Examinando por Autor "Apostolovski, Yordanka"

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    A dense, solar metallicity ISM in the z = 4.2 dusty star-forming galaxy SPT 0418-47
    (EDP Sciences, 2019-11-01) De Breuck, Carlos; Weiß, Axel; Béthermin, Matthieu; Cunningham, Daniel; Apostolovski, Yordanka; Aravena, Manuel; Archipley, Melanie; Chapman, Scott; Chen, Chian-Chou; Fu, Jianyang; Jarugula, Sreevani; Malkan, Matt
    We present a study of six far-infrared fine structure lines in the z = 4.225 lensed dusty star-forming galaxy SPT 0418-47 to probe the physical conditions of its interstellar medium (ISM). In particular, we report Atacama Pathfinder EXperiment (APEX) detections of the [OI] 145 μm and [OIII] 88 μm lines and Atacama Compact Array (ACA) detections of the [NII] 122 and 205 μm lines. The [OI] 145 μm/[CII] 158 μm line ratio is ∼5× higher compared to the average of local galaxies. We interpret this as evidence that the ISM is dominated by photo-dissociation regions with high gas densities. The line ratios, and in particular those of [OIII] 88 μm and [NII] 122 μm imply that the ISM in SPT 0418-47 is already chemically enriched to nearly solar metallicity. While the strong gravitational amplification was required to detect these lines with APEX, larger samples can be observed with the Atacama Large Millimeter/submillimeter Array (ALMA), and should allow observers to determine if the dense, solar metallicity ISM is common among these highly star-forming galaxies.
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    Source Structure and Molecular Gas Properties from High-resolution CO Imaging of SPT-selected Dusty Star-forming Galaxies
    (Astrophysical Journal, 2019) Dong (董辰兴), Chenxing; Justin S., Spilker; Gonzalez, Anthony H.; Apostolovski, Yordanka; Aravena, Manuel; Béthermin, Matthieu; Chapman, Scott C.; Chen (陳建州), Chian-Chou; Hayward, Christopher C.; Hezaveh, Yashar D.; Litke, Katrina C.; Ma (马京哲), Jingzhe; Marrone, Daniel P.; Morningstar, Warren R.; Phadke, Kedar A.; Reuter, Cassie A.; Sreevani, Jarugula; Stark, Antony A.; Vieira, Joaquin D.; Weiß, Axel
    We present Atacama Large Millimeter/submillimeter Array (ALMA) observations of high-J CO lines (J up = 6, 7, 8) and associated dust continuum toward five strongly lensed, dusty, star-forming galaxies at redshift z = 2.7-5.7. These galaxies, discovered in the South Pole Telescope survey, are observed at 0.″2-0.″4 resolution with ALMA. Our high-resolution imaging coupled with the lensing magnification provides a measurement of the structure and kinematics of molecular gas in the background galaxies with spatial resolutions down to kiloparsec scales. We derive visibility-based lens models for each galaxy, accurately reproducing observations of four of the galaxies. Of these four targets, three show clear velocity gradients, of which two are likely rotating disks. We find that the reconstructed region of CO emission is less concentrated than the region emitting dust continuum even for the moderate-excitation CO lines, similar to what has been seen in the literature for lower-excitation transitions. We find that the lensing magnification of a given source can vary by 20%-50% across the line profile, between the continuum and line, and between different CO transitions. We apply Large Velocity Gradient modeling using apparent and intrinsic line ratios between lower-J and high-J CO lines. Ignoring these magnification variations can bias the estimate of physical properties of interstellar medium of the galaxies. The magnitude of the bias varies from galaxy to galaxy and is not necessarily predictable without high-resolution observations.