Near-infrared observations of star formation and gas flows in the NUGA galaxy NGC 1365

Fazeli, Nastaran; Busch, G.; Valencia-S., M.; Eckart, A.; Combes, F.; García‐Burillo, S.

doi:10.1051/0004-6361/201834255

Cited by 25 publications

(23 citation statements)

References 163 publications

(225 reference statements)

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“…The latter ratios are similar to those in other circum-nuclear rings that show star formation activity (e.g. Falcón-Barroso et al 2014;Riffel et al 2016;Busch et al 2017;Fazeli et al 2019) and therefore strongly suggest star formation as the dominating H 2 excitation mechanism. On the other hand, the behaviour for the other apertures is different, suggesting that these apertures are excited by a different mechanism and not by star formation.…”

Section: H 2 Excitationsupporting

confidence: 83%

“…These are typical line ratios for clusters in circum-nuclear star-forming rings (e.g. Falcón-Barroso et al 2014;Riffel et al 2016;Busch et al 2017;Fazeli et al 2019). We note that most of the spots in the circum-nuclear ring (R) are located in the young star formation regions.…”

Section: Near-infrared Diagnostic Diagramssupporting

confidence: 53%

“…In many galaxies these dust features coincide with molecular gas streaming motions such as inflows (e.g. Davies et al 2014;Busch et al 2017;Fazeli et al 2019).…”

Section: Another Bar-inside-a-bar or An Inclined Nuclear Discmentioning

confidence: 94%

“…5 and was measured by fitting a two-dimensional Gaussian profile to the combined images of the standard star. More information on the specifics of the data reduction and calibration can be found in Fazeli et al (2019).…”

Section: Observations and Data Reductionmentioning

confidence: 99%

“…Near-infrared emission lines allow for an analysis of recent star formation events (e.g. Davies et al 2007;Böker et al 2008;Bedregal et al 2009;Falcón-Barroso et al 2014;Busch et al 2015;Fazeli et al 2019). Furthermore kinematics of the old, mass dominating stellar populations have been mapped which trace the stellar potential.…”

Section: Introductionmentioning

confidence: 99%

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Central kiloparsec of NGC 1326 observed with SINFONI

Fazeli

Busch

Eckart

et al. 2020

A&A

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Gas inflow processes in the vicinity of galactic nuclei play a crucial role in galaxy evolution and supermassive black hole growth. Exploring the central kiloparsec of galaxies is essential to shed more light on this subject. We present near-infrared H- and K-band results of the nuclear region of the nearby galaxy NGC 1326, observed with the integral-field spectrograph SINFONI mounted on the Very Large Telescope. The field of view covers 9″ × 9″ (650 × 650 pc2). Our work is concentrated on excitation conditions, morphology, and stellar content. The nucleus of NGC 1326 was classified as a LINER, however in our data we observed an absence of ionised gas emission in the central r ∼ 3″. We studied the morphology by analysing the distribution of ionised and molecular gas, and thereby detected an elliptically shaped, circum-nuclear star-forming ring at a mean radius of 300 pc. We estimate the starburst regions in the ring to be young with dominating ages of < 10 Myr. The molecular gas distribution also reveals an elongated east to west central structure about 3″ in radius, where gas is excited by slow or mild shock mechanisms. We calculate the ionised gas mass of 8 × 105 M⊙ completely concentrated in the nuclear ring and the warm molecular gas mass of 187 M⊙, from which half is concentrated in the ring and the other half in the elongated central structure. The stellar velocity fields show pure rotation in the plane of the galaxy. The gas velocity fields show similar rotation in the ring, but in the central elongated H2 structure they show much higher amplitudes and indications of further deviation from the stellar rotation in the central 1″ aperture. We suggest that the central 6″ elongated H2 structure might be a fast-rotating central disc. The CO(3–2) emission observations with the Atacama Large Millimeter/submillimeter Array reveal a central 1″ torus. In the central 1″ of the H2 velocity field and residual maps, we find indications for a further decoupled structure closer to a nuclear disc, which could be identified with the torus surrounding the supermassive black hole.

