A1 Refereed original research article in a scientific journal
Milky Way mass galaxies with X-shaped bulges are not rare in the local Universe
Authors: Laurikainen E., Salo H., Athanassoula E., Bosma A., Herrera-Endoqui M.
Publisher: Royal Astronomical Society
Publishing place: Burlington House, Piccadilly, London W1J 0BQ, UK
Publication year: 2014
Journal: Monthly Notices of the Royal Astronomical Society: Letters
Journal acronym: MNRASL
Volume: 444
Issue: 1
First page : L80
Last page: L84
Number of pages: 5
ISSN: 0035-8711
eISSN: 0035-8711
DOI: https://doi.org/10.1093/mnrasl/slu118
Web address : http://adsabs.harvard.edu/abs/2014MNRAS.444L..80L
Boxy/Peanut/X-shaped (B/P/X) bulges are studied using the 3.6
âµm images from the Spitzer Survey of Stellar Structure in Galaxies,
and the Ks -band images from the Near-IR S0 galaxy Survey. They are
compared with the properties of barlenses, defined as lens-like
structures embedded in bars, with sizes of \sim 50 per cent of bars
and axial ratios of \sim 0.6 - 0.9. Based on observations (extending
Laurikainen et al.) and recent simulation models, we show evidence
that barlenses are the more face-on counterparts of B/P/X-shaped
bulges. Using unsharp masks 18 new X-shaped structures are identified,
covering a large range of galaxy inclinations. The similar masses and
red B - 3.6 µm colours of the host galaxies, and the fact that the
combined axial ratio distribution of the host galaxy discs is flat,
support the interpretation that barlenses and X-shapes are physically
the same phenomenon. In Hubble types -3 < T < 2 even half of the bars
contain either a barlens or an X-shaped structure. Our detailed 2D
multicomponent decompositions for 29 galaxies, fitting the
barlens/X-shape with a separate component, indicate very small or
non-existent classical bulges. Taking into account that the structures
we study have similar host galaxy masses as the Milky Way (MW), our
results imply that MW mass galaxies with no significant classical
bulges are common in the nearby Universe.