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Abstract We present spatially resolved spectroscopy from the Keck Cosmic Web Imager (KCWI) of a star-forming galaxy at z = 0.6942, which shows emission from the Mg ii λ λ 2796, 2803 doublet in the circumgalactic medium (CGM) extending ∼37 kpc at 3 σ significance in individual spaxels (1 σ detection limit 4.8 × 10 −19 erg s −1 cm −2 arcsec −2 ). The target galaxy, selected from a near-UV spectroscopic survey of Mg ii line profiles at 0.3 < z < 1.4, has a stellar mass log ( M * / M ⊙ ) = 9.9, a star formation rate of 50 M ⊙ yr −1 , and a morphology indicative of a merger. After deconvolution with the seeing, we obtain 5 σ detections of Mg ii line emission extending for ∼31 kpc measured in 7-spaxel (1.1 arcsec 2 ) apertures. Spaxels covering the galaxy stellar regions show clear P Cygni−like emission/absorption profiles, with the blueshifted absorption extending to relative velocities of v = −800 km s −1 ; however, the P Cygni profiles give way to pure emission at large radii from the central galaxy. We have performed 3D radiative transfer modeling to infer the geometry and velocity and density profiles of the outflowing gas. Our observations are most consistent with an isotropic outflow rather than biconical wind models with half-opening angles ϕ ≤ 80°. Furthermore, our modeling suggests that a wind velocity profile that decreases with radius is necessary to reproduce the velocity widths and strengths of Mg ii line emission profiles at large circumgalactic radii. The extent of the Mg ii emission we measure directly is further corroborated by our modeling, where we rule out outflow models with extent <30 kpc.
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The 3D Kinematics of the Orion Nebula Cluster: NIRSPEC-AO Radial Velocities of the Core Population
Abstract The kinematics and dynamics of stellar and substellar populations within young, still-forming clusters provide valuable information for constraining theories of formation mechanisms. Using Keck II NIRSPEC+AO data, we have measured radial velocities for 56 low-mass sources within 4′ of the core of the Orion Nebula Cluster (ONC). We also remeasure radial velocities for 172 sources observed with SDSS/APOGEE. These data are combined with proper motions measured using HST ACS/WFPC2/WFC3IR and Keck II NIRC2, creating a sample of 135 sources with all three velocity components. The velocities measured are consistent with a normal distribution in all three components. We measure intrinsic velocity dispersions of ( σ v α , σ v δ , σ v r ) = (1.64 ± 0.12, 2.03 ± 0.13, 2.56 − 0.17 + 0.16 ) km s −1 . Our computed intrinsic velocity dispersion profiles are consistent with the dynamical equilibrium models from Da Rio et al. (2014) in the tangential direction but not in the line-of-sight direction, possibly indicating that the core of the ONC is not yet virialized, and may require a nonspherical potential to explain the observed velocity dispersion profiles. We also observe a slight elongation along the north–south direction following the filament, which has been well studied in previous literature, and an elongation in the line-of-sight to tangential velocity direction. These 3D kinematics will help in the development of realistic models of the formation and early evolution of massive clusters.
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- Award ID(s):
- 1714816
- PAR ID:
- 10406592
- Date Published:
- Journal Name:
- The Astrophysical Journal
- Volume:
- 926
- Issue:
- 2
- ISSN:
- 0004-637X
- Page Range / eLocation ID:
- 141
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.3847/1538-4357/ac3252
