Quantifying stellar radial migration in an<i>N</i>-body simulation: blurring, churning, and the outer regions of galaxy discs

Halle, Anaelle; Matteo, P. Di; Haywood, M.; Combes, F.

doi:10.1051/0004-6361/201525612

Cited by 75 publications

(114 citation statements)

References 53 publications

Supporting

Mentioning

101

Contrasting

Order By: Relevance

“…The explanation of such result is twofold: (1) since bars are quite efficient in driving the gas within their corotational radius toward the centre, after few bar orbits the central region of the galaxy is mostly gas free (as already noted by Berentzen et al 1998), and there is no remaining gas to be torqued by the bar; (2) in our simulations the forming bar slows down as the galaxy evolves, increasing its ILR and corotational radii (in agreement with, e.g. Sellwood 1981; Combes & Sanders 1981;Halle et al 2015). As a consequence, the gas that is perturbed by the early fast-precessing bar reaches regions significantly more nuclear than gas perturbed at later times.…”

Section: Discussionsupporting

confidence: 88%

“…The bar slow-down, already extensively discussed in literature (e.g. Sellwood 1981;Combes & Sanders 1981;Halle et al 2015), results in a RILR growing in time, from ∼ 1 kpc up to ∼ 1.4 kpc at the end of the run, as observable in the lower panel of figure 4. The bar forms thin, and buckles in its centre as the time goes by, as observable in the edge on view of the stellar disc at t =4 and 7 Gyr.…”

Section: Simulation Suitesupporting

confidence: 61%

See 1 more Smart Citation

Bar formation as driver of gas inflows in isolated disc galaxies

Fanali¹,

Dotti²,

Fiacconi³

et al. 2015

Mon. Not. R. Astron. Soc.

View full text Add to dashboard Cite

Stellar bars are a common feature in massive disc galaxies. On a theoretical ground, the response of gas to a bar is generally thought to cause nuclear starbursts and, possibly, AGN activity once the perturbed gas reaches the central super-massive black hole. By means of high resolution numerical simulations we detail the purely dynamical effects that a forming bar exerts on the gas of an isolated disc galaxy. The galaxy is initially unstable to the formation of non-axisymmetric structures, and within ∼ 1 Gyr it develops spiral arms that eventually evolve into a central stellar bar on kpc scale. A first major episode of gas inflow occurs during the formation of the spiral arms while at later times, when the stellar bar is establishing, a low density region is carved between the bar co-rotational and inner Lindblad resonance radii. The development of such "dead zone" inhibits further massive gas inflows. Indeed, the gas inflow reaches its maximum during the relatively fast bar formation phase and not, as often assumed, when the bar is fully formed. We conclude that the low efficiency of long-lived, evolved bars in driving gas toward galactic nuclei is the reason why observational studies have failed to establish an indisputable link between bars and AGNs. On the other hand, the high efficiency in driving strong gas inflows of the intrinsically transient process of bar formation suggests that the importance of bars as drivers of AGN activity in disc galaxies has been overlooked so far. We finally prove that our conclusions are robust against different numerical implementations of the hydrodynamics routinely used in galaxy evolution studies.

show abstract

Section: Discussionsupporting

confidence: 88%

Section: Simulation Suitesupporting

confidence: 61%

Bar formation as driver of gas inflows in isolated disc galaxies

Fanali¹,

Dotti²,

Fiacconi³

et al. 2015

Mon. Not. R. Astron. Soc.

View full text Add to dashboard Cite

show abstract

“…We see that the guiding radii of the thick disc particles are in general smaller than the instantaneous birth radii and that all these stars have guiding radii inside the OLR (see also Halle et al 2015), while stars can have instantaneous birth radii outside the OLR. Therefore, we see that thick disc stars enter the bar-b/p region due to blurring, i.e.…”