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Section: H 2 Excitationsupporting

confidence: 83%

Section: Near-infrared Diagnostic Diagramssupporting

confidence: 53%

“…In many galaxies these dust features coincide with molecular gas streaming motions such as inflows (e.g. Davies et al 2014;Busch et al 2017;Fazeli et al 2019).…”

Section: Another Bar-inside-a-bar or An Inclined Nuclear Discmentioning

confidence: 94%

Section: Observations and Data Reductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Central kiloparsec of NGC 1326 observed with SINFONI

Fazeli

Busch

Eckart

et al. 2020

A&A

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High-resolution, 3D radiative transfer modelling

Nersesian

Verstocken

Viaene

et al. 2020

A&A

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Context. Dust in late-type galaxies in the local Universe is responsible for absorbing approximately one third of the energy emitted by stars. It is often assumed that dust heating is mainly attributable to the absorption of ultraviolet and optical photons emitted by the youngest (≤ 100 Myr) stars. Consequently, thermal re-emission by dust at far-infrared wavelengths is often linked to the starformation activity of a galaxy. However, several studies argue that the contribution to dust heating by much older stellar populations might be more significant than previously thought. Advances in radiation transfer simulations finally allow us to actually quantify the heating mechanisms of diffuse dust by the stellar radiation field. Aims. As one of the main goals in the DustPedia project, we have developed a framework to construct detailed 3D stellar and dust radiative transfer models for nearby galaxies. In this study, we analyse the contribution of the different stellar populations to the dust heating in four nearby face-on barred galaxies: NGC 1365, M 83, M 95, and M 100. We aim to quantify the fraction directly related to young stellar populations, both globally and on local scales, and to assess the influence of the bar on the heating fraction. Methods. From 2D images we derive the 3D distributions of stars and dust. To model the complex geometries, we used SKIRT, a state-of-the-art 3D Monte Carlo radiative transfer code designed to self-consistently simulate the absorption, scattering, and thermal re-emission by the dust for arbitrary 3D distributions. Results. We derive global attenuation laws for each galaxy and confirm that galaxies of high specific star-formation rate have shallower attenuation curves and weaker UV bumps. On average, 36.5% of the bolometric luminosity is absorbed by dust in our galaxy sample. We report a clear effect of the bar structure on the radial profiles of the dust-heating fraction by the young stellar populations, and the dust temperature. We find that the young stellar populations are the main contributors to the dust heating, donating, on average ∼ 59% of their luminosity to this purpose throughout the galaxy. This dust-heating fraction drops to ∼ 53% in the bar region and ∼ 38% in the bulge region where the old stars are the dominant contributors to the dust heating. We also find a strong link between the heating fraction by the young stellar populations and the specific star-formation rate.

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Near-infrared observations of the gas structure and kinematics in the circumnuclear region of NGC 1672

Fazeli

Eckart

Busch

et al. 2020

A&A

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We present our near-infrared, integral-field spectroscopy observations of the central 550 × 550 pc2 (10″ × 10″) of the local galaxy NGC 1672. Our aim is to investigate the morphology and kinematics of gas and stars to probe evidence for feeding and feedback phenomena. For this purpose the near-infrared wavelength regime and integral-field unit technique provide a vast amount of useful information. The narrow emission line ratios suggest that the galaxy hosts a low-luminosity active galactic nucleus. From the MBH − σ* relation, we find a black hole mass of a few 107 M⊙. The total reservoir of hot molecular and ionised gas is estimated, using flux of H2 and Brγ emission lines, to be 258 M⊙ and 2.3 × 106 M⊙ respectively. The most striking feature in the emission line flux maps is the star-forming ring at a radius of ∼3″. The stellar and gaseous kinematics both show a rotation pattern in a disc that is blue-shifted in the north-west and red-shifted in the south-east. However, unlike the stellar kinematics, gas kinematics show various complexities, such as higher amplitudes in the central region (within the star-forming ring). The molecular gas velocity-field map shows deviations from pure disc motion in the form of an S-shaped zero-velocity line. In particular the position angle of the zero-velocity line changes in the central arcsecond, resembling the decoupled nuclear disc or molecular torus found in CO(3–2). There is an offset of 0.″5 between the nuclear continuum barycentre and kinematic centre of molecular gas towards the north-west. The velocity field of Brγ emitting gas on the other hand, is highly red-shifted in the centre and offset from the continuum emission peak by about 1″. Investigating the spectra of this region we detect a doubled-horn Brγ emission line in the nucleus and north-west. This region is also luminous in radio 3 cm emission connecting the nucleus to the star-forming ring.

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Near-infrared observations of star formation and gas flows in the NUGA galaxy NGC 1365

Cited by 25 publications

References 163 publications

Central kiloparsec of NGC 1326 observed with SINFONI

Central kiloparsec of NGC 1326 observed with SINFONI

High-resolution, 3D radiative transfer modelling

Near-infrared observations of the gas structure and kinematics in the circumnuclear region of NGC 1672

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