Clocking the assembly of double-barred galaxies with the MUSE TIMER project

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

doi:10.1093/mnras/stz221

Cited by 31 publications

(27 citation statements)

References 78 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%

“…In fact, some nuclear discs develop bars themselves, resulting in the remarkable situation of having a small disc with a small bar embedded within a large disc with a large bar. 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: 79%

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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: 79%

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

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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: 80%

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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“…The funneled gas might eventually be spent in central starbursts, and contribute to the buildup and evolution of disk-like bulges (Kormendy & Kennicutt 2004). Observational evidence of secular evolution within the bar region comes from detections of inner rotating stellar and gaseous substructures in the center of barred galaxies (e.g., Comerón et al 2008;Pérez et al 2009;Kormendy 2013;Méndez-Abreu et al 2014;Seidel et al 2015, and references therein), including nuclear rings (e.g., Knapen et al 1995;Knapen 2005;Comerón et al 2010;Leaman et al 2019) and inner bars (e.g., Erwin & Sparke 2002;de Lorenzo-Cáceres et al 2019;Méndez-Abreu et al 2019); from enhanced central SF and chemical abundances (e.g., Ellison et al 2011;Oh et al 2012;Florido et al 2015;Vera et al 2016;Catalán-Torrecilla et al 2017;Lin et al 2020); and in general from stellar populations analyses (e.g., Pérez et al 2007Pérez et al , 2009Pérez et al , 2017Coelho & Gadotti 2011;Sánchez-Blázquez et al 2011, 2014de Lorenzo-Cáceres et al 2012Gadotti et al 2015Gadotti et al , 2019Seidel et al 2016;Fraser-McKelvie et al 2019;Neumann et al 2020).…”

Section: Evidence For Bar-induced Secular Evolution In the Central Regions Of Disk Galaxiesmentioning

confidence: 99%

Distribution of star formation in galactic bars as seen with Hαand stacked GALEX UV imaging

Díaz-García

Moyano

Comerón

et al. 2020

A&A

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Context. Stellar bars are known to gradually funnel gas to the central parts of disk galaxies. It remains a matter of debate why the distribution of ionized gas along bars and in the circumnuclear regions varies among galaxies. Aims. Our goal is to investigate the spatial distribution of star formation (SF) within bars of nearby low-inclination disk galaxies (i < 65°) from the S4G survey. We aim to link the loci of SF to global properties of the hosts (morphological type, stellar mass, gas fraction, and bar-induced gravitational torques), providing constraints for the conditions that regulate SF in bars. Methods. We use archival GALEX far- and near-UV imaging for 772 barred galaxies, and for a control sample of 423 non-barred galaxies. We also assemble a compilation of continuum-subtracted Hα images for 433 barred galaxies, 70 of which we produced from ancillary photometry and MUSE and CALIFA integral field unit data cubes. We employ two complementary approaches: (i) the analysis of bar (2D) and disk (1D) stacks built from co-added UV images (oriented and scaled with respect to the stellar bars and the extent of disks) of hundreds of galaxies that are binned based on their Hubble stage (T) and bar family; and (ii) the visual classification of the morphology of ionized regions (traced from Hα and UV data) in individual galaxies into three main SF classes: (A) only circumnuclear SF; (B) SF at the bar ends, but not along the bar; and (C) SF along the bar. Barred galaxies with active and passive inner rings are likewise classified. Results. Massive, gas-poor, lenticular galaxies typically belong to SF class A; this is probably related to bar-induced quenching of SF in the disk. The distribution of SF class B peaks for early- and intermediate-type spirals; this most likely results from the interplay of gas flow, shocks, and enhanced shear in massive centrally concentrated galaxies with large bar amplitudes (the latter is supported by the lack of a dip in the radial distribution of SF in non-barred galaxies). Late-type gas-rich galaxies with high gravitational torques are mainly assigned to SF class C; we argue that this is a consequence of low shear among the faintest galaxies. In bar stacks of spiral galaxies the UV emission traces the stellar bars and dominates on their leading side, as witnessed in simulations. Among early-type spirals the central UV emission is ∼0.5 mag brighter in strongly barred galaxies, relative to their weakly barred counterparts; this is probably related to the efficiency of strong bars sweeping the disk gas and triggering central starbursts. On the contrary, in later types the UV emission is stronger at all radii in strongly barred galaxies than in weakly barred and non-barred ones. We also show that the distributions of SF in inner-ringed galaxies are broadly the same in barred and non-barred galaxies, including a UV and Hα deficit in the middle part of the bar; this hints at the effect of resonance rings trapping gas that is no longer funneled inwards. Conclusions. Distinct distributions of SF within bars are reported in galaxies of different morphological types. Star-forming bars are most common among late-type gas-rich galaxies. Bars are important agents in the regulation of SF in disks.

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Clocking the assembly of double-barred galaxies with the MUSE TIMER project

Cited by 31 publications

References 78 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

Distribution of star formation in galactic bars as seen with Hαand stacked GALEX UV imaging

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