scholarly journals Theoretical Aspects of Galaxy Dynamics Using Planetary Nebulae

2003 ◽  
Vol 209 ◽  
pp. 615-616
Author(s):  
Anne Mathieu
Keyword(s):  
Planetary Nebulae ◽  
Elliptical Galaxies ◽  
Emission Lines ◽  
Absorption Lines ◽  
Dark Halo ◽  
Galaxy Dynamics ◽  
The Galaxy ◽  
Stellar Body

The dynamics of the outer regions of elliptical galaxies is still poorly known. Their lack of gas means that it is not possible to use the usual optical and 21cm emission lines to determine the kinematics out to large radii, and the faintness of their stellar body means that data calculated using absorption lines are limited to the inner part of the galaxy. It is only by measuring the kinematics out to several optical scalelengths that one gets any unambiguous measure of the dark halo properties (Kent 1986).

scholarly journals Ultraviolet emission line imaging of planetary nebulae with GALEX

2011 ◽  
Vol 7 (S283) ◽  
pp. 308-309 ◽  
Author(s):  
Luciana Bianchi ◽  
Arturo Manchado ◽  
Karl Forster
Keyword(s):  
Galaxy Evolution ◽  
Broad Band ◽  
Planetary Nebulae ◽  
Emission Lines ◽  
Continuum Emission ◽  
Ultraviolet Emission ◽  
The Galaxy ◽  
Optical Domain ◽  
Line Imaging ◽  
Shock Fronts

AbstractGALEX (the Galaxy Evolution Explorer) has provided far-UV(1344-1786Å) and near-UV(1771-2831Å) imaging of several Planetary Nebulae (e.g., Bianchi et al. 2008, Bianchi 2012), with flux limits ~27.5 mag/sq.arcsec for objects in the Medium-deph Imaging Survey (MIS). PNe images in the GALEX broad-band UV filters include flux from both nebular line and continuum emission. We use the GALEX grism observing mode to obtain slitless spectral imaging of a sample of PNe with diameters >1′, in the near-UV. We show the first data from this program. The grism produces 2D images of the prominent UV nebular emission lines, when such lines dominate the flux. Combined with monochromatic images of diagnostic lines in the optical domain, such data help detect and interpret ionization and shock fronts, especially in faint nebular regions.

scholarly journals The Dark Halo – Spheroid Conspiracy

2012 ◽  
Vol 8 (S295) ◽  
pp. 208-208
Author(s):  
Rhea-Silvia Remus ◽  
Andreas Burkert ◽  
Klaus Dolag ◽  
Peter H. Johansson ◽  
Thorsten Naab ◽  
...  
Keyword(s):  
Elliptical Galaxies ◽  
Total Density ◽  
Dark Halo ◽  
Coma Cluster ◽  
Density Profiles ◽  
Stellar Component ◽  
Strong Lensing ◽  
The Galaxy ◽  
Good Agreement

AbstractObservational results from strong lensing and dynamical modeling indicate that the total density profiles of early-type galaxies are close to isothermal, i.e. ρtot ∝ rγ with γ ≈ −2. To understand the origin of this universal slope we study a set of simulated spheroids formed in cosmological hydrodynamical zoom-in simulations (see Oser et al. 2010 for more details). We find that the total stellar plus dark matter density profiles of all our simulations on average can be described by a power law with a slope of γ ≈ −2.1, with a tendency towards steeper slopes for more compact, lower mass ellipticals, while the total intrinsic velocity dispersion is flat for all simulations, independent of the values of γ. Our results are in good agreement with observations of Coma cluster ellipticals (Thomas et al. 2007) and results from strong lensing (Sonnenfeld et al. 2012). We find that for z ≳ 2 the majority of the stellar build-up occurs through in-situ star formation, i.e. the gas falls to the center of the galaxy and forms stars, causing the galaxy to be more compact and thus the stellar component to be more dominant. As a result, the total density slopes at z ≈ 2 are generally steeper (around γ ≈ −3). Between z = 2 and z = 0 galaxies grow mostly through dry merging, with each merging event shifting the slope more towards γ ≈ −2. We conclude from our simulations that the steepness of the slope of present day galaxies is a signature of the importance of mostly dry mergers in the formation of an elliptical, and suggest that all elliptical galaxies will with time end up in a configuration with a density slope of γ ≈ −2. For a more detailed analysis with a larger sample of simulations see Remus et al. (2013).

scholarly journals The Galaxy Merger Origin of Hot Gaseous Halos of Ellipticals

2004 ◽  
Vol 217 ◽  
pp. 412-417
Author(s):  
X. Y. Xia ◽  
Z. Y. Huo ◽  
S. J. Xue
Keyword(s):  
Central Region ◽  
Elliptical Galaxies ◽  
Emission Lines ◽  
Central Nucleus ◽  
Nuclear Region ◽  
Feedback Process ◽  
X Ray ◽  
The Galaxy ◽  
Low Metallicity ◽  
Gaseous Halo

