Disk ◽  
Star Formation Activity ◽  
Ram Pressure ◽  
Hydrodynamical Interaction

AbstractWe use high-resolution n-body/SPH simulations to study the hydrodynamical interaction between the Large Magellanic Cloud and the hot halo of the Milky Way. We investigate whether the ram-pressure acting on the gaseous disk of the satellite can explain the peculiarities observed in the Hidistribution and the location of the recent star formation activity.

scholarly journals Gaia Data Release 2

2018 ◽  
Vol 616 ◽  
pp. A12 ◽  
Author(s):  
◽  
A. Helmi ◽  
F. van Leeuwen ◽  
P. J. McMillan ◽  
D. Massari ◽  
...  
Keyword(s):  
Globular Clusters ◽  
Milky Way ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Proper Motions ◽  
Single Plane ◽  
Dwarf Spheroidal Galaxies ◽  
Orbital Parameters ◽  
Data Release ◽  
Using Data

Context. Aims. The goal of this paper is to demonstrate the outstanding quality of the second data release of the Gaia mission and its power for constraining many different aspects of the dynamics of the satellites of the Milky Way. We focus here on determining the proper motions of 75 Galactic globular clusters, nine dwarf spheroidal galaxies, one ultra-faint system, and the Large and Small Magellanic Clouds. Methods. Using data extracted from the Gaia archive, we derived the proper motions and parallaxes for these systems, as well as their uncertainties. We demonstrate that the errors, statistical and systematic, are relatively well understood. We integrated the orbits of these objects in three different Galactic potentials, and characterised their properties. We present the derived proper motions, space velocities, and characteristic orbital parameters in various tables to facilitate their use by the astronomical community. Results. Our limited and straightforward analyses have allowed us for example to (i) determine absolute and very precise proper motions for globular clusters; (ii) detect clear rotation signatures in the proper motions of at least five globular clusters; (iii) show that the satellites of the Milky Way are all on high-inclination orbits, but that they do not share a single plane of motion; (iv) derive a lower limit for the mass of the Milky Way of 9.1-2.6+6.2 × 1011 M⊙ based on the assumption that the Leo I dwarf spheroidal is bound; (v) derive a rotation curve for the Large Magellanic Cloud based solely on proper motions that is competitive with line-of-sight velocity curves, now using many orders of magnitude more sources; and (vi) unveil the dynamical effect of the bar on the motions of stars in the Large Magellanic Cloud. Conclusions. All these results highlight the incredible power of the Gaia astrometric mission, and in particular of its second data release.

Sign in / Sign up

Export Citation Format

Share Document