scholarly journals Nebular-line emission during the Epoch of Reionization

2020 ◽  
Vol 493 (4) ◽  
pp. 6079-6094 ◽  
Author(s):  
Stephen M Wilkins ◽  
Christopher C Lovell ◽  
Ciaran Fairhurst ◽  
Yu Feng ◽  
Tiziana Di Matteo ◽  
...  
Keyword(s):  
Luminosity Function ◽  
Rest Frame ◽  
Line Emission ◽  
Optical Emission ◽  
H Ii Regions ◽  
Ionized Gas ◽  
Near Ir ◽  
Hydrodynamical Simulation ◽  
Lower Redshift ◽  
Good Agreement

ABSTRACT Nebular emission lines associated with galactic H ii regions carry information about both physical properties of the ionized gas and the source of ionizing photons as well as providing the opportunity of measuring accurate redshifts and thus distances once a cosmological model is assumed. While nebular-line emission has been extensively studied at lower redshift there are currently only few constraints within the epoch of reionization (EoR; z > 6), chiefly due to the lack of sensitive near-IR spectrographs. However, this will soon change with the arrival of the Webb Telescope providing sensitive near-IR spectroscopy covering the rest-frame UV and optical emission of galaxies in the EoR. In anticipation of Webb, we combine the large cosmological hydrodynamical simulation BlueTides with photoionization modelling to predict the nebular emission-line properties of galaxies at z = 8 → 13. We find good agreement with the, albeit limited, existing direct and indirect observational constraints on equivalent widths though poorer agreement with luminosity function constraints.

scholarly journals On the origins of the diffuse Hα emission: ionized gas or dust-scattered Hα halos?

2012 ◽  
Vol 10 (H16) ◽  
pp. 576-576
Author(s):  
Kwang-Il Seon ◽  
Adolf N. Witt
Keyword(s):  
Interstellar Medium ◽  
Absorption Feature ◽  
H Ii Regions ◽  
Ionized Gas ◽  
Elemental Abundances ◽  
Hα Emission ◽  
Good Agreement

AbstractWe find that the dust-scattering origin of the diffuse Hα emission cannot be ruled out. As opposed to the previous contention, the expected dust-scattered Hα halos surrounding H II regions are, in fact, in good agreement with the observed Hα morphology. We calculate an extensive set of photoionization models by varying elemental abundances, ionizing stellar types, and clumpiness of the interstellar medium (ISM) and find that the observed line ratios of [S II]/Hα, [N II]/Hα, and He I λ5876/Hα in the diffuse ISM accord well with the dust-scattered halos around H II regions, which are photoionized by late O- and/or early B-type stars. We also demonstrate that the Hα absorption feature in the underlying continuum from the dust-scattered starlight (“diffuse galactic light”) and unresolved stars is able to substantially increase the [S II]/Hα and [N II]/Hα line ratios in the diffuse ISM.

scholarly journals WARPFIELD-EMP: The self-consistent prediction of emission lines from evolving H ii regions in dense molecular clouds

2020 ◽  
Vol 496 (1) ◽  
pp. 339-363 ◽  
Author(s):  
E W Pellegrini ◽  
D Rahner ◽  
S Reissl ◽  
S C O Glover ◽  
R S Klessen ◽  
...  
Keyword(s):  
Line Emission ◽  
Continuum Emission ◽  
Physical Parameters ◽  
Model Parameters ◽  
Stellar Winds ◽  
H Ii Regions ◽  
Stellar Feedback ◽  
Wide Range ◽  
H Ii Region ◽  
Good Agreement

ABSTRACT We present the warpfield emission predictor, warpfield-emp, which couples the 1D stellar feedback code warpfield with the cloudy H iiregion/PDR code and the polaris radiative transfer code, in order to make detailed predictions for the time-dependent line and continuum emission arising from the H ii region and PDR surrounding an evolving star cluster. warpfield-emp accounts for a wide range of physical processes (photoionization, stellar winds, supernovae, radiation pressure, gravity, thermal conduction, radiative cooling, dust extinction etc.) and yet runs quickly enough to allow us to explore broad ranges of different model parameters. We compare the results of an extensive set of models with SITELLE observations of a large sample of H ii regions in NGC 628 and find very good agreement, particularly for the highest signal-to-noise observations. We show that our approach of modelling individual clouds from first principles (instead of in terms of dimensionless quantities such as the ionization parameter) allows us to avoid long-standing degeneracies in the interpretation of H ii region diagnostics and enables us to relate these diagnostics to important physical parameters such as cloud mass or cluster age. Finally, we explore the implications of our models regarding the reliability of simple metallicity diagnostics, the properties of long-lived embedded clusters, and the role played by winds and supernovae in regulating H ii region and PDR line emission.

