scholarly journals sígame v3: Gas Fragmentation in Postprocessing of Cosmological Simulations for More Accurate Infrared Line Emission Modeling

2021 ◽  
Vol 922 (1) ◽  
pp. 88
Author(s):  
Karen Pardos Olsen ◽  
Blakesley Burkhart ◽  
Mordecai-Mark Mac Low ◽  
Robin G. Treß ◽  
Thomas R. Greve ◽  
...  
Keyword(s):  
Radiative Transfer ◽  
Probability Distribution Function ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Sample Selection ◽  
Line Emission ◽  
Far Infrared ◽  
Emission Lines ◽  
Nearby Galaxies ◽  
A New Technique

Abstract We present an update to the framework called Simulator of Galaxy Millimeter/submillimeter Emission (sígame). sígame derives line emission in the far-infrared (FIR) for galaxies in particle-based cosmological hydrodynamics simulations by applying radiative transfer and physics recipes via a postprocessing step after completion of the simulation. In this version, a new technique is developed to model higher gas densities by parameterizing the probability distribution function (PDF) of the gas density in higher-resolution simulations run with the pseudo-Lagrangian, Voronoi mesh code arepo. The parameterized PDFs are used as a look-up table, and reach higher densities than in previous work. sígame v3 is tested on redshift z = 0 galaxies drawn from the simba cosmological simulation for eight FIR emission lines tracing vastly different phases of the interstellar medium. This version of sígame includes dust radiative transfer with Skirt and high-resolution photoionization models with Cloudy, the latter sampled according to the density PDF of the arepo simulations to augment the densities in the cosmological simulation. The quartile distributions of the predicted line luminosities overlap with the observed range for nearby galaxies of similar star formation rate (SFR) for all but two emission lines: [O i]63 and CO(3–2), which are overestimated by median factors of 1.3 and 1.0 dex, respectively, compared to the observed line–SFR relation of mixed-type galaxies. We attribute the remaining disagreement with observations to the lack of precise attenuation of the interstellar light on sub-grid scales (≲200 pc) and differences in sample selection.

scholarly journals High-resolution, 3D radiative transfer modelling

2020 ◽  
Vol 637 ◽  
pp. A25 ◽  
Author(s):  
Angelos Nersesian ◽  
Sam Verstocken ◽  
Sébastien Viaene ◽  
Maarten Baes ◽  
Emmanuel M. Xilouris ◽  
...  
Keyword(s):  
Star Formation ◽  
Radiative Transfer ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Far Infrared ◽  
Stellar Populations ◽  
Barred Galaxies ◽  
Bolometric Luminosity ◽  
Radial Profiles ◽  
Galaxy Sample

Context. Dust in late-type galaxies in the local Universe is responsible for absorbing approximately one third of the energy emitted by stars. It is often assumed that dust heating is mainly attributable to the absorption of ultraviolet and optical photons emitted by the youngest (≤100 Myr) stars. Consequently, thermal re-emission by dust at far-infrared wavelengths is often linked to the star-formation activity of a galaxy. However, several studies argue that the contribution to dust heating by much older stellar populations might be more significant than previously thought. Advances in radiation transfer simulations finally allow us to actually quantify the heating mechanisms of diffuse dust by the stellar radiation field. Aims. As one of the main goals in the DustPedia project, we have developed a framework to construct detailed 3D stellar and dust radiative transfer models for nearby galaxies. In this study, we analyse the contribution of the different stellar populations to the dust heating in four nearby face-on barred galaxies: NGC 1365, M 83, M 95, and M 100. We aim to quantify the fraction directly related to young stellar populations, both globally and on local scales, and to assess the influence of the bar on the heating fraction. Methods. From 2D images we derive the 3D distributions of stars and dust. To model the complex geometries, we used SKIRT, a state-of-the-art 3D Monte Carlo radiative transfer code designed to self-consistently simulate the absorption, scattering, and thermal re-emission by the dust for arbitrary 3D distributions. Results. We derive global attenuation laws for each galaxy and confirm that galaxies of high specific star-formation rate have shallower attenuation curves and weaker UV bumps. On average, 36.5% of the bolometric luminosity is absorbed by dust in our galaxy sample. We report a clear effect of the bar structure on the radial profiles of the dust-heating fraction by the young stellar populations, and the dust temperature. We find that the young stellar populations are the main contributors to the dust heating, donating, on average ∼59% of their luminosity to this purpose throughout the galaxy. This dust-heating fraction drops to ∼53% in the bar region and ∼38% in the bulge region where the old stars are the dominant contributors to the dust heating. We also find a strong link between the heating fraction by the young stellar populations and the specific star-formation rate.

scholarly journals AKARI/IRC broadband mid-infrared data as an indicator of the Star Formation Rate

2011 ◽  
Vol 7 (S284) ◽  
pp. 357-359
Author(s):  
Fang-Ting Yuan ◽  
Tsutomu T. Takeuchi ◽  
Véronique Buat ◽  
Sébastien Heinis ◽  
Elodie Giovannoli ◽  
...  
Keyword(s):  
Star Formation ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Infrared Camera ◽  
Far Infrared ◽  
Mid Infrared ◽  
Extended Sources ◽  
Nearby Galaxies ◽  
First Time ◽  
Infrared Data

