TY - JOUR

T1 - Tilted outer and inner structures in edge-on galaxies?

AU - Мосенков, Александр Владимирович

AU - Смирнов, Антон Александрович

AU - Сильченко, Ольга

AU - Rich, R Michael

AU - Решетников, Владимир Петрович

AU - Kormendy, John

N1 - Publisher Copyright: © 2020 The Author(s).

PY - 2020/9

Y1 - 2020/9

N2 - Tilted and warped discs inside tilted dark matter haloes are predicted from numerical and semi-analytical studies. In this paper, we use deep imaging to demonstrate the likely existence of tilted outer structures in real galaxies. We consider two SB0 edge-on galaxies, NGC 4469 and NGC 4452, which exhibit apparent tilted outer discs with respect to the inner structure. In NGC 4469, this structure has a boxy shape, inclined by APA «a 3° with respect to the inner disc, whereas NGC 4452 harbours a discy outer structure with APA «a 6°. In spite of the different shapes, both structures have surface brightness profiles close to exponential and make a large contribution (~30 per cent) to the total galaxy luminosity. In the case of NGC 4452, we propose that its tilted disc likely originates from a former fast tidal encounter (probably with IC3381). For NGC 4469, a plausible explanation may also be galaxy harassment, which resulted in a tilted or even a tumbling dark matter halo. A less likely possibility is accretion of gas-rich satellites several Gyr ago. New deep observations may potentially reveal more such galaxies with tilted outer structures, especially in clusters. We also consider galaxies, mentioned in the literature, where a central component (a bar or a bulge) is tilted with respect to the stellar disc. According to our numerical simulations, one of the plausible explanations of such observed 'tilts' of the bulge/bar is a projection effect due to a not exactly edge-on orientation of the galaxy coupled with a skew angle of the triaxial bulge/bar.

AB - Tilted and warped discs inside tilted dark matter haloes are predicted from numerical and semi-analytical studies. In this paper, we use deep imaging to demonstrate the likely existence of tilted outer structures in real galaxies. We consider two SB0 edge-on galaxies, NGC 4469 and NGC 4452, which exhibit apparent tilted outer discs with respect to the inner structure. In NGC 4469, this structure has a boxy shape, inclined by APA «a 3° with respect to the inner disc, whereas NGC 4452 harbours a discy outer structure with APA «a 6°. In spite of the different shapes, both structures have surface brightness profiles close to exponential and make a large contribution (~30 per cent) to the total galaxy luminosity. In the case of NGC 4452, we propose that its tilted disc likely originates from a former fast tidal encounter (probably with IC3381). For NGC 4469, a plausible explanation may also be galaxy harassment, which resulted in a tilted or even a tumbling dark matter halo. A less likely possibility is accretion of gas-rich satellites several Gyr ago. New deep observations may potentially reveal more such galaxies with tilted outer structures, especially in clusters. We also consider galaxies, mentioned in the literature, where a central component (a bar or a bulge) is tilted with respect to the stellar disc. According to our numerical simulations, one of the plausible explanations of such observed 'tilts' of the bulge/bar is a projection effect due to a not exactly edge-on orientation of the galaxy coupled with a skew angle of the triaxial bulge/bar.

KW - Galaxies: evolution

KW - Galaxies: formation

KW - Galaxies: haloes

KW - Galaxies: interactions

KW - Galaxies: photometry

KW - Galaxies: structure

KW - DISC GALAXIES

KW - STELLAR HALOES

KW - SPIRAL GALAXIES

KW - galaxies: evolution

KW - galaxies: interactions

KW - galaxies: photometry

KW - DARK-MATTER HALOES

KW - STAR-FORMATION

KW - ACS-VIRGO-CLUSTER

KW - COOL INTERSTELLAR-MEDIUM

KW - galaxies: formation

KW - galaxies: structure

KW - DIGITAL SKY SURVEY

KW - ANGULAR-MOMENTUM DISTRIBUTION

KW - MILKY-WAY

KW - galaxies: haloes

UR - https://academic.oup.com/mnras/article-abstract/497/2/2039/5866843?redirectedFrom=fulltext

UR - http://www.scopus.com/inward/record.url?scp=85095457429&partnerID=8YFLogxK

UR - https://www.mendeley.com/catalogue/1a77f1d5-5669-3396-a4ac-48f88e3d85df/

U2 - 10.1093/mnras/staa1885

DO - 10.1093/mnras/staa1885

M3 - Article

VL - 497

SP - 2039

EP - 2056

JO - Monthly Notices of the Royal Astronomical Society

JF - Monthly Notices of the Royal Astronomical Society

SN - 0035-8711

IS - 2

ER -