scholarly journals LINER-like emission in red galaxies: evolutionary phase or recurring phenomenon?

2007 ◽  
Vol 3 (S245) ◽  
pp. 181-184
Author(s):  
Genevieve J. Graves
Keyword(s):  
Stellar Population ◽  
Velocity Dispersion ◽  
Large Fraction ◽  
Optical Emission ◽  
Ionized Gas ◽  
Satellite Galaxy ◽  
The Galaxy ◽  
Evolutionary Phase ◽  
Interstellar Material ◽  
Red Galaxies

AbstractWe present recent results showing that a large fraction of red sequence galaxies contain ionized gas with LINER-like optical emission line ratios. This emission is more frequently found in galaxies with lower central velocity dispersion (σ) and these galaxies typically have younger mean ages than galaxies at the same σ which do not host emission. We suggest that the presence of LINER-like emission may be determined by the quantity of interstellar material in these galaxies and may be associated with the recent accretion of a gas-rich satellite galaxy or alternatively with stellar mass loss that declines as the galaxy stellar population ages.

scholarly journals Optical spectral characterization of the TeV extreme blazar 2WHSP J073326.7+515354

2020 ◽  
Vol 494 (4) ◽  
pp. 6036-6042
Author(s):  
J Becerra González ◽  
J A Acosta-Pulido ◽  
R Clavero
Keyword(s):  
Stellar Population ◽  
Gamma Ray ◽  
Velocity Dispersion ◽  
Optical Emission ◽  
Absolute Magnitude ◽  
Brightness Distribution ◽  
Host Galaxy ◽  
Mass Relation ◽  
Relativistic Jets

ABSTRACT The emission from the relativistic jets in blazars usually outshines their host galaxies, challenging the determination of their distances and the characterization of the stellar population. The situation becomes more favourable in the case of the extreme blazars (EHBLs), for which the bulk of the emission of the relativistic jets is emitted at higher energies, unveiling the optical emission from the host galaxy. The distance determination is fundamental for the study of the intrinsic characteristics of the blazars, especially to estimate the intrinsic gamma-ray spectra distorted due to the interaction with the extragalactic background light. In this work, we report on the properties of 2WHSP J073326.7+515354 host galaxy in the optical band, which is one of the few EHBLs detected at TeV energies. We present the first measurement of the distance of the source, z = 0.065 04 ± 0.000 02 (velocity dispersion $\sigma =237 \pm 9\, \mathrm{km s^{-1}}$). We also perform a detailed study of the stellar population of its host galaxy. We find that the mass-weighted mean stellar age is $11.72\pm 0.06\, \mathrm{Gyr}$ and the mean metallicity [M/H] = 0.159 ± 0.016. In addition, a morphological study of the host galaxy is also carried out. The surface brightness distribution is modelled by a composition of a dominant classical bulge (Re = 3.77 ± 1 arcsec or equivalently 4.74 kpc) plus an unresolved source which corresponds to the active nucleus. The black hole mass is estimated using both the mass relation with the velocity dispersion and the absolute magnitude from the bulge yielding comparable results: $(4.8\pm 0.9)\times 10^8$ and $(3.7\pm 1.0)\times 10^8\, \mathrm{ M}_{\odot }$, respectively.

scholarly journals A Multiwavelength Optical Emission Line Survey of Warm Ionized Gas in the Galaxy

2006 ◽  
Vol 652 (1) ◽  
pp. 401-425 ◽  
Author(s):  
G. J. Madsen ◽  
R. J. Reynolds ◽  
L. M. Haffner
Keyword(s):  
Emission Line ◽  
Optical Emission ◽  
Ionized Gas ◽  
The Galaxy ◽  
Line Survey

scholarly journals Ionized Disk/Halo Gas: Insight from Optical Emission Lines and Pulsar Dispersion Measures

1991 ◽  
Vol 144 ◽  
pp. 67-76
Author(s):  
R. J. Reynolds
Keyword(s):  
Galactic Disk ◽  
Large Fraction ◽  
Optical Emission ◽  
Interstellar Matter ◽  
Power Budget ◽  
Ionized Gas ◽  
Lyman Continuum ◽  
Dominant State ◽  
Dispersion Measures ◽  
Halo Gas

Warm (≈ 104 K), diffuse H+ is a significant component of the interstellar medium within the Galactic disk and lower halo. This gas accounts for about one quarter of the interstellar atomic hydrogen, consumes a large fraction of the interstellar power budget, and appears to be the dominant state of interstellar matter 1 kpc above the midplane. The origin of this ionized gas is not yet established; however, of the known sources of ionization only 0 stars and perhaps supernovae produce enough power to balance the “cooling” rate of the gas. If 0 stars are the source of the ionization, then the interstellar HI, including the extended “Lockman layer”, must have a morphology that allows about 14% of the Lyman continuum photons emitted by the stars to travel hundreds of parsecs within the Galactic disk and up into the lower halo.