AbstractWith the goal of constructing Star-Formation Rates (SFR) from AKARI Infrared Camera (IRC) data, we analyzed an IR-selected GALEX-SDSS-2MASS-AKARI(IRC & Far-Infrared Surveyor) sample of 153 nearby galaxies. The far-infrared fluxes were obtained from AKARI diffuse maps to correct the underestimation for extended sources raised by PSF photometry. SFRs of these galaxies were derived using the SED fitting program CIGALE. In spite of complicated features contained in these bands, both the S9W and L18W emissions correlate with the SFR of galaxies. The SFR calibrations using S9W and L18W are presented for the first time. These calibrations agree well with previous work based on Spitzer data within the scatter, and should be applicable to dust-rich galaxies.

scholarly journals The Resolved Kennicutt-Schmidt Law in Nearby Galaxies

2012 ◽  
Vol 8 (S292) ◽  
pp. 335-335
Author(s):  
R. Momose ◽  
J. Koda ◽  
R. C. Kennicutt ◽  
F. Egusa ◽  
S. K. Okumura ◽  
...  
Keyword(s):  
Star Formation ◽  
Power Law ◽  
Surface Density ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Line Emission ◽  
Molecular Gas ◽  
Disk Galaxies ◽  
Nearby Galaxies ◽  
Power Law Index

AbstractThe Kennicutt-Schmidt law (Schmidt 1959; Kennicutt 1998, hereafter K-S law) is a power law correlation between area averaged star formation rate (ΣSFR) and gas surface density (Σgas). Despite its importance, the physics that underlie this correlation has remained unclear. The power law index, N, is a prime discriminator of the mechanisms that regulate star formation and form the K-S law (e.g. Leroy et al. 2008; Tan 2010). We present a study of the resolved K-S law for 10 nearby disk galaxies using our new CO(1-0) data at 750 and 500 pc resolutions. The CO(1-0) line emission is established as a tracer of the molecular gas column density, and results in a super-linear correlation (N = 1.3 and 1.8). We discuss the cause of the discrepancy between previous studies, and the mechanism of star formation indicated from our new results.

scholarly journals A physical model for [C ii] line emission from galaxies

2019 ◽  
Vol 489 (1) ◽  
pp. 1-12 ◽  
Author(s):  
A Ferrara ◽  
L Vallini ◽  
A Pallottini ◽  
S Gallerani ◽  
S Carniani ◽  
...  
Keyword(s):  
Star Formation ◽  
Surface Brightness ◽  
Star Formation Rate ◽  
High Redshift ◽  
Formation Rate ◽  
Line Emission ◽  
Emission Lines ◽  
Additional Information ◽  
Low Metallicity ◽  
Local Relation

ABSTRACT A tight relation between the [C ii] 158 $\mu$m line luminosity and star formation rate is measured in local galaxies. At high redshift (z > 5), though, a much larger scatter is observed, with a considerable (15–20 per cent) fraction of the outliers being [C ii]-deficient. Moreover, the [C ii] surface brightness ($\Sigma_{\rm [C\, \small {II}]}$) of these sources is systematically lower than expected from the local relation. To clarify the origin of such [C ii]-deficiency, we have developed an analytical model that fits local [C ii] data and has been validated against radiative transfer simulations performed with cloudy. The model predicts an overall increase of $\Sigma_{\rm [C\, \small {II}]}$ with ΣSFR. However, for ΣSFR ${\gtrsim} 1 \, \mathrm{M}_\odot \,{\rm yr}^{-1}\,{\rm kpc}^{-2}$, $\Sigma_{\rm [C\, \small {II}]}$ saturates. We conclude that underluminous [C ii] systems can result from a combination of three factors: (a) large upward deviations from the Kennicutt–Schmidt relation (κs ≫ 1), parametrized by the ‘burstiness’ parameter κs; (b) low metallicity; (c) low gas density, at least for the most extreme sources (e.g. CR7). Observations of [C ii] emission alone cannot break the degeneracy among the above three parameters; this requires additional information coming from other emission lines (e.g. [O iii]88 $\mu$m, C iii]1909 Å, CO lines). Simple formulae are given to interpret available data for low- and high-z galaxies.

