Analysing the structure of the bulge with Mira variables

Chrobáková, Ž.; López-Corredoira, M.; Garzón, F.
Bibliographical reference

Astronomy and Astrophysics

Advertised on:
10
2022
Number of authors
3
IAC number of authors
3
Citations
1
Refereed citations
1
Description
Context. The Galactic bulge at latitude 4 < |b|(deg) < 10 was claimed to show an X-shape, which means that stellar density distributions along the line of sight have a double peak. However, this double peak is only observed with the red-clump population, and doubt has been cast on its use as a perfect standard candle. As such, a boxy bulge without an X-shape is not discarded.
Aims: We aim to constrain the shape of the bulge making use of a different population: Mira variables from the new Optical Gravitational Lensing Experiment data release, OGLE-IV, with an average age of 9 Gyr.
Methods: We analysed an area of the bulge far from the plane, where we fitted the density of the Miras with boxy bulge and X-shaped bulge models and calculated the probability of each model.
Results: We find that the probability of a boxy bulge fitting the data is p = 0.19, whereas the probability for the X-shaped bulge is only p = 2.85 × 10−6 (equivalent to a tension of the model with the data of a 4.7σ level). Therefore, the boxy bulge model seems to be more appropriate for describing the Galactic bulge, although we cannot exclude any model with complete certainty.
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NGC 2808 Globular Cluster
Milky Way and Nearby Galaxies

The general aim of the project is to research the structure, evolutionary history and formation of galaxies through the study of their resolved stellar populations, both from photometry and spectroscopy. The group research concentrates in the most nearby objects, namely the Local Group galaxies including the Milky Way and M33 under the hypothesis

Martín
López Corredoira