Redistribution of stars and gas in the star formation deserts of barred galaxies

Donohoe-Keyes, C E; Martig, Marie; James, P. A.; Kraljic, Katarina

doi:10.1093/mnras/stz2474

Cited by 36 publications

(25 citation statements)

References 82 publications

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“…In real galaxies these regions are often found to have "star formation deserts" (SFDs) (James & Percival 2016 with ages older than the average. Stellar populations in the SFDs are slowly refilled by stars trapped by the bar at a later stage (Donohoe-Keyes et al 2019). Since our N -body model lacks significant late time bar growth, the presence of these hollows in our model is perhaps not surprising.…”

Section: Metallicity Assignment From the Actionsmentioning

confidence: 82%

Box/peanut-shaped bulges in action space

Debattista

Liddicott

Khachaturyants

et al. 2020

Monthly Notices of the Royal Astronomical Society

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We introduce the study of box/peanut (B/P) bulges in the action space of the initial axisymmetric system. We explore where populations with different actions end up once a bar forms and a B/P bulge develops. We find that the density bimodality due to the B/P bulge (the X-shape) is better traced by populations with low radial, $\rm J_{R,0}$, or vertical, $\rm J_{z,0}$, actions, or high azimuthal action, $\rm J_{\phi ,0}$. Generally populations separated by $\rm J_{R,0}$ have a greater variation in bar strength and vertical heating than those separated by $\rm J_{z,0}$. While the bar substantially weakens the initial vertical gradient of $\rm J_{z,0}$, it also drives a strikingly monotonic vertical profile of $\rm J_{R,0}$. We then use these results to guide us in assigning metallicity to star particles in a pure N-body model. Because stellar metallicity in unbarred galaxies depends on age as well as radial and vertical positions, the initial actions are particularly well suited for assigning metallicities. We argue that assigning metallicities based on single actions, or on positions, results in metallicity distributions inconsistent with those observed in real galaxies. We therefore use all three actions to assign metallicity to an N-body model by comparing with the actions of a star-forming, unbarred simulation. The resulting metallicity distribution is pinched on the vertical axis, has a realistic vertical gradient and has a stronger X-shape in metal-rich populations, as found in real galaxies.

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Section: Metallicity Assignment From the Actionsmentioning

confidence: 82%

Box/peanut-shaped bulges in action space

Debattista

Liddicott

Khachaturyants

et al. 2020

Monthly Notices of the Royal Astronomical Society

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“…With the aid of stacking techniques applied to far-UV images, showed that massive barred galaxies (total stellar masses M * 10 10 M ) are typically characterised by a dip in the radial distribution of SF that is not seen in nonbarred systems (see also James et al 2009). These 'SF deserts' indeed exist in barred galaxies (James & Percival 2016Spinoso et al 2017;Donohoe-Keyes et al 2019).…”

Section: Introductionmentioning

confidence: 94%

Molecular gas and star formation within 12 strong galactic bars observed with IRAM-30 m

