scholarly journals Understanding Galaxy Evolution Through Emission Lines

2019 ◽  
Vol 57 (1) ◽  
pp. 511-570 ◽  
Author(s):  
Lisa J. Kewley ◽  
David C. Nicholls ◽  
Ralph S. Sutherland
Keyword(s):  
Emission Line ◽  
Galaxy Evolution ◽  
Sample Selection ◽  
Cosmic Time ◽  
Emission Lines ◽  
Ionized Gas ◽  
Fundamental Properties ◽  
Integral Field Spectroscopy ◽  
Diffuse Ionized Gas ◽  
Ionization Parameter

We review the use of emission lines for understanding galaxy evolution, focusing on excitation source, metallicity, ionization parameter, ISM pressure, and electron density. We discuss the physics, benefits, and caveats of emission line diagnostics, including the effects of theoretical model uncertainties, diffuse ionized gas, and sample selection bias. In anticipation of upcoming telescope facilities, we provide new self-consistent emission line diagnostic calibrations for complete spectral coverage from the UV to the IR. These diagnostics can be used in concert to understand how fundamental galaxy properties have changed across cosmic time. We conclude the following: ▪ The UV, optical, and IR contain complementary diagnostics that can probe the conditions within different nebular ionization zones. ▪ Accounting for complex density gradients and temperature profiles is critical for reliably estimating the fundamental properties of Hii regions and galaxies. ▪ Diffuse ionized gas can raise metallicity estimates, flatten metallicity gradients, and introduce scatter in ionization parameter measurements. ▪ New 3D emission line diagnostics successfully separate the contributions from star formation, AGN, and shocks using integral field spectroscopy. We summarize with a discussion of the challenges and major opportunities for emission line diagnostics in the coming years.

scholarly journals H ii regions in the CALIFA survey: I. catalogue presentation

2020 ◽  
Vol 494 (2) ◽  
pp. 1622-1646 ◽  
Author(s):  
C Espinosa-Ponce ◽  
S F Sánchez ◽  
C Morisset ◽  
J K Barrera-Ballesteros ◽  
L Galbany ◽  
...  
Keyword(s):  
Stellar Populations ◽  
Spectroscopic Properties ◽  
Emission Lines ◽  
H Ii Regions ◽  
Ionized Gas ◽  
New Approach ◽  
Integral Field Spectroscopy ◽  
Diffuse Ionized Gas ◽  
Spectroscopic Information ◽  
Selection Of

ABSTRACT We present a new catalogue of H ii regions based on the integral field spectroscopy (IFS) data of the extended CALIFA and PISCO samples. The selection of H ii regions was based on two assumptions: a clumpy structure with high contrast of H α emission and an underlying stellar population comprising young stars. The catalogue provides the spectroscopic information of 26 408 individual regions corresponding to 924 galaxies, including the flux intensities and equivalent widths of 51 emission lines covering the wavelength range between 3745 and 7200 Å. To our knowledge, this is the largest catalogue of spectroscopic properties of H ii regions. We explore a new approach to decontaminate the emission lines from diffuse ionized gas contribution. This diffuse gas correction was estimated to correct every emission line within the considered spectral range. With the catalogue of H ii regions corrected, new demarcation lines are proposed for the classical diagnostic diagrams. Finally, we study the properties of the underlying stellar populations of the H ii regions. It was found that there is a direct relationship between the ionization conditions on the nebulae and the properties of stellar populations besides the physicals condition on the ionized regions.

scholarly journals 3D optical spectroscopic study of NGC 3344 with SITELLE: I. Identification and confirmation of supernova remnants

2019 ◽  
Vol 488 (1) ◽  
pp. 803-829 ◽  
Author(s):  
I Moumen ◽  
C Robert ◽  
D Devost ◽  
R P Martin ◽  
L Rousseau-Nepton ◽  
...  
Keyword(s):  
Supernova Remnants ◽  
Flux Ratio ◽  
Large Magellanic Cloud ◽  
Emission Lines ◽  
Ionization Mechanism ◽  
H Ii Regions ◽  
Nearby Galaxy ◽  
Galactocentric Distance ◽  
Ionized Gas ◽  
Diffuse Ionized Gas

ABSTRACT We present the first optical identification and confirmation of a sample of supernova remnants (SNRs) in the nearby galaxy NGC 3344. Using high spectral and spatial resolution data, obtained with the CFHT imaging Fourier transform spectrograph SITELLE, we identified about 2200 emission line regions, many of which are H ii regions, diffuse ionized gas regions, and also SNRs. Considering the stellar population and diffuse ionized gas background, which are quite important in NGC 3344, we have selected 129 SNR candidates based on four criteria for regions where the emission lines flux ratio [S ii]/H α ≥ 0.4. Emission lines of [O ii] λ3727, H β, [O iii] λλ4959,5007, H α, [N ii] λλ6548,6583, and [S ii] λλ6716,6731 have been measured to study the ionized gas properties of the SNR candidates. We adopted a self-consistent spectroscopic analysis, based on Sabbadin plots and Baldwin, Phillips & Terlevich diagrams, to confirm the shock-heated nature of the ionization mechanism in the candidates sample. With this analysis, we end up with 42 Confirmed SNRs, 45 Probable SNRs, and 42 Less likely SNRs. Using shock models, the confirmed SNRs seem to have a metallicity ranging between Large Magellanic Cloud and 2×solar. We looked for correlations between the size of the confirmed SNRs and their emission lines ratios, their galaxy environment, and their galactocentric distance: We see a trend for a metallicity gradient among the SNR population, along with some evolutionary effects.

