scholarly journals Understanding the Spatial Distributions of the Ionic/Atomic/Molecular/Dust Components in PNe

Galaxies ◽  
2019 ◽  
Vol 7 (1) ◽  
pp. 10
Author(s):  
Toshiya Ueta ◽  
Masaaki Otsuka ◽  
Keyword(s):  
Central Star ◽  
H Ii Regions ◽  
Data Sets ◽  
Ionized Gas ◽  
X Ray ◽  
Neutral Gas ◽  
Photoionization Model ◽  
The Universe ◽  
Circumstellar Environment ◽  
Do So

Planetary nebulae (PNe) are often recognized as the hallmark of compact H ii regions in the Universe. However, there exist dusty neutral regions extending beyond the central ionized region. We demonstrate that such dusty neutral regions (also known as photo-dissociation regions, or PDRs) around the central ionized region are significant parts of PNe in terms of energetics and mass. We do so by using our latest dusty photoionization model of NGC 6781 (of 13 parameters) based on one of the most comprehensive panchromatic data sets ever assembled for a PN encompassing from X-ray to radio (of 136 constraining data, including 19 flux densities, 78 line fluxes, and 37 band fluxes). We find that NGC 6781, evolved out of a 2.25–3.0 M ⊙ star located 460 pc away from us, possesses a massive concentration of neutral gas (molecular hydrogen) just beyond the central ionized region and that the amount of ionized gas in NGC 6781 is only 22% of the observationally accounted amount of matter in the circumstellar environment, which itself does not even account for the amount of mass presumably ejected by the central star during the last thermal pulse event according to the latest evolutionary models. This means that the observed nebula in this PN is only the tip of the iceberg.

scholarly journals Imaging and spectroscopy of the LMC He II nebula N 44C and its ionizing star

1999 ◽  
Vol 193 ◽  
pp. 480-481
Author(s):  
Vanessa C. Galarza ◽  
Donald R. Garnett ◽  
You-Hua Chu
Keyword(s):  
Large Magellanic Cloud ◽  
Convincing Evidence ◽  
H Ii Regions ◽  
Uv Spectrum ◽  
Ionized Gas ◽  
X Ray ◽  
H Ii Region ◽  
Recombination Emission ◽  
Imaging And Spectroscopy ◽  
Echelle Spectroscopy

We present results from new HST imaging and spectroscopy of the peculiar Large Magellanic Cloud H II region N 44C and its ionizing star. While this nebula exhibits strong He II recombination emission, the source of the He+ ionizing photons has not been found. The UV spectrum of the ionizing star suggests an approximate spectral class of 07–08; the UV Si IV, He II, and N IV features do not show P-Cygni profiles, indicating that the ionizing star is not a supergiant. No companion star has yet been detected. Ground-based and HST optical spectroscopy of the ionized gas shows that the nebular abundances of C, N, O and He are not anomalous relative to other LMC H II regions, suggesting that no previous WR/SN companion has disappeared. Echelle spectroscopy has also ruled out the presence of high velocity shocked gas. Deep ROSAT imaging shows no X-ray point source in this location. The “fossil X-ray binary” hypothesis of Pakull & Motch (1989) remains the best explanation for the ionization of this nebula; however, convincing evidence for this hypothesis remains elusive.

scholarly journals X-ray Absorption by Ionized Gas in EXOSAT Spectra from the Binary System 4U1700-37/HD153919

1990 ◽  
Vol 115 ◽  
pp. 201-204
Author(s):  
F. Haberl ◽  
T.R. Kallman ◽  
N.E. White
Keyword(s):  
Binary System ◽  
Column Density ◽  
Asymmetric Distribution ◽  
Photoelectric Absorption ◽  
Ionized Gas ◽  
X Ray ◽  
Neutral Gas ◽  
Orbital Phase ◽  
Energy Excess ◽  
X Ray Absorption

AbstractWe observed the 3.41 day eclipsing, massive binary system 4U1700-37/HD153919 with EXOSAT for more than one complete binary period to investigate the spectral variations during the orbital cycle of the neutron star. The spectra show a low energy excess below ~ 3 keV when modelled by a powerlaw spectrum attenuated by photoelectric absorption by neutral gas, suggesting partial ionization of the absorbing gas. The column density derived from spectra above 3 keV shows an asymmetric distribution around orbital phase 0.5 with higher absorption before eclipse ingress. We approximated the with distance to the X-ray source gradually decreasing ionization of the wind by two zones. One of higher ionized wind around the X-ray source for which X-ray opacities of a gas in photoionization equilibrium were used and a zone of neutral gas further away from the X-ray source. We find that our spectra below 3 keV can be well fitted by a powerlaw which is attenuated first by photoelectric absorption of ionized gas and then by neutral gas. Since around phase 0.5 the major contribution of the wind column density along the line of sight arises from the ionized part we found that the total column density can be higher up to a factor of about 4 taking ionization into account.

