scholarly journals Mass Determination in the Late-Type Spiral NGC 5457

2004 ◽  
Vol 220 ◽  
pp. 321-322
Author(s):  
Ivânio Puerari ◽  
Margarita Valdez-Gutiérrez ◽  
Margarita Rosado
Keyword(s):  
Dark Matter ◽  
Hii Regions ◽  
Matter Content ◽  
Gas Content ◽  
Dynamical Analysis ◽  
Mass Determination ◽  
Late Type ◽  
Ionized Gas ◽  
Fabry Perot ◽  
Insight Into

We have performed a kinematical and dynamical analysis of the ionized gas content of the late–type spiral NGC 5457 (M101) by means of scanning Fabry–Perot interferometry. the purpose of this study is to gain insight into the dark matter content in this galaxy. A sample of 263 HII regions were catalogued. We calculated radial velocity and velocity dispersions. From the dynamics of the ionized gas we were able to infer a mass of 9.8 × 1010 M⊙ inside a radius of 4'8 (or 10 kpc).

scholarly journals Hα Kinematics of Tidal Tails in Interacting Systems: Projection Effects and Dark Matter in TDGs

2004 ◽  
Vol 217 ◽  
pp. 526-531
Author(s):  
Philippe Amram ◽  
Fréderic Bournaud ◽  
Pierre-Alain Duc
Keyword(s):  
Dark Matter ◽  
Dwarf Galaxies ◽  
Matter Content ◽  
Field Of View ◽  
Large Field ◽  
Ionized Gas ◽  
Tidal Tail ◽  
Fabry Perot ◽  
Interacting Systems ◽  
Tidal Tails

Several interacting systems exhibit at the tip of their long tidal tails massive condensations of atomic hydrogen, which may be the progenitors of Tidal Dwarf Galaxies. Because, quite often, these tails are observed edge-on, projection effects have been claimed to account for the large HI column densities measured there. Here we show that determining the velocity field all along the tidal features, one may disentangle projection effects along the line of view from real bound structures. Due to its large field of view, high spectral and 2D spatial resolutions, Fabry-Perot observations of the ionized gas are well adapted to detect a kinematical signature of either streaming motions along a bent tidal tail or of in-falling/rotating material associated with a forming TDG. Spectroscopic observations also allow to measure the dynamical masses of the TDGs that are already relaxed and check their dark matter content.

scholarly journals Statistical Properties of Highly Luminous HII Regions in the Interacting Zone of the Antennae Galaxies, and Comparison with the Molecular Cloud Component

2012 ◽  
Vol 8 (S292) ◽  
pp. 156-156
Author(s):  
Joan Font ◽  
John E. Beckman ◽  
Javier Zaragoza ◽  
Santi Erroz-Ferrer ◽  
Begoña Garcia-Lorenzo
Keyword(s):  
Line Emission ◽  
Hii Regions ◽  
Molecular Data ◽  
Data Cube ◽  
Ionized Gas ◽  
La Palma ◽  
Fabry Perot ◽  
Different Populations ◽  
The Masses ◽  
Two Populations

AbstractWe have used the package CLOUDPROPS (Rosolowsky & Leroy 2008) in order to identify clouds, which are contained in data cubes of molecular/Hα line emission, and extract their properties. The molecular data cube is taken from the ALMA public archive and the ionized hydrogen data cube was obtained with the Fabry-Perot interferometer, GHαFaS, on the 4.2 m WHT in La Palma. In our study of the overlap region of the Antennae galaxies we have identified two populations of molecular clouds, above and below log M/M⊙ = 6.75 (in agreement with Wei et al. 2012 who find the break in mass at log M/M⊙ = 6.5) and two different populations of ionized gas clouds; the break in the luminosity occurs near log L = 37.6 (see Fig. 1). We have measured the masses, velocity dispersions and luminosities of the clouds, and derived relation between them for each population. Population II clouds (both molecular and ionized) tend to be located in the most luminous regions, while population I clouds can be found in the outskirts. This work will be published in Font et al. (2013).

scholarly journals Kinematic Study of the Northwestern Part of the Bar of the LMC

1999 ◽  
Vol 190 ◽  
pp. 152-153
Author(s):  
P. Ambrocio-Cruz ◽  
A. Laval ◽  
M. Marcelin ◽  
P. Amram
Keyword(s):  
Hii Regions ◽  
Magellanic Clouds ◽  
Northwestern Part ◽  
Ionized Gas ◽  
European Southern Observatory ◽  
Kinematic Study ◽  
Fabry Perot

