Mass Of Large Magellanic Cloud Research Articles

S5: Probing the Milky Way and Magellanic Clouds potentials with the 6D map of the Orphan–Chenab stream

ABSTRACTWe present a 6D map of the Orphan–Chenab (OC) stream by combining the data from Southern Stellar Stream Spectroscopic Survey (S5) and Gaia. We reconstruct the proper motion, radial velocity, distance, on-sky track, and stellar density along the stream with spline models. The stream has a total luminosity of MV = −8.2 and metallicity of [Fe/H] = −1.9, similar to classical Milky Way (MW) satellites like Draco. The stream shows drastic changes in its physical width varying from 200 pc to 1 kpc, but a constant line-of-sight velocity dispersion of 5 $\mathrm{km\, s^{-1}}$. Despite the large apparent variation in the stellar number density along the stream, the flow rate of stars along the stream is remarkably constant. We model the 6D stream track by a Lagrange-point stripping method with a flexible MW potential in the presence of a moving extended Large Magellanic Cloud (LMC). This allows us to constrain the mass profile of the MW within the distance range 15.6 < r < 55.5 kpc, with the best measured enclosed mass of $(2.85\pm 0.1)\times 10^{11}\, \mathrm{\, M_\odot }$ within 32.4 kpc. Our stream measurements are highly sensitive to the LMC mass profile with the most precise measurement of its enclosed mass made at 32.8 kpc, $(7.02\pm 0.9)\times 10^{10}\, {\rm M}_\odot$. We also detect that the LMC dark matter halo extends to at least 53 kpc. The fitting of the OC stream allows us to constrain the past LMC trajectory and the degree of dynamical friction it experienced. We demonstrate that the stars in the OC stream show large energy and angular momentum spreads caused by LMC perturbation.

Measuring the Milky Way mass distribution in the presence of the LMC

ABSTRACTThe ongoing interaction between the Milky Way (MW) and its largest satellite – the Large Magellanic Cloud (LMC) – creates a significant perturbation in the distribution and kinematics of distant halo stars, globular clusters and satellite galaxies, and leads to biases in MW mass estimates from these tracer populations. We present a method for compensating these perturbations for any choice of MW potential by computing the past trajectory of LMC and MW and then integrating the orbits of tracer objects back in time until the influence of the LMC is negligible, at which point the equilibrium approximation can be used with any standard dynamical modelling approach. We add this orbit-rewinding step to the mass estimation approach based on simultaneous fitting of the potential and the distribution function of tracers, and apply it to two data sets with the latest Gaia EDR3 measurements of 6D phase-space coordinates: globular clusters and satellite galaxies. We find that models with LMC mass in the range $(1\!-\!2) \times 10^{11}\, \mathrm{M}_\odot$ better fit the observed distribution of tracers, and measure MW mass within 100 kpc to be $(0.75\pm 0.1)\times 10^{12}\, \mathrm{M}_\odot$, while neglecting the LMC perturbation increases it by ∼15 per cent.

Measuring the Mass of the Large Magellanic Cloud with Stellar Streams Observed by S 5

Abstract Stellar streams are excellent probes of the underlying gravitational potential in which they evolve. In this work, we fit dynamical models to five streams in the Southern Galactic hemisphere, combining observations from the Southern Stellar Stream Spectroscopic Survey (S 5), Gaia EDR3, and the Dark Energy Survey, to measure the mass of the Large Magellanic Cloud (LMC). With an ensemble of streams, we find a mass of the LMC ranging from ∼14–19 × 1010 M ⊙, probed over a range of closest approach times and distances. With the most constraining stream (Orphan–Chenab), we measure an LMC mass of 18.8 − 4.0 + 3.5 × 10 10 M ⊙ , probed at a closest approach time of 310 Myr and a closest approach distance of 25.4 kpc. This mass is compatible with previous measurements, showing that a consistent picture is emerging of the LMC’s influence on structures in the Milky Way. Using this sample of streams, we find that the LMC’s effect depends on the relative orientation of the stream and LMC at their point of closest approach. To better understand this, we present a simple model based on the impulse approximation and we show that the LMC’s effect depends both on the magnitude of the velocity kick imparted to the stream and the direction of this kick.

