Inner bars also buckle. The MUSE TIMER view of the double-barred galaxy NGC 1291

Méndez-Abreu, J.; Lorenzo-Cáceres, A. de; Gadotti, Dimitri A.; Fragkoudi, Francesca; Ven, Glenn van de; Falcón-Barroso, J.; Leaman, Ryan; Pérez, I.; Sánchez‐Blázquez, P.; Seidel, M. K.

doi:10.1093/mnrasl/sly196

Cited by 32 publications

(45 citation statements)

References 54 publications

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“…In NGC 1291, the stellar populations in the nuclear disc are dominated by an inner bar and we explore these stellar population profiles in a dedicated study in the future. Nonetheless, previous studies of the TIMER team suggest that the centre of NGC 1291 is dominated by a kinematically hot spheroid (de Lorenzo-Cáceres et al 2019a;Méndez-Abreu et al 2019). This idea is consistent with the stellar population and velocity dispersion profiles presented here: the oldest ages, highest metallicities, and highest velocity dispersion are detected in the centre of the galaxy.…”

Section: The Absence Of Kinematically Hot Spheroidssupporting

confidence: 91%

“…These inner bars do not only resemble the shape of regular bars, but they also seem to form and evolve in the same way main bars do (de Lorenzo-Cáceres et al 2019a. In fact, inner bars buckle vertically just like main bars (Méndez-Abreu et al 2019) and even exhibit the same v − h 3 correlation typically associated with bars (Bittner et al 2019).…”

Section: Introductionmentioning

confidence: 76%

“…The stellar velocity dispersion continuously increases towards its centre, consistent with the presence of a kinematically hot spheroid that dominates the stellar light in the centre of this galaxy. On the other hand de Lorenzo-Cáceres et al (2019a) claim that NGC 1291 and NGC 5850 host a small, kinematically hot spheroid within their (more prominent) nuclear discs (see also Méndez-Abreu et al 2019;de Lorenzo-Cáceres et al 2019b) and, thus, they constitute galaxies with composite bulges. Only the elevated central velocity dispersions in IC 1438, NGC 1097, and NGC 4984 might indeed be related to previously undetected kinematically hot spheroids.…”

Section: The Absence Of Kinematically Hot Spheroidsmentioning

confidence: 99%

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Inside-out formation of nuclear discs and the absence of old central spheroids in barred galaxies of the TIMER survey

Bittner

Sánchez‐Blázquez

Gadotti

et al. 2020

A&A

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The centres of disc galaxies host a variety of structures built via both internal and external processes. In this study, we constrain the formation and evolution of these central structures, in particular, nuclear rings and nuclear discs, by deriving maps of mean stellar ages, metallicities, and [α/Fe] abundances. We use observations obtained with the MUSE integral-field spectrograph for the TIMER sample of 21 massive barred galaxies. Our results indicate that nuclear discs and nuclear rings are part of the same physical component, with nuclear rings constituting the outer edge of nuclear discs. All nuclear discs in the sample are clearly distinguished based on their stellar population properties. As expected in the picture of bar-driven secular evolution, nuclear discs are younger, more metal-rich, and exhibit lower [α/Fe] enhancements, as compared to their immediate surroundings. Moreover, nuclear discs exhibit well-defined radial gradients, with ages and metallicities decreasing, and [α/Fe] abundances increasing with radius out to the nuclear ring. Often, these gradients show no breaks from the edge of the nuclear disc up through the centre, suggesting that these structures extend to the very centres of galaxies. We argue that continuous (stellar) nuclear discs may form from a series of bar-built (initially gas-rich) nuclear rings that expand in their radius as the bar evolves. In this picture, nuclear rings are simply the (often) star-forming outer edge of nuclear discs. Finally, by combining our results with those taken from a accompanying kinematic study, we do not find evidence for the presence of large, dispersion-dominated components in the centres of these galaxies. This could be a result of quiet merger histories, despite the large galaxy masses, or, perhaps, due to high angular momentum and strong feedback processes preventing the formation of these kinematically hot components.

