scholarly journals Outflows and extended [C ii] haloes in high-redshift galaxies

2020 ◽  
Vol 495 (1) ◽  
pp. 160-172 ◽  
Author(s):  
E Pizzati ◽  
A Ferrara ◽  
A Pallottini ◽  
S Gallerani ◽  
L Vallini ◽  
...  
Keyword(s):  
High Redshift ◽  
Galactic Nuclei ◽  
Dark Matter Halo ◽  
Additional Energy ◽  
Dynamical Mass ◽  
High Redshift Galaxies ◽  
Star Forming ◽  
Outflow Rate ◽  
Pm 10 ◽  
Η Value

ABSTRACT Recent stacked ALMA observations have revealed that normal, star-forming galaxies at z ≈ 6 are surrounded by extended (≈10 kpc) [C ii]-emitting haloes, which are not predicted by the most advanced, zoom-in simulations. We present a model in which these haloes are the result of supernova-driven cooling outflows. Our model contains two free parameters, the outflow mass loading factor, η, and the parent galaxy dark matter halo circular velocity, vc. The outflow model successfully matches the observed [C ii] surface brightness profile if η = 3.20 ± 0.10 and $v_{\rm c} = 170 \pm 10 \, \rm km\, s^{-1}$, corresponding to a dynamical mass of ${\approx }10^{11}\, {\rm M}_{\odot }$. The predicted outflow rate and velocity range are $128 \pm 5\, {\rm M}_{\odot }\, {\rm yr}^{-1}$ and 300–500 $\, \rm km\, s^{-1}$, respectively. We conclude that (a) extended haloes can be produced by cooling outflows; (b) the large η value is marginally consistent with starburst-driven outflows, but it might indicate additional energy input from active galactic nuclei; and (c) the presence of [C ii] haloes requires an ionizing photon escape fraction from galaxies fesc ≪ 1. The model can be readily applied also to individual high-z galaxies, as those observed, e.g. by the ALMA ALPINE survey now becoming available.

scholarly journals Constraints on the production and escape of ionizing radiation from the emission-lines of metal-poor star-forming galaxies

2019 ◽  
Vol 15 (S352) ◽  
pp. 121-122
Author(s):  
A. Plat ◽  
S. Charlot ◽  
G. Bruzual ◽  
A. Feltre ◽  
A. Vidal-Garca ◽  
...  
Keyword(s):  
Ionizing Radiation ◽  
Emission Line ◽  
Active Galactic Nuclei ◽  
High Redshift ◽  
Galactic Nuclei ◽  
Emission Lines ◽  
High Redshift Galaxies ◽  
Star Forming ◽  
Radiative Shocks ◽  
Metal Poor Star

AbstractTo understand how the nature of the ionizing sources and the leakage of ionizing photons in high-redshift galaxies can be constrained from their emission-line spectra, we compare emission-line models of star-forming galaxies including leakage of ionizing radiation, active galactic nuclei (AGN) and radiative shocks, with observations of galaxies at various redshifts with properties expected to approach those of primeval galaxies.

Spectral Modeling of Star‐forming Regions in the Ultraviolet: Stellar Metallicity Diagnostics for High‐Redshift Galaxies

2004 ◽  
Vol 615 (1) ◽  
pp. 98-117 ◽  
Author(s):  
Samantha A. Rix ◽  
Max Pettini ◽  
Claus Leitherer ◽  
Fabio Bresolin ◽  
Rolf‐Peter Kudritzki ◽  
...  
Keyword(s):  
High Redshift ◽  
Spectral Modeling ◽  
High Redshift Galaxies ◽  
Star Forming ◽  
Star Forming Regions ◽  
Redshift Galaxies

scholarly journals HCN Observations of Dense Star-forming Gas in High-Redshift Galaxies