Hubble Space Telescope Observations of Two Faint Dwarf Satellites of Nearby LMC Analogs from MADCASH*

Abstract We present a deep Hubble Space Telescope (HST) imaging study of two dwarf galaxies in the halos of Local Volume Large Magellanic Cloud (LMC) analogs. These dwarfs were discovered as part of our Subaru+Hyper Suprime-Cam MADCASH survey: MADCASH-1 is a satellite of NGC 2403 (D ∼ 3.2 Mpc), and MADCASH-2 is a previously unknown dwarf galaxy near NGC 4214 (D ∼ 3 Mpc). Our HST data reach >3.5 mag below the tip of the red giant branch (TRGB) of each dwarf, allowing us to derive their structural parameters and assess their stellar populations. We measure TRGB distances ( D MADCASH − 1 = 3.41 − 0.23 + 0.24 Mpc, D MADCASH − 2 = 3.00 − 0.15 + 0.13 Mpc), and confirm the dwarfs’ associations with their host galaxies. MADCASH-1 is a predominantly old, metal-poor stellar system (age ∼13.5 Gyr, [M/H] ∼ −2.0), similar to many Local Group dwarfs. Modelling of MADCASH-2's color–magnitude diagram suggests that it contains mostly ancient, metal-poor stars (age ∼13.5 Gyr, [M/H] ∼ −2.0), but that ∼10% of its stellar mass was formed 1.1–1.5 Gyr ago and ∼1% was formed 400–500 Myr ago. Given its recent star formation, we search MADCASH-2 for neutral hydrogen using the Green Bank Telescope, but find no emission and estimate an upper limit on the H i mass of <4.8 × 104 M ⊙. These are the faintest dwarf satellites known around host galaxies of LMC mass outside the Local Group (M V,MADCASH−1 = −7.81 ± 0.18, M V,MADCASH−2 = −9.15 ± 0.12), and one of them shows signs of recent environmental quenching by its host. Once the MADCASH survey for faint dwarf satellites is complete, our census will enable us to test predictions from cold dark matter models for hierarchical structure formation and discover the physical mechanisms by which low-mass hosts influence the evolution of their satellites.

Tango for three: Sagittarius, LMC, and the Milky Way

ABSTRACT We assemble a catalogue of candidate Sagittarius stream members with 5D and 6D phase-space information, using astrometric data from Gaia DR2, distances estimated from RR Lyrae stars, and line-of-sight velocities from various spectroscopic surveys. We find a clear misalignment between the stream track and the direction of the reflex-corrected proper motions in the leading arm of the stream, which we interpret as a signature of a time-dependent perturbation of the gravitational potential. A likely cause of this perturbation is the recent passage of the most massive Milky Way satellite – the Large Magellanic Cloud (LMC). We develop novel methods for simulating the Sagittarius stream in the presence of the LMC, using specially tailored N-body simulations and a flexible parametrization of the Milky Way halo density profile. We find that while models without the LMC can fit most stream features rather well, they fail to reproduce the misalignment and overestimate the distance to the leading arm apocentre. On the other hand, models with an LMC mass in the range $(1.3\pm 0.3)\times 10^{11}\, \mathrm{M}_\odot$ rectify these deficiencies. We demonstrate that the stream can not be modelled adequately in a static Milky Way. Instead, our Galaxy is required to lurch toward the massive in-falling Cloud, giving the Sgr stream its peculiar shape and kinematics. By exploring the parameter space of Milky Way potentials, we determine the enclosed mass within 100 kpc to be $(5.6\pm 0.4)\times 10^{11}\, \mathrm{M}_\odot$, and the virial mass to be $(9.0\pm 1.3)\times 10^{11}\, \mathrm{M}_\odot$, and find tentative evidence for a radially-varying shape and orientation of the Galactic halo.

Quantifying the Stellar Halo's Response to the LMC's Infall with Spherical Harmonics

Abstract The vast majority of the mass in the Milky Way (MW) is in dark matter (DM); we therefore cannot directly observe the MW mass distribution and have to use tracer populations in order to infer properties of the MW DM halo. However, MW halo tracers do not only feel the gravitational influence of the MW itself. Tracers can also be affected by MW satellites; Garavito-Camargo et al. (2109) demonstrate that the Large Magellanic Cloud (LMC) induces a density wake in the MW DM, resulting in large-scale kinematic patterns in the MW stellar halo. In this work, we use spherical harmonic expansion (SHE) of the velocity fields of simulated stellar halos in an effort to disentangle perturbations on large scales (e.g., due to the LMC itself, as well as the LMC-induced DM wake) and small scales (due to substructure). Using the Garavito-Camargo et al. simulations, we demonstrate how the different terms in the SHE of the stellar velocity field reflect the different wake components and show that these signatures are a strong function of the LMC mass. An exploration of model halos built from accreted dwarfs suggests that stellar debris from massive, recent accretion events can produce much more power in the velocity angular power spectra than the perturbation from the LMC-induced wake. We therefore consider two models for the Sagittarius (Sgr) stream—the most recent, massive accretion event in the MW apart from the LMC—and find that the angular power on large scales is generally dominated by the LMC-induced wake, even when Sgr is included. We conclude that SHE of the MW stellar halo velocity field may therefore be a useful tool in quantifying the response of the MW DM halo to the LMC’s infall.