scholarly journals CONSTRAINTS ON THE COSMOLOGICAL DENSITY PARAMETERS AND COSMIC TOPOLOGY

2007 ◽  
Vol 16 (02n03) ◽  
pp. 207-217 ◽  
Author(s):  
M. J. REBOUÇAS
Keyword(s):  
Mass Fraction ◽  
Type Ia Supernovae ◽  
Data Sets ◽  
X Ray ◽  
Set Constraints ◽  
Type Ia ◽  
Ia Supernovae ◽  
The Universe ◽  
Nontrivial Topology ◽  
Spatial Section

A nontrivial topology of the spatial section of the universe is an observable which can be probed for all homogeneous and isotropic universes, without any assumption on the cosmological density parameters. We discuss how one can use this observable to set constraints on the density parameters of the universe by using a specific spatial topology along with type Ia supernovae and X-ray gas mass fraction data sets.

scholarly journals Multiphase outflows in post-starburst E+A galaxies - II. A direct connection between the neutral and ionized outflow phases

2020 ◽  
Vol 494 (4) ◽  
pp. 5396-5420 ◽  
Author(s):  
Dalya Baron ◽  
Hagai Netzer ◽  
Ric I Davies ◽  
J Xavier Prochaska
Keyword(s):  
Molecular Gas ◽  
Mass Ratio ◽  
Ionized Gas ◽  
Gas Phases ◽  
Spatially Resolved ◽  
Neutral Gas ◽  
Major Merger ◽  
A Minor ◽  
First Time ◽  
Photoionization Model

ABSTRACT Post-starburst E+A galaxies are systems that hosted a powerful starburst that was quenched abruptly. Simulations suggest that these systems provide the missing link between major merger ULIRGs and red and dead ellipticals, where AGN feedback is responsible for the expulsion or destruction of the molecular gas. However, many details remain unresolved and little is known about AGN-driven winds in this short-lived phase. We present spatially resolved IFU spectroscopy with MUSE/VLT of SDSS J124754.95-033738.6, a post-starburst E+A galaxy with a recent starburst that started 70 Myr ago and ended 30 Myr ago, with a peak SFR of $\sim 150\, \mathrm{M_{\odot }\,yr^{ -1}}$. We detect disturbed gas throughout the entire field of view, suggesting triggering by a minor merger. We detect fast-moving multiphased gas clouds, embedded in a double-cone face-on outflow, which are traced by ionized emission lines and neutral NaID emission and absorption lines. We find remarkable similarities between the kinematics, spatial extents, and line luminosities of the ionized and neutral gas phases, and propose a model in which they are part of the same outflowing clouds, which are exposed to both stellar and AGN radiation. Our photoionization model provides consistent ionized line ratios, NaID absorption optical depths and EWs, and dust reddening. Using the model, we estimate, for the first time, the neutral-to-ionized gas mass ratio (about 20), the sodium neutral fraction, and the size of the outflowing clouds. This is one of the best ever observed direct connections between the neutral and ionized outflow phases in AGN.

scholarly journals The Distribution Of Dark Mass In Galaxies

1996 ◽  
Vol 173 ◽  
pp. 165-174 ◽  
Author(s):  
Penny D. Sackett
Keyword(s):  
Dark Matter ◽  
Temperature Profile ◽  
Gravitational Lensing ◽  
Milky Way ◽  
Stellar Kinematics ◽  
X Ray ◽  
Neutral Gas ◽  
Complementary Techniques ◽  
Gas Layer ◽  
The Universe

Gravitational lensing is one of a number of methods used to probe the distribution of dark mass in the Universe. On galactic scales, complementary techniques include the use of stellar kinematics, the kinematics and morphology of the neutral gas layer, kinematics of satellites, and the morphology and temperature profile of X-ray halos. These methods are compared, with emphasis on their relative strengths and weaknesses in constraining the distribution and extent of dark matter in the Milky Way and other galaxies. It is concluded that (1) the extent of dark halos remains ill-constrained, (2) halos need not be isothermal, and (3) the dark mass is probably quite flattened.

scholarly journals The multiphase gas structure and kinematics in the circumnuclear region of NGC 5728

