Two Orders of Magnitude Variation in the Star Formation Efficiency Across the Pre-Merger Galaxy NGC 2276. (arXiv:1812.05048v1 [astro-ph.GA])
<a href="http://arxiv.org/find/astro-ph/1/au:+Tomicic_N/0/1/0/all/0/1">Neven Tomicic</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hughes_A/0/1/0/all/0/1">Annie Hughes</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kreckel_K/0/1/0/all/0/1">Kathryn Kreckel</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Renaud_F/0/1/0/all/0/1">Florent Renaud</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Pety_J/0/1/0/all/0/1">Jerome Pety</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Schinnerer_E/0/1/0/all/0/1">Eva Schinnerer</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Saito_T/0/1/0/all/0/1">Toshiki Saito</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Querejeta_M/0/1/0/all/0/1">Miguel Querejeta</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Faesi_C/0/1/0/all/0/1">Christopher Faesi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Garcia_Burillo_S/0/1/0/all/0/1">Santiago Garcia-Burillo</a>
We present the first spatially resolved (~0.5 kpc) measurements of the
molecular gas depletion time $tau_{depl}$ across the disk of the interacting
spiral galaxy NGC,2276, a system with an asymmetric morphology in various SFR
tracers. To estimate $tau_{depl}$, we use new NOEMA observations of the
$^{12}$CO(1-0) emission tracing the bulk molecular gas reservoir in NGC 2276,
and extinction-corrected H$alpha$ measurements obtained with the PMAS/PPaK
integral field unit for robust estimates of the SFR. We find a systematic
decrease in $tau_{depl}$ of 1-1.5 dex across the disk of NGC 2276, with a
further, abrupt drop in $tau_{depl}$ of ~1 dex along the galaxy’s western
edge. The global $tau_{depl}$ in NGC 2776 is $tau_{depl}=0.55$ Gyr, insistent
with literature measurements for the nearby galaxy population. Such a large
range in $tau_{depl}$ on sub-kpc scales has never previously been observed
within an individual isolated or pre-merger system. When using a
metallicity-dependent molecular gas conversion factor X$rm_{CO}$ the variation
decreases by 0.5 dex. We attribute the variation in $tau_{depl}$ to the
influence of galactic-scale tidal forces and ram pressure on NGC 2276’s
molecular interstellar medium (ISM). Our observations add to the growing body
of numerical and observational evidence that galaxy-galaxy interactions
significantly modify the molecular gas properties and star-forming activity
within galactic disks throughout the interaction, and not just during the final
merger phase.
We present the first spatially resolved (~0.5 kpc) measurements of the
molecular gas depletion time $tau_{depl}$ across the disk of the interacting
spiral galaxy NGC,2276, a system with an asymmetric morphology in various SFR
tracers. To estimate $tau_{depl}$, we use new NOEMA observations of the
$^{12}$CO(1-0) emission tracing the bulk molecular gas reservoir in NGC 2276,
and extinction-corrected H$alpha$ measurements obtained with the PMAS/PPaK
integral field unit for robust estimates of the SFR. We find a systematic
decrease in $tau_{depl}$ of 1-1.5 dex across the disk of NGC 2276, with a
further, abrupt drop in $tau_{depl}$ of ~1 dex along the galaxy’s western
edge. The global $tau_{depl}$ in NGC 2776 is $tau_{depl}=0.55$ Gyr, insistent
with literature measurements for the nearby galaxy population. Such a large
range in $tau_{depl}$ on sub-kpc scales has never previously been observed
within an individual isolated or pre-merger system. When using a
metallicity-dependent molecular gas conversion factor X$rm_{CO}$ the variation
decreases by 0.5 dex. We attribute the variation in $tau_{depl}$ to the
influence of galactic-scale tidal forces and ram pressure on NGC 2276’s
molecular interstellar medium (ISM). Our observations add to the growing body
of numerical and observational evidence that galaxy-galaxy interactions
significantly modify the molecular gas properties and star-forming activity
within galactic disks throughout the interaction, and not just during the final
merger phase.
http://arxiv.org/icons/sfx.gif