2007 ◽  
Vol 660 (2) ◽  
pp. L93-L96 ◽  
Author(s):  
Yu Gao ◽  
Chris L. Carilli ◽  
Philip M. Solomon ◽  
Paul A. Vanden Bout
Keyword(s):  
High Redshift ◽  
High Redshift Galaxies ◽  
Star Forming ◽  
Redshift Galaxies

scholarly journals Observations of the Lyman-α Universe

2020 ◽  
Vol 58 (1) ◽  
pp. 617-659
Author(s):  
Masami Ouchi ◽  
Yoshiaki Ono ◽  
Takatoshi Shibuya
Keyword(s):  
Star Formation ◽  
Dwarf Galaxy ◽  
High Redshift ◽  
Formation Rate ◽  
Neutral Hydrogen ◽  
Resonant Scattering ◽  
Dark Matter Halo ◽  
Emission Data ◽  
Star Forming ◽  
High Redshift Universe

Hydrogen Lyman-α (Lyα) emission has been one of the major observational probes for the high-redshift Universe since the first discoveries of high- z Lyα-emitting galaxies in the late 1990s. Due to the strong Lyα emission originated by resonant scattering and recombination of the most abundant element, Lyα observations witness not only Hii regions of star formation and active galactic nuclei (AGNs) but also diffuse Hi gas in the circumgalactic medium (CGM) and the intergalactic medium (IGM). Here, we review Lyα sources and present theoretical interpretations reached to date. We conclude the following: ▪  A typical Lyα emitter (LAE) at z ≳ 2 with a L* Lyα luminosity is a high- z counterpart of a local dwarf galaxy, a compact metal-poor star-forming galaxy (SFG) with an approximate stellar (dark matter halo) mass and star-formation rate of 108−9M⊙ (1010−11M⊙) and 1–10 M⊙ year−1, respectively. ▪  High- z SFGs ubiquitously have a diffuse Lyα-emitting halo in the CGM extending to the halo virial radius and beyond. ▪  Remaining neutral hydrogen at the epoch of cosmic reionization makes a strong dimming of Lyα emission for galaxies at z > 6 that suggests the late reionization history. The next-generation large-telescope projects will combine Lyα emission data with Hi Lyα absorptions and 21-cm radio data that map out the majority of hydrogen (Hi+Hii) gas, uncovering the exchanges of ( a) matter by outflow and inflow and ( b) radiation, relevant to cosmic reionization, between galaxies and the CGM/IGM.

scholarly journals Was the Milky Way Bulge Formed from the Buckling Disk Instability, Hierarchical Collapse, Accretion of Clumps, or All of the Above?

2017 ◽  
Vol 34 ◽  
Author(s):  
David M. Nataf
Keyword(s):  
Stellar Population ◽  
Milky Way ◽  
Velocity Dispersion ◽  
High Redshift ◽  
Rapid Development ◽  
High Redshift Galaxies ◽  
Star Forming ◽  
Thin And Thick Disks ◽  
Bulge Formation ◽  
Redshift Galaxies

AbstractThe assembly of the Milky Way bulge is an old topic in astronomy, one now in a period of renewed and rapid development. That is due to tremendous advances in observations of bulge stars, motivating observations of both local and high-redshift galaxies, and increasingly sophisticated simulations. The dominant scenario for bulge formation is that of the Milky Way as a nearly pure disk galaxy, with the inner disk having formed a bar and buckled. This can potentially explain virtually all bulge stars with [Fe/H] ≳ −1.0, which comprise 95% of the stellar population. The evidence is the incredible success in N-body models of this type in making non-trivial, non-generic predictions, such as the rotation curve and velocity dispersion measured from radial velocities, and the spatial morphologies of the peanut/X-shape and the long bar. The classical bulge scenario, whereby the bulge formed from early dissipative collapse and mergers, remains viable for stars with [Fe/H] ≲ −1.0 and potentially a minority of the other stars. A classical bulge is expected from Λ-CDM cosmological simulations, can accentuate the properties of an existing bar in a hybrid system, and is most consistent with the bulge abundance trends such as [Mg/Fe], which are elevated relative to both the thin and thick disks. Finally, the clumpy-galaxy scenario is considered, as it is the correct description of most Milky Way precursors given observations of high-redshift galaxies. Simulations predict that these star-forming clumps will sometimes migrate to the centres of galaxies where they may form a bulge, and galaxies often include a bulge clump as well. They will possibly form a bar with properties consistent with those of the Milky Way, such as the exponential profile and metallicity gradient. Given the relative successes of these scenarios, the Milky Way bulge is plausibly of composite origin, with a classical bulge and/or inner halo numerically dominant for stars with [Fe/H] ≲ −1.0, a buckling thick disk for stars with − 1.0 ≲ [Fe/H]] ≲ -0.50 perhaps descended from the clumpy-galaxy phase, and a buckling thin disk for stars with [Fe/H] ≳ −0.50. Overlaps from these scenarios are uncertain throughout.

scholarly journals The Evolution of Luminous Compact Blue Galaxies: Disks or Spheroids?

