Dynamical Masses in Luminous Infrared Galaxies

Hinz, J. L.; Rieke, G. H.

doi:10.1086/505071

Cited by 32 publications

(34 citation statements)

References 57 publications

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“…Our mass estimates agree with those obtained for LIRGs in Hinz & Rieke (2006) and Väisänen et al (2008), which are in the range (10 10 −10 11 ) M .…”

Section: Summary Of the Global Kinematical Propertiessupporting

confidence: 89%

Studying the kinematic asymmetries of disks and post-coalescence mergers using a new “kinemetry” criterion

Bellocchi

Arribas

Colina

2012

A&A

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Context. Ultra luminous and luminous infrared galaxies [(U)LIRGs] are important galaxy populations for studying galaxy evolution, and are likely to have been responsible for a significant fraction of the star formation that occurred prior to z ∼ 1. Local (U)LIRGs can be used to study criteria that are suitable for characterizing similar high redshift populations. We are particularly interested in identifying reliable kinematic-based methods capable of distinguishing disks and mergers, as their relative fraction is a key observational input to constrain different evolutionary scenarios. Aims. Our goal is to analyze in detail the kinematics of the ionized gas of a small sample of LIRGs and study criteria that permit us to characterize the evolutionary status of these systems. Methods. We obtained Very Large Telescope VIMOS optical integral field spectroscopy (IFS) data of four LIRGs selected at similar distances (∼70 Mpc) to avoid relative resolution effects. Two of these systems had been previously classified as regular isolated disks galaxies and the other two as post-coalescence mergers based on their morphology. The kinemetry method (developed by Krajnović and coworkers) is used to characterize the kinematic properties of these galaxies and discuss new criteria for distinguishing their status.Results. We present and discuss new kinematic maps (i.e., velocity field and velocity dispersion) for these four galaxies. These kinematic data suggest that nuclear outflows exist in all these galaxies, and are particularly intense for the post-coalescence merger systems. The v c /σ c parameter has values between those that are typical of local spiral galaxies (i.e., v c /σ c = 5−15) and those obtained for Lyman break analogs at z ∼ 0.2 (i.e., v c /σ c = 0.4−1.8). Our use of one-dimensional parameters, such as v c /σ c or v shear /Σ, does not allow us to distinguish between the two groups (i.e., disks, post-coalescence systems). However, when the full two-dimensional kinematic information of the IFS data is analyzed by means of kinemetry, their morphological and kinematic classifications are consistent, with disks having lower kinematic asymmetries than post-coalescence mergers. We propose and discuss a new kinematic criterion to differentiate between these two groups. In particular, we introduce a weighting that favors the outer parts of the kinematic maps when computing the total asymmetries. This step is taken because post-coalescence mergers display relatively small kinematic asymmetries in their inner parts as a consequence of the rapid relaxation of gas into a rotating disk, whereas the outer parts continue to be out of equilibrium (i.e., to have larger asymmetries). We find that, in addition to distinguishing post-coalescence mergers from rotating disks, this new criterion has the advantage of being less sensitive to angular resolution effects. According to previous kinemetry-based analyses designed to distinguish disks and mergers at high-z, the present post-coalescence systems would have been classified a...

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“…Our mass estimates agree with those obtained for LIRGs in Hinz & Rieke (2006) and Väisänen et al (2008), which are in the range (10 10 −10 11 ) M .…”

Section: Summary Of the Global Kinematical Propertiessupporting

confidence: 89%

Studying the kinematic asymmetries of disks and post-coalescence mergers using a new “kinemetry” criterion

Bellocchi

Arribas

Colina

2012

A&A

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“…This relation predicts metallicities of Z ∼ 1.9−2.8 Z 3 for galaxies with masses as those expected in typical LIRGs (∼10 10 −10 12 M , e.g., Hinz & Rieke 2006;Väisänen et al 2008a,b). Similar findings for the nuclear region of these kinds of galaxies have been reported by Rupke et al (2008).…”

Section: Ionization Mechanisms In the Extra-nuclear Ionized Regions: supporting

confidence: 58%

“…In Arp 220, the ionized gas plumes that could be associated with superwinds generated in the nuclear starburst form an elongated structure up to a distance of about 2 kpc from the nucleus. However, for the present sample of LIRGs, which show a significant lower starforming activity based on their L IR but similar dynamical mass (Hinz & Rieke 2006;Väisänen et al 2008b,a) and hence similar escape velocity, a smaller area of influence of the stellar superwinds should be expected.…”

Section: Ionization Mechanisms In the Extra-nuclear Ionized Regions: mentioning

confidence: 50%

VLT-VIMOS integral field spectroscopy of luminous and ultraluminous infrared galaxies

Monreal-Ibero

Arribas

Colina

et al. 2010

A&A

101

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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 10 11 −10 12 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 v s < ∼ 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 10 11.0 −10 12.3 L luminosity range). This preliminary result needs to be investigated further with a larger sample of ULIRGs.

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“…Therefore, it might be impossible to explain the mass discrepancy in the centre region of NGC 3256 with the traditional MOND theory. However, it was well known that the standard X CO , derived from molecular clouds in the Galactic plane, might over-estimate the molecular mass in the central regions of LIRGs (Hinz & Rieke 2006). It was suggested the true conversion factor in LIRGs might be a factor of 5 lower than the standard value.…”

Section: Dark Matter In the Central Region Of Ngc 3256mentioning

confidence: 99%