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Section: The Absence Of Kinematically Hot Spheroidssupporting

confidence: 91%

Section: Introductionmentioning

confidence: 76%

Section: The Absence Of Kinematically Hot Spheroidsmentioning

confidence: 99%

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Inside-out formation of nuclear discs and the absence of old central spheroids in barred galaxies of the TIMER survey

Bittner

Sánchez‐Blázquez

Gadotti

et al. 2020

A&A

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“…These nuclear discs often host inner bars, nuclear spiral arms and nuclear rings. The formation of inner bars and nuclear spiral arms appear to be simply scaled-down versions of the formation of a bar and spiral arms in the main galaxy disc (Méndez-Abreu et al 2019;de Lorenzo-Cáceres et al 2019), confirming the theoretical work by Wozniak (2015) and Du et al (2015), who also found that nuclear discs and inner bars can be long-lived. Crucially, however, excluding the nuclear disc, the central regions of disc galaxies are dynamically hotter than the regions where the main disc dominates, and thus these processes still need to be better understood.…”

Section: Introductionsupporting

confidence: 82%

Kinematic signatures of nuclear discs and bar-driven secular evolution in nearby galaxies of the MUSE TIMER project

Gadotti

Bittner

Falcón-Barroso

et al. 2020

A&A

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The central regions of disc galaxies hold clues to the processes that dominate their formation and evolution. To exploit this, the TIMER project has obtained high signal-to-noise and spatial resolution integral-field spectroscopy data of the inner few kpc of 21 nearby massive barred galaxies, which allows studies of the stellar kinematics in their central regions with unprecedented spatial resolution. We confirm theoretical predictions of the effects of bars on stellar kinematics and identify box/peanuts through kinematic signatures in mildly and moderately inclined galaxies, finding a lower limit to the fraction of massive barred galaxies with box/peanuts at ∼62%. Further, we provide kinematic evidence of the connection between barlenses, box/peanuts, and bars. We establish the presence of nuclear discs in 19 galaxies and show that their kinematics are characterised by near-circular orbits with low pressure support and that they are fully consistent with the bar-driven secular evolution picture for their formation. In fact, we show that these nuclear discs have, in the region where they dominate, larger rotational support than the underlying main galaxy disc. In addition, we define a kinematic radius for the nuclear discs and show that it relates to bar radius, ellipticity and strength, and bar-to-total ratio. Comparing our results with photometric studies of galaxy bulges, we find that careful, state-of-the-art galaxy image decompositions are generally able to discern nuclear discs from classical bulges if the images employed have high enough physical spatial resolution. In fact, we show that nuclear discs are typically identified in such image decompositions as photometric bulges with (near-)exponential profiles. However, we find that the presence of composite bulges (galaxies hosting both a classical bulge and a nuclear disc) can often be unnoticed in studies based on photometry alone and suggest a more stringent threshold to the Sérsic index to identify galaxies with pure classical bulges.

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“…4). We also detected for the first time the presence of a box/peanut in an inner bar, (in NGC 1291;Méndez-Abreu et al 2019), which demonstrates that the dynamics of inner and main bars is similar (see also de Lorenzo-Cáceres et al 2019).…”

Section: Box/peanutssupporting

confidence: 66%

Kinematical signatures of disc instabilities and secular evolution in the MUSE TIMER Survey

Gadotti¹,

Bittner²,

Falcón-Barroso³

et al. 2019

Proc. IAU

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The MUSE TIMER Survey has obtained high signal and high spatial resolution integral-field spectroscopy data of the inner ~ 6×6 kpc of 21 nearby massive disc galaxies. This allows studies of the stellar kinematics of the central regions of massive disc galaxies that are unprecedented in spatial resolution. We confirm previous predictions from numerical and hydrodynamical simulations of the effects of bars and inner bars on stellar and gaseous kinematics, and also identify box/peanuts via kinematical signatures in mildly and moderately inclined galaxies, including a box/peanut in a face-on inner bar. In 20/21 galaxies we find inner discs and show that their properties are fully consistent with the bar-driven secular evolution picture for their formation. In addition, we show that these inner discs have, in the region where they dominate, larger rotational support than the main galaxy disc, and discuss how their stellar population properties can be used to estimate when in cosmic history the main bar formed. Our results are compared with photometric studies in the context of the nature of galaxy bulges and we show that inner discs are identified in image decompositions as photometric bulges with exponential profiles (i.e., Sérsic indices near unity).

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Inner bars also buckle. The MUSE TIMER view of the double-barred galaxy NGC 1291

Cited by 32 publications

References 54 publications

Inside-out formation of nuclear discs and the absence of old central spheroids in barred galaxies of the TIMER survey

Inside-out formation of nuclear discs and the absence of old central spheroids in barred galaxies of the TIMER survey

Kinematic signatures of nuclear discs and bar-driven secular evolution in nearby galaxies of the MUSE TIMER project

Kinematical signatures of disc instabilities and secular evolution in the MUSE TIMER Survey

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