New constraints on the nature and origin of the Leading Arm of the Magellanic Stream

Abstract

We present a new precision measurement of gas-phase abundances of S, O, N, Si, Fe, P, Al, Ca as well as molecular hydrogen (H_2) in the Leading Arm (region II, LAII) of the Magellanic Stream (MS) towards the Seyfert galaxy NGC 3783. The results are based on high-quality archival ultraviolet/optical/radio data from various different instruments (HST/STIS, FUSE, AAT, GBT, GB140ft, ATCA). Our study updates previous results from lower-resolution data and provides for the first time a self-consistent component model of the complex multi-phase absorber, delivering important constraints on the nature and origin of LAII. We derive a uniform, moderate alpha abundance in the two main absorber groups at +245 and +190 km s^-1 of alpha/H = 0.30 pm 0.05 solar, a low nitrogen abundance of N/H = 0.05 pm 0.01 solar, and a high dust content with substantial dust depletion values for Si, Fe, Al, and Ca. These alpha, N, and dust abundances in LAII are similar to those observed in the Small Magellanic Cloud (SMC). From the analysis of the H_2 absorption, we determine a high thermal pressure of P/k = 1680 K cm^-3 in LAII, in line with the idea that LAII is located in the inner Milky Way halo at a z-height of <20 kpc where it hydrodynamically interacts with the ambient hot coronal gas. Our study supports a scenario, in which LAII stems from the break-up of a metal- and dust-enriched progenitor cloud that was recently (200-500 Myr ago) stripped from the SMC.

arXiv comment18 pages, 12 figures; accepted for publication in ApJ

References in corpus (69)

