Planetary nebulae as kinematic tracers of galaxy halos

2015 ◽  
Vol 11 (A29B) ◽  
pp. 20-25 ◽  
Author(s):  
Lodovico Coccato ◽  
Keyword(s):  
Surface Brightness ◽  
Velocity Dispersion ◽  
Spiral Galaxies ◽  
Planetary Nebulae ◽  
Early Type ◽  
Number Density ◽  
Host Galaxies ◽  
Galaxy Halos ◽  
Radial Profiles ◽  
Dynamical Properties

AbstractThe kinematics and dynamical properties of galaxy stellar halos are difficult to measure, given the faint surface brightness that characterizes these regions. Gas-rich systems such as spiral galaxies can be probed using the radio Hi emission. Early-type galaxies contain less gas, therefore alternative kinematic tracers need to be used. Planetary Nebulae (PNe) can be easily detected far out in the halo thanks to their bright [O iii] emission at 5007 Å. It is therefore possible to map the halo kinematics also in early-type galaxies, typically out to 5 effective radii or beyond. Thanks to the recent spectroscopic surveys targeting extra-galactic PNe, we can now rely on few tens of galaxies where the kinematics of the stellar halos are measured. I will discuss the most important results: (a) the relation of the stellar surface brightness and the PNe number density; (b) the velocity and velocity dispersion two-dimensional fields; (c) the radial profiles of angular momentum; and (d) the relation between the derived kinematics physical properties of the host galaxies.

scholarly journals Planetary nebulae as kinematic tracers of galaxy halos

2015 ◽  
Vol 11 (A29B) ◽  
Author(s):  
Lodovico Coccato ◽  
Keyword(s):  
Surface Brightness ◽  
Velocity Dispersion ◽  
Spiral Galaxies ◽  
Planetary Nebulae ◽  
Early Type ◽  
Number Density ◽  
Host Galaxies ◽  
Galaxy Halos ◽  
Radial Profiles ◽  
Dynamical Properties

AbstractThe kinematics and dynamical properties of galaxy stellar halos are difficult to measure, given the faint surface brightness that characterizes these regions. Gas-rich systems such as spiral galaxies can be probed using the radio Hi emission. Early-type galaxies contain less gas, therefore alternative kinematic tracers need to be used. Planetary Nebulae (PNe) can be easily detected far out in the halo thanks to their bright [Oiii] emission at 5007 Å. It is therefore possible to map the halo kinematics also in early-type galaxies, typically out to 5 effective radii or beyond. Thanks to the recent spectroscopic surveys targeting extra-galactic PNe, we can now rely on few tens of galaxies where the kinematics of the stellar halos are measured. I will discuss the most important results: (a) the relation of the stellar surface brightness and the PNe number density; (b) the velocity and velocity dispersion two-dimensional fields; (c) the radial profiles of angular momentum; and (d) the relation between the derived kinematics physical properties of the host galaxies.

scholarly journals Stellar systems following the R1/m luminosity law

2019 ◽  
Vol 626 ◽  
pp. A110 ◽  
Author(s):  
Maarten Baes ◽  
Luca Ciotti
Keyword(s):  
Entire Range ◽  
Surface Brightness ◽  
Velocity Dispersion ◽  
Spiral Galaxies ◽  
Analytical Techniques ◽  
The Other ◽  
Early Type ◽  
Dispersion Tensor ◽  
Low Mass ◽  
Dynamical Properties

The Sérsic or R1/m model has become the de facto standard model to describe the surface brightness profiles of early-type galaxies and the bulges of spiral galaxies. The photometric, intrinsic, and dynamical properties of this model have been investigated, but mainly for fairly large Sérsic indices m. For small values of m, appropriate for low-mass and dwarf ellipticals, a detailed investigation of these properties is still lacking. In this study, we used a combination of numerical and analytical techniques to investigate the Sérsic model over the entire range of Sérsic parameters, focussing on the small m regime, where a number of interesting and surprising properties are found. For all values m <  1, the model is characterised by a finite central luminosity density, and for m < 1/2, even a central depression in the luminosity density profile. This behaviour translates to the dynamical properties: we show that all Sérsic models with m ⩾ 1/2 can be supported by an isotropic velocity dispersion tensor, and that these isotropic models are stable to both radial and non-radial perturbations. The models with m < 1/2, on the other hand, cannot be supported by an isotropic velocity dispersion tensor.

