A SINFONI view of the nuclear activity and circumnuclear star formation in NGC4303-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. 2019. A SINFONI view of the nuclear activity and circumnuclear star formation in NGC4303-II. Spatially resolved stellar populations. Monthly Notices of the Royal Astronomical Society 482, 4, 4437-4453 DOI: 10.1093/mnras/sty2996

We present a spatially resolved stellar population study of the inner similar to 200 pc radius of NGC4303 based on near-infrared integral field spectroscopy with SINFONI/VLT at a spatial resolution of 40-80 pc and using the STARLIGHT code. We found that 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 <= 50 Myr) and one with intermediate-age stars (50 Myr < t <= 2 Gyr), 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 that star formation has occurred through multiple bursts in this source. Furthermore, the youngest stellar populations (t less than or similar to 2 Gyr) are distributed along a circumnuclear star-forming ring with r similar to 250 pc. The ring displays star formation rates (SFRs) in the range of 0.002-0.14 M-circle dot yr(-1), favouring the ‘pearls-on-a-string’ scenario. The old underlying bulge stellar population component (t > 2 Gyr) is distributed outside the two blob structures. For the nuclear region (inner similar to 60 pc radius) we derived an SFR of 0.43 M-circle dot yr(-1) and found no signatures of non-thermal featureless continuum and hot dust emission, supporting the scenario in which an 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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