We report on the properties of the hot gaseous halos of 10 nearby ultraluminous IRAS galaxies from Chandra observations. There exists diffuse soft X-ray emission surrounding the central nucleus within 10 kpc of the nuclear region with a temperature of about 0.7 keV and metallicity about Z ~ 1.0Z⊙. Also, emission lines from α elements and ions for are seen in all nearby ULIRGs in our sample. Outside the central region, the Chandra observations reveal a more extended hot gaseous halo with a temperature of about 0.6 keV and low metallicity (Z ~ 0.1Z⊙) for some of the ULIRGs. We discuss the nature and the implications of our results for the origin of X-ray halos in elliptical galaxies and the constraints this places on the feedback process.

scholarly journals The Radial Velocities of Planetary Nebulae in NGC 3379

1993 ◽  
Vol 155 ◽  
pp. 570-570
Author(s):  
Robin Ciardullo ◽  
George Jacoby
Keyword(s):  
Radial Velocity ◽  
Absorption Line ◽  
Planetary Nebula ◽  
Velocity Dispersion ◽  
Planetary Nebulae ◽  
Elliptical Galaxies ◽  
Emission Lines ◽  
Surface Photometry ◽  
Stellar Kinematics ◽  
Velocity Measurements

Several authors have analyzed the kinematics of elliptical galaxies using surface photometry in combination with absorption line velocity dispersion measurements. However, these analyses never explore the halos of galaxies, since the best absorption line measurements extend only ∼1 re. The only way to extend our knowledge of stellar kinematics to larger radii is to use the emission lines of planetary nebula for radial velocity measurements.

scholarly journals Evolution of the Coronae in Early-Type Galaxies

1990 ◽  
Vol 115 ◽  
pp. 240-244
Author(s):  
L.P. David ◽  
W. Forman ◽  
C. Jones
Keyword(s):  
Mass Loss ◽  
Numerical Simulations ◽  
Elliptical Galaxies ◽  
Compact Groups ◽  
Type I ◽  
Dark Halo ◽  
Early Type ◽  
X Ray ◽  
Galactic Winds ◽  
The Galaxy

AbstractWe present numerical simulations of the gaseous coronae in elliptical galaxies. These models consist of a modified King profile for the luminous portion of the galaxy and an isothermal dark halo. We include evolving stellar mass loss from planetary nebulae, and type I and II supernovae. Our models show that elliptical galaxies are likely to produce strong galactic winds at early times with x-ray luminosities of 1042 — 1044 ergs s-1 and temperatures of 10 keV. Galaxies can lose approximately 10-30% of their initial luminous mass in the wind which has an oxygen-to-iron ratio twice the solar value. Since elliptical galaxies are a principle component of rich clusters and compact groups this early wind phase affects the metallicity and temperature of the intracluster medium.

scholarly journals Physical Properties of Nearby Dwarf Elliptical Galaxies

2006 ◽  
Vol 2 (S235) ◽  
pp. 69-69
Author(s):  
M. R. Seo ◽  
H. B. Ann
Keyword(s):  
Physical Properties ◽  
Stellar Populations ◽  
Elliptical Galaxies ◽  
High Density ◽  
Emission Lines ◽  
Dwarf Elliptical Galaxies ◽  
Nuclear Regions

AbstractMost dwarf elliptical galaxies except for ‘dE, N’ galaxies which are characterized by young stellar populations in the nuclear regions are located in the high density environment. The colors and spectra of ‘dE, N’ galaxies are different from other types, in the sense that they have redder colors with little emission lines. The majority of dwarf elliptical galaxies are younger than 7 Gyr with metallicity larger than [z/H]=−0.5.

scholarly journals Resolving the Disk-Halo Degeneracy using Planetary Nebulae

2016 ◽  
Vol 12 (S323) ◽  
pp. 284-287
Author(s):  
S. Aniyan ◽  
K. C. Freeman ◽  
M. Arnaboldi ◽  
O. Gerhard ◽  
L. Coccato ◽  
...  
Keyword(s):  
Vertical Velocity ◽  
Velocity Dispersion ◽  
Mass Density ◽  
Planetary Nebulae ◽  
Disk Surface ◽  
Scale Height ◽  
Dark Halo ◽  
Surface Mass ◽  
Star Forming ◽  
Light Spectra

