UV Dust Attenuation in Normal Star‐Forming Galaxies. I. Estimating theLTIR/LFUVRatio

ABSTRACT The H α and H β emission-line luminosities measured in a single integrated spectrum are affected in non-trivial ways by point-to-point variations in dust attenuation in a galaxy. This work investigates the impact of this variation when estimating global H α luminosities corrected for the presence of dust by a global Balmer decrement. Analytical arguments show that the dust-corrected H α luminosity is always underestimated when using the global H α/H β flux ratio to correct for dust attenuation. We measure this effect on 156 face-on star-forming galaxies from the Mapping Nearby Galaxies at APO (MaNGA) survey. At 1–2 kpc spatial resolution, the effect is small but systematic, with the integrated dust-corrected H α luminosity underestimated by 2–4 per cent (and typically not more than by 10 per cent), and depends on the specific star formation rate of the galaxy. Given the spatial resolution of MaNGA, these are lower limits for the effect. From Multi Unit Spectroscopic Explorer (MUSE) observations of NGC 628 with a resolution of 36 pc, we find the discrepancy between the globally and the point-by-point dust-corrected H α luminosity to be 14 ± 1 per cent, which may still underestimate the true effect. We use toy models and simulations to show that the true difference depends strongly on the spatial variance of the H α/H β flux ratio, and on the slope of the relation between H αluminosity and dust attenuation within a galaxy. Larger samples of higher spatial resolution observations are required to quantify the dependence of this effect as a function of galaxy properties.

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VLA imaging of the XMM-LSS/VIDEO deep field at 1–2 GHz

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa1770 ◽

2020 ◽

Vol 496 (3) ◽

pp. 3469-3481

Author(s):

I Heywood ◽

C L Hale ◽

M J Jarvis ◽

S Makhathini ◽

J A Peters ◽

...

Keyword(s):

Angular Resolution ◽

Cosmic Time ◽

Wide Field ◽

Radio Telescopes ◽

Very Large Array ◽

Star Forming ◽

Normal Star ◽

Average Spectrum ◽

Field Imaging ◽

Wide Field Imaging

ABSTRACT Modern radio telescopes are routinely reaching depths where normal star-forming galaxies are the dominant observed population. Realizing the potential of radio as a tracer of star formation and black hole activity over cosmic time involves achieving such depths over representative volumes, with radio forming part of a larger multiwavelength campaign. In pursuit of this, we used the Karl G. Jansky Very Large Array (VLA) to image ∼5 deg2 of the VIDEO/XMM-LSS extragalactic deep field at 1–2 GHz. We achieve a median depth of 16 µJy beam−1 with an angular resolution of 4.5 arcsec. Comparisons with existing radio observations of XMM-LSS showcase the improved survey speed of the upgraded VLA: we cover 2.5 times the area and increase the depth by ∼20 per cent in 40 per cent of the time. Direction-dependent calibration and wide-field imaging were required to suppress the error patterns from off-axis sources of even modest brightness. We derive a catalogue containing 5762 sources from the final mosaic. Sub-band imaging provides in-band spectral indices for 3458 (60 per cent) sources, with the average spectrum becoming flatter than the canonical synchrotron slope below 1 mJy. Positional and flux density accuracy of the observations, and the differential source counts are in excellent agreement with those of existing measurements. A public release of the images and catalogue accompanies this article.

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Star cluster formation and cloud dispersal by radiative feedback: dependence on metallicity and compactness

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa2062 ◽

2020 ◽

Vol 497 (3) ◽

pp. 3830-3845 ◽

Cited By ~ 1

Author(s):

Hajime Fukushima ◽

Hidenobu Yajima ◽

Kazuyuki Sugimura ◽

Takashi Hosokawa ◽

Kazuyuki Omukai ◽

...

Keyword(s):

Star Formation ◽

Massive Stars ◽

Cluster Formation ◽

Star Clusters ◽

Star Cluster ◽

Star Forming ◽

Dynamical Time ◽

Low Metallicity ◽

Higher Temperature ◽

Dust Attenuation

ABSTRACT We study star cluster formation in various environments with different metallicities and column densities by performing a suite of 3D radiation hydrodynamics simulations. We find that the photoionization feedback from massive stars controls the star formation efficiency (SFE) in a star-forming cloud, and its impact sensitively depends on the gas metallicity Z and initial cloud surface density Σ. At Z = 1 Z⊙, SFE increases as a power law from 0.03 at Σ = 10 M⊙ pc−2 to 0.3 at $\Sigma = 300\,\mathrm{M}_{\odot }\, {\rm pc^{-2}}$. In low-metallicity cases $10^{-2}\!-\!10^{-1}\, \mathrm{Z}_{\odot }$, star clusters form from atomic warm gases because the molecule formation time is not short enough with respect to the cooling or dynamical time. In addition, the whole cloud is disrupted more easily by expanding H ii bubbles that have higher temperature owing to less efficient cooling. With smaller dust attenuation, the ionizing radiation feedback from nearby massive stars is stronger and terminate star formation in dense clumps. These effects result in inefficient star formation in low-metallicity environments: the SFE drops by a factor of ∼3 at Z = 10−2 Z⊙ compared to the results for Z = 1 Z⊙, regardless of Σ. Newborn star clusters are also gravitationally less bound. We further develop a new semi-analytical model that can reproduce the simulation results well, particularly the observed dependencies of the SFEs on the cloud surface densities and metallicities.