scholarly journals Planetary nebulae as kinematic tracers of galaxy stellar halos

2016 ◽  
Vol 12 (S323) ◽  
pp. 271-278
Author(s):  
Lodovico Coccato
Keyword(s):  
Surface Brightness ◽  
Spiral Galaxies ◽  
Planetary Nebulae ◽  
Emission Lines ◽  
Early Type ◽  
Dynamical Properties ◽  
Bright Emission

AbstractThe kinematic and dynamical properties of galaxy stellar halos are difficult to measure because of the faint surface brightness that characterizes these regions. Spiral galaxies can be probed using the radio Hiemission; on the contrary, early-type galaxies contain less gas, therefore alternative kinematic tracers need to be used. Planetary nebulae (PNe) can be easily detected far out in the halo thanks to their bright emission lines. It is therefore possible to map the halo kinematics also in early-type galaxies, typically out to 5 effective radii or beyond. Thanks to the recent spectroscopic surveys targeting extra-galactic PNe, we can now rely on a few tens of galaxies where the kinematics of the stellar halos are measured. Here, I will review the main results obtained in this field in the last decades.

scholarly journals Abundance of dwarf galaxies around low-mass spiral galaxies in the Local Volume

2020 ◽  
Vol 644 ◽  
pp. A91
Author(s):  
Oliver Müller ◽  
Helmut Jerjen
Keyword(s):  
Surface Brightness ◽  
Spiral Galaxies ◽  
Dwarf Galaxies ◽  
Dwarf Galaxy ◽  
Current Model ◽  
Host Galaxies ◽  
Local Volume ◽  
Satellite Problem ◽  
Low Mass ◽  
Crucial Test

The abundance of satellite dwarf galaxies has long been considered a crucial test for the current model of cosmology leading to the well-known missing satellite problem. Recent advances in simulations and observations have allowed the study of dwarf galaxies around host galaxies in more detail. Using the Dark Energy Camera we surveyed a 72 deg2 area of the nearby Sculptor group, also encompassing the two low-mass Local Volume galaxies NGC 24 and NGC 45 residing behind the group, to search for as yet undetected dwarf galaxies. Apart from the previously known dwarf galaxies we found only two new candidates down to a 3σ surface brightness detection limit of 27.4 r mag arcsec−2. Both systems are in projection close to NGC 24. However, one of these candidates could be an ultra-diffuse galaxy associated with a background galaxy. We compared the number of known dwarf galaxy candidates around NGC 24, NGC 45, and five other well-studied low-mass spiral galaxies (NGC 1156, NGC 2403, NGC 5023, M 33, and the LMC) with predictions from cosmological simulations, and found that for the stellar-to-halo mass models considered, the observed satellite numbers tend to be on the lower end of the expected range. This could mean either that there is an overprediction of luminous subhalos in ΛCDM or that we are missing some of the satellite members due to observational biases.

scholarly journals The mass–size plane of EAGLE galaxies

2019 ◽  
Vol 629 ◽  
pp. L3 ◽  
Author(s):  
M. S. Rosito ◽  
P. B. Tissera ◽  
S. E. Pedrosa ◽  
C. D. P. Lagos
Keyword(s):  
Velocity Dispersion ◽  
Bimodal Distribution ◽  
Early Type ◽  
Chemical Abundances ◽  
Radial Profiles ◽  
Mass Size ◽  
Hydrodynamical Simulations ◽  
Star Formation Histories ◽  
Disc Galaxies ◽  
Second Peak