AbstractThe decomposition of the 21 cm rotation curve of galaxies into contribution from the disk and dark halo depends on the adopted mass to light ratio (M/L) of the disk. Given the vertical velocity dispersion (σz) of stars in the disk and its scale height (hz), the disk surface density and hence the M/L can be estimated. Earlier works have used this technique to conclude that galaxy disks are submaximal. Here we address an important conceptual problem: star-forming spirals have an old (kinematically hot) disk population and a young cold disk population. Both of these populations contribute to the integrated light spectra from which σz is measured. The measured scale height hz is for the old disk population. In the Jeans equation, σz and hz must pertain to the same population. We have developed techniques to extract the velocity dispersion of the old disk from integrated light spectra and from samples of planetary nebulae. We present the analysis of the disk kinematics of the galaxy NGC 628 using IFU data in the inner regions and planetary nebulae as tracers in the outer regions of the disk. We demonstrate that using the scale height of the old thin disk with the vertical velocity dispersion of the same population, traced by PNe, results in a maximal disk for NGC 628. Our analysis concludes that previous studies underestimate the disk surface mass density by ~ 2, sufficient to make a maximal disk for NGC 628 appear like a submaximal disk.

scholarly journals Spectrophotometry of Supernovae

1974 ◽  
Vol 3 ◽  
pp. 533-544
Author(s):  
R. P. Kirshner
Keyword(s):  
Emission Lines ◽  
Absorption Lines ◽  
Spectral Energy ◽  
Line Profiles ◽  
Energy Distributions ◽  
Maximum Light ◽  
Balmer Lines ◽  
B Lines ◽  
Infrared Triplet ◽  
The Continuum

AbstractAbsolute spectral energy distributions for supernovae of both types I and II have been obtained. These observations demonstrate three facets of supernova spectra. First, both SN I’s and SN II’s have a continuum that varies slowly and uniformly with time, and which carries the bulk of the radiated flux at early epochs. Second, some lines in both SN I’s and SN II’s have P Cygni profiles: broad emissions flanked on their violet edges by broad absorptions. Third, some lines are common to SN I’s and SN II’s and persist throughout the evolution of the spectrum. The continuum temperatures for both SN I’s and SN II’s are about 10000 K at the earliest times of observation and drop in one month’s time to about 6000 K for SN II’s and about 7000 K for SN I’s. After several months, the continuum may cease to carry the bulk of the flux, which might be in emission lines, but continues to exist, as shown by the presence of absorption lines. The P Cygni line profiles indicate expansion velocities of 15000 km s-1 in SN II’s and 20000 km s-11 in the SN I 1972e in NGC 5253. Line identifications for SN II’s include Hα, Hβ, H and K of Ca II, the Ca II infrared triplet at λ8600, the Na I D-lines, the Mg I b-lines at λ5174, and perhaps Fe II. The [O I] lines λλ6300, 6363 and [Ca II] lines λλ7291, 7323 appear after eight months. For SN I’s, the lines identified are H and K of Ca II, the infrared Ca II lines, the Na I D-lines, and the Mg I b-lines. There is some evidence that Balmer lines are present two weeks after maximum. The strong and puzzling λ4600 features drifts with time from λ4600 near maximum light to λ4750 after 400 days.

scholarly journals Limits to Ionization-parameter Mapping as a Diagnostic of Hii Region Optical Depth

2021 ◽  
Vol 923 (1) ◽  
pp. 78
Author(s):  
Amit N. Sawant ◽  
Eric W. Pellegrini ◽  
M. S. Oey ◽  
Jesús López-Hernández ◽  
Genoveva Micheva
Keyword(s):  
Optical Depth ◽  
Strong Dependence ◽  
Light Flux ◽  
Emission Lines ◽  
Ionization State ◽  
Hii Region ◽  
Parameter Mapping ◽  
Ionization Structure ◽  
The Galaxy ◽  
Ionization Parameter

Abstract We employ ionization-parameter mapping (IPM) to infer the optical depth of H ii regions in the northern half of M33. We construct [O iii]λ5007/[O ii]λ3727 and [O iii]λ5007/[S ii]λ6724 ratio maps from narrowband images continuum-subtracted in this way, from which we classify the H ii regions by optical depth to ionizing radiation, based on their ionization structure. This method works relatively well in the low-metallicity regime, 12 + log ( O / H ) ≤ 8.4 , where [O iii]λ λ4959, 5007 is strong. However, at higher metallicities, the method breaks down due to the strong dependence of the [O iii]λ λ4959, 5007 emission lines on the nebular temperature. Thus, although O++ may be present in metal-rich H ii regions, these commonly used emission lines do not serve as a useful indicator of its presence, and hence the O ionization state. In addition, IPM as a diagnostic of optical depth is limited by spatial resolution. We also report a region of highly excited [O iii] extending over an area ∼1 kpc across and [O iii]λ5007 luminosity of 4.9 ± 1.5 × 1038 erg s−1, which is several times higher than the ionizing budget of any potential sources in this portion of the galaxy. Finally, this work introduces a new method for continuum subtraction of narrowband images based on the dispersion of pixels around the mode of the diffuse-light flux distribution. In addition to M33, we demonstrate the method on C iii]λ1909 imaging of Haro 11, ESO 338-IG004, and Mrk 71.

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