We have been conducting a Fabry-Perot kinematic survey of ionized gas in the Magellanic Clouds in the Hα and [O III]λ5007 lines, using a 36-cm telescope at the European Southern Observatory. This poster presents our kinematic study of HII regions located at the northwestern parts of the LMC bar.

scholarly journals The Large Range of Dark Matter content in Dwarf Galaxies and its Implications

1996 ◽  
Vol 171 ◽  
pp. 435-435
Author(s):  
S.A. Pustilnik ◽  
V.A. Lipovetsky ◽  
J.-M. Martin ◽  
T.X. Thuan
Keyword(s):  
Dark Matter ◽  
Galaxy Formation ◽  
Large Range ◽  
Dwarf Galaxy ◽  
Rotational Velocity ◽  
Matter Content ◽  
Optical Observations ◽  
Strong Interactions ◽  
Formation Mechanisms ◽  
Mass Ratio

We present the analysis of a new set of radio and optical observations of a large sample of Byurakan Blue Compact Galaxies. HI spectra were obtained with the Nançay 300-m and Green Bank 43-m radio telescopes. CCD-images were taken with the KPNO 0.9-m and Whipple Observatory 1.2-m telescopes. Dark Matter (DM) to luminous mass ratios in these BCGs were found to vary from about less than 0.5 up to 14. Recent data taken from the literature indicate this same range. This result has important consequences on models of dwarf galaxy formation, indicating possibly different formation mechanisms. The standard CDM model of dwarfs formation requires large DM halos. However the formation of dwarfs as tidal debris resulting from strong interactions of massive spirals leads naturally to dwarfs with low content of DM. On Fig.1 we show DM to luminous mass ratio versus rotational velocity for our BCGs and some other galaxies.

scholarly journals Dark matter-deficient dwarf galaxies form via tidal stripping of dark matter in interactions with massive companions

2021 ◽  
Vol 502 (2) ◽  
pp. 1785-1796
Author(s):  
R A Jackson ◽  
S Kaviraj ◽  
G Martin ◽  
J E G Devriendt ◽  
A Slyz ◽  
...  
Keyword(s):  
Dark Matter ◽  
Galaxy Evolution ◽  
Cold Dark Matter ◽  
Dwarf Galaxies ◽  
Stellar Mass ◽  
Matter Content ◽  
Mass Relation ◽  
Potential Wells ◽  
Tidal Interactions ◽  
New Interactions

ABSTRACT In the standard ΛCDM (Lambda cold dark matter) paradigm, dwarf galaxies are expected to be dark matter-rich, as baryonic feedback is thought to quickly drive gas out of their shallow potential wells and quench star formation at early epochs. Recent observations of local dwarfs with extremely low dark matter content appear to contradict this picture, potentially bringing the validity of the standard model into question. We use NewHorizon, a high-resolution cosmological simulation, to demonstrate that sustained stripping of dark matter, in tidal interactions between a massive galaxy and a dwarf satellite, naturally produces dwarfs that are dark matter-deficient, even though their initial dark matter fractions are normal. The process of dark matter stripping is responsible for the large scatter in the halo-to-stellar mass relation in the dwarf regime. The degree of stripping is driven by the closeness of the orbit of the dwarf around its massive companion and, in extreme cases, produces dwarfs with halo-to-stellar mass ratios as low as unity, consistent with the findings of recent observational studies. ∼30 per cent of dwarfs show some deviation from normal dark matter fractions due to dark matter stripping, with 10 per cent showing high levels of dark matter deficiency (Mhalo/M⋆ < 10). Given their close orbits, a significant fraction of dark matter-deficient dwarfs merge with their massive companions (e.g. ∼70 per cent merge over time-scales of ∼3.5 Gyr), with the dark matter-deficient population being constantly replenished by new interactions between dwarfs and massive companions. The creation of these galaxies is therefore a natural by-product of galaxy evolution and their existence is not in tension with the standard paradigm.

scholarly journals Does the Cosmological Expansion Change Local Dynamics?

