Stellar Populations of Bulges at Low Redshift

Sánchez‐Blázquez, P.

doi:10.1007/978-3-319-19378-6_6

Cited by 10 publications

(8 citation statements)

References 153 publications

(278 reference statements)

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“…The latter study also shows that the metallicities of bulge and disk are correlated (see also, e.g., Moorthy & Holtzman 2006), in agreement with the trend in Fig. 7b, whereas no correlation was found between the age of the two components (see also, Sánchez-Blázquez 2016). Another insight from the study by Sánchez-Blázquez et al (2014) is that the slope of the relation between central velocity dispersion and luminosity-weighted age and metallicity is similar for the central parts of bulges and at a galactocentric radius equivalent to ∼2.4 exponential disk scale lengths.…”

Section: Bulge-to-disk Age and Metallicity Contrastsupporting

confidence: 82%

“…Additionally, the fact that older disks in our sample host older bulges (judging from a comparison of m 9 ratios and panels a&c of Fig. 7) with a within ∼0.2 dex equal metallicity (panel d) points to an interwoven bulge-disk evolution, as already suggested by some previous photometric or spectroscopic studies in the local universe and at higher redshifts (e.g., Carollo et al 2007;van Dokkum et al 2013;Papovich et al 2015;Sánchez-Blázquez et al 2014;Sánchez-Blázquez 2016;Lang et al 2014; Article number, page 11 of 24 A&A proofs: manuscript no. BredaPapaderos_astroph a b c d Fig.…”

Section: The Continuous Rise Of Bulges Out Of Galactic Diskssupporting

confidence: 82%

“…Although recent IFS studies have explored various physical relations between, for example, Σ , t L , Z L and SFR for LTGs as a function of galactocentric radius (e.g., , 2016Cano-Díaz et al 2016;Zibetti et al 2017), they generally did not incorporate a structural analysis that would have permitted extraction and spectral modeling of the total bulge emission within a uniformly defined radius. An exception to this is the work by Sánchez-Blázquez et al (2014) where the bulge extent was estimated from image decomposition as the radius where the intensity of the bulge equals that of the disk, to which that study was mainly devoted.…”

Section: Introductionmentioning

confidence: 99%

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The continuous rise of bulges out of galactic disks

Breda

Papaderos

2018

A&A

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Context. A key subject in extragalactic astronomy concerns the chronology and driving mechanisms of bulge formation in late-type galaxies (LTGs). The standard scenario distinguishes between classical bulges and pseudo-bulges (CBs and PBs, respectively), the first thought to form monolithically prior to disks and the second gradually out of disks. These two bulge formation routes obviously yield antipodal predictions on the bulge age and bulge-to-disk age contrast, both expected to be high (low) in CBs (PBs). Aims. Our main goal is to explore whether bulges in present-day LTGs segregate into two evolutionary distinct classes, as expected from the standard scenario. Other questions motivating this study center on evolutionary relations between LTG bulges and their hosting disks, and the occurrence of accretion-powered nuclear activity as a function of bulge stellar mass M and stellar surface density Σ . Methods. In this study we have combined three techniques -surface photometry, spectral modeling of integral field spectroscopy data and suppression of stellar populations younger than an adjustable age cutoff with the code REMOVEYOUNG (RY) -toward a systematic analysis of the physical and evolutionary properties (e.g., M , Σ and mass-weighted stellar age t M and metallicity Z M , respectively) of a representative sample of 135 nearby (≤130 Mpc) LTGs from the CALIFA survey that cover a range between 10 8.9 M and 10 11.5 M in total stellar mass M ,T . In particular, the analysis here revolves around <δµ 9G >, a new distance-and formally extinction-independent measure of the contribution by stellar populations of age ≥9 Gyr to the mean r-band surface brightness of the bulge. We argue that <δµ 9G > offers a handy semi-empirical tracer of the physical and evolutionary properties of LTG bulges and a promising means for their characterization. Results. The essential insight from this study is that LTG bulges form over three dex in M and more than one dex in Σ a tight continuous sequence of increasing <δµ 9G > with increasing M , Σ , t M and Z M . Along this continuum of physical and evolutionary properties, our sample spans a range of ∼4 mag in <δµ 9G >: high-<δµ 9G > bulges are the oldest, densest and most massive ones ( t M ∼11.7 Gyr, Σ > 10 9 M kpc −2 , M ≥ 10 10 M ), whereas the opposite is the case for low-<δµ 9G > bulges ( t M ∼7 Gyr) that generally reside in low-mass LTGs. Furthermore, we find that the bulge-to-disk age and metallicity contrast, as well as the bulge-todisk mass ratio, show a positive trend with M ,T , raising from, respectively, ∼0 Gyr, ∼0 dex and 0.25 to ∼3 Gyr, ∼0.3 dex and 0.67 across the mass range covered by our sample. Whereas gas excitation in lower-mass ( 10 9.7 M ) bulges is invariably dominated by star formation (SF), LINER-and Seyfert-specific emission-line ratios were exclusively documented in high-mass ( 10 10 M ), high-Σ ( 10 9 M kpc −2 ) bulges. This is in agreement with previous work and consistent with the notion that the Eddington ratio or the black hole-to-bulge mass rati...