Limit on the LMC mass from a census of its satellites

ABSTRACT We study the orbits of dwarf galaxies in the combined presence of the Milky Way and Large Magellanic Cloud (LMC) and find six dwarfs that were likely accreted with the LMC (Car 2, Car 3, Hor 1, Hyi 1, Phe 2, and Ret 2), in addition to the Small Magellanic Cloud (SMC), representing strong evidence of dwarf galaxy group infall. This procedure depends on the gravitational pull of the LMC, allowing us to place a lower bound on the Cloud’s mass of $M_{\rm LMC} \gt 1.24\times 10^{11} \, \mathrm{M}_\odot$ if we assume that these are LMC satellites. This mass estimate is validated by applying the technique to a cosmological zoom-in simulation of a Milky Way-like galaxy with an LMC analogue where we find that while this lower bound may be overestimated, it will improve in the future with smaller observational errors. We apply this technique to dwarf galaxies lacking radial velocities and find that Eri 3 has a broad range of radial velocities for which it has a significant chance (>0.4) of having been bound to the Cloud. We study the non-Magellanic classical satellites and find that Fornax has an appreciable probability of being an LMC satellite if the LMC is sufficiently massive ($\text{$\sim$} 2.5\times 10^{11} \, \mathrm{M}_\odot$). In addition, we explore how the orbits of Milky Way satellites change in the presence of the LMC and find a significant change for several objects. Finally, we find that the dwarf galaxies likely to be LMC satellites are slightly smaller than Milky Way satellites at a fixed luminosity, possibly due to the different tidal environments they have experienced.

The total mass of the Large Magellanic Cloud from its perturbation on the Orphan stream

In a companion paper by Koposov et al., RR Lyrae from \textit{Gaia} Data Release 2 are used to demonstrate that stars in the Orphan stream have velocity vectors significantly misaligned with the stream track, suggesting that it has received a large gravitational perturbation from a satellite of the Milky Way. We argue that such a mismatch cannot arise due to any realistic static Milky Way potential and then explore the perturbative effects of the Large Magellanic Cloud (LMC). We find that the LMC can produce precisely the observed motion-track mismatch and we therefore use the Orphan stream to measure the mass of the Cloud. We simultaneously fit the Milky Way and LMC potentials and infer that a total LMC mass of $1.38^{+0.27}_{-0.24} \times10^{11}\,\rm{M_\odot}$ is required to bend the Orphan Stream, showing for the first time that the LMC has a large and measurable effect on structures orbiting the Milky Way. This has far-reaching consequences for any technique which assumes that tracers are orbiting a static Milky Way. Furthermore, we measure the Milky Way mass within 50 kpc to be $3.80^{+0.14}_{-0.11}\times10^{11} M_\odot$. Finally, we use these results to predict that, due to the reflex motion of the Milky Way in response to the LMC, the outskirts of the Milky Way's stellar halo should exhibit a bulk, upwards motion.

An ALMA archival study of the clump mass function in the Large Magellanic Cloud

We present 1.3 and 3.2 mm continuum maps of three star forming regions in the Large Magellanic Cloud (LMC) observed with the Atacama Large Millimeter/Submillimeter Array (ALMA). The data were taken as part of two projects retrieved from the ALMA public archive plus one project observed specifically for this work. We develop a technique to combine maps at these wavelengths to estimate dust-only emission corrected for free-free emission contamination. From these observations we identify 32 molecular clumps in the LMC and estimate their total mass from their dust emission to range from 205 to 5740 M$_{\odot}$. We derive a cumulative clump mass function ($N(\geq M) \propto M^{\alpha + 1}$) and fit it with a double power law to find $\alpha_{\mathrm{low}} = -1.76^{+0.04}_{-0.05}$, $\alpha_{\mathrm{high}} = -3.3 \pm 0.2$, and a break mass of 2500$^{+300}_{-200}$ M$_{\odot}$. A comparison to the 30 Doradus-10 mass function derived previously from CO (2-1) data reveals a consistent range of clump masses and good agreement between the fitted slopes. We also find that the low mass index of the LMC mass function agrees well with the high mass index for core and clump mass functions from several star forming regions in the Milky Way. This agreement may indicate an extension of the Milky Way power law to higher masses than previously observed.