scholarly journals KiDS+GAMA: Intrinsic alignment model constraints for current and future weak lensing cosmology

2019 ◽  
Vol 624 ◽  
pp. A30 ◽  
Author(s):  
Harry Johnston ◽  
Christos Georgiou ◽  
Benjamin Joachimi ◽  
Henk Hoekstra ◽  
Nora Elisa Chisari ◽  
...  
Keyword(s):  
Sloan Digital Sky Survey ◽  
Weak Lensing ◽  
Satellite Galaxy ◽  
Sky Survey ◽  
The Galaxy ◽  
Resolution Imaging ◽  
Cosmic Shear ◽  
Linear Alignment ◽  
Red Galaxies ◽  
Blue Galaxy

We directly constrain the non-linear alignment (NLA) model of intrinsic galaxy alignments, analysing the most representative and complete flux-limited sample of spectroscopic galaxies available for cosmic shear surveys. We measure the projected galaxy position-intrinsic shear correlations and the projected galaxy clustering signal using high-resolution imaging from the Kilo Degree Survey (KiDS) overlapping with the GAMA spectroscopic survey, and data from the Sloan Digital Sky Survey. Separating samples by colour, we make no significant detection of blue galaxy alignments, constraining the blue galaxy NLA amplitude AIAB = 0.21−0.36+0.37 to be consistent with zero. We make robust detections (∼9σ) for red galaxies, with AIAR = 3.18−0.46+0.47, corresponding to a net radial alignment with the galaxy density field, and we find no evidence for any scaling of alignments with galaxy luminosity. We provide informative priors for current and future weak lensing surveys, an improvement over de facto wide priors that allow for unrealistic levels of intrinsic alignment contamination. For a colour-split cosmic shear analysis of the final KiDS survey area, we forecast that our priors will improve the constraining power on S8 and the dark energy equation of state w0, by up to 62% and 51%, respectively. Our results indicate, however, that the modelling of red/blue-split galaxy alignments may be insufficient to describe samples with variable central/satellite galaxy fractions.

Velocity dispersion and the stellar population in the central 1.2 parsecs of the Galaxy

1990 ◽  
Vol 359 ◽  
pp. 112 ◽  
Author(s):  
K. Sellgren ◽  
M. T. McGinn ◽  
E. E. Becklin ◽  
D. N. Hall
Keyword(s):  
Stellar Population ◽  
Velocity Dispersion ◽  
The Galaxy

scholarly journals A Survey of the Interstellar Medium in Elliptical Galaxies: the Ionized Gas

1996 ◽  
Vol 171 ◽  
pp. 348-348
Author(s):  
N. Caon ◽  
F. Macchetto ◽  
M. Pastoriza
Keyword(s):  
Large Fraction ◽  
Broad Band ◽  
Elliptical Galaxies ◽  
Ionized Gas ◽  
X Ray ◽  
Lenticular Galaxies ◽  
The Galaxy ◽  
Extensive Program ◽  
Galaxy Center ◽  
S0 Galaxies

We have carried out an extensive program of observations of the ionized gas in 74 luminous elliptical and lenticular galaxies, selected to include a variety of properties in radio and X-ray emission, and in kinematical behavior. For each galaxy we have obtained broad-band R and V images and narrow-band images, centered at the Hα and [NII] emission lines, to derive the luminosity and distribution of the ionized gas. We found that a large fraction (≃ 70%) of E and S0 galaxies in our sample contain ionized gas. The gas morphology and size varies from small disks (mean diameter 1 – 4 kpc) to large filamentary structures (extending up to 10 kpc from the galaxy center). Comparison with previous measurements shows reasonable agreement for a few galaxies, but considerable scatter for a large fraction, possibly due to differences in the limiting flux thresholds.

scholarly journals NGC 474 as viewed with KCWI: diagnosing a shell galaxy

2020 ◽  
Vol 497 (1) ◽  
pp. 626-631 ◽  
Author(s):  
Adebusola B Alabi ◽  
Anna Ferré-Mateu ◽  
Duncan A Forbes ◽  
Aaron J Romanowsky ◽  
Jean P Brodie
Keyword(s):  
Galaxy Formation ◽  
Surface Brightness ◽  
Stellar Population ◽  
Shell System ◽  
Satellite Galaxy ◽  
Galaxy Formation And Evolution ◽  
Low Surface Brightness ◽  
The Galaxy ◽  
Formation And Evolution ◽  
Star Formation Histories

