scholarly journals Jet‐induced Emission‐Line Nebulosity and Star Formation in the High‐Redshift Radio Galaxy 4C 41.17

2000 ◽  
Vol 540 (2) ◽  
pp. 678-686 ◽  
Author(s):  
Geoffrey V. Bicknell ◽  
Ralph S. Sutherland ◽  
Wil J. M. van Breugel ◽  
Michael A. Dopita ◽  
Arjun Dey ◽  
...  
Keyword(s):  
Star Formation ◽  
Emission Line ◽  
Radio Galaxy ◽  
High Redshift

scholarly journals Optical Polarization of 3C 265

1996 ◽  
Vol 175 ◽  
pp. 223-226 ◽  
Author(s):  
M.H. Cohen ◽  
H.D. Tran ◽  
P.M. Ogle ◽  
R.W. Goodrich
Keyword(s):  
Emission Line ◽  
Radio Galaxy ◽  
High Redshift ◽  
Optical Polarization ◽  
Alignment Effect ◽  
Distant Galaxies ◽  
Extended Emission

3C 265 is a high-redshift (z=0.811) radio galaxy showing extended emission line regions (EELR) to 50 kpc from the nucleus (McCarthy et al 1995). However, it does not show the alignment effect (McCarthy 1993) that is common in distant galaxies: the EELR is not extended along the radio axis.

scholarly journals Star Formation in Damped Lyman α Selected Galaxies

2007 ◽  
Vol 3 (S244) ◽  
pp. 284-288
Author(s):  
Lise Christensen
Keyword(s):  
Star Formation ◽  
Emission Line ◽  
High Redshift ◽  
Neutral Hydrogen ◽  
Disk Galaxies ◽  
Local Universe ◽  
High Redshift Galaxies ◽  
Neutral Gas ◽  
Integral Field Spectroscopy ◽  
Integral Field

AbstractI present results from an ongoing survey to study galaxies associated with damped Lyman-α (DLA) systems at redshifts z>2. Integral field spectroscopy is used to search for Lyα emission line objects at the wavelengths where the emission from the quasars have been absorbed by the DLAs. The DLA galaxy candidates detected in this survey are found at distances of 10–20 kpc from the quasar line of sight, implying that galaxies are surrounded by neutral hydrogen at large distances. If we assume that the distribution of neutral gas is exponential, the scale length of the neutral gas is ~6 kpc, similar to large disk galaxies in the local Universe. The emission line luminosities imply smaller star formation rates compared to other high redshift galaxies found in luminosity selected samples.

scholarly journals Blue galaxies: modelling nebular He ii emission in high redshift galaxies

2019 ◽  
Vol 491 (3) ◽  
pp. 4509-4522 ◽  
Author(s):  
Kirk S S Barrow
Keyword(s):  
Star Formation ◽  
Emission Line ◽  
High Redshift ◽  
Mass Function ◽  
Initial Mass Function ◽  
High Mass ◽  
Test Case ◽  
Good Test ◽  
Cosmological Simulations ◽  
Modelling Studies

ABSTRACT Using cosmological simulations to make useful, scientifically relevant emission line predictions is a relatively new and rapidly evolving field. However, nebular emission lines have been particularly challenging to model because they are extremely sensitive to the local photoionization balance, which can be driven by a spatially dispersed distribution of stars amidst an inhomogeneous absorbing medium of dust and gas. As such, several unmodelled mysteries in observed emission line patterns exist in the literature. For example, there is some question as to why He ii λ4686/H β ratios in observations of lower metallicity dwarf galaxies tend to be higher than model predictions. Since hydrodynamic cosmological simulations are best suited to this mass and metallicity regime, this question presents a good test case for the development of a robust emission line modelling pipeline. The pipeline described in this work can model a process that produces high He ii λ4686/H β ratios and eliminate some of the modelling discrepancy for ratios below 3 per cent without including AGNs, X-ray binaries, high mass binaries, or a top-heavy stellar initial mass function. These ratios are found to be more sensitive to the presence of 15 Myr or longer gaps in the star formation histories than to extraordinary ionization parameters or specific star formation rates. They also closely correspond to the WR phase of massive stars. In addition to the investigation into He ii λ4686/H β ratios, this work charts a general path forward for the next generation of nebular emission line modelling studies.

