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arXiv · 1811.01875

A SINFONI view of the nuclear activity and circumnuclear star formation in NGC 4303 - II: Spatially resolved stellar populations

Natacha Z. Dametto·Rogério Riffel·Luis Colina·Rogemar Riffel·Javier Piqueras López·Richard Davies·Leonard Burtscher·Roberto Menezes·Santiago Arribas·Miriani Pastoriza·Alvaro Labiano·Thaisa Storchi-Bergmann·Luis Dahmer-Hahn·Dinalva Sales
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Abstract

We present a spatially resolved stellar population study of the inner $\sim$200\,pc radius of NGC4303 based on near-infrared integral field spectroscopy with SINFONI/VLT at a spatial resolution of 40-80pc and using the STARLIGHT code. We found the distribution of the stellar populations presents a spatial variation, suggesting an age stratification. Three main structures stand out. Two nuclear blobs, one composed by young stars (t $\leq$ 50Myr) and one with intermediate-age stars (50Myr $<$ t $\leq$ 2Gyr) both shifted from the centre. The third one is an internal intermediate-age spiral arm-like structure, surrounding the blob of young stars. Our results indicate star formation has occurred through multiple bursts in this source. Furthermore, the youngest stellar populations (t $\lesssim$ 2Gyr) are distributed along a circumnuclear star-forming ring with r$\sim$250pc. The ring displays star formation rates (SFRs) in the range of 0.002-0.14M$_{\odot}$yr$^{-1}$, favoring the `pearls-on-a-string' scenario. The old underlying bulge stellar population component (t $>$ 2Gyr) is distributed outside the two blob structures. For the nuclear region (inner $\sim$60pc radius) we derived a SFR of 0.43\,M$_{\odot}$yr$^{-1}$ and found no signatures of non-thermal featureless continuum and hot dust emission, supporting the scenario in which a LLAGN/LINER-like source is hidden in the centre of NGC4303. Thus, our results reveal a rather complex star formation history in NGC4303, with different stellar population components coexisting with a low efficiency accreting black hole in its centre.

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Natacha Z. Dametto, Rogério Riffel, Luis Colina, Rogemar Riffel, Javier Piqueras López, Richard Davies, Leonard Burtscher, Roberto Menezes, Santiago Arribas, Miriani Pastoriza, Alvaro Labiano, Thaisa Storchi-Bergmann, Luis Dahmer-Hahn, Dinalva Sales. 2018-11-05. A SINFONI view of the nuclear activity and circumnuclear star formation in NGC 4303 - II: Spatially resolved stellar populations. https://doi.org/10.1093/mnras%2Fsty2996

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