2010 ◽  
Vol 6 (S277) ◽  
pp. 291-295
Author(s):  
D. J. Pisano ◽  
K. Rabidoux ◽  
C. A. Garland ◽  
R. Guzmán ◽  
F. J. Castander ◽  
...  
Keyword(s):  
Star Formation ◽  
High Redshift ◽  
High Surface ◽  
Blue Color ◽  
Dynamical Mass ◽  
Star Forming ◽  
Blue Galaxies ◽  
Multi Wavelength ◽  
Fisher Relation ◽  
Combined Data

AbstractLuminous compact blue galaxies (LCBGs) are a diverse class of galaxies characterized by high luminosity, blue color, and high surface brightness that sit at the critical juncture of galaxies evolving from the blue to the red sequence. As part of our multi-wavelength survey of local LCBGs, we have been studying the HI content of these galaxies using both single-dish telescopes and interferometers. Our goals are to determine if single-dish HI observations represent a true measure of the dynamical mass of LCBGs and to look for signatures of recent interactions that may be triggering star formation in LCBGs. Our data show that while some LCBGs are undergoing interactions, many appear isolated. While all LCBGs contain HI and show signatures of rotation, the population does not lie on the Tully-Fisher relation nor can it evolve onto it. Furthermore, the HI maps of many LCBGs show signatures of dynamically hot components, suggesting that we are seeing the formation of a thick disk or spheroid in at least some LCBGs. There is good agreement between the HI and Hα kinematics for LCBGs, and both are similar in appearance to the Hα kinematics of high redshift star-forming galaxies. Our combined data suggest that star formation in LCBGs is primarily quenched by virial heating, consistent with model predictions.

scholarly journals Extremely metal-poor galaxies with HST/COS: laboratories for models of low-metallicity massive stars and high-redshift galaxies

2019 ◽  
Vol 488 (3) ◽  
pp. 3492-3506 ◽  
Author(s):  
Peter Senchyna ◽  
Daniel P Stark ◽  
Jacopo Chevallard ◽  
Stéphane Charlot ◽  
Tucker Jones ◽  
...  
Keyword(s):  
Massive Stars ◽  
High Redshift ◽  
Formation Rate ◽  
Uv Spectra ◽  
High Redshift Galaxies ◽  
Star Forming ◽  
High Ionization ◽  
Moderate Resolution ◽  
Low Metallicity ◽  
Nearby Galaxies

Abstract Ultraviolet (UV) observations of local star-forming galaxies have begun to establish an empirical baseline for interpreting the rest-UV spectra of reionization-era galaxies. However, existing high-ionization emission line measurements at z > 6 ($\rm W_{C\, {\scriptscriptstyle IV},0}{} \gtrsim 20$ Å) are uniformly stronger than observed locally ($\rm W_{C\, {\scriptscriptstyle IV},0}{} \lesssim 2$ Å), likely due to the relatively high metallicities (Z/Z$\odot$ > 0.1) typically probed by UV surveys of nearby galaxies. We present new HST/COS spectra of six nearby (z < 0.01) extremely metal-poor galaxies (XMPs, Z/Z$\odot$ ≲ 0.1) targeted to address this limitation and provide constraints on the highly uncertain ionizing spectra powered by low-metallicity massive stars. Our data reveal a range of spectral features, including one of the most prominent nebular C iv doublets yet observed in local star-forming systems and strong He ii emission. Using all published UV observations of local XMPs to date, we find that nebular C iv emission is ubiquitous in very high specific star formation rate systems at low metallicity, but still find equivalent widths smaller than those measured in individual lensed systems at z > 6. Our moderate-resolution HST/COS data allow us to conduct an analysis of the stellar winds in a local nebular C iv emitter, which suggests that some of the tension with z > 6 data may be due to existing local samples not yet probing sufficiently high α/Fe abundance ratios. Our results indicate that C iv emission can play a crucial role in the JWST and ELT era by acting as an accessible signpost of very low metallicity (Z/Z$\odot$ < 0.1) massive stars in assembling reionization-era systems.

scholarly journals Is the dark-matter halo spin a predictor of galaxy spin and size?

