Abstract
We present direct images in the H α and S ii λλ6717,6731 Å lines of the Galactic supernova remnant (SNR) G109.1-1.0 (CTB 109). We confirm that the filaments detected are the optical ...counterpart of the X-ray and radio SNR due to their high S ii/H α line ratios. We study for the first time the kinematics of the optical counterpart of SNR CTB 109 using the Universidad Nacional Autónoma de México scanning Fabry–Perot interferometer PUMA. We estimate a systemic velocity of VLSR = −50 ± 6 km s−1 for this remnant and an expansion velocity of Vexp = 230 ± 5 km s−1. From this velocity and taking into account previous studies of the kinematics of objects at that Galactic longitude, we derive a distance to SNR CTB 109 of 3.1 ± 0.2 kpc, locating it in the Perseus arm. Using the S ii λ6717/S ii λ6731 line ratio, we find an electronic density value around ne = 580 cm−3. Considering that this remnant is evolving in a low-density medium with higher-density cloudlets responsible for the optical emission, we determine the age and energy deposited in the ISM by the supernova explosion (E0) in both the Sedov–Taylor phase and the radiative phase. For both cases, the age is thousands of years and E0 is rather typical of SNRs containing simple pulsars, so that the energy released to the ISM cannot be used to distinguish between SNRs hosting typical pulsars from those hosting powerful magnetars, like CTB 109.
ABSTRACT
We present Fabry-Pérot observations in the H α and S ii lines to study the kinematics of the Magellanic-type dwarf irregular galaxy NGC 1569, these observations allowed us to compute the H α ...velocity field of this galaxy. Doing a detailed analysis of the velocity along the line of sight and H α velocity profiles, we identified the origin of most of the motions in the innermost parts of the galaxy and discarded the possibility of deriving a rotation curve that traces the gravitational well of the galaxy. We analysed the kinematics of the ionized gas around 31 supernova remnants previously detected in NGC 1569 by other authors, in optical and radio emission. We found that the H α velocity profiles of the supernova remnants are complex indicating the presence of shocks. Fitting these profiles with several Gaussian functions, we computed their expansion velocities which rank from 87 to 188 km s−1 confirming they are supernova remnants. Also, we determined the physical properties such as electron density, mechanical energy, and kinematic age for 30 of the 31 supernova remnants and found they are in the radiative phase with an energy range from 1 to 39 × 1050 erg s−1 and an age from 2.3 to 8.9 × 104 yr. Finally, we estimated the Surface Brightness–Diameter (Σ–D) relation for NGC 1569 and obtained a slope β = 1.26 ± 0.2, comparable with the β value obtained for supernova remnants in galaxies M31 and M33.
Context. Encounters between galaxies modify their morphology, kinematics, and star formation history. The relation between these changes and external perturbations is not straightforward. The great ...number of parameters involved requires both the study of large samples and individual encounters where particular features, motions, and perturbations can be traced and analysed in detail. Aims. We analysed the morphology, kinematics, and dynamics of two luminous infrared spiral galaxies of almost equal mass, NGC 5257 and NGC 5258, in which star formation is mostly confined to the spiral arms, in order to understand interactions between galaxies of equivalent masses and star-forming processes during the encounter. Methods. Using scanning Fabry–Perot interferometry, we studied the contribution of circular and non-circular motions and the response of the ionized gas to external perturbations. We compared the kinematics with direct images and traced the star-forming processes and gravitational effects due to the presence of the other galaxy. The spectral energy distribution of each member of the pair was fitted. A mass model was fitted to the rotation curve of each galaxy. Results. Large, non-circular motions detected in both galaxies are associated with a bar, spiral arms, and HII regions for the inner parts of the galaxies, and with the tidal interaction for the outer parts of the discs. Bifurcations in the rotation curves indicate that the galaxies have recently undergone pericentric passage. The pattern speed of a perturbation of one of the galaxies is computed. Location of a possible corotation seems to indicate that the gravitational response of the ionized gas in the outer parts of the disc is related to the regions where ongoing star formation is confined. The spectral energy distribution fit indicates slightly different star formation history for each member of the pair. For both galaxies, a pseudo-isothermal halo better fits the global mass distribution.
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IMAGES Puech, M.; Flores, H.; Hammer, F. ...