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.

scholarly journals Testing star formation rate indicators using galaxy merger simulations and radiative transfer

2009 ◽  
Vol 5 (S262) ◽  
pp. 257-260
Author(s):  
Christopher C. Hayward ◽  
Patrik Jonsson ◽  
Kai Noeske ◽  
Stijn Wuyts ◽  
T. J. Cox ◽  
...  
Keyword(s):  
Star Formation ◽  
Radiative Transfer ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Star Formation History ◽  
Spectral Energy ◽  
Merging Galaxies ◽  
Formation History ◽  
Particle Hydrodynamics ◽  
Smoothed Particle

AbstractWe discuss our ongoing project analyzing N-body/smoothed-particle hydrodynamics simulations of isolated and merging galaxies, performed using GADGET-2 (Springel 2005), with the 3-D adaptive grid, polychromatic Monte Carlo radiative transfer code SUNRISE (Jonsson 2006). We apply commonly used UV, optical, and IR star formation rate (SFR) indicators to the integrated spectral energy distributions (SEDs) of the simulated galaxies in order to determine how well the SFR indicators recover the instantaneous SFR in the simulations. The models underlying each SFR indicator must necessarily make assumptions about physical properties of the galaxies, e.g., the star formation history (SFH), whereas all such properties are known in the simulations. This enables us to test and compare SFR indicators in a way that is complementary to observational studies. We present one preliminary result of interest: even after correcting the Hα luminosity for dust using the Calzetti et al. (2000) attenuation law the SFR is significantly underestimated for simulated galaxies with SFR ≳ 10 M⊙ yr−1.

scholarly journals Far-Infrared Emission from Clumpy Irregular Galaxies

1987 ◽  
Vol 115 ◽  
pp. 647-647
Author(s):  
U. Klein ◽  
J. Heidmann ◽  
R. Wielebinski ◽  
E. Wunderlich
Keyword(s):  
Star Formation ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Hubble Constant ◽  
Far Infrared ◽  
Hii Regions ◽  
Infrared Emission ◽  
Star Forming ◽  
Irregular Galaxies

The four clumpy irregular galaxies Mkr 8, 296,297 and 325 have been observed by IRAS. All galaxies have been detected in at least two of the four detector bands. The ratios of the 100 to 60-m flux densities are comparable to those of HII regions or violently star forming galaxies. The average star formation rate in clumpy irregular galaxies is of the order of a few solar masses per year (based on their average far-infrared luminosity and a Hubble constant of 75 km s−1 Mpc−1.

scholarly journals THE CALIBRATION OF MONOCHROMATIC FAR-INFRARED STAR FORMATION RATE INDICATORS

2010 ◽  
Vol 714 (2) ◽  
pp. 1256-1279 ◽  
Author(s):  
D. Calzetti ◽  
S.-Y. Wu ◽  
S. Hong ◽  
R. C. Kennicutt ◽  
J. C. Lee ◽  
...  
Keyword(s):  
Star Formation ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Far Infrared ◽  
Infrared Star

scholarly journals Local star-forming dwarf galaxies as windows on reionization-era stellar populations

2019 ◽  
Vol 15 (S352) ◽  
pp. 316-316
Author(s):  
Peter Senchyna
Keyword(s):  
Line Emission ◽  
Stellar Populations ◽  
Star Forming ◽  
Star Models ◽  
Relative Paucity ◽  
High Ionization ◽  
Low Metallicity ◽  
Nearby Galaxies ◽  
A New Technique

AbstractThe recent detections of high-ionization nebular line emission from species including CIV in a number of z > 6 galaxies have highlighted substantial deficiencies in our understanding of metal poor stars. Prominent nebular CIV has never been detected in purely star-forming systems locally, and the massive star models used to model this emission in photoionization codes have not been empirically calibrated below the metallicity of the SMC (20% solar). As a result, we are presently entirely unprepared to correctly interpret nebular emission from metal-poor stars observed with JWST and ALMA in the reionization era. We present results from a multi-pronged ongoing local ultraviolet/optical observation campaign with HST/COS, Keck/ESI, and MMT designed to address this issue by locating and characterizing stellar populations capable of powering such high-ionization emission. This work has already demonstrated that strong nebular CIV can be powered by extremely metal-poor (< 10% solar) massive stars, indicating that we may already have evidence of such low-metallicity populations in the reionization era. However, CIV at the equivalent widths detected at z > 6 remains elusive locally, potentially in part due to the relative paucity of known nearby galaxies at these metallicities with massive stellar populations comparable to those in z > 6 systems. We present a new technique to locate such nearby galaxies, and results from optical follow-up which indicate that a substantial population of highly star- forming metal-poor galaxies likely resides just below the detection limits of previous large spectroscopic surveys.

scholarly journals The HerMES Local Luminosity Function

2015 ◽  
Vol 11 (S315) ◽  
Author(s):  
Lucia Marchetti ◽  
Mattia Vaccari ◽  
Alberto Franceschini
Keyword(s):  
Star Formation ◽  
Data Fusion ◽  
Luminosity Function ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Accurate Determination ◽  
Far Infrared ◽  
Rate Function ◽  
Model Predictions ◽  
Multi Wavelength

AbstractWe exploit the Herschel Extragalactic Multi-Tiered Survey (HerMES) dataset along with ancillary multi-wavelength photometry and spectroscopy from the Spitzer Data Fusion to provide the most accurate determination to date of the local (0.02<z<0.5) Far-Infrared Luminosity and Star Formation Rate Function. We present and compare our results with model predictions as well as other multi-wavelength estimates of the local star formation rate density.

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