Driving Galactic Outflows with Magnetic Fields at Low and High Redshift

Abstract Although galactic outflows play a key role in our understanding of the evolution of galaxies, the exact mechanism by which galactic outflows are driven is still far from being understood and, therefore, our understanding of associated feedback mechanisms that control the evolution of galaxies is still plagued by many enigmas. In this work, we present a simple toy model that can provide insight on how non-axisymmetric instabilities in galaxies (bars, spiral arms, warps) can lead to local exponential magnetic field growth by radial flows beyond the equipartition value by at least two orders of magnitude on a timescale of a few 100 Myr. Our predictions show that the process can lead to galactic outflows in barred spiral galaxies with a mass-loading factor η ≈ 0.1, in agreement with our numerical simulations. Moreover, our outflow mechanism could contribute to an understanding of the large fraction of barred spiral galaxies that show signs of galactic outflows in the chang-es survey. Extending our model shows the importance of such processes in high-redshift galaxies by assuming equipartition between magnetic energy and turbulent energy. Simple estimates for the star formation rate in our model together with cross correlated masses from the star-forming main sequence at redshifts z ∼ 2 allow us to estimate the outflow rate and mass-loading factors by non-axisymmetric instabilities and a subsequent radial inflow dynamo, giving mass-loading factors of η ≈ 0.1 for galaxies in the range of M ⋆ = 109–1012 M ⊙, in good agreement with recent results of sinfoni and kmos 3D.

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Infrared Emission from Barred Spiral Galaxies

International Astronomical Union Colloquium ◽

10.1017/s0252921100049411 ◽

1996 ◽

Vol 157 ◽

pp. 54-62

Author(s):

Tim G. Hawarden ◽

J. H. Huang ◽

Q. S. Gu

Keyword(s):

Star Formation ◽

Spiral Galaxies ◽

Star Formation Rate ◽

Formation Rate ◽

Infrared Emission ◽

Stellar Radiation ◽

The Galaxy ◽

Barred Spiral Galaxies ◽

Star Formation Regions ◽

Ir Emission

AbstractAmongst relatively undisturbed spiral galaxies of type ≤ Sc barred morphology is unquestionably associated with powerful mid- and Far-IR emission. On the other hand, even amongst early type galaxies, those with LFIR/LB < 1/3 exhibit no association of high relative FIR luminosity with barred morphology, but some association of IR colors resembling those of star formation regions (SFRs). Amongst systems with LFIR/LB < 0.1 this ratio may be anti-correlated with barredness. It appears that enhanced IR emission from those galaxies whose star formation rate is currently elevated by the the bar translates them into the group with higher FIR-to-optical luminosity ratios. Depletion of extended nearnuclear gas and dust, once the bar has swept up the currently-available supplies, may reduce the fraction of the background stellar radiation field which can be converted to FIR radiation in the inner, most luminous parts of the galaxy. Thus, after the starburst has subsided, such galaxies may be less FIR-luminous than unbarred systems. Several uncertainties remain: it is still not clear whether barred morphology is a necessary condition for the generation of a starburst in an otherwise undisturbed galaxy, while evidence as to the effect of differing bar strengths is conflicting.

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Ultra-Fast Outflows in Typical Redshift 2 Star-Forming Galaxies

Proceedings of the International Astronomical Union ◽

10.1017/s1743921315010340 ◽

2015 ◽

Vol 11 (S319) ◽

pp. 41-44

Author(s):

Orianne Roos ◽

Frédéric Bournaud

Keyword(s):

High Resolution ◽

First Principles ◽

High Redshift ◽

Host Galaxy ◽

Mass Loading ◽

Star Forming ◽

Stellar Feedback ◽

Galactic Outflows ◽

Very High

AbstractGalactic outflows are observed in star-forming galaxies up to high redshift. Still, their physical origins are not well understood, and most simulations fail to reproduce all observed parameters from first principles. With the POGO simulations (Physical Origins of Galactic Outflows), we model AGN and stellar feedback (FB) based on physical assumptions, and investigate their impact on the outflow parameters and on the host-galaxy at very high resolution (1.5 pc). Here, we show that AGN and stellar FB couple non-linearly, and that the mass loading of the resulting outflow highly depends on the mass of the host.

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Fast molecular outflow from a dusty star-forming galaxy in the early Universe

Science ◽

10.1126/science.aap8900 ◽

2018 ◽

Vol 361 (6406) ◽

pp. 1016-1019 ◽

Cited By ~ 37

Author(s):

J. S. Spilker ◽

M. Aravena ◽

M. Béthermin ◽

S. C. Chapman ◽

C.-C. Chen ◽

...

