| 1. |
- Fathi, Kambiz, et al.
(författare)
-
Spiral Inflow Feeding the Nuclear Starburst in M83 : Observed in Hα Emission with the GHαFaS Fabry-Perot Interferometer
- 2008
-
Ingår i: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 675:1, s. L17-L20
-
Tidskriftsartikel (refereegranskat)abstract
- We present observations of the nearby barred starburst galaxy M83 (NGC 5236), with the new Fabry-Perot interferometer GHαFaS mounted on the 4.2 m William Herschel Telescope on La Palma. The unprecedented high-resolution observations, of 16 pc FWHM-1, of the Hα-emitting gas cover the central 2 kpc of the galaxy. The velocity field displays the dominant disk rotation with signatures of gas inflow from kpc scales down to the nuclear regions. At the inner inner Lindblad resonance radius of the main bar and centered at the dynamical center of the main galaxy disk, a nuclear (5.5 +/- 0.9) × 108 Msolar rapidly rotating disk with scale length of 60+/-20 pc has formed. The nuclear starburst is found in the vicinity as well as inside this nuclear disk, and our observations confirm that gas spirals in from the outer parts to feed the nuclear starburst, giving rise to several star formation events at different epochs, within the central 100 pc radius of M83.
|
|
| 2. |
- Della Bruna, Lorenza, et al.
(författare)
-
Stellar feedback in M 83 as observed with MUSE II. Analysis of the H II region population : Ionisation budget and pre-SN feedback
- 2022
-
Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 666
-
Tidskriftsartikel (refereegranskat)abstract
- Context. Energy and momentum injected by young, massive stars into the surrounding gas play an important role in regulating further star formation and in determining the galaxy's global properties. Before supernovae begin to explode, stellar feedback consists of two main processes: radiation pressure and photoionisation.Aims. We study pre-supernova feedback and constrain the leakage of Lyman continuum (LyC) radiation in a sample of similar to 4700 H II regions in the nearby spiral galaxy M 83. We explore the impact that the galactic environment and intrinsic physical properties (metallicity, extinction, and stellar content) have on the early phases of H II region evolution.Methods. We combined VLT/MUSE observations of the ionised gas with young star cluster physical properties derived from HST multiwavelength data. We identified H II regions based on their Hα emission, and cross-matched the sample with planetary nebulae and supernova remnants to assess contaminant sources and identify evolved H II regions. We also spectroscopically identified Wolf-Rayet (WR) stars populating the star-forming regions. We estimated the physical properties of the H II regions (luminosity, size, oxygen abundance, and electron density). For each H II region, we computed the pressure of ionised gas (Pion) and the direct radiation pressure (Pdir) acting in the region, and investigated how they vary with galactocentric distance, with the physical properties of the region, and with the pressure of the galactic environment (PDE). For a subset of similar to 500 regions, we also investigated the link between the pressure terms and the properties of the cluster population (age, mass, and LyC flux). By comparing the LyC flux derived from Hα emission with the one modelled from their clusters and WRs, we furthermore constrained any escape of LyC radiation (fesc).Results. We find that Pion dominates over Pdir by at least a factor of 10 on average over the disk. Both pressure terms are strongly enhanced and become almost comparable in the central starburst region. In the disk (R ≥ 0.15Re), we observe that Pdir stays approximately constant with galactocentric distance. We note that Pdir is positively correlated with an increase in radiation field strength (linked to the negative metallicity gradient in the galaxy), while it decreases in low extinction regions, as is expected if the amount of dust to which the momentum can be imparted decreases. In addition, Pion decreases constantly for increasing galactocentric distances; this trend correlates with the decrease in extinction - indicative of more evolved and thus less compact regions - and with changes in the galactic environment (traced by a decrease in PDE). In general, we observe that H II regions near the centre are underpressured with respect to their surroundings, whereas regions in the rest of the disk are overpressured and hence expanding. We find that regions hosting younger clusters or those that have more mass in young star clusters have a higher internal pressure, indicating that clustered star formation likely plays a dominant role in setting the pressure. Finally, we estimate that only 13% of H II regions hosting young clusters and WR stars have fesc ≥ 0, which suggests that star formation taking place outside young clusters makes a non-negligible contribution to ionising H II regions.
|
|
| 3. |
|
|
| 4. |
- Della Bruna, Lorenza, et al.
