First Light And Reionisation Epoch Simulations (FLARES) XII: The consequences of star-dust geometry on galaxies in the EoR

Abstract

Using the First Light And Reionisation Epoch Simulations ($\mathrm{F}\mathrm{LARES}$), a suite of hydrodynamical simulations we explore the consequences of a realistic model for star--dust geometry on the observed properties of galaxies. We find that the UV attenuation declines rapidly from the central regions of galaxies, and bright galaxies have spatially extended star formation that suffers less obscuration than their fainter counterparts, demonstrating a non-linear relationship between the UV luminosity and the UV attenuation, giving a double power-law shape to the UVLF. Spatially distinct stellar populations within galaxies experience a wide range of dust attenuation due to variations in the dust optical depth along their line-of-sight; which can range from completely dust obscured to being fully unobscured. The overall attenuation curve of a galaxy is then a complex combination of various lines-of-sight within the galaxy. We explore the manifestation of this effect to study the reliability of line ratios to infer galaxy properties, in particular the Balmer decrement and the BPT diagram. We find the Balmer decrement predicted Balmer line attenuation to be higher (factor of $1$ to $\gtrsim 10$) than expected from commonly used attenuation curves. The observed BPT line ratios deviate from their intrinsic values (median difference of 0.08 (0.02) and standard deviation of 0.2 (0.05) for log${}_{10}$([N$\mathrm{II}$]$\lambda 6585/$H${}_{\alpha }$) (log${}_{10}$([O$\mathrm{III}$]$\lambda 5008/$H${}_{\beta }$)). Finally, we explore the variation in observed properties (UV attenuation, UV slope and Balmer decrement) with viewing angle, finding average differences of $\sim 0.3$ magnitudes in the UV attenuation.

17 pages, 13 figures. Published MNRAS. Data available at https://flaresimulations.github.io

References in corpus (44)

• Array Programming with NumPy
• The Astropy Project: Sustaining and Growing a Community-oriented Open-source Project and the Latest Major Release (v5.0) of the Core Package
• The EAGLE project: Simulating the evolution and assembly of galaxies and their environments
• The EAGLE simulations of galaxy formation: calibration of subgrid physics and model variations
• UV Luminosity Functions at redshifts z~4 to z~10: 10000 Galaxies from HST Legacy Fields
• Simba: Cosmological Simulations with Black Hole Growth and Feedback
• A Comprehensive Study on Galaxies at z~9-16 Found in the Early JWST Data: UV Luminosity Functions and Cosmic Star-Formation History at the Pre-Reionization Epoch
• Two Remarkably Luminous Galaxy Candidates at $z\approx 10-12$ Revealed by JWST
• The evolution of the galaxy UV luminosity function at redshifts z ~ 8-15 from deep JWST and ground-based near-infrared imaging
• Early results from GLASS-JWST. III: Galaxy candidates at z$\sim$9-15
• CMasher: Scientific colormaps for making accessible, informative and 'cmashing' plots
• Discovery and properties of ultra-high redshift galaxies ($9<z<12$) in the JWST ERO SMACS 0723 Field
• Nebular Emission Line Ratios in z~2-3 Star-Forming Galaxies with KBSS-MOSFIRE: Exploring the Impact of Ionization, Excitation, and Nitrogen-to-Oxygen Ratio
• New insights into the stellar content and physical conditions of star-forming galaxies at z = 2-3 from spectral modelling
• The MOSDEF Survey: Excitation Properties of $z\sim 2.3$ Star-forming Galaxies
• On the Stellar Populations of Galaxies at z=9-11: The Growth of Metals and Stellar Mass at Early Times
• A JWST/NIRCam Study of Key Contributors to Reionization: The Star-forming and Ionizing Properties of UV-faint $z\sim 7-8$ Galaxies
• JADES: Probing interstellar medium conditions at $z\sim 5.5-9.5$ with ultra-deep JWST/NIRSpec spectroscopy
• Panic! At the Disks: First Rest-frame Optical Observations of Galaxy Structure at $z>3$ with JWST in the SMACS 0723 Field
• Normal, Dust-Obscured Galaxies in the Epoch of Reionization
• CEERS Key Paper V: A triality on the nature of HST-dark galaxies
• The GREATS H$\beta$+[OIII] Luminosity Function and Galaxy Properties at $\mathbf{z}\sim 8$: Walking the Way of JWST
• A First Look at the Abundance Pattern -- O/H, C/O, and Ne/O -- in $z>7$ Galaxies with JWST/NIRSpec
• The ALMA REBELS Survey: The Dust-obscured Cosmic Star Formation Rate Density at Redshift 7
• The ALMA REBELS Survey. Epoch of Reionization giants: properties of dusty galaxies at $z\approx 7$
• JWST unveils heavily obscured (active and passive) sources up to z~13
• Detailed dust modelling in the L-Galaxies semi-analytic model of galaxy formation
• Dust Attenuation in High Redshift Galaxies -- 'Diamonds in the Sky'
• Spatially Resolved Properties of High Redshift Galaxies in the SMACS0723 JWST ERO Field
• First Light And Reionisation Epoch Simulations (FLARES) V: The redshift frontier
• JWST/NIRCam Observations of Stars and HII Regions in $z\simeq 6-8$ Galaxies: Properties of Star Forming Complexes on 150 pc Scales
• First Light And Reionisation Epoch Simulations (FLARES) IV: The size evolution of galaxies at $z\ge 5$
• Dust Obscured Star Forming Galaxies in the Early Universe
• The JWST UNCOVER Treasury survey: Ultradeep NIRSpec and NIRCam ObserVations before the Epoch of Reionization
• The ALPINE-ALMA [CII] survey: dust attenuation curves at z=4.4-5.5
• First Light And Reionisation Epoch Simulations (FLARES) VII: The Star Formation and Metal Enrichment Histories of Galaxies in the early Universe
• The BPT Diagram in Cosmological Galaxy Formation Simulations: Understanding the Physics Driving Offsets at High-Redshift
• How Well Can We Measure Galaxy Dust Attenuation Curves? The Impact of the Assumed Star-Dust Geometry Model in SED Fitting
• Geometry effects on dust attenuation curves with different grain sources at high redshift
• First Light And Reionisation Epoch Simulations (FLARES) VI: The colour evolution of galaxies $z=5-15$
• Unveiling the main sequence of galaxies at $z\ge 5$ with the James Webb Space Telescope: predictions from simulations
• Excitation and Ionization Properties of Star-forming Galaxies at z=2.0-9.3 with JWST/NIRSpec
• Effects of dust sources on dust attenuation properties in IllustrisTNG galaxies at $z\sim 7$
• The need for multicomponent dust attenuation in modeling nebular emission: Constraints from SDSS-IV MaNGA

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• The JWST-PRIMAL Legacy Survey. A JWST/NIRSpec reference sample for the physical properties and Lyman-$\alpha$ absorption and emission of $\sim 500$ galaxies at $z=5.5-13.4$
• The Structure of Massive Star-Forming Galaxies from JWST and ALMA: Dusty, High Redshift Disk Galaxies
• The Extreme Low-mass End of the Mass-Metallicity Relation at $z\sim 7$
• First Light And Reionisation Epoch Simulations (FLARES) XVI: Size Evolution of Massive Dusty Galaxies at Cosmic Dawn from UV to IR