Modelling the Tucana III stream - a close passage with the LMC

We present results of the first dynamical stream fits to the recently discovered Tucana III stream. These fits assume a fixed Milky Way potential and give proper motion predictions, which can be tested with the upcoming Gaia Data Release 2. These fits reveal that Tucana III is on an eccentric orbit around the Milky Way and, more interestingly, that Tucana III passed within 15 kpc of the Large Magellanic Cloud (LMC) approximately 75 Myr ago. Given this close passage, we fit the Tucana III stream in the combined presence of the Milky Way and the LMC. We find that the predicted proper motions depend on the assumed mass of the LMC and that the LMC can induce a substantial proper motion perpendicular to the stream track. A detection of this misalignment will directly probe the extent of the LMC's influence on our Galaxy, and has implications for nearly all methods which attempt to constraint the Milky Way potential. Such a measurement will be possible with the upcoming Gaia DR2, allowing for a measurement of the LMC's mass.

A timing constraint on the (total) mass of the Large Magellanic Cloud

Abstract This paper explores the effect of the Large Magellanic Cloud (LMC) on the mass estimates obtained from the timing argument. We show that accounting for the presence of the LMC systematically lowers the Local Group mass (MLG) derived from the relative motion of the Milky Way–Andromeda pair. Motivated by this result, we apply a Bayesian technique devised by Peñarrubia et al. to simultaneously fit (i) distances and velocities of galaxies within 3 Mpc and (ii) the relative motion between the Milky Way and Andromeda derived from HST observations, with the LMC mass (MLMC) as a free parameter. Our analysis returns a Local Group mass $M_{\rm LG}=2.64^{+0.42}_{-0.38}\times 10^{12}\,\mathrm{M}_{\odot }$ at a 68 per cent confidence level. The masses of the Milky Way, $M_{\rm MW}=1.04_{-0.23}^{+0.26}\times 10^{12}\,\mathrm{M}_{\odot }$, and Andromeda, $M_{{\rm M}31}=1.33_{-0.33}^{+0.39}\times 10^{12}\,\mathrm{M}_{\odot }$, are consistent with previous estimates that neglect the impact of the LMC on the observed Hubble flow. We find a (total) LMC mass $M_{\rm LMC}=0.25_{-0.08}^{+0.09}\times 10^{12}\,\mathrm{M}_{\odot }$, which is indicative of an extended dark matter halo and supports the scenario where this galaxy is just past its first pericentric approach. Consequently, these results suggest that the LMC may induce significant perturbations on the Galactic potential.

Formation of the off-centre bar in the Large Magellanic Cloud: a collision with a dark satellite?

Abstract Recent observations of the structural properties of the Large Magellanic Cloud (LMC) based on the Deep Near-Infrared Southern Sky Survey and Two Micron All-Sky Survey have revealed that the LMC has an off-centre bar even in the older stellar populations. Previous dynamical models including tidal interaction between the LMC, the Small Magellanic Cloud (SMC) and the Galaxy, however, did not reproduce the older off-centre bar so well. Here, we show that the off-centre bar can be formed if the LMC with an already-existing bar can collide with a low-mass Galactic subhalo as massive as ∼5 × 108M⊙ (roughly corresponding to a few per cent of the LMC mass). The simulated stellar distribution after the collision appears to show an ‘off-centre bar’, not because the centre of the bar significantly deviates from the dynamical centre of the LMC, but because the underlying stellar distribution of the disc is significantly asymmetric with respect to the centre of the bar. We discuss whether off-centre bars observed in Magellanic-type dwarf galaxies can be formed as a result of tidal interaction with low-mass haloes with no or little visible matter.

Mass of large Magellanic Cloud X-3

view Abstract Citations (35) References (12) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Mass of Large Magellanic Cloud X-3. Paczynski, B. Abstract The lower mass limit for LMC X-3 is obtained taking into account the absence of X-ray eclipses and not allowing the B star to exceed its Roche lobe radius. The mass limit depends on the B star radius. For a plausible value of 6 solar radii, the minimum mass of the X-ray component is 10 solar masses. This result does not depend on the structure or evolutionary status of either component. The upper mass limit for the B star is estimated to be 6.6 solar masses, almost independent of its evolutionary status. This implies that the optical star is less massive than the X-ray component and that the Roche lobe overflow may be stable. If the B star is on the main sequence, then its expansion due to nuclear evolution may give rise to the mass transfer rate of 10 to the -7th solar mass per year and the total accretion luminosity of 10 to the 39th ergs/s. Reflection effect due to X-ray heating as well as ellipsoidal light variations are expected to be seen in the light curve of this system. Publication: The Astrophysical Journal Pub Date: October 1983 DOI: 10.1086/184134 Bibcode: 1983ApJ...273L..81P Keywords: Binary Stars; Black Holes (Astronomy); Magellanic Clouds; Stellar Mass; X Ray Sources; B Stars; Mass To Light Ratios; Stellar Evolution; Stellar Mass Accretion; Astrophysics full text sources ADS | data products SIMBAD (3)