(författare)
-
Stellar feedback in M83 as observed with MUSE I. Overview, an unprecedented view of the stellar and gas kinematics and evidence of outflowing gas
- 2022
-
Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 660
-
Tidskriftsartikel (refereegranskat)abstract
- Context. Young massive stars inject energy and momentum into the surrounding gas, creating a multi-phase interstellar medium (ISM) and regulating further star formation. The main challenge of studying stellar feedback proves to be the variety of scales spanned by this phenomenon, ranging from the immediate surrounding of the stars (H II regions, 10s pc scales) to galactic-wide kiloparsec scales.Aims. We present a large mosaic (3.8 × 3.8 kpc) of the nearby spiral galaxy M83, obtained with the MUSE instrument at ESO Very Large Telescope. The integral field spectroscopy data cover a large portion of the optical disk at a resolution of ∼20 pc, allowing the characterisation of single H II regions while sampling diverse dynamical regions in the galaxy.Methods. We obtained the kinematics of the stars and ionised gas, and compared them with molecular gas kinematics observed in CO(2-1) with the ALMA telescope array. We separated the ionised gas into H II regions and diffuse ionised gas (DIG) and investigated how the fraction of Hα luminosity originating from the DIG (fDIG) varies with galactic radius.Results. We observe that both stars and gas trace the galactic disk rotation, as well as a fast-rotating nuclear component (30″ ≃ 700 pc in diameter), likely connected to secular processes driven by the galactic bar. In the gas kinematics, we observe a stream east of the nucleus (50″ ≃ 1250 pc in size), redshifted with respect to the disk. The stream is surrounded by an extended ionised gas region (1000 × 1600 pc) with enhanced velocity dispersion and a high ionisation state, which is largely consistent with being ionised by slow shocks. We interpret this feature as either the superposition of the disk and an extraplanar layer of DIG, or as a bar-driven inflow of shocked gas. A double Gaussian component fit to the Hα line also reveals the presence of a nuclear biconic structure whose axis of symmetry is perpendicular to the bar. The two cones (20″ ≃ 500 pc in size) appear blue- and redshifted along the line of sight. The cones stand out for having an Hα emission separated by up to 200 km s−1 from that of the disk, and a high velocity dispersion ∼80–200 km s−1. At the far end of the cones, we observe that the gas is consistent with being ionised by shocks. These features had never been observed before in M83; we postulate that they are tracing a starburst-driven outflow shocking into the surrounding ISM. Finally, we obtain fDIG ∼ 13% in our field of view, and observe that the DIG contribution varies radially between 0.8 and 46%, peaking in the interarm region. We inspect the emission of the H II regions and DIG in ‘BPT’ diagrams, finding that in H II regions photoionisation accounts for 99.8% of the Hα flux, whereas the DIG has a mixed contribution from photoionisation (94.9%) and shocks (5.1%).
|
|
| 5. |
- Dicaire, Isabel, et al.
(författare)
-
Hα kinematics of the Spitzer Infrared Nearby Galaxies Survey
- 2008
-
Ingår i: Monthley Notices of Royal Astronomical Society (MNRAS). - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 385, s. 52-
-
Tidskriftsartikel (refereegranskat)abstract
- This is the second part of an Hα kinematics follow-up survey of the Spitzer Infrared Nearby Galaxies Survey (SINGS) sample. The aim of this paper is to shed new light on the role of baryons and their kinematics and on the dark/luminous matter relation in the star-forming regions of galaxies, in relation with studies at other wavelengths. The data for 37 galaxies are presented. The observations were made using Fabry-Perot interferometry with the photon-counting camera FaNTOmM on four different telescopes, namely the Canada-France-Hawaii 3.6-m, the ESO La Silla 3.6-m, the William Herschel 4.2-m and the Observatoire du mont Mégantic 1.6-m telescopes. The velocity fields are computed using custom IDL routines designed for an optimal use of the data. The kinematical parameters and rotation curves are derived using the GIPSY software. It is shown that non-circular motions associated with galactic bars affect the kinematical parameters fitting and the velocity gradient of the rotation curves. This leads to incorrect determinations of the baryonic and dark matter distributions in the mass models derived from those rotation curves.
|
|
| 6. |
- Font, Joan, et al.
