S0 galaxies are faded spirals: clues from their angular momentum content

Rizzo, Francesca; Fraternali, Filippo; Iorio, Giuliano

doi:10.1093/mnras/sty347

Cited by 52 publications

(58 citation statements)

References 103 publications

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“…Neumann et al (2017) argued that the galaxy has a merger-built classical bulge with a bulge-to-total flux ratio (B/T ) ∼ 0.44, consistent with the fit by Gilhuly & Courteau (2018) which yielded a high Sérsic index for bulge (n ∼ 5.1), suggestive of a classical bulge. In contrast, the bulge + disk fit by Rizzo et al (2018) yielded a lower value of n (∼ 2.4) and a smaller B/T of ∼ 0.3 for the bulge component.…”

Section: Introductionmentioning

confidence: 76%

High-resolution MEGARA Integral-field Unit Spectroscopy and Structural Analysis of a Fast-rotating, Disky Bulge in NGC 7025

Dullo

Chamorro-Cazorla

Paz

et al. 2019

ApJ

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Disky bulges in spiral galaxies are commonly thought to form out of disk materials (mainly) via bar driven secular processes, they are structurally and dynamically distinct from 'classical bulges' built in violent merger events. We use high-resolution GTC/MEGARA integral-field unit spectroscopic observations of the Sa galaxy NGC 7025, obtained during the MEGARA commissioning run, together with detailed 1D and 2D decompositions of this galaxy's SDSS i-band data to investigate the formation of its disky (bulge) component which makes up ∼ 30% of the total galaxy light. With a Sérsic index n ∼ 1.80 ± 0.24, half-light radius R e ∼ 1.70 ± 0.43 kpc and stellar mass M * ∼ (4.34 ± 1.70) × 10 10 M ⊙ , this bulge dominates the galaxy light distribution in the inner R ∼ 15 ′′ (∼ 4.7 kpc). Measuring the spins (λ) and ellipticities (ǫ) enclosed within nine different circular apertures with radii R ≤ R e , we show that the bulge, which exhibits a spin track of an outwardly rising λ and ǫ, is a fast rotator for all the apertures considered. Our findings suggest that this inner disky component is a pseudo-bulge, consistent with the stellar and dust spiral patterns seen in the galaxy down to the innermost regions but in contrast to the classical bulge interpretation favored in the past. We propose that a secular process involving the tightly wound stellar spiral arms of NGC 7025 may drive gas and stars out of the disk into the inner regions of the galaxy, building up the massive pseudo-bulge.

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Section: Introductionmentioning

confidence: 76%

High-resolution MEGARA Integral-field Unit Spectroscopy and Structural Analysis of a Fast-rotating, Disky Bulge in NGC 7025

Dullo

Chamorro-Cazorla

Paz

et al. 2019

ApJ

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“…Lastly, we remind the reader that our classification of FR+/FR−, i.e., dynamically-cold/two-component disks, is based on the distribution of λ r e as a function of of galaxies, without applying any kinematic decomposition of the velocity field such as those introduced by Tabor et al (2017) and Rizzo et al (2018). The next step for this type of study is to start separating different kinematic components within galaxies and to quantify their contribution to the stellar mass budget in the local Universe.…”

Section: Discussionmentioning

confidence: 99%

“…This should provide bet-ter constraints on the different physical processes regulating the mass growth of galaxies as, at this stage, we are sensitive only to processes significantly perturbing the global stellar velocity fields. Given that both observational (Tabor et al 2017(Tabor et al , 2019Rizzo et al 2018) and theoretical (Scannapieco et al 2010;Martig et al 2012;Wang et al 2019;Zhu et al 2018) works have clearly shown that photometric and kinematic decomposition do not always agree, we cannot blindly rely on 2D bulge-to-disk decomposition if we aim at improving our reconstruction of the accretion histories of nearby galaxies. by the Australian Research Council Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D), through project number CE170100013.…”