Keyword(s):

Star Formation ◽

High Redshift ◽

Large Fraction ◽

Formation Rate ◽

Free Fall ◽

Big Bang ◽

Star Forming ◽

Molecular Outflow ◽

The Galaxy ◽

The Big Bang

Galaxies grow inefficiently, with only a small percentage of the available gas converted into stars each free-fall time. Feedback processes, such as outflowing winds driven by radiation pressure, supernovae, or supermassive black hole accretion, can act to halt star formation if they heat or expel the gas supply. We report a molecular outflow launched from a dust-rich star-forming galaxy at redshift 5.3, 1 billion years after the Big Bang. The outflow reaches velocities up to 800 kilometers per second relative to the galaxy, is resolved into multiple clumps, and carries mass at a rate within a factor of 2 of the star formation rate. Our results show that molecular outflows can remove a large fraction of the gas available for star formation from galaxies at high redshift.

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Dorado and its member galaxies

Astronomy and Astrophysics ◽

10.1051/0004-6361/202038996 ◽

2020 ◽

Vol 643 ◽

pp. A176

Author(s):

R. Rampazzo ◽

S. Ciroi ◽

P. Mazzei ◽

F. Di Mille ◽

E. Congiu ◽

...

Keyword(s):

Star Formation ◽

Spiral Galaxies ◽

Star Formation Rate ◽

Large Fraction ◽

Formation Rate ◽

Morphological Type ◽

Gas Content ◽

Early Type ◽

Late Type ◽

Star Formation Activity

Context. Dorado is a nearby, rich and clumpy galaxy group that extends for several degrees in the southern hemisphere. Although several studies have been dedicated to defining its members, their kinematics, and the hot and cold gas content, in particular H I, their present star formation activity remains unknown. Aims. For the first time, we map the Hα distribution as a possible indicator of the star formation activity of Dorado members, a large fraction of which show interaction and merging signatures independently of their morphological type. Methods. With the 2.5 m du Pont and the 1m Swope telescopes, we obtained narrow-band calibrated images of 14 galaxies that form the backbone of the group, mapping Hα+[N II] down to a few 10−17 erg cm−2 s−1 arcsec−2. We estimated the galaxy star formation rate from the Hα fluxes and corrected for Galaxy foreground extinction and [N II] contamination. Results. We detected Hα+[N II] emission in all galaxies. H II regions clearly emerge in late-type galaxies, while in early-type galaxies the Hα+[N II] emission is dominated by [N II], especially in the central regions. However, H II complexes are revealed in four early-type galaxies. Even in the compact group SGC 0414-5559, in the projected centre of Dorado, H II regions are found both throughout the late-type galaxies and in the very outskirts of early-type members. Considering the Dorado group as a whole, we notice that the Hα+[N II] equivalent width, a measure of the specific star formation, increases with morphological type from early- to late-type members, although it remains lower than that observed in similar surveys of spiral galaxies. The star formation rate of the spiral members is in the range of what is observed in similar galaxies surveys (James et al., 2004). However, in three spiral galaxies, NGC 1536, PGC 75125, and IC 2058, the star formation rate is well below the median for their morphological classes. Conversely, the star formation rate of some early-type members tends to be higher than the average derived from Hα+[N II] surveys of this morphological family. Conclusions. We detected Hα+[N II] in all the early-type galaxies observed and half of them show H II regions in well-shaped rings as well as in their outskirts. These findings suggest that early-type galaxies in this group are not dead galaxies: their star formation has not yet shut down. Mechanisms such as gas stripping and gas accretion through galaxy–galaxy interaction seem relevant in modifying star formation in this evolutionary phase of Dorado.

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The Hubble expansion as ascribed to mutual magnetic induction between neighboring galaxies

Laser and Particle Beams ◽

10.1017/s0263034600005346 ◽

1988 ◽

Vol 6 (3) ◽

pp. 405-408 ◽

Cited By ~ 1

Author(s):

W. H. Bostick

Keyword(s):

Spiral Galaxies ◽

Magnetic Energy ◽

Simple Calculation ◽

Big Bang ◽

Particle In Cell ◽

Hubble Expansion ◽

Expansion Of The Universe ◽

Barred Spiral Galaxies ◽

The Big Bang ◽

The Universe

A 32-year-old hypothesis of the formation of barred-spiral galaxies (Bostick 1957, 1958, 1986; Laurence, 1956) which become coherent-self-exciting homopolar generators has recently gained confirmative support from 3-D, particle-in-cell computer simulations (Nielsen et al. 1979; Buneman et al. 1980; Peratt et al. 1980, 1984, 1986). Such galaxies should be able to convert an appreciable fraction, f, of the energy from their gravitationally-collapsing plasmas to coherently-increasing magnetic energy via their coherent, self-exciting, homopolar-generator action. The following simple calculation shows that the resulting mutually-induced magnetic repulsions (Len's law) between neighboring galaxies is greater than the gravitational attractive forces between the galaxies. The observed expansion of the Universe can be thus simply accounted for without recourse to the ‘Big Bang’ hypothesis, with its unaccounted-for mysteries.