(författare)
-
The ratio of pattern speeds in double-barred galaxies
- 2014
-
Ingår i: Monthly notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966 .- 1745-3933 .- 1745-3925. ; 444:1, s. l85-L89
-
Tidskriftsartikel (refereegranskat)abstract
- We have obtained two-dimensional velocity fields in the ionized gas of a set of eight double-barred galaxies, at high spatial and spectral resolution, using their H alpha emission fields measured with a scanning Fabry-Perot spectrometer. Using the technique by which phase reversals in the non-circular motion indicate a radius of corotation, taking advantage of the high angular and velocity resolution, we have obtained the corotation radii and the pattern speeds of both the major bar and the small central bar in each of the galaxies; there are few such measurements in the literature. Our results show that the inner bar rotates more rapidly than the outer bar by a factor between 3.3 and 3.6.
|
|
| 7. |
|
|
| 8. |
- Marquart, Thomas, et al.
(författare)
-
Star-gas decoupling and a non-rotating stellar core in He 2-10. : Integral field spectroscopy with FLAMES/ARGUS
- 2007
-
Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 474:L9
-
Tidskriftsartikel (refereegranskat)abstract
- Aims: We study the two-dimensional distribution and kinematics of the stellar and gaseous components in the centre of the blue compact dwarf galaxy He 2-10. The aim is to compare the kinematics of gas and stars in order to determine whether they are consistent with one another, or if stars and gas can be decoupled due to gravitational perturbations and feedback from star formation. Methods: We have used the integral field unit ARGUS, part of FLAMES on the European Southern Observatory's Very Large Telescope, to target the Ca ii λλ8498,8542,8662 Å triplet in the central 300 × 480 parsecs of He 2-10. The selected wavelength regime includes several prominent spectral features, including the Paschen series and the [S iii] emission-line, which we have used to derive the kinematics of the ionised interstellar medium. Results: We find no systematic trend in the velocities of the stars over the observed field of view and conclude that the stellar kinematics is governed by random motions. This is in contrast to the motions the ionised interstellar medium, where we find spatial velocity variations up to 60 km s-1. Our gas velocity field is consistent with previous studies of both the molecular gas and the feedback-driven outflow in He 2-10. We interpret the kinematic decoupling between the stars and the gas as He 2-10 being in the process of transformation to a dwarf elliptical galaxy.
|
|
| 9. |
- Marquart, Thomas, et al.
(författare)
-
The Kinematics of Extended Hα Emission in Blue Compact Galaxies
- 2007
-
Ingår i: Galaxy Evolution Across the Hubble Time. - Cambridge : Cambridge University Press. ; , s. 321-321
-
Konferensbidrag (refereegranskat)abstract
- Blue Compact Galaxies are gas-rich systems with strong star formation and spectra that are dominated by young stars and emission lines. Many are true starburts in the sense that the gas consumption timescales are short. The trigger of the starburst is poorly understood, although mergers are likely to play a role. We have observed a large sample (∼50) of low-z emission-line galaxies with a Fabry-Perot instrument, targeting the H-alpha line at high spectral and spatial resolution. Here, we present a small subsample of objects where we detect emission to large radii in the objects. The near-spherical outer isophotes indicate a central ionising source. In addition, the kinematics of the extended emission is different from that of the central starburst, strengthening the hypothesis of a merging event, triggering the central burst while the surrounding gas is still rather undisturbed. We use additional data from own observations and from the literature to quantify the ionising radiation, as well as to estimate the mass in gas and stars that is compared to the dynamical mass.
|
|
| 10. |
|
|