scholarly journals The relation between the radio jet and the near-IR line emission in Seyfert galaxies

2010 ◽  
Vol 6 (S275) ◽  
pp. 172-173
Author(s):  
Rogemar A. Riffel ◽  
Thaisa Storchi-Bergmann
Keyword(s):  
Line Emission ◽  
Seyfert Galaxies ◽  
Molecular Gas ◽  
Gas Emission ◽  
Ionized Gas ◽  
Integral Field Spectroscopy ◽  
Near Ir ◽  
Field Spectroscopy ◽  
Molecular Flux ◽  
Integral Field

AbstractWe used near-IR integral field spectroscopy, obtained with Gemini NIFS and GNIRS integral field units (IFUs), to map the ionized and molecular flux distributions and kinematics in the central few hundreds of parsecs of Seyfert galaxies. We conclude that the molecular gas emission can be considered a tracer of the feeding of the AGN, while the emission of the ionized gas a tracer of its feedback.

scholarly journals Near-IR spectroscopic studies of galaxies at z ∼ 1–3

2019 ◽  
Vol 15 (S352) ◽  
pp. 216-227
Author(s):  
Irene Shivaei
Keyword(s):  
Star Formation ◽  
Dynamic Range ◽  
High Redshift ◽  
Cosmic Time ◽  
Optical Emission ◽  
Spectroscopic Studies ◽  
Current Status ◽  
Molecular Gas ◽  
Ionized Gas ◽  
Near Ir

AbstractISM comprises multiple components, including molecular, neutral, and ionized gas, and dust, which are related to each other mainly through star formation – some are fuel for star formation (molecular gas) while some are the products of it (ionized gas, dust). To fully understand the physics of star formation and its evolution throughout cosmic time, it is crucial to measure and observe different ISM components of galaxies out to high redshifts. I will review the current status of near-IR studies of galaxies during the peak of star formation activity (z ∼ 1 – 3). Using rest-frame optical emission lines, we measure dust, star formation, and gaseous properties of galaxies. JWST will advance such studies by probing lower luminosities and higher redshifts, owing to its significantly higher sensitivity. Incorporating ALMA observations of cold dust and molecular gas at z > 1 will give us a nearly complete picture of the ISM in high-redshift galaxies over a large dynamic range in mass.

scholarly journals Interpreting the Spitzer/IRAC colours of 7 ≤ z ≤ 9 galaxies: distinguishing between line emission and starlight using ALMA

2020 ◽  
Vol 497 (3) ◽  
pp. 3440-3450 ◽  
Author(s):  
G W Roberts-Borsani ◽  
R S Ellis ◽  
N Laporte
Keyword(s):  
Optical Properties ◽  
Rest Frame ◽  
High Redshift ◽  
Line Emission ◽  
Intense Line ◽  
High Redshift Galaxies ◽  
Star Forming ◽  
History Of ◽  
Dependent Behaviour ◽  
Lower Redshift

ABSTRACT Prior to the launch of JWST, Spitzer/IRAC photometry offers the only means of studying the rest-frame optical properties of z >7 galaxies. Many such high-redshift galaxies display a red [3.6]−[4.5] micron colour, often referred to as the ‘IRAC excess’, which has conventionally been interpreted as arising from intense [O iii]+H β emission within the [4.5] micron bandpass. An appealing aspect of this interpretation is similarly intense line emission seen in star-forming galaxies at lower redshift as well as the redshift-dependent behaviour of the IRAC colours beyond z ∼ 7 modelled as the various nebular lines move through the two bandpasses. In this paper, we demonstrate that, given the photometric uncertainties, established stellar populations with Balmer (4000 Å rest frame) breaks, such as those inferred at z > 9 where line emission does not contaminate the IRAC bands, can equally well explain the redshift-dependent behaviour of the IRAC colours in 7 ≲ z ≲ 9 galaxies. We discuss possible ways of distinguishing between the two hypotheses using ALMA measures of [O iii] λ88 micron and dust continuum fluxes. Prior to further studies with JWST, we show that the distinction is important in determining the assembly history of galaxies in the first 500 Myr.