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Dust attenuation in the rest-frame ultraviolet: constraints from star-forming galaxies at

Monthly Notices of the Royal Astronomical Society ◽

10.1111/j.1365-2966.2010.16266.x ◽

2010 ◽

Cited By ~ 4

Author(s):

Charlie Conroy

Keyword(s):

Rest Frame ◽

Star Forming ◽

Dust Attenuation

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A HARD X-RAY STUDY OF THE NORMAL STAR-FORMING GALAXY M83 WITH NuSTAR

The Astrophysical Journal ◽

10.3847/0004-637x/824/2/107 ◽

2016 ◽

Vol 824 (2) ◽

pp. 107 ◽

Cited By ~ 13

Author(s):

M. Yukita ◽

A. E. Hornschemeier ◽

B. D. Lehmer ◽

A. Ptak ◽

D. R. Wik ◽

...

Keyword(s):

X Ray ◽

Star Forming ◽

Normal Star

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A redshift-dependent IRX–β dust attenuation relation for TNG50 galaxies

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa1900 ◽

2020 ◽

Vol 497 (4) ◽

pp. 4773-4794 ◽

Cited By ~ 1

Author(s):

Sebastian Schulz ◽

Gergö Popping ◽

Annalisa Pillepich ◽

Dylan Nelson ◽

Mark Vogelsberger ◽

...

Keyword(s):

Star Formation ◽

Galaxy Formation ◽

Main Sequence ◽

Infrared Excess ◽

Star Forming ◽

Dust Composition ◽

Metal Ratio ◽

Stellar Masses ◽

Dust Attenuation ◽

Star Formation Histories

ABSTRACT We study the relation between the UV slope, β, and the ratio between the infrared- and UV luminosities (IRX) of galaxies from TNG50, the latest installment of the IllustrisTNG galaxy formation simulations. We select 7280 star-forming main-sequence (SFMS) galaxies with stellar mass ≥109 M⊙ at redshifts 0 ≤ z ≤ 4 and perform radiative transfer with skirt to model effects of interstellar medium dust on the emitted stellar light. Assuming a Milky Way dust type and a dust-to-metal ratio of 0.3, we find that TNG50 SFMS galaxies generally agree with observationally derived IRX–β relations at z ≲ 1. However, we find a redshift-dependent systematic offset with respect to empirically derived local relations, with the TNG50 IRX–β relation shifting towards lower β and steepening at higher redshifts. This is partially driven by variations in the dust-uncorrected UV slope of galaxies, due to different star formation histories of galaxies selected at different cosmic epochs; we suggest the remainder of the effect is caused by differences in the effective dust attenuation curves of galaxies as a function of redshift. We find a typical galaxy-to-galaxy variation of 0.3 dex in infrared excess (IRX) at fixed β, correlated with intrinsic galaxy properties: galaxies with higher star formation rates, star formation efficiencies, gas metallicities and stellar masses exhibit larger IRX values. We demonstrate a degeneracy between stellar age, dust geometry, and dust composition: z = 4 galaxies with a Small Magellanic Cloud dust type follow the same IRX–β relation as low-redshift galaxies with MW dust. We provide a redshift-dependent fitting function for the IRX–β relation for MW dust based on our models.

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Which attenuation curves for star-forming galaxies?

Proceedings of the International Astronomical Union ◽

10.1017/s1743921319002692 ◽

2019 ◽

Vol 15 (S341) ◽

pp. 70-73

Author(s):

Véronique Buat ◽

David Corre ◽

Médéric Boquien ◽

Katarzyna Małek

Keyword(s):

Radiative Transfer ◽

Spectral Energy ◽

Spectral Energy Distributions ◽

Energy Distributions ◽

Star Forming ◽

Radiative Transfer Models ◽

Attenuation Law ◽

Dust Attenuation ◽

Attenuation Laws ◽

Transfer Models

AbstractDust attenuation shapes the spectral energy distributions of galaxies and any modelling and fitting procedure of their spectral energy distributions must account for this process. We present results of two recent works dedicated at measuring the dust attenuation curves in star forming galaxies at redshift from 0.5 to 3, by fitting continuum (photometric) and line (spectroscopic) measurements simultaneously with CIGALE using variable attenuation laws based on flexible recipes. Both studies conclude to a large variety of effective attenuation laws with an attenuation law flattening when the obscuration increases. An extra attenuation is found for nebular lines. The comparison with radiative transfer models implies a flattening of the attenuation law up to near infrared wavelengths, which is well reproduced with a power-laws recipe inspired by the Charlot and Fall recipe. Here we propose a global modification of the Calzetti attenuation law to better reproduce the results of radiative transfer models.

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