Symmetry ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1417
Author(s):  
Marcelo Schiffer
Keyword(s):  
Dark Matter ◽  
Modified Gravity ◽  
Hubble Constant ◽  
Matter Content ◽  
Matter Distribution ◽  
Present Value ◽  
Field Equations ◽  
Local Dynamics ◽  
Cosmological Expansion ◽  
Modified Gravity Theories

It is a well-known fact that the Newtonian description of dynamics within Galaxies for its known matter content is in disagreement with the observations as the acceleration approaches a0≈1.2×10−10 m/s2 (slighter larger for clusters). Both the Dark Matter scenario and Modified Gravity Theories (MGT) fail to explain the existence of such an acceleration scale. Motivated by the closeness of the acceleration scale and the Hubble constant cH0≈10−9 h m/s2, we are led to analyze whether this coincidence might have a Cosmological origin for scalar-tensor and spinor-tensor theories by performing detailed calculations for perturbations that represent the local matter distribution on the top of the cosmological background. Then, we solve the field equations for these perturbations in a power series in the present value of the Hubble constant. As we shall see, for both theories, the power expansion contains only even powers in the Hubble constant, a fact that renders the cosmological expansion irrelevant for the local dynamics.

scholarly journals Hybrid 3-D Spectrophotometry of Emission-Line Nebulae at Ohio State

1995 ◽  
Vol 149 ◽  
pp. 167-171
Author(s):  
Richard W. Pogge ◽  
Nancy Joanne Lame
Keyword(s):  
Emission Line ◽  
Planetary Nebulae ◽  
Hii Regions ◽  
Ohio State University ◽  
State University ◽  
Considerable Success ◽  
Fabry Perot ◽  
The Ohio State University ◽  
Scientific Results ◽  
Narrowband Filter

AbstractA program of 3-D spectrophotometry of emission nebulae being carried out at the Ohio State University will be described. We have had considerable success combining Fabry-Perot imaging, long-slit spectroscopy, and narrowband filter imaging into a hybrid 3-D spectroscopic approach that we have used to obtain detailed spectrophotometric maps of the density, temperature, extinction, and ionization in HII regions and Planetary Nebulae. The centerpiece instrument of this effort, the OSU Imaging Fabry-Perot Spectrograph (IFPS), will be described, and scientific results illustrative of our work will be presented.

scholarly journals POTENSI ENERGI LISTRIK YANG DIHASILKAN DARI EMISI GAS METANA DI TPA SUWUNG PROVINSI BALI

2017 ◽  
Vol 11 (2) ◽  
pp. 132 ◽  
Author(s):  
Putu Dian Paramitha Dewi ◽  
I Wayan Suarna ◽  
I Wayan Budiarsa Suyasa
Keyword(s):  
Dry Matter ◽  
Organic Waste ◽  
Electrical Power ◽  
Value Added ◽  
Electrical Energy ◽  
Methane Emissions ◽  
Matter Content ◽  
Gas Content ◽  
Dry Matter Content ◽  
Methane Gas

Waste is one source of greenhouse gas emissions (GHG) that has methane gas form which caused an early multi-dimensional, massive and complex problems. The rapid increase of garbage volume entering landfill, annually result a high garbage dumps in the Suwung Landfill area. It should have been considered a handing solution for example by converting the methane gas content in the waste into a useful value added product. The objective of this research is determining the amount of electrical energy that can be produced through methane gas emission at Suwung Landfill. The characteristic and composition of waste could give effect to the formation of methane emissions. The research on the composition and characteristic of waste were done by sorting 1 m3 of garbage sample from new garbage entering landfill. Garbage is divided based on the source of DLHK waste, market waste, and private waste. The volume of waste that went to Suwung Landfill in 2016 calculated 1.296.438 m3 which was dominated by organic waste (78,1%). The density of the waste that went into Suwung Landfill, based on the research's results, amounted to 135,09 kg / m3, there fore could be assumed that the weight of waste that went to Suwung Landfill in 2016 was 175.135,81 tons. Based on these data, the number of 136.785,13 tons of waste, which was organic waste, could increase the concentration of greenhouse gases in the atmosphere if this situation does not manage properly. Gravimeter method is using for measures the dry matter content value of waste. From the measurement, the results obtained the waste components that have the highest dry matter content is from rubber and leather garbage (76,52%) while the lowest dry matter is food waste (19,13%). By using calculations based on IPCC 2006, it was found that the amount of methane emissions could be generated by the waste at the Suwung Landfill in 2016, amounted to 3.535,06 tons. Based on the energy equivalence table, the electrical power that is generated from the potential methane emissions at the Suwung Landfill is 6,66 MW. Keywords: waste composition, waste characteristics, methane emissions, ipcc2006, electrical power.

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