TY - JOUR
T1 - Revisiting FUSE O vi Emission in Galaxy Halos
AU - Chung, Haeun
AU - Vargas, Carlos J.
AU - Hamden, Erika
N1 - Publisher Copyright:
© 2021. The American Astronomical Society. All rights reserved..
PY - 2021/7/20
Y1 - 2021/7/20
N2 - A significant fraction of baryons in galaxies are in the form of diffuse gas of the circumgalactic medium (CGM). One critical component of the multiphases of CGM, the so-called "coronal"warm-hot phase gas (105-106 K) traced by O vi 1031.93, 1037.62 Å resonance lines, has rarely been detected in emission from galaxy halos other than that of the Milky Way. Here we report four additional detections of O vi emission gas in the halos of nearby edge-on galaxies, NGC 4631 and NGC 891, using archival Far Ultraviolet Spectroscopic Explorer data and an updated data pipeline. We find the most intense O vi emission to be from fields forming a vertical line near the center of NGC 4631, despite the close proximity to the disk of two other fields. The detected O vi emission surface brightness is about (1.1 ± 0.3) × 10-18 to (3.9 ± 0.8) × 10-18 erg s-1 cm-2 arcsec-2. The spatial distribution of the five 30″ × 30″ O vi detection fields in NGC 4631 can be interpreted as the existence of filamentary structures of more intense O vi emission superimposed within a diffuse and faint O vi halo in star-forming galaxies. Volume-filled O vi emission mapping is greatly needed to determine the structure and prevalence of warm-hot gas and the role it plays in the cycling of gas between the galaxy disk and the halo. Finally, we present the sensitivity of future funded and proposed UV missions (LUVOIR-A, LUVOIR-B, CETUS, and Aspera) to the detection of diffuse and faint O vi emission in nearby galaxy halos.
AB - A significant fraction of baryons in galaxies are in the form of diffuse gas of the circumgalactic medium (CGM). One critical component of the multiphases of CGM, the so-called "coronal"warm-hot phase gas (105-106 K) traced by O vi 1031.93, 1037.62 Å resonance lines, has rarely been detected in emission from galaxy halos other than that of the Milky Way. Here we report four additional detections of O vi emission gas in the halos of nearby edge-on galaxies, NGC 4631 and NGC 891, using archival Far Ultraviolet Spectroscopic Explorer data and an updated data pipeline. We find the most intense O vi emission to be from fields forming a vertical line near the center of NGC 4631, despite the close proximity to the disk of two other fields. The detected O vi emission surface brightness is about (1.1 ± 0.3) × 10-18 to (3.9 ± 0.8) × 10-18 erg s-1 cm-2 arcsec-2. The spatial distribution of the five 30″ × 30″ O vi detection fields in NGC 4631 can be interpreted as the existence of filamentary structures of more intense O vi emission superimposed within a diffuse and faint O vi halo in star-forming galaxies. Volume-filled O vi emission mapping is greatly needed to determine the structure and prevalence of warm-hot gas and the role it plays in the cycling of gas between the galaxy disk and the halo. Finally, we present the sensitivity of future funded and proposed UV missions (LUVOIR-A, LUVOIR-B, CETUS, and Aspera) to the detection of diffuse and faint O vi emission in nearby galaxy halos.
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U2 - 10.3847/1538-4357/ac04af
DO - 10.3847/1538-4357/ac04af
M3 - Article
AN - SCOPUS:85112663099
SN - 0004-637X
VL - 916
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 1
M1 - 7
ER -