| 1. |
- Blasco-Herrera, Javier, 1981-, et al.
(författare)
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Halpha kinematics of 11 starburst galaxies selected from the Sloan Digital Sky Survey
- 2012
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- We present analysis of Fabry-Perot interferometric observations for a sample of 11starburst galaxies with redshift z . 0.03 selected from the Sloan Digital Sky Survey.We have targeted the H 6562.78 emission line at spatial sampling of 0.002−0.004 andat spectral resolution of R 16000, and studying two-dimensional velocity, velocitydispersion, line emission and continuum maps deliver new insights into the nature ofstarburst and postburst galaxies. The velocity fields are fitted to an exponential discmodel, providing scale lengths and masses, to be compared with the photometric scalelength and the mass estimated from the velocity dispersions. From the line emissionthe star formation rates are also calculated and compared with values in the literature.We have found that between 55% and 64% of our sample show large scale dominatingrotation, while 27% show local rotation typically restricted to the central part of eachsystem. The morphology and line profiles in the centre of eight objects are consistentwith a recent merger, while another two seem to be involved in a accretion processwhich has not disrupted their kin
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| 2. |
- Blasco-Herrera, Javier, 1981-, et al.
(författare)
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Structural parameters of starburst and postburst galaxies
- 2012
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- We present two samples of 1173 starbursts and 145 postburst in the redshift range0.01 < z < 0.083, selected from Sloan Digital Sky Survey Data Release 7. We charac-terize both samples using 2D Sersic profiles and measure their asymmetry. The Sersicindex, n, and the effective radii show that starburst galaxies are more concentratedthan the postburst sample, with median n 1.85 for starbursts and 2.85 for post-bursts. There is a large fraction of disky (n < 2) postbursts, a fraction larger thanreported by previous studies. Part of the excess comes from low luminosity (Mr > −19)objects, vastly dominated by discs. We estimate the mass from the velocity dispersionof the H emission line, both for the starbursts and those postbursts with residualemission, finding that Lr / Mb, with b = 1.35 for starbursts and b = 1.5 for post-bursts. The typical values of the mass-to-light ratio range between 0 and 10. This,now, is surprising for starburst galaxies, for which mass-to-light ratios 1 have beenpreviously found.
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| 3. |
- Fathi, Kambiz, et al.
(författare)
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Disc scalelengths out to redshift 5.8
- 2012
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Ingår i: Monthly notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966 .- 1745-3925. ; 423:1, s. l112-L116
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Tidskriftsartikel (refereegranskat)abstract
- We compute the exponential disc scalelength for 686 disc galaxies with spectroscopic redshifts out to redshift 5.8 based on Hubble Space Telescope archival data. We compare the results with our previous measurements based on 30 000 nearby galaxies from the Sloan Digital Sky Survey. Our results confirm the presence of a dominating exponential component in galaxies out to this redshift. At the highest redshifts, the disc scalelength for the brightest galaxies with absolute magnitude between -24 and -22 is up to a factor of 8 smaller compared to that in the local Universe. This observed scalelength decrease is significantly greater than the value predicted by a cosmological picture in which baryonic disc scalelength scales with the virial radius of the dark matter halo.
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| 4. |
- Nilsson, R., et al.
(författare)
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VLT imaging of the beta Pictoris gas disk
- 2012
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 544
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Tidskriftsartikel (refereegranskat)abstract
- Context. Circumstellar debris disks older than a few Myr should be largely devoid of primordial gas remaining from the protoplanetary disk phase. Tracing the origin of observed atomic gas in Keplerian rotation in the edge-on debris disk surrounding the similar to 12 Myr old star beta Pictoris requires more detailed information about its spatial distribution than has previously been acquired by limited slit spectroscopy. Especially indications of asymmetries and presence of Ca II gas at high disk latitudes call for additional investigation to exclude or confirm its connection to observed dust structures or suggested cometary bodies on inclined eccentric orbits. Aims. We set out to recover a complete image of the Fe I and Ca II gas emission around beta Pic by spatially resolved, high-resolution spectroscopic observations to better understand the morphology and origin of the gaseous disk component. Methods. The multiple fiber facility FLAMES/GIRAFFE at the Very Large Telescope (VLT), with the large integral-field-unit ARGUS, was used to obtain spatially resolved optical spectra (from 385.9 to 404.8 nm) in four regions covering the northeast and southwest side of the disk. Emission lines from Fe I (at 386.0 nm) and Ca II (at 393.4 and 396.8 nm) were mapped and could be used to fit a parametric function for the disk gas distribution, using a gas-ionisation code for gas-poor debris disks. Results. Both Fe I and Ca II emission are clearly detected, with the former dominating along the disk midplane, and the latter revealing vertically more extended gas. The surface intensity of the Fe I emission is lower but more extended in the northeast (reaching the 210 AU limit of our observations) than in the southwest, while Ca II shows the opposite asymmetry. The modelled Fe gas disk profile shows a linear increase in scale height with radius, and a vertical profile that suggests dynamical interaction with the dust. We also qualitatively demonstrate that the Ca II emission profile can be explained by optical thickness in the disk midplane, and does not require Ca to be spatially separated from Fe.
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| 5. |
- Pinol-Ferrer, Nuria, et al.
(författare)
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Analytic gas orbits in an arbitrary rotating galactic potential using the linear epicyclic approximation
- 2012
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Ingår i: Monthly notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 421:2, s. 1089-1102
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Tidskriftsartikel (refereegranskat)abstract
- A code, EPIC5, has been developed which computes, in the two-dimensional case, the initially circular orbits of guiding centra in an arbitrary axisymmetric potential with an arbitrary, weak perturbing potential in solid body rotation. This perturbing potential is given by its Fourier expansion. The analytic solution solves the linear epicyclic approximation of the equations of motion. To simulate the motion of interstellar matter and to damp the Lindblad resonances, in these equations we have introduced a friction which is proportional to the deviation from circular velocity. The corotation resonance is also damped by a special parameter. The program produces, in just a few seconds, orbital and density maps, as well as line-of-sight velocity maps for a chosen orientation of the galaxy. We test EPIC5 by comparing its results with previous simulations and observations from the literature, which gives satisfactory agreement. The aim is that this program should be a useful complement to elaborate numerical simulations. Particularly so are its abilities to quickly explore the parameter space, to construct artificial galaxies and to isolate various single agents important for developing the structure of interstellar matter in disc galaxies. The EPIC5 code can be obtained from npi@astro.su.se.
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