H II galaxies as distance estimators at high redshift

1999 ◽  
Vol 193 ◽  
pp. 692-702
Author(s):  
Jorge Melnick ◽  
Roberto J. Terlevich ◽  
Elena Terlevich ◽  
Benoit Joguet
Keyword(s):  
Star Formation ◽  
Emission Line ◽  
High Redshift ◽  
High Mass ◽  
Mass Star ◽  
Distance Indicator ◽  
Line Widths ◽  
Distance Indicators ◽  
Considerable Detail ◽  
Better Than

Owing to their large luminosities per unit mass H II galaxies allow us to investigate in considerable detail the process of high mass star formation out to redshifts of cosmological importance. In this contribution we discuss the calibration of the correlation between the Hβ luminosity and the emission line width of H II galaxies as a distance indicator. We show that H II galaxies can be reliably used as distance indicators out to redshifts z > 3 provided that their line widths and fluxes can be determined with accuracies better than 10%.

scholarly journals Tracing Metallicity in High Redshift Quasars

2009 ◽  
Vol 5 (S265) ◽  
pp. 183-184
Author(s):  
Leah E. Simon ◽  
Fred Hamann
Keyword(s):  
Star Formation ◽  
Emission Line ◽  
Gas Phase ◽  
High Redshift ◽  
Ultra Violet ◽  
Far Infrared ◽  
Sloan Digital Sky Survey ◽  
Host Galaxies ◽  
Composite Spectra ◽  
Sky Survey

AbstractWe present two ongoing studies of gas phase abundances around high redshift quasars. First, we examine broad emission line (BEL) metallicities for 29 quasars with 2.3 < z < 4.6 and far-infrared (far-IR) luminosities (LFIR) from 1013.4 to ≤ 1012.2 L⊙, corresponding to star formation rates (SFRs) of 6740 to ≤ 1360 M⊙ yr−1. Quasar samples sorted by LFIR might represent an evolutionary sequence if SFRs in quasar hosts generally diminish across quasar lifetimes. We create three composite spectra from rest-frame ultra-violet Sloan Digital Sky Survey spectra with increasing far-IR luminosity. We measure the N V(λ1240)/C IV(λ1550) and Si IV(λ1397)+O IV](λ1402)/C IV(λ1550) emission line flux ratios for each composite and find uniformly high (~5-10 times solar) metallicities for the three composites, and no evidence for changes in metal enrichment with changes in ongoing SFR. Second, we present preliminary results from the largest ever survey of high resolution associated absorption line (AAL) region metallicities and physical properties in a sample of high redshift (z > 3) quasars. This includes five quasars with previously known AALs at z > 4 and two well measured z ~3 quasars with unusually rich absorption spectra. We determine well-constrained metallicities of about twice solar for five AAL systems. We find a range of lower limits for AAL metallicities in the z > 4 quasars from 1/100ths solar to 3 times solar. Overall, these results for typically super-solar gas-phase metallicities near quasars are consistent with evolutionary schemes where the major episodes of star formation in the host galaxies occur before the visibly luminous quasar phase. High SFRs (comparable to ULIRGs) in the host galaxies are not clearly linked to younger or chemically less mature quasar environments.

scholarly journals A Powerful Jet/Cloud Interaction in the Radio Galaxy PKS 2250-41

1996 ◽  
Vol 175 ◽  
pp. 227-229
Author(s):  
R. Morganti ◽  
C.N. Tadhunter ◽  
N. Clark ◽  
N. Killeen
Keyword(s):  
Emission Line ◽  
Strong Evidence ◽  
Radio Galaxy ◽  
High Redshift ◽  
Radio Galaxies ◽  
Radio Sources ◽  
Excitation Mechanism ◽  
Powerful Radio ◽  
Radio Jets ◽  
Extended Emission

Extended emission line regions aligned with the radio axis are a common feature of powerful radio galaxies and there is much interest in the origin of the extended gas and excitation mechanism. One model that can produce this alignment is photoionization by anisotropic nuclear continuum radiation. However, strong evidence exists, especially in high redshift radio galaxies, for powerful interactions between the relativistic radio jets and the ISM/IGM. Here we present the results of our study of the southern radio galaxy PKS 2250–41 (z = 0.308). This object is the most spectacular found in a sample of southern radio sources studied by Tadhunter et al. (1993) and it displays particularly clear evidence for such an interaction (Tadhunter et al. 1994; Dickson et al. 1995).

scholarly journals EDGE: a new approach to suppressing numerical diffusion in adaptive mesh simulations of galaxy formation

2020 ◽  
Vol 501 (2) ◽  
pp. 1755-1765
Author(s):  
Andrew Pontzen ◽  
Martin P Rey ◽  
Corentin Cadiou ◽  
Oscar Agertz ◽  
Romain Teyssier ◽  
...  
Keyword(s):  
Star Formation ◽  
Galaxy Formation ◽  
Adaptive Mesh Refinement ◽  
Large Scale ◽  
Initial Conditions ◽  
Dwarf Galaxy ◽  
High Redshift ◽  
Morphological Structure ◽  
Adaptive Mesh ◽  
Numerical Diffusion