Context. Current observational results show that both late- and early-type galaxies follow tight mass–size planes on which physical properties such as age, velocity dispersion, and metallicity correlate with the scatter on the plane. Aims. We study the mass–size plane of galaxies in cosmological hydrodynamical simulations, as a function of velocity dispersion, age, chemical abundances, ellipticity, and spin parameters with the aim of assessing to what extent the current cosmological paradigm can reproduce these observations and provide a physical interpretation of them. Methods. We selected a sample of well-resolved galaxies from the (100 Mpc)3 simulation of the EAGLE Project. This sample is composed of 508 spheroid-dominated galaxies and 1213 disc-dominated galaxies. The distributions of velocity dispersion, age, metallicity indicators and gradients, and spin parameters across the mass–size plane are analysed. Furthermore, we study the relation between shape and kinematic parameters. The results are compared with observations. Results. The mass-weighted ages of the EAGLE galaxies are found to vary along lines of constant velocity dispersion on the mass–size plane, except for galaxies with velocity dispersions higher than ∼150 km s−1. Negative age gradients tend to be found in extended disc galaxies in agreement with observations. However, the age distributions of early-type galaxies show a larger fraction with inverted radial profiles. The distribution of metallicity gradients does not show any clear dependence on this plane. Galaxies with similar spin parameters (λ) display larger sizes as their dynamical masses increase. Stellar-weighted ages are found to be good proxies for λ in galaxies with low ellipticity (ε). A bimodal distribution of λ is found so that the high-λ peak is dominated by discs with young stellar populations (SPs), while the second peak is mainly populated by slow rotators (λ <  0.2) with old stars. Our findings suggest that the physical processes that regulate the star formation histories in galaxies might also affect the angular moment budgets of gas and stars, and as a consequence their morphology.

scholarly journals The stellar velocity dispersion in nearby spirals: radial profiles and correlations

2019 ◽  
Author(s):  
Keoikantse Moses Mogotsi ◽  
Alessandro B Romeo
Keyword(s):  
Velocity Dispersion ◽  
Spiral Galaxies ◽  
Gravitational Instability ◽  
Stellar Mass ◽  
Radial Profiles ◽  
Stellar Velocity ◽  
The One ◽  
Radial Average ◽  
Field Area ◽  
Integral Field

Abstract The stellar velocity dispersion, σ, is a quantity of crucial importance for spiral galaxies, where it enters fundamental dynamical processes such as gravitational instability and disc heating. Here we analyse a sample of 34 nearby spirals from the Calar Alto Legacy Integral Field Area (CALIFA) spectroscopic survey, deproject the line-of-sight σ to σR and present reliable radial profiles of σR as well as accurate measurements of ⟨σR⟩, the radial average of σR over one effective (half-light) radius. We show that there is a trend for σR to increase with decreasing R, that ⟨σR⟩ correlates with stellar mass (M⋆) and tested correlations with other galaxy properties. The most significant and strongest correlation is the one with M⋆: $\langle \sigma _{R}\rangle \propto M_{\star }^{0.5}$. This tight scaling relation is applicable to spiral galaxies of type Sa–Sd and stellar mass M⋆ ≈ 109.5–1011.5 M⊙. Simple models that relate σR to the stellar surface density and disc scale length roughly reproduce that scaling, but overestimate ⟨σR⟩ significantly.

scholarly journals The σc — Vcirc correlation in high and low surface brightness galaxies

2004 ◽  
Vol 220 ◽  
pp. 339-340 ◽  
Author(s):  
A. Pizzella ◽  
E. Dalla Bontà ◽  
E. M. Corsini ◽  
L. Coccato ◽  
F. Bertola
Keyword(s):  
Surface Brightness ◽  
Velocity Dispersion ◽  
Spiral Galaxies ◽  
High Surface ◽  
Linear Scale ◽  
High Surface Brightness ◽  
Circular Velocity ◽  
Straight Line ◽  
Low Surface Brightness ◽  
Low Surface Brightness Galaxies

