scholarly journals An uncertainty principle for star formation – V. The influence of dust extinction on star formation rate tracer lifetimes and the inferred molecular cloud lifecycle

2020 ◽  
Vol 497 (4) ◽  
pp. 5076-5089
Author(s):  
Daniel T Haydon ◽  
Yusuke Fujimoto ◽  
Mélanie Chevance ◽  
J M Diederik Kruijssen ◽  
Mark R Krumholz ◽  
...  
Keyword(s):  
Star Formation ◽  
Time Scales ◽  
Molecular Cloud ◽  
Column Density ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Disc Galaxy ◽  
Dust Extinction ◽  
Stellar Feedback ◽  
Emission Time

ABSTRACT Recent observational studies aiming to quantify the molecular cloud lifecycle require the use of known ‘reference time-scales’ to turn the relative durations of different phases of the star formation process into absolute time-scales. We previously constrained the characteristic emission time-scales of different star formation rate (SFR) tracers, as a function of the SFR surface density and metallicity. However, we omitted the effects of dust extinction. Here, we extend our suite of SFR tracer emission time-scales by accounting for extinction, using synthetic emission maps of a high-resolution hydrodynamical simulation of an isolated, Milky Way-like disc galaxy. The stellar feedback included in the simulation is inefficient compared to observations, implying that it represents a limiting case in which the duration of embedded star formation (and the corresponding effect of extinction) is overestimated. Across our experiments, we find that extinction mostly decreases the SFR tracer emission time-scale, changing the time-scales by factors of 0.04–1.74, depending on the gas column density. UV filters are more strongly affected than H α filters. We provide the limiting correction factors as a function of the gas column density and flux sensitivity limit for a wide variety of SFR tracers. Applying these factors to observational characterizations of the molecular cloud lifecycle produces changes that broadly fall within the quoted uncertainties, except at high kpc-scale gas surface densities ($\Sigma _{\rm g}\gtrsim 20~{\mathrm{M_{\odot }\, pc^{-2}}}$). Under those conditions, correcting for extinction may decrease the measured molecular cloud lifetimes and feedback time-scales, which further strengthens previous conclusions that molecular clouds live for a dynamical time and are dispersed by early, pre-supernova feedback.

scholarly journals The VANDELS survey: the role of ISM and galaxy physical properties in the escape of Lyα emission in z ∼ 3.5 star-forming galaxies

2019 ◽  
Vol 631 ◽  
pp. A19 ◽  
Author(s):  
F. Marchi ◽  
L. Pentericci ◽  
L. Guaita ◽  
M. Talia ◽  
M. Castellano ◽  
...  
Keyword(s):  
Star Formation ◽  
Physical Properties ◽  
Emission Line ◽  
Column Density ◽  
Star Formation Rate ◽  
Spectral Energy Distribution ◽  
Formation Rate ◽  
Stellar Mass ◽  
Dust Extinction

Aims. We wish to investigate the physical properties of a sample of Lyα emitting galaxies in the VANDELS survey, with particular focus on the role of kinematics and neutral hydrogen column density in the escape and spatial distribution of Lyα photons. Methods. From all the Lyα emitting galaxies in the VANDELS Data Release 2 at 3.5 ≲ z ≲ 4.5, we selected a sample of 52 galaxies that also have a precise systemic redshift determination from at least one nebular emission line (HeII or CIII]). For these galaxies, we derived different physical properties (stellar mass, age, dust extinction, and star formation rate) from spectral energy distribution (SED) fitting of the exquisite multiwavelength photometry available in the VANDELS fields, using the dedicated spectral modeling tool BEAGLE and the UV β slope from the observed photometry. We characterized the Lyα emission in terms of kinematics, equivalent width (EW), full width at half-maximum, and spatial extension and then estimated the velocity of the neutral outflowing gas. The ultra-deep VANDELS spectra (up to 80 h on-source integration) enable this for individual galaxies without the need to rely on stacks. We then investigated the correlations between the Lyα properties and the other measured properties to study how they affect the shape and intensity of Lyα emission. Results. We reproduce some of the well-known correlations between Lyα EW and stellar mass, dust extinction, and UV β slope, in the sense that the emission line appears brighter in galaxies with lower mass that are less dusty and bluer. We do not find any correlation with the SED-derived star formation rate, while we find that galaxies with brighter Lyα tend to be more compact in both UV and in Lyα. Our data reveal an interesting correlation between the Lyα velocity offset and the shift of the interstellar absorption lines with respect to the systemic redshift, observed for the first time at high redshifts: galaxies with higher interstellar medium (ISM) outflow velocities show smaller Lyα velocity shifts. We interpret this relation in the context of the shell-model scenario, where the velocity of the ISM and the HI column density contribute together in determining the Lyα kinematics. In support to our interpretation, we observe that galaxies with high HI column densities have much more extended Lyα spatial profiles; this is a sign of increased scattering. However, we do not find any evidence that the HI column density is related to any other physical properties of the galaxies, although this might be due in part to the limited range of parameters that our sample spans.