ABSTRACT We introduce a new method to mitigate numerical diffusion in adaptive mesh refinement (AMR) simulations of cosmological galaxy formation, and study its impact on a simulated dwarf galaxy as part of the ‘EDGE’ project. The target galaxy has a maximum circular velocity of $21\, \mathrm{km}\, \mathrm{s}^{-1}$ but evolves in a region that is moving at up to $90\, \mathrm{km}\, \mathrm{s}^{-1}$ relative to the hydrodynamic grid. In the absence of any mitigation, diffusion softens the filaments feeding our galaxy. As a result, gas is unphysically held in the circumgalactic medium around the galaxy for $320\, \mathrm{Myr}$, delaying the onset of star formation until cooling and collapse eventually triggers an initial starburst at z = 9. Using genetic modification, we produce ‘velocity-zeroed’ initial conditions in which the grid-relative streaming is strongly suppressed; by design, the change does not significantly modify the large-scale structure or dark matter accretion history. The resulting simulation recovers a more physical, gradual onset of star formation starting at z = 17. While the final stellar masses are nearly consistent ($4.8 \times 10^6\, \mathrm{M}_{\odot }$ and $4.4\times 10^6\, \mathrm{M}_{\odot }$ for unmodified and velocity-zeroed, respectively), the dynamical and morphological structure of the z = 0 dwarf galaxies are markedly different due to the contrasting histories. Our approach to diffusion suppression is suitable for any AMR zoom cosmological galaxy formation simulations, and is especially recommended for those of small galaxies at high redshift.

scholarly journals Self-consistent proto-globular cluster formation in cosmological simulations of high-redshift galaxies

2020 ◽  
Vol 493 (3) ◽  
pp. 4315-4332 ◽  
Author(s):  
Xiangcheng Ma ◽  
Michael Y Grudić ◽  
Eliot Quataert ◽  
Philip F Hopkins ◽  
Claude-André Faucher-Giguère ◽  
...  
Keyword(s):  
High Pressure ◽  
Star Formation ◽  
High Redshift ◽  
Cluster Formation ◽  
Mass Function ◽  
Cosmological Simulations ◽  
High Redshift Galaxies ◽  
Cluster Mass ◽  
Formation Efficiency ◽  
Redshift Galaxies

ABSTRACT We report the formation of bound star clusters in a sample of high-resolution cosmological zoom-in simulations of z ≥ 5 galaxies from the Feedback In Realistic Environments project. We find that bound clusters preferentially form in high-pressure clouds with gas surface densities over $10^4\, \mathrm{ M}_{\odot }\, {\rm pc}^{-2}$, where the cloud-scale star formation efficiency is near unity and young stars born in these regions are gravitationally bound at birth. These high-pressure clouds are compressed by feedback-driven winds and/or collisions of smaller clouds/gas streams in highly gas-rich, turbulent environments. The newly formed clusters follow a power-law mass function of dN/dM ∼ M−2. The cluster formation efficiency is similar across galaxies with stellar masses of ∼107–$10^{10}\, \mathrm{ M}_{\odot }$ at z ≥ 5. The age spread of cluster stars is typically a few Myr and increases with cluster mass. The metallicity dispersion of cluster members is ∼0.08 dex in $\rm [Z/H]$ and does not depend on cluster mass significantly. Our findings support the scenario that present-day old globular clusters (GCs) were formed during relatively normal star formation in high-redshift galaxies. Simulations with a stricter/looser star formation model form a factor of a few more/fewer bound clusters per stellar mass formed, while the shape of the mass function is unchanged. Simulations with a lower local star formation efficiency form more stars in bound clusters. The simulated clusters are larger than observed GCs due to finite resolution. Our simulations are among the first cosmological simulations that form bound clusters self-consistently in a wide range of high-redshift galaxies.

scholarly journals Quasi-equilibrium models of high-redshift disc galaxy evolution

2020 ◽  
Vol 500 (3) ◽  
pp. 3394-3412
Author(s):  
Steven R Furlanetto
Keyword(s):  
Star Formation ◽  
Galaxy Evolution ◽  
Galaxy Formation ◽  
High Redshift ◽  
Formation Rate ◽  
New Physics ◽  
Small Scale ◽  
Quasi Equilibrium ◽  
Mass Relation ◽  
Disc Galaxy

ABSTRACT In recent years, simple models of galaxy formation have been shown to provide reasonably good matches to available data on high-redshift luminosity functions. However, these prescriptions are primarily phenomenological, with only crude connections to the physics of galaxy evolution. Here, we introduce a set of galaxy models that are based on a simple physical framework but incorporate more sophisticated models of feedback, star formation, and other processes. We apply these models to the high-redshift regime, showing that most of the generic predictions of the simplest models remain valid. In particular, the stellar mass–halo mass relation depends almost entirely on the physics of feedback (and is thus independent of the details of small-scale star formation) and the specific star formation rate is a simple multiple of the cosmological accretion rate. We also show that, in contrast, the galaxy’s gas mass is sensitive to the physics of star formation, although the inclusion of feedback-driven star formation laws significantly changes the naive expectations. While these models are far from detailed enough to describe every aspect of galaxy formation, they inform our understanding of galaxy formation by illustrating several generic aspects of that process, and they provide a physically grounded basis for extrapolating predictions to faint galaxies and high redshifts currently out of reach of observations. If observations show violations from these simple trends, they would indicate new physics occurring inside the earliest generations of galaxies.

Sign in / Sign up

Export Citation Format

Share Document