Census of and Lyα, [Oiii]5007, Hα, and [Ciii]158 μm line emission wiht ∼1000 galaxies at z = 4.9 – 7.0 revealed with Subaru/HSC, Spitzer, and ALMA

2019 ◽  
Vol 15 (S341) ◽  
pp. 206-210
Author(s):  
Yuichi Harikane
Keyword(s):  
Rest Frame ◽  
Formation Rate ◽  
Line Emission ◽  
Flux Ratio ◽  
Optical Emission ◽  
Far Infrared ◽  
Infrared Emission ◽  
Emission Lines ◽  
The Galaxy ◽  
Turn Over

AbstractWe investigate rest-frame UV to far-infrared emission lines and SEDs from 1124 galaxies at z = 4.9 – 7.0. Our sample is composed of 1092 Lyα emitters (LAEs) at z = 4.9–7.0 identified by Subaru/Hyper Suprime-Cam (HSC) narrowband surveys and 34 galaxies at z = 5.148–7.508 with deep [Cii]158μm ALMA data. The SEDs clearly show flux excesses in the Spitzer/IRAC 3.6 and 4.5μm bands, suggesting strong rest-frame optical emission lines of [Oiii] and/or Hα. We model the galaxy SEDs with a flexible code combining stellar population and photoionization models (BEAGLE; Chevallard & Charlot 2016), and investigate relations between the emission lines of Lyα, [Oiii], Hα, and [CII]. We find 1) a positive correlation between the rest-frame Hα equivalent width (EW) and the Lyα, EW, ${\EW {^0_Ly\alpha}} $, 2) an interesting turn-over trend that the [Oiii]/Hα flux ratio increases in ${\EW {^0_Ly\alpha}} $ ≃ 0–30 Å, and then decreases out to ${\EW {^0_Ly\alpha}} $ ≃ 130 Å, and 3) a > 99% anti-correlation between a [Cii] luminosity to star-formation rate ratio L[Cii]/SFR) and ${\EW {^0_Ly\alpha}} $. Modeling with BEAGLE also suggests that a simple anticorrelation between ${\EW {^0_Ly\alpha}} $ and metallicity explains self-consistently all of the relations of Lyα, Hα, [Oiii]/Hα, and [Cii] in our study, indicative of detections of very metal-poor (∼0.03Z⊙) galaxies with ${\EW {^0_Ly\alpha}} $ ∼200 Å.

Ionized AGN outflows are less powerful than assumed: A multi-wavelength census of outflows in type II AGN

2019 ◽  
Vol 15 (S356) ◽  
pp. 225-225
Author(s):  
Dalya Baron
Keyword(s):  
Optical Emission ◽  
Infrared Emission ◽  
Type Ii ◽  
Ionized Gas ◽  
Kinetic Coupling ◽  
Mass Outflow ◽  
Multi Wavelength ◽  
Novel Method ◽  
First Time ◽  
Ionization Parameter

AbstractIn this talk I will show that multi-wavelength observations can provide novel constraints on the properties of ionized gas outflows in AGN. I will present evidence that the infrared emission in active galaxies includes a contribution from dust which is mixed with the outflow and is heated by the AGN. We detect this infrared component in thousands of AGN for the first time, and use it to constrain the outflow location. By combining this with optical emission lines, we constrain the mass outflow rates and energetics in a sample of 234 type II AGN, the largest such sample to date. The key ingredient of our new outflow measurements is a novel method to estimate the electron density using the ionization parameter and location of the flow. The inferred electron densities, ∼104.5 cm−3, are two orders of magnitude larger than found in most other cases of ionized outflows. We argue that the discrepancy is due to the fact that the commonly-used [SII]-based method underestimates the true density by a large factor. As a result, the inferred mass outflow rates and kinetic coupling efficiencies are 1–2 orders of magnitude lower than previous estimates, and 3–4 orders of magnitude lower than the typical requirement in hydrodynamic cosmological simulations. These results have significant implications for the relative importance of ionized outflows feedback in this population.

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 The Rest-frame Optical (900 nm) Galaxy Luminosity Function atz∼ 4–7: Abundance Matching Points to Limited Evolution in theMSTAR/MHALORatio atz≥ 4

2017 ◽  
Vol 843 (1) ◽  
pp. 36 ◽  
Author(s):  
Mauro Stefanon ◽  
Rychard J. Bouwens ◽  
Ivo Labbé ◽  
Adam Muzzin ◽  
Danilo Marchesini ◽  
...  
Keyword(s):  
Luminosity Function ◽  
Rest Frame ◽  
Galaxy Luminosity Function

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.

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