We investigate the relation between the central velocity dispersion, σc, and the circular velocity, Vcirc, in galaxies. in addition to previously obtained data, we consider an observationally homogeneus sample of 52 high surface brightness and 11 low surface brightness spiral galaxies. We performed a straight line regression analysis in a linear scale, finding a good fit, also for low σc galaxies, always rejected in the previous studies. Low surface brightness galaxies seem to behave differently, showing either higher values of Vcirc or lower values of σc with respect to their high surface brightness counterparts.

scholarly journals Spiral galaxies in the SAURON survey

2007 ◽  
Vol 3 (S245) ◽  
pp. 271-276
Author(s):  
Reynier F. Peletier ◽  
Katia Ganda ◽  
Jesús Falcón-Barroso ◽  
Roland Bacon ◽  
Michele Cappellari ◽  
...  
Keyword(s):  
Radial Velocity ◽  
Velocity Dispersion ◽  
Spiral Galaxies ◽  
Line Strength ◽  
Early Type ◽  
Late Type ◽  
Integral Field Spectroscopy ◽  
Field Spectroscopy ◽  
New Ideas ◽  
Integral Field

AbstractWe discuss some recent integral field spectroscopy using the SAURON instrument of a sample consisting of 24 early-type spirals, part of the SAURON Survey, and 18 late-type spirals. Using 2-dimensional maps of their stellar radial velocity, velocity dispersion, and absorption line strength, it is now much easier to understand the nature of nearby galactic bulges. We discuss a few highlights of this work, and point out some new ideas about the formation of galactic bulges.

scholarly journals Planetary Nebulae and Halo Dynamics in Early Type Galaxies

1993 ◽  
Vol 155 ◽  
pp. 533-540 ◽  
Author(s):  
X. Hui ◽  
H.C. Ford
Keyword(s):  
Quantum Efficiency ◽  
Stellar Evolution ◽  
Late Stage ◽  
Planetary Nebulae ◽  
Rapid Progress ◽  
Early Type ◽  
Host Galaxies ◽  
High Quantum Efficiency ◽  
Mass Distributions ◽  
Test Particles

The study of extragalactic planetary nebulae has made rapid progress in recent years with the help of high quantum efficiency detectors. A brief but distinctive phase in the late stage of stellar evolution, planetary nebulae (PNe) are not only interesting objects in their own right, but also are extremely valuable and unique tools for probing the host galaxies. Recent studies have used planetary nebulae as test particles to investigate the dynamics and mass distributions in the halos of early type galaxies.

scholarly journals The PN.S ETG survey

2016 ◽  
Vol 12 (S323) ◽  
pp. 279-283 ◽  
Author(s):  
M. Arnaboldi ◽  
C. Pulsoni ◽  
O. Gerhard ◽  
Keyword(s):  
Angular Momentum ◽  
Velocity Dispersion ◽  
Planetary Nebulae ◽  
Velocity Fields ◽  
Field Of View ◽  
Line Of Sight ◽  
Early Type ◽  
Velocity Data ◽  
Pn Velocity ◽  
Current Sample

AbstractWe have analyzed the velocity fields in the halos of thirty-three early-type galaxies (ETGs) with planetary nebulae (PNs) as tracers, reaching radii of up to ~8Re. The sample comprises twenty-five galaxies from the Planetary Nebulae Spectrograph (PN.S) ETG survey and eight further galaxies with extended PN velocity data from the literature and new Counter-Dispersed imaging observations. The catalogues from these thirty-three ETGs provide astrometric positions and heliocentric line-of-sight velocities for a total of 8354 extragalactic PNs. All these catalogues are treated homogeneously for the identification of kinematic outliers and the separation between main galaxy/satellites in each galaxy field-of-view. We discuss the rotation velocities, velocity dispersion profiles and radial trends of the specific angular momentum, separating between slow rotators and fast rotators. We compare the properties of the V/σ(R) and σ(R) profiles with predictions of 2D velocity fields from hydro-dynamical cosmological simulations. We briefly mention the possible origin of the quasi-Keplerian steeply decreasing profile galaxies which encompasses about one fourth of the current sample.

Sign in / Sign up

Export Citation Format

Share Document