Astronomy and astrophysics (Berlin),
06/2008, Volume:
484, Issue:
1
Journal Article
Peer reviewed
Open access
Using the multi-integral field spectrograph GIRAFFE at VLT, we have derived the K-band Tully-Fisher relation (TFR) at z sim 0.6 for a representative sample of 65 galaxies with emission lines ...(W_\mathrm{0}\mathrm\ge15 similar to \AA). We confirm that the scatter in the z sim 0.6 TFR is caused by galaxies with anomalous kinematics, and find a positive and strong correlation between the complexity of the kinematics and the scatter that they contribute to the TFR. Considering only relaxed-rotating disks, the scatter, and possibly also the slope, of the TFR, do not appear to evolve with redshift. We detect an evolution of the K-band TFR zero point between z sim 0.6 and z =0, which, if interpreted as an evolution of the K-band luminosity of rotating disks, would imply that a brightening of 0.66 pm 0.14 mag occurs between z sim 0.6 and z =0. Any disagreement with the results of Flores et al. (2006, A&A, 455, 107) are attributed to both an improvement of the local TFR and the more detailed accurate measurement of the rotation velocities in the distant sample. Most of the uncertainty can be explained by the relatively coarse spatial-resolution of the kinematical data. Because most rotating disks at z sim 0.6 are unlikely to experience further merging events, one may assume that their rotational velocity, which is taken as a proxy of the total mass, does not evolve dramatically. If true, our result implies that rotating disks observed at z sim 0.6 are rapidly transforming their gas into stars, to be able to double their stellar masses and be observed on the TFR at z =0. The rotating disks observed are indeed emission-line galaxies that are either starbursts or LIRGs, which implies that they are forming stars at a high rate. Thus, a significant fraction of the rotating disks are forming the bulk of their stars within 6 to 8 Gyr, in good agreement with former studies of the evolution of the mass-metallicity relationship.
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Nearly half the stellar mass of present-day spiral galaxies has formed since $z = 1$, and galaxy kinematics is an ideal tool to identify the underlying mechanisms responsible for the galaxy mass ...assembly since that epoch. Here, we present the first results of the ESO large program, “IMAGES”, which aims at obtaining robust measurements of the kinematics of distant galaxies using the multi-IFU mode of GIRAFFE on the VLT. 3D spectroscopy is essential to robustly measure the often distorted kinematics of distant galaxies (e.g., Flores et al. 2006, A&A, 455, 107). We derive the velocity fields and σ-maps of 36 galaxies at $0.4 < z < 0.75$ from the kinematics of the O ii emission line doublet, and generate a robust technique to identify the nature of the velocity fields based on the pixels of the highest signal-to-noise ratios (S/N). Combining these observations with those of Flores et al., we have gathered a unique sample of 63 velocity fields of emission line galaxies (W0(O ii) ≥ 15 Å) at $z = 0.4$-0.75, which are a representative subsample of the population of $M_{\rm stellar} \ge 1.5$ $\times$ $10^{10}~M_{\odot}$ emission line galaxies in this redshift range, and are largely unaffected by cosmic variance. Taking into account all galaxies – with or without emission lines – in that redshift range, we find that at least 41 ± 7% of them have anomalous kinematics, i.e., they are not dynamically relaxed. This includes 26 ± 7% of distant galaxies with complex kinematics, i.e., they are not simply pressure or rotationally supported. Our result implies that galaxy kinematics are among the most rapidly evolving properties, because locally, only a few percent of the galaxies in this mass range have complex kinematics. It is well-established that galaxies undergoing a merger have complex large-scale motions and thus are likely responsible for the strong evolution of the galaxy kinematics that we observe.
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We present a kinematical study of the nearly edge-on galaxy ESO 379-006 that shows the existence of extraplanar ionized gas. With Fabry-Perot spectroscopy at H alpha , we study the kinematics of ESO ...379-006 using velocity maps and position-velocity diagrams parallel to the major and to the minor axis of the galaxy. We build the rotation curve of the disk and discuss the role of projection effects due to the fact of viewing this galaxy nearly edge-on. The twisting of the isovelocities in the radial velocity field of the disk of ESO 379-006 as well as the kinematical asymmetries found in some position-velocity diagrams parallel to the minor axis of the galaxy suggest the existence of deviations to circular motions in the disk that can be modeled and explained with the inclusion of a radial inflow probably generated by a bar or by spiral arms. We succeeded in detecting extraplanar diffuse ionized gas in this galaxy. At the same time, from the analysis of position-velocity diagrams, we found some evidence that the extraplanar gas could lag in rotation velocity with respect to the midplane rotation.