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Section: Bulge-to-disk Age and Metallicity Contrastsupporting

confidence: 82%

Section: The Continuous Rise Of Bulges Out Of Galactic Diskssupporting

confidence: 82%

Section: Introductionmentioning

confidence: 99%

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The continuous rise of bulges out of galactic disks

Breda

Papaderos

2018

A&A

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“…The different formation mechanisms, for the two bulge types, leave their imprint on the stellar population of these bulges. Previous studies have associated formation of classical bulge with rapid and efficient star formation, while the pseudobulges are formed slowly E-mail: preetish@ncra.tifr.res.in † E-mail: barway@saao.ac.za ‡ E-mail: yogesh@ncra.tifr.res.in at lower redshift (Sánchez-Blázquez 2016). As as result, the stellar populations of pseudobulges are found to be younger, on average, as compared to those of classical bulges (Gadotti 2009).…”

Section: Introductionmentioning

confidence: 99%

Age bimodality in the central region of pseudo-bulges in S0 galaxies

Mishra

Barway

Wadadekar

2017

Monthly Notices of the Royal Astronomical Society: Letters

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We present evidence for bimodal stellar age distribution of pseudobulges of S0 galaxies as probed by the D n (4000) index. We do not observe any bimodality in age distribution for pseudobulges in spiral galaxies. Our sample is flux limited and contains 2067 S0 and 2630 spiral galaxies drawn from the Sloan Digital Sky Survey. We identify pseudobulges in S0 and spiral galaxies, based on the position of the bulge on the Kormendy diagram and their central velocity dispersion. Dividing the pseudobulges of S0 galaxies into those containing old and young stellar populations, we study the connection between global star formation and pseudobulge age on the u − r color-mass diagram. We find that most old pseudobulges are hosted by passive galaxies while majority of young bulges are hosted by galaxies which are star forming. Dividing our sample of S0 galaxies into early-type S0s and S0/a galaxies, we find that old pseudobulges are mainly hosted by early-type S0 galaxies while most of the pseudobulges in S0/a galaxies are young. We speculate that morphology plays a strong role in quenching of star formation in the disc of these S0 galaxies, which stops the growth of pseudobulges, giving rise to old pseudobulges and the observed age bimodality.

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“…The stellar populations of classical bulges show similarities with those of ellipticals of the same mass. In general, they are old and metal-rich with a short formation timescale (see Sánchez-Blázquez 2016, for a review on their stellar populations). Nevertheless, this dichotomy of the observed properties is still controversial since recent studies claim the different properties of bulges can be just driven by the bulge mass (Costantin et al 2017).…”

Section: Introductionmentioning

confidence: 99%

Morpho-kinematic properties of field S0 bulges in the CALIFA survey

Méndez-Abreu

Aguerri

Falcón-Barroso

et al. 2017

Monthly Notices of the Royal Astronomical Society

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We study a sample of 28 S0 galaxies extracted from the integral-field spectroscopic (IFS) survey CALIFA. We combine an accurate two-dimensional (2D) multicomponent photometric decomposition with the IFS kinematic properties of their bulges to understand their formation scenario. Our final sample is representative of S0s with high stellar masses (M ⋆ /M ⊙ > 10 10 ). They lay mainly on the red sequence and live in relatively isolated environments similar to that of the field and loose groups.We use our 2D photometric decomposition to define the size and photometric properties of the bulges, as well as their location within the galaxies. We perform mock spectroscopic simulations mimicking our observed galaxies to quantify the impact of the underlying disc on our bulge kinematic measurements (λ and v/σ). We compare our bulge corrected kinematic measurements with the results from Schwarzschild dynamical modelling. The good agreement confirms the robustness of our results and allows us to use bulge deprojected values of λ and v/σ. We find that the photometric (n and B/T ) and kinematic (v/σ and λ) properties of our field S0 bulges are not correlated. We demonstrate that this morpho-kinematic decoupling is intrinsic to the bulges and it is not due to projection effects.We conclude that photometric diagnostics to separate different types of bulges (disc-like vs classical) might not be useful for S0 galaxies. The morpho-kinematics properties of S0 bulges derived in this paper suggest that they are mainly formed by dissipational processes happening at high redshift, but dedicated high-resolution simulations are necessary to better identify their origin.

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Stellar Populations of Bulges at Low Redshift

Abstract: This chapter summarizes our current understanding of the stellar population properties of bulges and outlines important future research directions.

Cited by 10 publications

References 153 publications

The continuous rise of bulges out of galactic disks

The continuous rise of bulges out of galactic disks

Age bimodality in the central region of pseudo-bulges in S0 galaxies

Morpho-kinematic properties of field S0 bulges in the CALIFA survey

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