scholarly journals SDSS-IV MaNGA: the impact of diffuse ionized gas on emission-line ratios, interpretation of diagnostic diagrams and gas metallicity measurements

2016 ◽  
Vol 466 (3) ◽  
pp. 3217-3243 ◽  
Author(s):  
Kai Zhang ◽  
Renbin Yan ◽  
Kevin Bundy ◽  
Matthew Bershady ◽  
L. Matthew Haffner ◽  
...  
Keyword(s):  
Emission Line ◽  
Ionized Gas ◽  
Diffuse Ionized Gas ◽  
The Impact

scholarly journals FROM GLOBAL TO SPATIALLY RESOLVED IN LOW-REDSHIFT GALAXIES

2021 ◽  
Vol 57 (1) ◽  
Author(s):  
S. F. Sánchez ◽  
C. J. Walcher ◽  
C. Lopez-Cobá ◽  
J. K. Barrera-Ballesteros ◽  
A. Mejía-Narváez ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Galaxy Evolution ◽  
Ionized Gas ◽  
Evolution Of Galaxies ◽  
Spatially Resolved ◽  
Integral Field Spectroscopy ◽  
Field Spectroscopy ◽  
Stellar Properties ◽  
Integral Field ◽  
Redshift Galaxies

Our understanding of the structure, composition and evolution of galaxies hasstrongly improved in the last decades, mostly due to new results based on large spectro-scopic and imaging surveys. In particular, the nature of ionized gas, its ionization mech-anisms, its relation with the stellar properties and chemical composition, the existence ofscaling relations that describe the cycle between stars and gas, and the corresponding evo-lution patterns have been widely explored and described. More recently, the introduction ofadditional techniques, in particular integral field spectroscopy, and their use in large galaxysurveys, have forced us to re-interpret most of those recent results from a spatially resolvedperspective. This review is aimed to complement recent efforts to compile and summarizethis change of paradigm in the interpretation of galaxy evolution. To this end we replicatepublished results, and present novel ones, based on the largest compilation of IFS data ofgalaxies in the nearby universe to date.

scholarly journals Diffuse ionized gas and its effects on nebular metallicity estimates of star-forming galaxies

2019 ◽  
Vol 489 (4) ◽  
pp. 4721-4733 ◽  
Author(s):  
N Vale Asari ◽  
G S Couto ◽  
R Cid Fernandes ◽  
G Stasińska ◽  
A L de Amorim ◽  
...  
Keyword(s):  
Formation Rate ◽  
Sloan Digital Sky Survey ◽  
Emission Lines ◽  
Strong Line ◽  
Galactocentric Distance ◽  
Ionized Gas ◽  
Star Forming ◽  
Diffuse Ionized Gas ◽  
Stellar Masses ◽  
The Impact

ABSTRACT We investigate the impact of the diffuse ionized gas (DIG) on abundance determinations in star-forming (SF) galaxies. The DIG is characterized using the H α equivalent width (WH α). From a set of 1 409 SF galaxies from the Mapping Nearby Galaxies at APO (MaNGA) survey, we calculate the fractional contribution of the DIG to several emission lines using high-S/N data from SF spaxels (instead of using noisy emission-lines in DIG-dominated spaxels). Our method is applicable to spectra with observed WH α ≳ 10 Å (which are not dominated by DIG emission). Since the DIG contribution depends on galactocentric distance, we provide DIG-correction formulae for both entire galaxies and single aperture spectra. Applying those to a sample of $\, \gt 90\, 000$ SF galaxies from the Sloan Digital Sky Survey, we find the following. (1) The effect of the DIG on strong-line abundances depends on the index used. It is negligible for the ([O iii]/H β)/([N ii]/H α) index, but reaches ∼0.1 dex at the high-metallicity end for [N ii]/H α. (2) This result is based on the ∼kpc MaNGA resolution, so the real effect of the DIG is likely greater. (3) We revisit the mass–metallicity–star formation rate (SFR) relation by correcting for the DIG contribution in both abundances and SFR. The effect of DIG removal is more prominent at higher stellar masses. Using the [N ii]/Hα index, O/H increases with SFR at high stellar mass, contrary to previous claims.

