Browsing by Author "Bureau, Martin"

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The Evolution of Ngc 7465 as Revealed by Its Molecular Gas Properties (Vol 909, 98, 2021)
(Iop Publishing Ltd, 2022) Young, Lisa M.; Meier, David S.; Bureau, Martin; Crocker, Alison; Davis, Timothy A.; Topal, Selcuk
Co Tully-Fisher Relation of Star-Forming Galaxies At=0.05-0.3
(Oxford Univ Press, 2018) Topal, Selcuk; Bureau, Martin; Tiley, Alfred L.; Davis, Timothy A.; Torii, Kazufumi
The Tully-Fisher relation (TFR) is an empirical relation between galaxy luminosity and rotation velocity. We present here the first TFR of galaxies beyond the local Universe that uses carbon monoxide (CO) as the kinematic tracer. Our final sample includes 25 isolated, non-interacting star-forming galaxies with double-horned or boxy CO integrated line profiles located at redshifts z <= 0.3, drawn from a larger ensemble of 67 detected objects. The best reverse K-s-band, stellar mass and baryonic mass CO TFRs are, respectively, M-Ks = (-8.4 +/- 2.9)[log (W-50/km s(-1)/sin i) - 2.5] + (-23.5 +/- 0.5), log (M-star/M-circle dot) = (5.2 +/- 3.0)[log (W-50/km s(-1)/sin i) - 2.5] + (10.1 +/- 0.5) and log (M-b/M-circle dot) = (4.9 +/- 2.8)[log (W-50/km s(-1)/sin i) - 2.5] + (10.2 +/- 0.5), where M-Ks is the total absolute K-s-band magnitude of the objects, M-star and M-b their total stellar and baryonic masses, and W-50 the width of their line profile at 50 per cent of the maximum. Dividing the sample into different redshift bins and comparing to the TFRs of a sample of local (z = 0) star-forming galaxies from the literature, we find no significant evolution in the slopes and zero-points of the TFRs since z approximate to 0.3, this in either luminosity or mass. In agreement with a growing number of CO TFR studies of nearby galaxies, we more generally find that CO is a suitable and attractive alternative to neutral hydrogen (HI). Our work thus provides an important benchmark for future higher redshift CO TFR studies.
The Evolution of Ngc 7465 as Revealed by Its Molecular Gas Properties
(Iop Publishing Ltd, 2021) Young, Lisa M.; Meier, David S.; Bureau, Martin; Crocker, Alison; Davis, Timothy A.; Topal, Selcuk
We present ALMA observations of CO isotopologues and high-density molecular tracers (HCN, HCO+, CN, etc.) in NGC 7465, an unusually gas-rich early-type galaxy that acquired its cold gas recently. In the inner 300 pc, the molecular gas kinematics are misaligned with respect to all other galaxy components; as the gas works its way inward, it is torqued into polar orbits about the stellar kinematically decoupled core (KDC), indicating that the stellar KDC is not related to the current gas accretion event. The galaxy also exhibits unusually high (CO)-C-12/(CO)-C-13 line ratios in its nucleus but typical (CO)-C-13/(CO)-O-18 ratios. Our calculations show that this result does not necessarily indicate an unusual [(CO)-C-12/(CO)-C-13] abundance ratio but rather that (CO)-C-12 (1-0) is optically thin due to high temperatures and/or large line widths associated with the inner decoupled, misaligned molecular structure. Line ratios of the higher-density tracers suggest that the densest phase of molecular gas in NGC 7465 has a lower density than is typical for nearby galaxies, possibly as a result of the recent gas accretion. All of the observed molecular properties of NGC 7465 are consistent with it having acquired its molecular (and atomic) gas from a spiral galaxy. Further detailed studies of the CO isotopologues in other early-type galaxies would be valuable for investigating the histories of those that may have acquired their gas from dwarfs. Finally, these ALMA data also show an unidentified line source that is probably a background galaxy similar to those found at z = 1-3 in blind CO surveys.