Section: Discussionmentioning

confidence: 99%

The SAMI Galaxy Survey: The contribution of different kinematic classes to the stellar mass function of nearby galaxies

Guo

Cortese

Obreschkow

et al. 2019

Monthly Notices of the Royal Astronomical Society

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We use the complete Sydney-AAO Multi-object Integral field spectrograph (SAMI) Galaxy Survey to determine the contribution of slow rotators, as well as different types of fast rotators, to the stellar mass function of galaxies in the local Universe. We use stellar kinematics not only to discriminate between fast and slow rotators, but also to distinguish between dynamically cold systems (i.e., consistent with intrinsic axis ratios< 0.3) and systems including a prominent dispersion-supported bulge. We show that fast rotators account for more than 80% of the stellar mass budget of nearby galaxies, confirming that their number density overwhelms that of slow rotators at almost all masses from 10 9 to 10 11.5 M . Most importantly, dynamically cold disks contribute to at least 25% of the stellar mass budget of the local Universe, significantly higher than what is estimated from visual morphology alone. For stellar masses up to 10 10.5 M , this class makes up >= 30% of the galaxy population in each stellar mass bin. The fact that many galaxies that are visually classified as having two-components have stellar spin consistent with dynamically cold disks suggests that the inner component is either rotationally-dominated (e.g., bar, pseudo-bulge) or has little effect on the global stellar kinematics of galaxies.

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“…Through various other methods, from simply masking out contaminated regions in order to look at spectral indices in bulge and disc regions (Fraser-McKelvie et al 2018), to more detailed processes, such as Johnston et al (2014), Taranu et al (2017). Coccato et al (2018) and Rizzo et al (2018), other studies have also demonstrated the existence of two distinct components containing different stellar populations, the relative ages and metallicities of which appear to vary intriguingly with mass and, potentially, environment.…”

Section: Introductionmentioning

confidence: 99%

SDSS-IV MaNGA: full spectroscopic bulge-disc decomposition of MaNGA early-type galaxies

Tabor

Merrifield

Aragón-Salamanca

et al. 2019

Monthly Notices of the Royal Astronomical Society

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By applying spectroscopic decomposition methods to a sample of MaNGA earlytype galaxies, we separate out spatially and kinematically distinct stellar populations, allowing us to explore the similarities and differences between galaxy bulges and discs, and how they affect the global properties of the galaxy. We find that the components have interesting variations in their stellar populations, and display different kinematics. Bulges tend to be consistently more metal rich than their disc counterparts, and while the ages of both components are comparable, there is an interesting tail of younger, more metal poor discs. Bulges and discs follow their own distinct kinematic relationships, both on the plane of the stellar spin parameter, λ R , and ellipticity, , and in the relation between stellar mass, M * , and specific angular momentum, j * , with the location of the galaxy as a whole on these planes being determined by how much bulge and disc it contains. As a check of the physical significance of the kinematic decompositions, we also dynamically model the individual galaxy components within the global potential of the galaxy. The resulting components exhibit kinematic parameters consistent with those from the spectroscopic decomposition, and though the dynamical modelling suffers from some degeneracies, the bulges and discs display systematically different intrinsic dynamical properties. This work demonstrates the value in considering the individual components of galaxies rather than treating them as a single entity, which neglects information that may be crucial in understanding where, when and how galaxies evolve into the systems we see today.

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S0 galaxies are faded spirals: clues from their angular momentum content

Cited by 52 publications

References 103 publications

High-resolution MEGARA Integral-field Unit Spectroscopy and Structural Analysis of a Fast-rotating, Disky Bulge in NGC 7025

High-resolution MEGARA Integral-field Unit Spectroscopy and Structural Analysis of a Fast-rotating, Disky Bulge in NGC 7025

The SAMI Galaxy Survey: The contribution of different kinematic classes to the stellar mass function of nearby galaxies

SDSS-IV MaNGA: full spectroscopic bulge-disc decomposition of MaNGA early-type galaxies

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