scholarly journals Galaxy Evolution in a Pilot Survey up toz=1and CDM Halos

2011 ◽  
Vol 2011 ◽  
pp. 1-13 ◽  
Author(s):  
E. Giraud ◽  
J. Melnick ◽  
Q.-S. Gu ◽  
H. Quintana ◽  
F. Selman ◽  
...  
Keyword(s):  
Star Formation ◽  
Emission Line ◽  
Galaxy Evolution ◽  
Galaxy Formation ◽  
Emission Lines ◽  
Pencil Beam ◽  
Spectral Evolution ◽  
Cosmological Time ◽  
Emission Line Galaxies ◽  
Individual Galaxy

We study spectral evolution of galaxies in a magnitude limited sample of 550 galaxies fromz=1down toz=0.3on a pencil beam of≈10′×10′. We concentrate on the large apparent cosmological structures along the line of sight, and we bin our individual galaxy spectra to obtain representative high S/N spectra based upon these structures. We divide the resulting average spectra in three groups to facilitate the analysis:galaxies with pure absorption line spectra, galaxies with emission lines and blue continua, and galaxies with emission lines and red continua. We revisit the question of downsizing in emission-line galaxies betweenz=0.9andz=0.45in our pencil-beam and find the following results: strong star formation in emission line galaxies, aging in emission line galaxies, and aging in absorption systems, are shifting from bright to faint systems as cosmological time increases. Each redshift bin is repopulated in new starbursts. Therefore at redshiftsz⩽1galaxy formation is downsizing both in luminosity and number density. Our observations indicate that atz⩽1star formation and hierarchical structure formation of CDM halos are not in phase.

scholarly journals 3.31. Tri-dimensional observation of the superbubble in the starburst galaxy NGC 2782

1998 ◽  
Vol 184 ◽  
pp. 151-152
Author(s):  
M. Yoshida
Keyword(s):  
Spatial Distribution ◽  
Emission Line ◽  
Emission Lines ◽  
Starburst Galaxy ◽  
Two Dimensional ◽  
Excitation Mechanism ◽  
Ionized Gas ◽  
Shock Heating

We present results of an optical tri-dimensional observation of the central 2′ × 12″ region of the starburst galaxy NGC 2782. The circumnuclear Hα emission lines consist of broad (δv ~ 300 km s−1), blue-shifted component and narrow (δv < 100 km s−1) component and we first revealed the two-dimensional spatial distribution of those two components. The broad Hα emitting region is extended to 6″ (> 1 kpc) south from the nucleus and the emission-line ratios indicates that shock heating may be the main excitation mechanism of the ionized gas in the region. We conclude that this region is a superbubble outflowing from the nuclear starburst region.

scholarly journals Investigating the origin of the Fe emission lines of the Seyfert 1 galaxy Mrk 205

2019 ◽  
Vol 486 (3) ◽  
pp. 3124-3133
Author(s):  
Sibasish Laha ◽  
Ritesh Ghosh ◽  
Shruti Tripathi ◽  
Matteo Guainazzi
Keyword(s):  
Emission Line ◽  
Broad Band ◽  
Accretion Disc ◽  
Emission Lines ◽  
X Rays ◽  
X Ray ◽  
Broad Emission ◽  
Reflection Model ◽  
Ionization Parameter ◽  
Thick Material

ABSTRACT We have investigated the nature and origin of the Fe K emission lines in Mrk 205 using observations with Suzaku and XMM–Newton, aiming to resolve the ambiguity between a broad emission line and multiple unresolved lines of higher ionization. We detect the presence of a narrow Fe K α emission line along with a broad-band Compton reflection hump at energies $E\gt 10\rm \, \, {\rm keV}$. These are consistent with reflected emission of hard X-ray photons off a Compton-thick material of $N_{\rm H}\ge 2.15\times 10^{24}\rm \, \, {\rm cm^{-2}}$. In addition we detect a partially covering ionized absorption with ionization parameter $\log (\xi /\rm \, erg\, cm\, s^{-1})=1.9_{-0.5}^{+0.1}$, column density $N_{\rm H}=(5.6_{-1.9}^{+2.0})\times 10^{22}\rm \, \, {\rm cm^{-2}}$, and a covering factor of $0.22_{-0.06}^{+0.09}$. We detect the presence of emission arising out of ionized disc reflection contributing in the soft and hard X-rays consistently in all the observations. We however, could not definitely ascertain the presence of a relativistically broadened Fe line in the X-ray spectra. Using relativistic reflection models, we found that the data are unable to statistically distinguish between the scenarios when the supermassive black hole is non-rotating and when it is maximally spinning. Using the disc reflection model we also find that the accretion disc of the active galactic nucleus may be truncated at a distance 6RG &lt; R &lt; 12RG, which may suggest why there may not be any broad Fe line. The Eddington rate of the source is low (λEdd = 0.03), which points to an inefficient accretion, possibly due to a truncated disc.

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