2019 ◽  
Vol 490 (4) ◽  
pp. 5860-5887 ◽  
Author(s):  
T Taro Shimizu ◽  
R I Davies ◽  
D Lutz ◽  
L Burtscher ◽  
M Lin ◽  
...  
Keyword(s):  
Spatial Scales ◽  
Molecular Gas ◽  
H Ii Regions ◽  
Data Sets ◽  
Rotating Disc ◽  
Ionized Gas ◽  
Star Forming ◽  
Gas Removal ◽  
Stellar Velocity ◽  
Outflow Rate

ABSTRACT We report on our combined analysis of HST, VLT/MUSE, VLT/SINFONI, and ALMA observations of the local Seyfert 2 galaxy, NGC 5728 to investigate in detail the feeding and feedback of the active galactic nucleus (AGN). The data sets simultaneously probe the morphology, excitation, and kinematics of the stars, ionized gas, and molecular gas over a large range of spatial scales (10 pc to 10 kpc). NGC 5728 contains a large stellar bar that is driving gas along prominent dust lanes to the inner 1 kpc where the gas settles into a circumnuclear ring. The ring is strongly star forming and contains a substantial population of young stars as indicated by the lowered stellar velocity dispersion and gas excitation consistent with H ii regions. We model the kinematics of the ring using the velocity field of the CO (2–1) emission and stars and find it is consistent with a rotating disc. The outer regions of the disc, where the dust lanes meet the ring, show signatures of inflow at a rate of 1 M$\odot$ yr−1. Inside the ring, we observe three molecular gas components corresponding to the circular rotation of the outer ring, a warped disc, and the nuclear stellar bar. The AGN is driving an ionized gas outflow that reaches a radius of 250 pc with a mass outflow rate of 0.08 M$\odot$ yr−1 consistent with its luminosity and scaling relations from previous studies. While we observe distinct holes in CO emission which could be signs of molecular gas removal, we find that largely the AGN is not disrupting the structure of the circumnuclear region.

scholarly journals The Mixing of Neutral Gas and Dust with the Ionized Gas of H II Regions

1973 ◽  
Vol 52 ◽  
pp. 477-481
Author(s):  
M. C. Lortet-Zuckermann
Keyword(s):  
H Ii Regions ◽  
Ionized Gas ◽  
Neutral Gas ◽  
Established Fact

Two arguments are presented in support of the now well-established fact of the tight mixing of neutral gas and dust with the ionized gas of H II regions.

The Nature of Time

2018 ◽  
Author(s):  
Donald C. Williams
Keyword(s):  
Large Scale ◽  
Time Travel ◽  
Dimensional Manifold ◽  
Nature Of Time ◽  
Manifold Theory ◽  
The Universe ◽  
Theoretical Cost ◽  
Do So

This chapter provides a fuller treatment of the pure manifold theory with an expanded discussion of competing doctrines. It is argued that competing doctrines fail to account for the extensive and/or transitory aspect(s) of time, or they do so at great theoretical cost. The pure manifold theory accounts for the extensive aspect of time because it admits a four-dimensional manifold and it accounts for the transitory aspect of time because it hypothesizes that the increase of entropy is the thing that is ‘felt’ in veridical cases of felt passage. A four-dimensionalist theory of time travel is outlined, along with a sketch of large-scale cosmological traits of the universe.

Ionized gas kinematics and luminosity profiles of Low-z Lyman Alpha Blobs

2019 ◽  
Vol 15 (S359) ◽  
pp. 413-414
Author(s):  
María P. Agüero ◽  
Rubén Díaz ◽  
Mischa Schirmer
Keyword(s):  
Emission Line ◽  
Galactic Nuclei ◽  
Host Galaxies ◽  
Ionized Gas ◽  
Lyman Alpha ◽  
Gas Kinematics ◽  
The Universe ◽  
Very High ◽  
The Continuum

AbstractThis work is focused on the characterization of the Seyfert-2 galaxies hosting very large, ultra-luminous narrow-line regions (NLRs) at redshifts z = 0.2−0.34. With a space density of 4.4 Gcp−3 at z ∼ 0.3, these “Low Redshift Lyman-α Blob” (LAB) host galaxies are amongst the rarest objects in the universe, and represent an exceptional and short-lived phenomenon in the life cycle of active galactic nuclei (AGNs). We present the study of GMOS spectra for 13 LAB galaxies covering the rest frame spectral range 3700–6700 Å. Predominantly, the [OIII]λ5007 emission line radial distribution is as widespread as that of the continuum one. The emission line profiles exhibit FWHM between 300–700 Km s−1. In 7 of 13 cases a broad kinematical component is detected with FWHM within the range 600–1100 Km s−1. The exceptionally high [OIII]λ5007 luminosity is responsible for very high equivalent width reaching 1500 Å at the nucleus.

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