Díaz-García

Lisenfeld

Pérez

et al. 2021

A&A

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Context. While some galactic bars show recent massive star formation (SF) along them, some others do not. Whether bars with low level of SF are a consequence of low star formation efficiency, low gas inflow rate, or dynamical effects remains a matter of debate. Aims. In order to study the physical conditions that enable or prevent SF, we perform a multi-wavelength analysis of 12 strongly barred galaxies with total stellar masses log10(M⋆/M⊙)∈[10.2, 11], chosen to host different degrees of SF along the bar major axis without any prior condition on gas content. We observe the CO(1–0) and CO(2–1) emission within bars with the IRAM-30 m telescope (beam sizes of 1.7–3.9 kpc and 0.9–2.0 kpc, respectively; 7–8 pointings per galaxy on average). Methods. We estimated molecular gas masses (Mmol) from the CO(1–0) and CO(2–1) emissions. SF rates (SFRs) were calculated from GALEX near-ultraviolet (UV) and WISE 12 μm images within the beam-pointings, covering the full bar extent (SFRs were also derived from far-UV and 22 μm). Results. We detect molecular gas along the bars of all probed galaxies. Molecular gas and SFR surface densities span the ranges log10(Σmol/[M⊙ pc−2]) ∈ [0.4,2.4] and log10(ΣSFR/[M⊙ pc−1 kpc−2]]) ∈ [−3.25, −0.75], respectively. The star formation efficiency (SFE; i.e., SFR/Mmol) in bars varies between galaxies by up to an order of magnitude (SFE ∈[0.1, 1.8] Gyr−1). On average, SFEs are roughly constant along bars. SFEs are not significantly different from the mean value in spiral galaxies reported in the literature (∼0.43 Gyr−1), regardless of whether we estimate Mmol from CO(1–0) or CO(2–1). Interestingly, the higher the total stellar mass of the host galaxy, the lower the SFE within their bars. In particular, the two galaxies in our sample with the lowest SFE and ΣSFR (NGC 4548 and NGC 5850, SFE ≲ 0.25 Gyr−1, ΣSFR ≲ 10−2.25 M⊙ yr−1 kpc−2, M⋆ ≳ 1010.7 M⊙) are also those hosting massive bulges and signs of past interactions with nearby companions. Conclusions. We present a statistical analysis of the SFE in bars for a sample of 12 galaxies. The SFE in strong bars is not systematically inhibited (either in the central, middle, or end parts of the bar). Both environmental and internal quenching are likely responsible for the lowest SFEs reported in this work.

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“…In the absence of an inner ring this region (CR -bar) will correspond to the so-called star formation desert (see e.g. James et al 2009;Donohoe-Keyes et al 2019), while in the presence of an inner ring this region will correspond to star formation inside the ring.…”

Section: Effect Of the Bar On The Inner Disc: Formation Of Inner Ringsmentioning

confidence: 99%

Chemodynamics of barred galaxies in cosmological simulations: On the Milky Way’s quiescent merger history and in-situ bulge

Fragkoudi

Grand

Pakmor

et al. 2020

Monthly Notices of the Royal Astronomical Society

118

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We explore the chemodynamical properties of a sample of barred galaxies in the Auriga magnetohydrodynamical cosmological zoom-in simulations, which form boxy/peanut (b/p) bulges, and compare these to the Milky Way (MW). We show that the Auriga galaxies which best reproduce the chemodynamical properties of stellar populations in the MW bulge have quiescent merger histories since redshift z ∼ 3.5: their last major merger occurs at $t_{\rm lookback}\gt 12\, \rm Gyr$, while subsequent mergers have a stellar mass ratio of ≤1:20, suggesting an upper limit of a few per cent for the mass ratio of the recently proposed Gaia Sausage/Enceladus merger. These Auriga MW-analogues have a negligible fraction of ex-situ stars in the b/p region ($\lt 1{{\ \rm per\ cent}}$), with flattened, thick disc-like metal-poor stellar populations. The average fraction of ex-situ stars in the central regions of all Auriga galaxies with b/p’s is 3 per cent – significantly lower than in those which do not host a b/p or a bar. While the central regions of these barred galaxies contain the oldest populations, they also have stars younger than 5 Gyr (>30 per cent) and exhibit X-shaped age and abundance distributions. Examining the discs in our sample, we find that in some cases a star-forming ring forms around the bar, which alters the metallicity of the inner regions of the galaxy. Further out in the disc, bar-induced resonances lead to metal-rich ridges in the Vϕ − r plane – the longest of which is due to the Outer Lindblad Resonance. Our results suggest the Milky Way has an uncommonly quiet merger history, which leads to an essentially in-situ bulge, and highlight the significant effects the bar can have on the surrounding disc.

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Redistribution of stars and gas in the star formation deserts of barred galaxies

Cited by 36 publications

References 82 publications

Box/peanut-shaped bulges in action space

Box/peanut-shaped bulges in action space

Molecular gas and star formation within 12 strong galactic bars observed with IRAM-30 m

Chemodynamics of barred galaxies in cosmological simulations: On the Milky Way’s quiescent merger history and in-situ bulge

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