ABSTRACT We present new spectra obtained using Keck/KCWI and perform kinematics and stellar population analyses of the shell galaxy NGC 474, from both the galaxy centre and a region from the outer shell. We show that both regions have similarly extended star formation histories although with different stellar population properties. The central region of NGC 474 is dominated by intermediate-aged stars (8.3 ± 0.3 Gyr) with subsolar metallicity ([Z/H] = −0.24 ± 0.07 dex) while the observed shell region, which hosts a substantial population of younger stars, has a mean luminosity-weighted age of 4.0 ± 0.5 Gyr with solar metallicities ([Z/H] = −0.03 ± 0.09 dex). Our results are consistent with a scenario in which NGC 474 experienced a major to intermediate merger with a log$(M_*/\rm M_\odot) \sim 10$ mass satellite galaxy at least ${\sim}2$ Gyr ago which produced its shell system. This work shows that the direct spectroscopic study of low-surface brightness stellar features, such as shells, is now feasible and opens up a new window to understanding galaxy formation and evolution.

scholarly journals Spatially resolved properties of supernova host galaxies in SDSS-IV MaNGA

2022 ◽  
Vol 21 (12) ◽  
pp. 306
Author(s):  
Hong-Xuan Zhang ◽  
Yan-Mei Chen ◽  
Yong Shi ◽  
Min Bao ◽  
Xiao-Ling Yu
Keyword(s):  
Stellar Population ◽  
Velocity Dispersion ◽  
Control Sample ◽  
Stellar Mass ◽  
Host Galaxies ◽  
Star Forming ◽  
Spatially Resolved ◽  
The Galaxy ◽  
Type Ia ◽  
Natural Result

Abstract We crossmatch galaxies from Mapping Nearby Galaxies at Apache Point Observatory with the Open Supernova Catalog, obtaining a total of 132 SNe within MaNGA bundle. These 132 SNe can be classified into 67 Type Ia and 65 Type CC. We study the global and local properties of supernova host galaxies statistically. Type Ia SNe are distributed in both star-forming galaxies and quiescent galaxies, while Type CC SNe are all distributed along the star-forming main sequence. As the stellar mass increases, the Type Ia/CC number ratio increases. We find: (1) there is no obvious difference in the interaction possibilities and environments between Type Ia SN hosts and a control sample of galaxies with similar stellar mass and SFR distributions, except that Type Ia SNe tend to appear in galaxies which are more bulge-dominated than their controls. For Type CC SNe, there is no difference between their hosts and the control galaxies in galaxy morphology, interaction possibilities as well as environments; (2) compared to galaxy centers, the SN locations have smaller velocity dispersion, lower metallicity, and younger stellar population. This is a natural result of radius gradients for all these parameters. The SN location and its symmetrical position relative to the galaxy center, as well as regions with similar effective radii have very similar [Mg/Fe], gas-phase metallicity, gas velocity dispersion and stellar population age.

Unveiling the nuclear region of NGC 6868: Mapping the stellar population and ionized gas

2019 ◽  
Vol 15 (S359) ◽  
pp. 418-420
Author(s):  
João P. V. Benedetti ◽  
Rogério Riffel ◽  
Tiago V. Ricci ◽  
João E. Steiner ◽  
Rogemar A. Riffel ◽  
...  
Keyword(s):  
Stellar Population ◽  
Star Formation History ◽  
Nuclear Region ◽  
Stellar Kinematics ◽  
Ionized Gas ◽  
Formation History ◽  
The Galaxy ◽  
History Of ◽  
Field Unit ◽  
New Generation

AbstractWe mapped the stellar population and emission gas properties in the nuclear region of NGC 6868 using datacubes extracted with Gemini Multi-Object Spectrograph (GMOS) in the Integral Field Unit (IFU) mode. To obtain the star-formation history of this galaxy we used the starlight code together with the new generation of MILES simple stellar population models. The stellar population dominating (95% in light fraction) the central region of NGC 6868 is old and metal rich (~10 Gyr, 2.2 Z⊙). We also derived the kinematics and emission line fluxes of ionized gas with the IFSCube package. A rotation disk is clearly detected in the nuclear region of the galaxy and no broad components were detected. Also, there is a region where the emission lines disappear almost completely, probably due to diffuse ionized gas component. Channel maps, diagnostic diagrams and stellar kinematics are still under analysis.

Statistical criteria of stellar population types

1966 ◽  
Vol 24 ◽  
pp. 101-110
Author(s):  
W. Iwanowska
Keyword(s):  
Stellar Population ◽  
Chemical Properties ◽  
Spectrophotometric Study ◽  
Physical And Chemical Properties ◽  
Population Type ◽  
The Galaxy ◽  
Distribution Parameters ◽  
Physical And Chemical ◽  
Statistical Criteria ◽  
And Chemical Properties

In connection with the spectrophotometric study of population-type characteristics of various kinds of stars, a statistical analysis of kinematical and distribution parameters of the same stars is performed at the Toruń Observatory. This has a twofold purpose: first, to provide a practical guide in selecting stars for observing programmes, second, to contribute to the understanding of relations existing between the physical and chemical properties of stars and their kinematics and distribution in the Galaxy.

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