We have options available for most vehicles 1996 and newer. Luminous infrared galaxies (LIRGs) are an important class of objects in the low-z universe bridging the gap between normal spirals and the strongly interacting and starbursting ultraluminous infrared galaxies (ULIRGs). Since a large fraction of the stars in the Universe have been formed in these objects, LIRGs are also relevant in a high-z context. Studies of the two-dimensional.
VLT-VIMOS integral field spectroscopy of luminous and ultraluminous infrared galaxies. II. Evidence for shock ionization caused by tidal forces in the extra-nuclear regions of interacting and merging LIRGs
Abstract
Context. Luminous infrared galaxies (LIRGs) are an important class of objects in the low-z universe bridging the gap between normal spirals and the strongly interacting and starbursting ultraluminous infrared galaxies (ULIRGs). Since a large fraction of the stars in the Universe have been formed in these objects, LIRGs are also relevant in a high-z context. Studies of the two-dimensional physical properties of LIRGs are still lacking.
Aims: We aim to understand the nature and origin of the ionization mechanisms operating in the extra-nuclear regions of LIRGs as a function of the interaction phase and infrared luminosity.
Methods: This study uses optical integral field spectroscopy (IFS) data obtained with VIMOS. Our analysis is based on over 25 300 spectra of 32 LIRGs covering all types of morphologies (isolated galaxies, interacting pairs, and advanced mergers), and the entire 1011-1012 L⊙ infrared luminosity range.
Results: We found strong evidence for shock ionization, with a clear trend with the dynamical status of the system. Specifically, we quantified the variation with interaction phase of several line ratios indicative of the excitation degree. While the [N ii]λ6584/Hα ratio does not show any significant change, the [S ii]λλ6717,6731/Hα and [O i]λ6300/Hα ratios are higher for more advanced interaction stages. Velocity dispersions are higher than in normal spirals and increase with the interaction class (medians of 37, 46, and 51 km s-1 for class 0-2, respectively). We constrained the main mechanisms causing the ionization in the extra-nuclear regions (typically for distances ranging from ~0.2-2.1 kpc to ~0.9-13.2 kpc) using diagnostic diagrams. Isolated systems are mainly consistent with ionization caused by young stars. Large fractions of the extra-nuclear regions in interacting pairs and more advanced mergers are consistent with ionization caused by shocks of vs ⪉ 200 km s-1. This is supported by the relation between the excitation degree and the velocity dispersion of the ionized gas, which we interpret as evidence for shock ionization in interacting galaxies and advanced mergers but not in isolated galaxies. This relation does not show any dependence with the infrared luminosity (i.e. the level of star formation). All this indicates that tidal forces play a key role in the origin of the ionizing shocks in the extra-nuclear regions. We also showed for the first time what appears to be a common log([O i]λ6300/Hα) - log (σ) relation for the extranuclear ionized gas in interacting (U)LIRGs (i.e. covering the entire 1011.0-1012.3 L⊙ luminosity range). This preliminary result needs to be investigated further with a larger sample of ULIRGs.
Aims: We aim to understand the nature and origin of the ionization mechanisms operating in the extra-nuclear regions of LIRGs as a function of the interaction phase and infrared luminosity.
Methods: This study uses optical integral field spectroscopy (IFS) data obtained with VIMOS. Our analysis is based on over 25 300 spectra of 32 LIRGs covering all types of morphologies (isolated galaxies, interacting pairs, and advanced mergers), and the entire 1011-1012 L⊙ infrared luminosity range.
Results: We found strong evidence for shock ionization, with a clear trend with the dynamical status of the system. Specifically, we quantified the variation with interaction phase of several line ratios indicative of the excitation degree. While the [N ii]λ6584/Hα ratio does not show any significant change, the [S ii]λλ6717,6731/Hα and [O i]λ6300/Hα ratios are higher for more advanced interaction stages. Velocity dispersions are higher than in normal spirals and increase with the interaction class (medians of 37, 46, and 51 km s-1 for class 0-2, respectively). We constrained the main mechanisms causing the ionization in the extra-nuclear regions (typically for distances ranging from ~0.2-2.1 kpc to ~0.9-13.2 kpc) using diagnostic diagrams. Isolated systems are mainly consistent with ionization caused by young stars. Large fractions of the extra-nuclear regions in interacting pairs and more advanced mergers are consistent with ionization caused by shocks of vs ⪉ 200 km s-1. This is supported by the relation between the excitation degree and the velocity dispersion of the ionized gas, which we interpret as evidence for shock ionization in interacting galaxies and advanced mergers but not in isolated galaxies. This relation does not show any dependence with the infrared luminosity (i.e. the level of star formation). All this indicates that tidal forces play a key role in the origin of the ionizing shocks in the extra-nuclear regions. We also showed for the first time what appears to be a common log([O i]λ6300/Hα) - log (σ) relation for the extranuclear ionized gas in interacting (U)LIRGs (i.e. covering the entire 1011.0-1012.3 L⊙ luminosity range). This preliminary result needs to be investigated further with a larger sample of ULIRGs.
Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere, Chile (ESO Programs 076.B-0479(A), 078.B-0072(A) and 081.B-0108(A)).Figures 14-17 are only available in electronic form at http://www.aanda.org
What Is Vlt In Sunglasses
- galaxies: active;
- galaxies: interactions;
- galaxies: starburst;
- infrared: galaxies;
- Astrophysics - Cosmology and Nongalactic Astrophysics
Site: Cerro Paranal –Deserto di Atacama - Cile
State: completed
Activities:
Detail Design, Manufacturing, Pre-Assembly in Europe, Packing &Transport, Erection on Site, Commissioning and Testing of the four Telescopes Main structures
Partner: AES Consortium
State: completed
Activities:
Detail Design, Manufacturing, Pre-Assembly in Europe, Packing &Transport, Erection on Site, Commissioning and Testing of the four Telescopes Main structures
Partner: AES Consortium
Date: 1991-2001
Client: ESO – European Southern Observatory
What Is Vlt
Category: astronomy
Credits: ESO Courtesy /EIE GROUP
Overview:
The VLT (Very Large Telescope), is an astronomical observatory by ESO (European Southern Observatory), made by four big optical telescopes, each with an 8.2m diameter primary mirror and complemented by four minor mobile units.
The VLT (Very Large Telescope), is an astronomical observatory by ESO (European Southern Observatory), made by four big optical telescopes, each with an 8.2m diameter primary mirror and complemented by four minor mobile units.
The four main telescopes can operate individually as well as one interferometric instrument for extra resolution or as a single large instrument capable to gather up to four times the light of a single unit.
When the VLTs were inaugurated in 1999, they were given the names of objects in the sky in the Mapuche native language:
Antu (Sun)
Kueyen (Moon)
Melipal (Southern Cross)
Yepun (Venus)
Antu (Sun)
Kueyen (Moon)
Melipal (Southern Cross)
Yepun (Venus)
As of today, the four VLTs are among the biggest telescopes around the world.
The main characteristics of the VLT Telescopes:
Besides the enclosures, EIE, in consortium with the Ansaldo and the Soimi industries, has also provided the VLT telescopes steel structures. Specifically, we designed and mounted the Coudé tubes, AZ frame, AZ platforms, intermediate structure, pedestal, Nasmyth platforms, drive system housing, center piece, Serrurier truss, top ring and spiders.
The telescope structure has also been equipped with a series of devices like: telescope control system, AZ auxiliary drive, EL manual drive, hydraulic brake system, encoders, EL cable wrap, AZ and EL locking pins, hard stops, stairs allowing the access between the AZ and the Nasmyth platforms, EL shutter, stop switches interlocks, UPS and electrical installations and hard stops.
Read Prof. Harry Van Der Laan – ESO DG at the time of the VLTs account
prof.-h.van-der-laan
prof.-h.van-der-laan
The Science with the VLT:
The VLT telescopes are equipped with a series of instruments permitting observations to be performed from the near-ultraviolet to the mid-infrared, thus a large portion of the light wavelengths accessible from the surface of the Earth. The VLTs are considered such refined instruments capable to obtain higher resolution images than the Hubble Space Telescope.
The following observations are possible with the VLTs:
• Observing high redshift galaxies;
• Stars formation;
• Exoplanets and Protoplanetary Systems observations.
• Stars formation;
• Exoplanets and Protoplanetary Systems observations.
Thanks to the observations performed with the VLTs, scientists and astronomers have been able to capture the first images of an extra-solar planet, they could track individual stars moving around the supermassive black hole at the centre of the Milky Way and they observed the furthest known Gamma-Ray Burst afterglow.
Links to ESO’s VLT web pages
What Does Vlt Mean On Goggles
http://www.eso.org/sci/facilities/paranal/telescopes/ut.html
http://www.eso.org/public/teles-instr/vlt/
http://www.eso.org/public/teles-instr/vlt/