scholarly journals Efficacy of early stellar feedback in low gas surface density environments

2019 ◽  
Vol 491 (2) ◽  
pp. 2088-2103 ◽  
Author(s):  
Rahul Kannan ◽  
Federico Marinacci ◽  
Christine M Simpson ◽  
Simon C O Glover ◽  
Lars Hernquist
Keyword(s):  
Star Formation ◽  
Radiation Pressure ◽  
Surface Density ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Medium Density ◽  
Hydrodynamic Simulations ◽  
Radiative Feedback ◽  
Stellar Feedback ◽  
Radiation Feedback

ABSTRACT We present a suite of high-resolution radiation hydrodynamic simulations of a small patch (1 kpc2) of the interstellar medium (ISM) performed with arepo-rt, with the aim to quantify the efficacy of various feedback processes like supernova (SN) explosions, photoheating, and radiation pressure in low gas surface density galaxies (Σgas ≃ 10 M⊙ pc−2). We show that radiative feedback decrease the star formation rate and therefore the total stellar mass formed by a factor of approximately two. This increases the gas depletion time-scale and brings the simulated Kennicutt–Schmidt relation closer to the observational estimates. Radiation feedback coupled with SN is more efficient at driving outflows with the mass and energy loading increasing by a factor of ∼10. This increase is mainly driven by the additional entrainment of medium-density (10−2  cm−3 ≤ n < 1 cm−3) warm (300 K ≤ T < 8000 K) material. Therefore, including radiative feedback tends to launch colder, denser, and more mass- and energy-loaded outflows. This is because photoheating of the high-density gas around a newly formed star overpressurizes the region, causing it to expand. This reduces the ambient density in which the SN explode by a factor of 10–100 which in turn increases their momentum output by a factor of ∼1.5–2.5. Finally, we note that in these low gas surface density environments, radiative feedback primarily impact the ISM via photoheating and radiation pressure has only a minimal role in regulating star formation.

scholarly journals ULTRA-FAINT ULTRAVIOLET GALAXIES ATz∼ 2 BEHIND THE LENSING CLUSTER A1689: THE LUMINOSITY FUNCTION, DUST EXTINCTION, AND STAR FORMATION RATE DENSITY

2013 ◽  
Vol 780 (2) ◽  
pp. 143 ◽  
Author(s):  
Anahita Alavi ◽  
Brian Siana ◽  
Johan Richard ◽  
Daniel P. Stark ◽  
Claudia Scarlata ◽  
...  
Keyword(s):  
Star Formation ◽  
Luminosity Function ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Dust Extinction

scholarly journals THE OBSERVED RELATION BETWEEN STELLAR MASS, DUST EXTINCTION, AND STAR FORMATION RATE IN LOCAL GALAXIES

