Photometric and kinematic DISKFIT models of four nearby spiral galaxies

Peters, W.; Naray, Rachel Kuzio de

doi:10.1093/mnras/stx821

Cited by 8 publications

(6 citation statements)

References 49 publications

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“…To study the molecular gas kinematics we use two different softwares, namely the 3D-Based Analysis of Rotating Object via Line Observations (3D BAROLO 1 ; Di Teodoro & Fraternali 2015) and DiskFit (Peters & Kuzio de Naray 2017). This paper is structured as follows.…”

Section: Introductionmentioning

confidence: 99%

Molecular gas kinematics in the nuclear region of nearby Seyfert galaxies with ALMA

Belete

Andreani

Fernández-Ontiveros

et al. 2021

A&A

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Context. The study of the distribution, morphology, and kinematics of cold molecular gas in the nuclear and circumnuclear regions of active galactic nuclei (AGNs) helps to characterise and hence to quantify the impact of the AGNs on the host galaxy over its lifetime. Aims. We present the analysis of the molecular gas in the nuclear regions of three Seyfert galaxies, NGC 4968, NGC 4845, and MCG-06-30-15, using Atacama Large sub-Millimetre Array (ALMA) observations of the CO(2−1) emission line. The aim is to determine the kinematics of the gas in the central (∼1 kpc) region and thereby to probe nuclear fueling and feedback of AGNs. Methods. We used two different softwares, namely the 3D-Based Analysis of Rotating Object via Line Observations and DiskFit, to model the kinematics of the gas in the molecular disc, and thereby to determine the gas rotation and any kinematical perturbations. Results. Circular motions dominate the kinematics of the molecular gas in the central discs, mainly in NGC 4845 and MCG-06-30-15; however there is clear evidence of non-circular motions in the central (∼1 kpc) region of NGC 4845 and NGC 4968. The strongest non-circular motion is detected in the inner disc of NGC 4968, mainly along the minor kinematic axis, with a velocity ∼115 km s−1. Of all DiskFit models, the bisymmetric model is found to give the best fit for NGC 4968 and NGC 4845, indicating that the observed non-circular motions in the inner disc of these galaxies could result from the nuclear barred structure, where the gas streams in elliptical orbits aligned along the bar. If the dynamics of NGC 4968 is modelled as a corotation pattern just outside of the bar, the bar pattern speed becomes Ωb = 52 km s−1 kpc−1; the corotation is set at 3.5 kpc; and the inner Lindblad resonance (ILR) ring is R = 300 pc, corresponding to the CO emission ring. In the NGC 4968 galaxy, the torques exerted on the gas by the bar are positive in the centre, within the gas nuclear ring, and negative outside. This shows that the gas is transiently trapped in the ILR. The comparison of the CO intensity maps with the map of the cold dust emission shows an absence of CO in the centre of NGC 4968; also the dust distribution and CO emission in and around the centre of NGC 4845 have similar extensions. The 1.2 mm ALMA continuum is peaked and compact in NGC 4968 and MCG-06-30-15, but their CO(2−1) emissions have extended distributions. Allowing the CO-to-H2 conversion factor αCO between 0.8 and 3.2, which is typical of nearby galaxies of the same type, the molecular mass M(H2) is estimated to be ∼3 − 12 × 107 M⊙ (NGC 4968), ∼9 − 36 × 107 M⊙ (NGC 4845), and ∼1 − 4 × 107 M⊙ (MCG-06-30-15). Conclusions. We conclude that the observed non-circular motions in the molecular disc of NGC 4968 and likely those seen in NGC 4845 are due to the presence of the bar in the nuclear region. We discuss the possibility that the observed pattern in the kinematics might be a consequence of the presence of AGNs, and this might be the case for NGC 4845. At the current spectral and spatial resolution and sensitivity, we cannot claim any strong evidence in these sources of the long sought feedback or feeding effect resulting from the presence of AGNs.

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Section: Introductionmentioning

confidence: 99%

Molecular gas kinematics in the nuclear region of nearby Seyfert galaxies with ALMA

Belete

Andreani

Fernández-Ontiveros

et al. 2021

A&A

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“…The failure of DiskFit to recover bulges in simulated S 4 G-like images highlights the importance of validating decomposition algorithms, especially before applying them to large samples of real systems (e.g. Schombert & Bothun 1987;Byun & Freeman 1995;Wadadekar et al 1999;MacArthur et al 2003;Gadotti 2008;Peters & Kuzio de Naray 2017). It is possible that the non-parametric nature of DiskFit makes bulge recovery more difficult than for parametric algorithms such as galfit, though Gadotti (2008) finds that bulges with r ef f comparable to the seeing radius are difficult to recover even when both the bulge and the disk are parametrized.…”