Section: Birth Radiimentioning

confidence: 84%

Bars and boxy/peanut bulges in thin and thick discs

Fragkoudi

Matteo

Haywood

et al. 2017

A&A

Self Cite

View full text Add to dashboard Cite

We explore trends in the morphology and line-of-sight (los) velocity of stellar populations in the inner regions of disc galaxies using N-body simulations with a thin (kinematically cold) and a thick (kinematically hot) disc which form a bar and a boxy/peanut (b/p) bulge. The bar in the thin disc component is ∼50% stronger than the thick disc bar and is more elongated, with an axis ratio almost half that of the thick disc bar. The thin disc b/p bulge has a pronounced X-shape, while the thick disc b/p is weaker with a rather boxy shape. This leads to the signature of the b/p bulge in the thick disc being weaker and further away from the plane than in the thin disc. Regarding the kinematics, we find that the los velocity of thick disc stars in the outer parts of the b/p bulge can be higher than that of thin disc stars, by up to 40% and 20% for side-on and Milky Way-like orientations of the bar, respectively. This is due to the different orbits followed by thin and thick disc stars in the bar-b/p region, which are affected by two factors. First, thin disc stars are trapped more efficiently in the bar-b/p instability and thus lose more angular momentum than their thick disc counterparts and second, thick disc stars have large radial excursions and therefore stars from large radii with high angular momenta can be found in the bar region. We also find that the difference between the los velocities of the thin and thick disc in the b/p bulge (∆v los ) correlates with the initial difference between the radial velocity dispersions of the two discs (∆σ). We therefore conclude that stars in the bar-b/p bulge will have considerably different morphologies and kinematics depending on the kinematic properties of the disc population they originate from.

show abstract

“…3). It may be that, as noted in Hallé et al (2015), radial migration has mixed the inner disk inside the OLR, but mixing stars that have uniform properties, independent of Galactocentric distance, will not change any observed trend.…”

Section: Radial Migrationmentioning

confidence: 87%

When the Milky Way turned off the lights: APOGEE provides evidence of star formation quenching in our Galaxy

Haywood

Lehnert

Matteo

et al. 2016

A&A

Self Cite

148

174

View full text Add to dashboard Cite

Quenching, the cessation of star formation, is one of the most significant events in the life cycle of galaxies. While quenching is generally thought to be linked to their central regions, the mechanism responsible for it is not known and may not even be unique. We show here the first evidence that the Milky Way experienced a generalised quenching of its star formation at the end of its thick-disk formation ∼9 Gyr ago. The fossil record imprinted on the elemental abundances of stars studied in the solar vicinity and as part of the APOGEE survey (APOGEE is part of the Sloan Digital Sky Survey III) reveals indeed that in less than ∼2 Gyr (from 10 to 8 Gyr ago) the star formation rate in our Galaxy dropped by an order of magnitude. Because of the tight correlation that exists between age and α abundance, the general cessation of the star formation activity reflects in the dearth of stars along the inner-disk sequence in the [Fe/H]-[α/Fe] plane. Before this phase, which lasted about 1.5 Gyr, the Milky Way was actively forming stars. Afterwards, the star formation resumed at a much lower level to form the thin disk. These events observed in our Galaxy are very well matched by the latest observation of MW-type progenitors at high redshifts. In late-type galaxies, the quenching mechanism is believed to be related to a long and secular exhaustion of gas. Our results show that in the Milky Way, the shut-down occurred on a much shorter timescale, while the chemical continuity between the stellar populations formed before and after the quenching indicates that it is not the exhaustion of the gas that was responsible for the cessation of the star formation. While quenching is generally associated with spheroids in the literature, our results show that it also occurs in galaxies like the Milky Way, where the classical bulge is thought to be small or non-existent, possibly when they are undergoing a morphological transition from thick to thin disks. Given the demographics of late-type galaxies in the local Universe, in which classical bulges are rare, we suggest further that this may hold true generally in galaxies with mass lower than or approximately of M * , where quenching could directly be a consequence of thick-disk formation, while quenching may be related to development of spheroids in higher mass galaxies. We emphasize that the quenching phase in the Milky Way could be contemporaneous with, and related to, the formation of the bar, at the end of the thick-disk phase. We sketch a scenario on how a strong bar may inhibit star formation.

show abstract

Quantifying stellar radial migration in anN-body simulation: blurring, churning, and the outer regions of galaxy discs

Cited by 75 publications

References 53 publications

Bar formation as driver of gas inflows in isolated disc galaxies

Bar formation as driver of gas inflows in isolated disc galaxies

Bars and boxy/peanut bulges in thin and thick discs

When the Milky Way turned off the lights: APOGEE provides evidence of star formation quenching in our Galaxy

Contact Info

Product

Resources

About