2019 ◽  
Vol 488 (4) ◽  
pp. 4801-4815 ◽  
Author(s):  
Fangzhou Jiang ◽  
Avishai Dekel ◽  
Omer Kneller ◽  
Sharon Lapiner ◽  
Daniel Ceverino ◽  
...  
Keyword(s):  
Dark Matter ◽  
Angular Momentum ◽  
High Redshift ◽  
General Relation ◽  
Retention Factor ◽  
Dark Matter Halo ◽  
High Redshift Galaxies ◽  
The Galaxy ◽  
One To One ◽  
Analytic Models

ABSTRACT The similarity between the distributions of spins for galaxies (λgal) and for dark-matter haloes (λhalo), indicated both by simulations and observations, is naively interpreted as a one-to-one correlation between the spins of a galaxy and its host halo. This is used to predict galaxy sizes in semi-analytic models via Re ≃ fjλhaloRvir, where Re is the half-mass radius of the galaxy, fj is the angular momentum retention factor, and Rvir is the halo radius. Using two suites of zoom-in cosmological simulations, we find that λgal and the λhalo of its host halo are in fact barely correlated, especially at z ≥ 1, in line with previous indications. Since the spins of baryons and dark matter are correlated at accretion into Rvir, the null correlation in the end reflects an anticorrelation between fj and λhalo, which can arise from mergers and a ‘wet compaction’ phase that many high-redshift galaxies undergo. It may also reflect that unrepresentative small fractions of baryons are tapped to the galaxies. The galaxy spin is better correlated with the spin of the inner halo, but this largely reflects the effect of the baryons on the halo. While λhalo is not a useful predictor for Re, our simulations reproduce a general relation of the form of Re = ARvir, in agreement with observational estimates. We find that the relation becomes tighter with A = 0.02(c/10)−0.7, where c is the halo concentration, which in turn introduces a dependence on mass and redshift.

scholarly journals The mass–metallicity and the fundamental metallicity relation revisited on a fully Te-based abundance scale for galaxies

2019 ◽  
Vol 491 (1) ◽  
pp. 944-964 ◽  
Author(s):  
Mirko Curti ◽  
Filippo Mannucci ◽  
Giovanni Cresci ◽  
Roberto Maiolino
Keyword(s):  
High Redshift ◽  
Formation Rate ◽  
Cosmic Time ◽  
Stellar Mass ◽  
Strong Line ◽  
High Redshift Galaxies ◽  
Star Forming ◽  
Theoretical Predictions ◽  
Galaxy Population ◽  
Good Agreement

ABSTRACT The relationships between stellar mass, gas-phase metallicity and star-formation rate (i.e. the mass–metallicity, MZR, and the fundamental metallicity relation, FMR) in the local Universe are revisited by fully anchoring the metallicity determination for SDSS galaxies on the Te abundance scale defined exploiting the strong-line metallicity calibrations presented by Curti et al. Self-consistent metallicity measurements allow a more unbiased assessment of the scaling relations involving M, Z and SFR, which provide powerful constraints for the chemical evolution models. We parametrize the MZR with a new functional form that allows us to better characterize the turnover mass. The slope and saturation metallicity are in good agreement with previous determinations of the MZR based on the Te method, while showing significantly lower normalization compared to those based on photoionization models. The Z–SFR dependence at fixed stellar mass is also investigated, being particularly evident for highly star-forming galaxies, where the scatter in metallicity is reduced up to a factor of ${\sim}30{{\ \rm per\ cent}}$. A new parametrization of the FMR is given by explicitly introducing the SFR dependence of the turnover mass into the MZR. The residual scatter in metallicity for the global galaxy population around the new FMR is 0.054 dex. The new FMR presented in this work represents a useful local benchmark to compare theoretical predictions and observational studies (of both local and high-redshift galaxies) whose metallicity measurements are tied to the abundance scale defined by the Te method, hence allowing proper assessment of its evolution with cosmic time.

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