2013 ◽  
Vol 763 (2) ◽  
pp. 92 ◽  
Author(s):  
H. J. Zahid ◽  
R. M. Yates ◽  
L. J. Kewley ◽  
R. P. Kudritzki
Keyword(s):  
Star Formation ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Stellar Mass ◽  
Dust Extinction

scholarly journals A LOFAR-IRAS cross-match study: the far-infrared radio correlation and the 150 MHz luminosity as a star-formation rate tracer

2019 ◽  
Vol 631 ◽  
pp. A109 ◽  
Author(s):  
L. Wang ◽  
F. Gao ◽  
K. J. Duncan ◽  
W. L. Williams ◽  
M. Rowan-Robinson ◽  
...  
Keyword(s):  
Star Formation ◽  
Rest Frame ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Value Added ◽  
Far Infrared ◽  
Star Forming ◽  
Dust Extinction ◽  
Best Fit ◽  
Cross Match

Aims. We aim to study the far-infrared radio correlation (FIRC) at 150 MHz in the local Universe (at a median redshift ⟨z⟩∼0.05) and improve the use of the rest-frame 150 MHz luminosity, L150, as a star-formation rate (SFR) tracer, which is unaffected by dust extinction. Methods. We cross-match the 60 μm selected Revised IRAS Faint Source Survey Redshift (RIFSCz) catalogue and the 150 MHz selected LOFAR value-added source catalogue in the Hobby-Eberly Telescope Dark Energy Experiment (HETDEX) Spring Field. We estimate L150 for the cross-matched sources and compare it with the total infrared (IR) luminosity, LIR, and various SFR tracers. Results. We find a tight linear correlation between log L150 and log LIR for star-forming galaxies, with a slope of 1.37. The median qIR value (defined as the logarithm of the LIR to L150 ratio) and its rms scatter of our main sample are 2.14 and 0.34, respectively. We also find that log L150 correlates tightly with the logarithm of SFR derived from three different tracers, i.e., SFRHα based on the Hα line luminosity, SFR60 based on the rest-frame 60 μm luminosity and SFRIR based on LIR, with a scatter of 0.3 dex. Our best-fit relations between L150 and these SFR tracers are, log L150 (L⊙) = 1.35(±0.06) × log SFRHα (M⊙ yr−1) + 3.20(±0.06), log L150 (L⊙) = 1.31(±0.05) × log SFR60 (M⊙ yr−1) + 3.14(±0.06), and log L150 (L⊙) = 1.37 (±0.05) × log SFRIR (M⊙ yr−1) + 3.09(±0.05), which show excellent agreement with each other.

scholarly journals The spatially resolved star formation history of mergers

2017 ◽  
Vol 607 ◽  
pp. A70 ◽  
Author(s):  
C. Cortijo-Ferrero ◽  
R. M. González Delgado ◽  
E. Pérez ◽  
R. Cid Fernandes ◽  
R. García-Benito ◽  
...  
Keyword(s):  
Star Formation ◽  
Time Scales ◽  
Time Scale ◽  
Star Formation Rate ◽  
Early Stage ◽  
Formation Rate ◽  
Small Sample ◽  
Star Formation History ◽  
Spatially Resolved ◽  
Formation History