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Star Formation in Nuclear Rings of Barred-Spiral Galaxies

Proceedings of the International Astronomical Union ◽

10.1017/s1743921316008024 ◽

2015 ◽

Vol 11 (S315) ◽

Author(s):

Woong-Tae Kim ◽

Woo-Young Seo

Keyword(s):

Star Formation ◽

Spiral Galaxies ◽

Formation Rate ◽

Early Time ◽

Young Star ◽

Late Time ◽

Spiral Arms ◽

Contact Points ◽

Nuclear Ring ◽

Barred Spiral Galaxies

AbstractWe study star formation occurring in nuclear rings of barred-spiral galaxies by using hydrodynamic simulations with the prescriptions of star formation and feedback included. In models without spiral arms, the star formation rate (SFR) in a ring exhibits a strong primary burst at early time and declines to small values at late time. The early burst is caused by a rapid gas infall due to the bar growth, consuming most of the gas inside the bar regions. On the other hand, models with spiral arms show multiple starburst activities at late time caused by arm-induced gas inflows, provided that the arm pattern speed is slower than that of the bar. The SFR in models with spirals is larger by a factor of ~ 1.4–4.0 than that in the bar-only models, with larger values corresponding to stronger and slower arms. In all models, young star clusters in nuclear ring show an azimuthal age gradient only when the SFR is small, such that younger clusters tend to locate closer to the contact points between the ring and dust lanes.

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Mapping large-scale-structure evolution over cosmic times

Experimental Astronomy ◽

10.1007/s10686-021-09755-3 ◽

2021 ◽

Author(s):

Marta B. Silva ◽

Ely D. Kovetz ◽

Garrett K. Keating ◽

Azadeh Moradinezhad Dizgah ◽

Matthieu Bethermin ◽

...

Keyword(s):

Galaxy Formation ◽

Large Scale ◽

High Redshift ◽

Formation Rate ◽

Far Infrared ◽

Large Scale Structure ◽

Scale Structure ◽

Structure Evolution ◽

Intensity Mapping ◽

Wide Range

AbstractThis paper outlines the science case for line-intensity mapping with a space-borne instrument targeting the sub-millimeter (microwaves) to the far-infrared (FIR) wavelength range. Our goal is to observe and characterize the large-scale structure in the Universe from present times to the high redshift Epoch of Reionization. This is essential to constrain the cosmology of our Universe and form a better understanding of various mechanisms that drive galaxy formation and evolution. The proposed frequency range would make it possible to probe important metal cooling lines such as [CII] up to very high redshift as well as a large number of rotational lines of the CO molecule. These can be used to trace molecular gas and dust evolution and constrain the buildup in both the cosmic star formation rate density and the cosmic infrared background (CIB). Moreover, surveys at the highest frequencies will detect FIR lines which are used as diagnostics of galaxies and AGN. Tomography of these lines over a wide redshift range will enable invaluable measurements of the cosmic expansion history at epochs inaccessible to other methods, competitive constraints on the parameters of the standard model of cosmology, and numerous tests of dark matter, dark energy, modified gravity and inflation. To reach these goals, large-scale structure must be mapped over a wide range in frequency to trace its time evolution and the surveyed area needs to be very large to beat cosmic variance. Only a space-borne mission can properly meet these requirements.

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Quasi-equilibrium models of high-redshift disc galaxy evolution

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa3451 ◽

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.

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First Light And Reionization Epoch Simulations (FLARES) – I. Environmental dependence of high-redshift galaxy evolution

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa3360 ◽

2020 ◽

Vol 500 (2) ◽

pp. 2127-2145

Author(s):

Christopher C Lovell ◽

Aswin P Vijayan ◽

Peter A Thomas ◽

Stephen M Wilkins ◽

David J Barnes ◽

...

Keyword(s):

Galaxy Evolution ◽

Galaxy Formation ◽

Dynamic Range ◽

High Redshift ◽

Formation Rate ◽

Mass Function ◽

Distribution Functions ◽

Large Area ◽

Composite Distribution ◽

Environmental Dependence

ABSTRACT We introduce the First Light And Reionisation Epoch Simulations (FLARES), a suite of zoom simulations using the EAGLE model. We resimulate a range of overdensities during the Epoch of Reionization (EoR) in order to build composite distribution functions, as well as explore the environmental dependence of galaxy formation and evolution during this critical period of galaxy assembly. The regions are selected from a large $(3.2 \, \mathrm{cGpc})^{3}$ parent volume, based on their overdensity within a sphere of radius 14 h−1 cMpc. We then resimulate with full hydrodynamics, and employ a novel weighting scheme that allows the construction of composite distribution functions that are representative of the full parent volume. This significantly extends the dynamic range compared to smaller volume periodic simulations. We present an analysis of the galaxy stellar mass function (GSMF), the star formation rate distribution function (SFRF), and the star-forming sequence (SFS) predicted by FLARES, and compare to a number of observational and model constraints. We also analyse the environmental dependence over an unprecedented range of overdensity. Both the GSMF and the SFRF exhibit a clear double-Schechter form, up to the highest redshifts (z = 10). We also find no environmental dependence of the SFS normalization. The increased dynamic range probed by FLARES will allow us to make predictions for a number of large area surveys that will probe the EoR in coming years, carried out on new observatories such as Roman and Euclid.

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