Section: Discussionmentioning

confidence: 99%

“…Bar parameters are thus often presented without uncertainties (Weinzirl et al 2008;Salo et al 2015;de Swardt et al 2015). Although modelling large galaxy samples is an effective means of minimizing the statistical uncertainties on measured values (Blanton et al 2005), detailed survey-and algorithm-specific tests are required to determine whether or not systematic biases are important (Schombert & Bothun 1987;Byun & Freeman 1995;Wadadekar et al 1999;MacArthur et al 2003;Gadotti 2008;Peters & Kuzio de Naray 2017).…”

Section: Introductionmentioning

confidence: 99%

Non-parametric decompositions of disc galaxies in S4G using diskfit

Lewis

Spekkens

2018

Monthly Notices of the Royal Astronomical Society

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We present photometric models of 532 disk galaxies in 3.6µm images from the Spitzer Survey of Stellar Structure in Galaxies ( S 4 G) using the non-parametric DiskFit algorithm. We first test DiskFit's performance on 400 synthetic S 4 G-like galaxy images. DiskFit is unreliable in the bulge region, but accurately disentangles exponential disks from Ferrers bars farther out as long as their position angles differ by more than 5 • . We then proceed to model the S 4 G galaxies, successfully fitting 489 of them using an automated approach for initializing DiskFit, optimizing the model and deriving uncertainties using a bootstrap-resampling technique. The resulting component geometries and surface brightness profiles are compared to those derived by Salo et al using the parametric model galfit. We find generally good agreement between the models, but discrepancies between best-fitting values for individual systems are often significant: the choice of algorithm clearly impacts the inferred disk and bar structure. In particular, we find that DiskFit typically assigns more light to the bar and less light to the disk relative to the Ferrers and exponential profiles derived using galfit in the bar region. Given DiskFit's reliability at disentangling these components in our synthetic images, we conclude that the surface brightness distributions of barred S 4 G galaxies are not well-represented by these functional forms. The results presented here underscore the importance of validating photometric decomposition algorithms before applying them to real data and the utility of DiskFit's non-parametric approach at measuring the structure of disks and bars in nearby galaxies.

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“…There are no signs of a classical bulge in the galaxy (Barentine & Kormendy 2012), but the nuclear disc is embedded within a boxy bulge with a peanut shape extending out to ∼ 35 arcsec along the major axis of the galaxy (Kuĳken & Merrifield 1995;Bureau & Freeman 1999). This structure actually corresponds to a bar seen at an intermediate angle, close to end-on (Peters & Kuzio de Naray 2017). Signatures of the bar are also seen in the kinematics of gas (Kuĳken & Merrifield 1995) and stars, with in particular a correlation between 𝑉 and ℎ 3 which is expected from a barred disc seen in projection (Chung & Bureau 2004;Molaeinezhad et al 2016).…”

Section: Ngc 5746mentioning

confidence: 97%

NGC 5746: formation history of a massive disc-dominated galaxy

Martig,

Pinna,

Falcón-Barroso

et al. 2021

Preprint

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The existence of massive galaxies lacking a classical bulge has often been proposed as a challenge to ΛCDM. However, recent simulations propose that a fraction of massive disc galaxies might have had very quiescent merger histories, and also that mergers do not necessarily build classical bulges. We test these ideas with deep MUSE observations of NGC 5746, a massive (∼ 10 11 M ) edge-on disc galaxy with no classical bulge. We analyse its stellar kinematics and stellar populations, and infer that a massive and extended disc formed very early: 80% of the galaxy's stellar mass formed more than 10 Gyr ago. Most of the thick disc and the bar formed during that early phase. The bar drove gas towards the center and triggered the formation of the nuclear disc followed by the growth of a boxy/peanut-shaped bulge. Around ∼ 8 Gyr ago, a ∼1:10 merger happened, possibly on a low-inclination orbit. The satellite did not cause significant vertical heating, did not contribute to the growth of a classical bulge, and did not destroy the bar and the nuclear disc. It was however an important event for the galaxy: by depositing its stars throughout the whole galaxy it contributed ∼ 30% of accreted stars to the thick disc. NGC 5746 thus did not completely escape mergers, but the only relatively recent significant merger did not damage the galaxy and did not create a classical bulge. Future observations will reveal if this is representative of the formation histories of massive disc galaxies.

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Photometric and kinematic DISKFIT models of four nearby spiral galaxies

Cited by 8 publications

References 49 publications

Molecular gas kinematics in the nuclear region of nearby Seyfert galaxies with ALMA

Molecular gas kinematics in the nuclear region of nearby Seyfert galaxies with ALMA

Non-parametric decompositions of disc galaxies in S4G using diskfit

NGC 5746: formation history of a massive disc-dominated galaxy

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