This paper presents the spatially resolved star formation history (2D-SFH) of a small sample of four local mergers: the early-stage mergers IC 1623, NGC 6090, and the Mice, and the more advanced merger NGC 2623, by analyzing IFS data from the CALIFA survey and PMAS in LArr mode. Full spectral fitting techniques are applied to the datacubes to obtain the spatially resolved mass growth histories, the time evolution of the star formation rate intensity (ΣSFR), and the local specific star formation rate (sSFR), over three different time scales (30 Myr, 300 Myr, and 1 Gyr). The results are compared with non-interacting Sbc–Sc galaxies, to quantify if there is an enhancement of the star formation and to trace its time scale and spatial extent. Our results for the three LIRGs (IC 1623 W, NGC 6090, and NGC 2623) show that a major phase of star formation is occurring in time scales of 107 yr to few 108 yr, with global SFR enhancements of between approximately two and six with respect to main-sequence star forming (MSSF) galaxies. In the two early-stage mergers IC 1623 W and NGC 6090, which are between first pericentre passage and coalescence, the most remarkable increase of the SFR with respect to non-interacting spirals occurred in the last 30 Myr, and it is spatially extended, with enhancements of factors between two and seven both in the centres (r < 0.5 half light radius, HLR), and in the disks (r > 1 HLR). In the more advanced merger NGC 2623 an extended phase of star formation occurred on a longer time scale of ~1 Gyr, with a SFR enhancement of a factor of approximately two-to-three larger than the one in Sbc–Sc MSSF galaxies over the same period, probably relic of the first pericentre passage epoch. A SFR enhancement in the last 30 Myr is also present, but only in NGC 2623 centre, by a factor of three. In general, the spatially resolved SFHs of the LIRG-mergers are consistent with the predictions from high spatial resolution simulations. In contrast, the star formation in the Mice, specially in Mice B, is not enhanced but inhibited with respect to Sbc–Sc MSSF galaxies. The fact that the gas fraction of Mice B is smaller than in most non-interacting spirals, and that the Mice are close to a prograde orbit, represents a new challenge for the models, which must cover a larger space of parameters in terms of the availability of gas and the orbital characteristics.

scholarly journals Obscured star formation atz= 0.84 with HiZELS: the relationship between star formation rate and Hα or ultraviolet dust extinction

2010 ◽  
Vol 402 (3) ◽  
pp. 2017-2030 ◽  
Author(s):  
Timothy Garn ◽  
David Sobral ◽  
Philip N. Best ◽  
James E. Geach ◽  
Ian Smail ◽  
...  
Keyword(s):  
Star Formation ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Dust Extinction ◽  
The Relationship

Effect of Dust Extinction on Estimating the Star Formation Rate of Galaxies: Lyman Continuum Extinction

2001 ◽  
Vol 555 (2) ◽  
pp. 613-624 ◽  
Author(s):  
Akio K. Inoue ◽  
Hiroyuki Hirashita ◽  
Hideyuki Kamaya
Keyword(s):  
Star Formation ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Dust Extinction ◽  
Lyman Continuum

scholarly journals On the origin of magnetic driven winds and the structure of the galactic dynamo in isolated galaxies

2020 ◽  
Vol 494 (3) ◽  
pp. 4393-4412 ◽  
Author(s):  
Ulrich P Steinwandel ◽  
Klaus Dolag ◽  
Harald Lesch ◽  
Benjamin P Moster ◽  
Andreas Burkert ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Star Formation ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Disc Galaxy ◽  
Isolated Galaxies ◽  
Induction Equation ◽  
Field Lines ◽  
The Magnetic Field ◽  
Good Agreement

ABSTRACT We investigate the build-up of the galactic dynamo and subsequently the origin of a magnetic driven outflow. We use a set-up of an isolated disc galaxy with a realistic circum-galactic medium (CGM). We find good agreement of the galactic dynamo with theoretical and observational predictions from the radial and toroidal components of the magnetic field as function of radius and disc scale height. We find several field reversals indicating dipole structure at early times and quadrupole structure at late times. Together with the magnetic pitch angle and the dynamo control parameters Rα, Rω, and D, we present strong evidence for an α2–Ω dynamo. The formation of a bar in the centre leads to further amplification of the magnetic field via adiabatic compression which subsequently drives an outflow. Due to the Parker instability the magnetic field lines rise to the edge of the disc, break out, and expand freely in the CGM driven by the magnetic pressure. Finally, we investigate the correlation between magnetic field and star formation rate. Globally, we find that the magnetic field is increasing as function of the star formation rate surface density with a slope between 0.3 and 0.45 in good agreement with predictions from theory and observations. Locally, we find that the magnetic field can decrease while star formation increases. We find that this effect is correlated with the diffusion of magnetic field from the spiral arms to the interarm regions which we explicitly include by solving the induction equation and accounting for non-linear terms.

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