• The chemical composition of the Sun
• A Unified Representation of Gas-Phase Element Depletions in the Interstellar Medium
• Structure of Stationary Photodissociation Fronts
• Gaseous Galaxy Halos
• The Star Formation History of the Small Magellanic Cloud
• The COS-Halos Survey: An Empirical Description of the Metal-Line Absorption in the Low-Redshift Circumgalactic Medium
• The Role of Dwarf Galaxy Interactions in Shaping the Magellanic System and Implications for Magellanic Irregulars
• The Origin of the Magellanic Stream and Its Leading Arm
• The disruption of nearby galaxies by the Milky Way
• Simulations of the Magellanic Stream in a First Infall Scenario
• Constraining the Milky Way's Hot Gas Halo with OVII and OVII Emission Lines
• The Parkes HI Survey of the Magellanic System
• Chemical Evolution of the Magellanic Clouds: analytical models
• The Distribution of Thermal Pressures in the Interstellar Medium from a Survey of C I Fine-Structure Excitation
• A FUSE Survey of Interstellar Molecular Hydrogen in the Small and Large Magellanic Clouds
• The Magellanic Stream: Circumnavigating the Galaxy
• The 200 Degree-Long Magellanic Stream System
• C, N, O Abundances in the Most Metal-Poor Damped Lyman alpha Systems
• The COS/UVES Absorption Survey of the Magellanic Stream. III: Ionization, Total Mass, and Inflow Rate onto the Milky Way
• The Fate of High-Velocity Clouds: Warm or Cold Cosmic Rain?
• Mining Circumgalactic Baryons in the Low-Redshift Universe
• Efficiency of gas cooling and accretion at the disc-corona interface
• The equilibrium view on dust and metals in galaxies: Galactic outflows drive low dust-to-metal ratios in dwarf galaxies
• An HST/COS legacy survey of high-velocity ultraviolet absorption in the Milky Way's circumgalactic medium and the Local Group
• The Metallicity and Dust Content of HVC 287.5+22.5+240: Evidence for a Magellanic Clouds Origin
• Exploring the Origin and Fate of the Magellanic Stream with Ultraviolet and Optical Absorption
• A FUSE survey of high-latitude Galactic molecular hydrogen
• FUSE Observations of Atomic Abundances and Molecular Hydrogen in the Leading Arm of the Magellanic Stream
• Gas Condensation in the Galactic Halo
• The Magellanic Stream System: I. Ram-pressure tails and the relics of the collision between the Magellanic Clouds
• The Ionized Gas and Nuclear Environment in NGC 3783 II. Averaged HST/STIS and FUSE Spectra
• The COS/UVES Absorption Survey of the Magellanic Stream: II. Evidence for a complex enrichment history of the Stream from the Fairall 9 sightline
• The COS/UVES Absorption Survey of the Magellanic Stream: I. One-Tenth Solar Abundances along the Body of the Stream
• The FUSE Spectrum of PG0804+761: A Study of Atomic and MolecularGas in the Lower Galactic Halo and Beyond
• A FUSE Survey of Molecular Hydrogen in Intermediate-Velocity Clouds in the Milky Way Halo
• Accurate Galactic 21-cm H I measurements with the NRAO Green Bank Telescope
• Absorption-Line Detections of $10^{5-6}$ K Gas in Spiral-Rich Groups of Galaxies
• The High Velocity Gas toward Messier 5: Tracing Feedback Flows in the Inner Galaxy
• A Near-Solar Metallicity, Nitrogen-Deficient Lyman Limit Absorber Associated with two S0 Galaxies
• Interstellar Gas-phase Element Depletions in the Small Magellanic Cloud: A Guide to Correcting for Dust in QSO Absorption Line Systems
• The Nitrogen and Oxygen abundances in the neutral gas at high redshift
• The neutral gas extent of galaxies as derived from weak intervening CaII absorbers
• Elemental depletions in the Magellanic Clouds and the evolution of depletions with metallicity
• Models of Tidally Induced Gas Filaments in the Magellanic Stream
• Calcium H & K Induced by Galaxy Halos
• An Interaction of a Magellanic Leading Arm High Velocity Cloud with the Milky Way Disk
• The Ionized Gas and Nuclear Environment in NGC 3783 III. Detection of a Decreasing Radial Velocity in an Intrinsic UV Absorber
• A population of weak metal-line absorbers surrounding the Milky Way
• C II Radiative Cooling of the Diffuse Gas in the Milky Way
• Low-column density gas clumps in the halo of the Milky Way
• Warm Ionized Gas Revealed in the Magellanic Bridge Tidal Remnant: Constraining the Baryon Content and the Escaping Ionizing Photons around Dwarf Galaxies
• The Magellanic Stream: break up and accretion onto the hot Galactic corona
• High-Velocity Clouds and the Local Intergalactic Medium
• COS-Weak: Probing the CGM using analogs of weak Mg II absorbers at z < 0.3
• Gas Accretion onto the Milky Way
• Chemical Abundances in the Leading Arm of the Magellanic Stream
• The four leading arms of the Magellanic Cloud system
• H_2 absorption in a dense interstellar filament in the Milky Way halo
• A Survey of Analogs to Weak MgII Absorbers in the Present
• Cold Neutral Gas in a z=4.2 Damped Lyman-alpha System: The Fuel for Star Formation
• The Milky Way halo as a QSO absorption-line system. New results from an HST/STIS absorption-line catalogue of Galactic high-velocity clouds
• Recent Star Formation in the Leading Arm of the Magellanic Stream
• An HST/COS legacy survey of intervening SiIII absorption in the extended gaseous halos of low-redshift galaxies
• Revealing the Ionization Properties of the Magellanic Stream using Optical Emission
• Down-the-barrel and transverse observations of the Large Magellanic Cloud: evidence for a symmetrical galactic wind on the near and far sides of the galaxy
• The Fate of Supernova-Heated Gas in Star-Forming Regions of the LMC: Lessons for Galaxy Formation?
• VLT/UVES observations of peculiar alpha abundances in a sub-DLA at z ~ 1.8 towards the quasar B1101-26
• The Distance and Properties of Hydrogen Clouds in the Leading Arm of the Magellanic System
• Chemical Composition of Young Stars in the Leading Arm of the Magellanic System

Cited by in corpus (13)

• The Magellanic System: the puzzle of the leading gas stream
• Kinematics of the Magellanic Stream and Implications for its Ionization
• Spectroscopy of the Young Stellar Association Price-Whelan 1: Origin in the Magellanic Leading Arm and Constraints on the Milky Way Hot Halo
• The Cosmic Ultraviolet Baryon Survey (CUBS) II: Discovery of an H${}_2$-Bearing DLA in the Vicinity of an Early-Type Galaxy at z = 0.576
• Radiative Turbulent Mixing Layers and the Survival of Magellanic Debris
• Detection of Dust in High-Velocity Cloud Complex C -- Enriched Gas Accreting onto the Milky Way
• H$\alpha$ Distances to the Leading Arm of the Magellanic Stream
• Circumgalactic gas at its extreme: tidal gas streams around the Whale galaxy NGC 4631 explored with HST/COS
• On the Origin of High-velocity Clouds in the Galaxy
• The Diffuse Ionized Gas of the Large Magellanic Cloud
• Young stars raining through the Galactic Halo: the nature and orbit of Price-Whelan 1
• The Origins of Young Stars in the Direction of the Leading Arm of the Magellanic Stream: Abundances, Kinematics, and Orbits
• A Search for 3-mm Molecular Absorption Line Transitions in the Magellanic Stream