We present a first combined analysis of the morphological and dynamical properties for the intermediate- mass Galaxy Evolution Sequence (IMAGES) sample. It is a representative sample of 52 z\sim0.6 ...galaxies with M_{\rm stell} from 1.5 to 15 times 10 6M_{\odot} that possesses 3D resolved kinematics and HST deep imaging in at least two broad band filters. We aim at evaluating the evolution of rotating spirals robustly since z\sim0.6, as well as at testing the different schemes for classifying galaxies morphologically. We used all the information provided by multi-band images, color maps, and 2D light fitting to assign a morphological class to each object. We divided our sample into spiral disks, peculiar objects, compact objects, and mergers. Using our morphological classification scheme, 4/5 of the identified spirals are rotating disks, and more than 4/5 of identified peculiar galaxies show complex kinematics, while automatic classification methods such as concentration-asymmetry and GINI-M20 severely overestimate the fraction of relaxed disk galaxies. Using this methodology, we find that the fraction of undisturbed rotating spirals has increased by a factor similar to 2 during the past 6 Gyr, a much higher fraction than was found previously based on morphologies alone. These rotating spiral disks are forming stars very rapidly, even doubling their stellar masses over the past 6 Gyr, while most of their stars were formed a few Gyr earlier, which reveals a large gas supply. Because they are the likely progenitors of local spirals, we can conjecture how their properties are evolving. Their disks show some evidence of inside-out growth, and the gas supply/accretion is not random since the disk needs to be stable in order to match the local disk properties.
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Aims. We quantify the intrinsic width of the red giant branches of three massive globular clusters in M 31 in a search for metallicity spreads within these objects. Methods. We present HST/ACS ...observations of three massive clusters in M 31, G78, G213, and G280. A thorough description of the photometry extraction and calibration is presented. After derivation of the color-magnitude diagrams, we quantify the intrinsic width of the red giant branch of each cluster. Results. This width translates into a metallicity dispersion that indicates a complex star formation history for this type of system. For G78, $ \sigma_{\rm Fe/H}=0.86 \pm 0.37 $; for G213, $ 0.89 \pm 0.20 $; and for G280, $1.03 \pm 0.26$. We find that the metallicity dispersion of the clusters does not scale with mean metallicity. We also find no trend with the cluster mass. We discuss some possible formation scenarios that would explain our results.
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Context. Intermediate mass galaxies (> 1010 $M_\odot$) at z ~ 0.6 are the likeliest progenitors of the present-day, numerous population of spirals. There is growing evidence that they have evolved ...rapidly in the last 6 to 8 Gyr, and likely already have formed a significant fraction of their stellar mass, often showing perturbed morphologies and kinematics. Aims. We have gathered a representative sample of 88 such galaxies and have provided robust estimates of their gas phase metallicity. Methods. We used moderate spectral resolution spectroscopy at VLT/FORS2 with an unprecedentedly high $S/N$ allowing us to remove biases coming from interstellar absorption lines and extinction, to establish robust values of R23 = (OIIλ3727 + OIII$\lambda\lambda$4959, 5007)/Hβ. Results. We definitively confirm that the predominant population of z ~ 0.6 starbursts and luminous IR galaxies (LIRGs) are on average two times less metal rich than the local galaxies at a given stellar mass. We do find that the metal abundance of the gaseous phase of galaxies evolves linearly with time, from $z = 1$ to $z = 0$ and after comparing with other studies, from $z = 3$ to $z = 0$. Combining our results with the reported evolution of the Tully Fisher relation, we find that such an evolution requires that ~30% of the stellar mass of local galaxies have been formed through an external supply of gas, thus excluding the closed box model. Distant starbursts & LIRGs have properties (metal abundance, star formation efficiency & morphologies) similar to those of local LIRGs. Their underlying physics is likely dominated by gas infall, probably through merging or interactions. Conclusions. Our study further supports the rapid evolution of z ~ 0.4–1 galaxies. Gas exchange between galaxies is likely the main cause of this evolution.
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