The future of galaxies and the fate of intelligent life

The Universe ◽

Made In

We investigate the influence of recent advances in research on the gaseous content of the universe on our knowledge of star formation histories of spiral galaxies. The discovery of low-redshift population of absorbers and first steps made in understanding of the transition between high-redshift intergalactic and low-redshift galactic population of QSO absorption systems significantly reshape our picture of the gaseous content of the universe. It turns out that large quantities of gas which has not been astrated or astrated only weakly are bound to galaxies at later epochs, and present a potential reservoir of gas not only for solution of the gas consumption puzzle in spiral disks, but also a fuel for future star formation. This baryonic transition, although still hard to establish quantitatively, is a result of the simple physical processes. The resulting increase in the star formation timescales of spiral galaxies has some interesting consequences for the long-term future development of life and intelligent observers in the galactic context. Admittedly highly speculative, this qualitative picture may hopefully provide a motivation for detailed numerical modelling of the physical processes involved.

High-Redshift Galaxies

Symposium - International Astronomical Union ◽

10.1017/s0074180900196743 ◽

2005 ◽

Vol 216 ◽

pp. 309-324

Author(s):

Amy Barger

Keyword(s):

Star Formation ◽

High Redshift ◽

Redshift Distribution ◽

Extragalactic Background Light ◽

High Redshift Galaxies ◽

Submillimeter Wavelengths ◽

Optical Star ◽

History Of ◽

The Universe ◽

Made In

Mapping the history of star formation requires combining observations at many wavelengths. The most dramatic episodes of star formation occurred in high-redshift (z > 1) galaxies obscured by dust. These galaxies can be seen at submillimeter wavelengths. While these episodes clearly constitute much of the star formation in the universe, we still do not know the redshift distribution. Although progess has been made in determining the nature of the brightest members of the submillimeter population, these galaxies comprise only a tiny fraction of the submillimeter extragalactic background light. Optical star formation, by contrast, is well mapped but hard to interpret because of the problems of extinction. At recent times there is still substantial star formation, but it primarily takes place in small galaxies. This cosmic downsizing is paralleled by similar evolution in the properties of AGNs.

Star Formation Histories of Spiral Galaxies from a Multi-Wavelength Study

Symposium - International Astronomical Union ◽

10.1017/s0074180900233895 ◽

1996 ◽

Vol 171 ◽

pp. 471-471

Author(s):

C. Xu

Keyword(s):

Star Formation ◽

Spiral Galaxies ◽

Star Formation Rate ◽

Formation Rate ◽

Radio Continuum ◽

Star Formation History ◽

The Past ◽

Formation History ◽

We study the star formation histories of a sample of 113 nearby spiral galaxies using their radio continuum (20cm), FIR (40-120μm), H (1.65μm) and B (4400Å) luminosities. The first two are used as indicators of star formation rate over the past ∼ 108 years, as suggested by the tight and nearly universal FIR/radio correlation (Xu et al. 1994). Compared to other indicators of recent star formation rate such as Hα and UV, FIR and radio continuum have the advantage of being insensitive to extinction. The B luminosity is taken as star formation indicator for the time scale of 3 109 years, and the H luminosity for the time scale of 1010 years. We find: 1.The long-term star-formation history (from a few billion years to the entire Hubble time), as indicated by the B-to-H luminosity ratio, depends strongly on the Hubble type.2.The recent star-formation history in the last a few billion years, as indicated by the radio-to-B luminosity ratio and the FIR-to-B luminosity ratio, does not depend on the Hubble type.3.Galaxies of a given Hubble type have similar long-term star-formation histories. On the other hand, their recent star-formation histories in the last a few billion years can be much different: the ratio between the star-formation rate averaged over the past 108 years to that over the past 3 109 years can be different by two orders of magnitude, as indicated by the scattering of the radio-to-B luminosity ratio and that of the FIR-to-B luminosity ratio. This is not likely to be due to the extinction on the B luminosity, because the scattering of the B-to-H luminosity ratio for a given type is much smaller.

Quenching star formation at intermediate redshifts: downsizing of the mass flux density in the green valley

Proceedings of the International Astronomical Union ◽

10.1017/s1743921313004572 ◽

2012 ◽

Vol 8 (S295) ◽

pp. 163-166

Author(s):

Thiago S. Gonçalves ◽

D. Christopher Martin ◽

Karín Menéndez-Delmestre ◽

Ted K. Wyder ◽

Anton Koekemoer

Keyword(s):

Star Formation ◽

Flux Density ◽

Mass Flux ◽

High Redshift ◽

Massive Galaxies ◽

Star Forming ◽

Intermediate Redshifts ◽

The Universe ◽

Red Sequence

AbstractThe bimodality in galaxy properties has been observed at low and high redshift, with a clear distinction between star-forming galaxies in the blue cloud and passively evolving objects in the red sequence; the absence of galaxies with intermediate properties indicates that the quenching of star formation and subsequent transition between populations must happen rapidly. In this work, we present a study of over 100 transiting galaxies in the so-called “green valley” at intermediate redshifts (z ~ 0.8). By using very deep spectroscopy with the DEIMOS instrument at the Keck telescope, we are able to infer the star formation histories of these objects and measure the stellar mass flux density transiting from the blue cloud to the red sequence when the Universe was half its current age. Our results indicate that the process happened more rapidly, affecting more massive galaxies in the past, suggesting a top-down scenario whereby the massive end of the red sequence assembles first. This represents another aspect of downsizing, with the mass flux density moving towards smaller galaxies in recent times.

Extreme variations in star formation activity in the first galaxies

Proceedings of the International Astronomical Union ◽

10.1017/s1743921319002527 ◽

2019 ◽

Vol 15 (S341) ◽

pp. 226-230

Author(s):

Christian Binggeli ◽

Erik Zackrisson ◽

Xiangcheng Ma ◽

Akio K. Inoue ◽

Anton Vikaeus ◽

...

Keyword(s):

Star Formation ◽

Rest Frame ◽

High Redshift ◽

Formation Rate ◽

High Redshift Galaxies ◽

James Webb Space Telescope ◽

Star Formation Activity ◽

The Galaxy ◽

First Galaxies ◽

AbstractRecently, spectroscopic detections of O[III] 88 μm and Ly-α emission lines from the z ≍ 9.1 galaxy MACS1149-JD1 have been presented, and with these, some interesting properties of this galaxy were uncovered. One such property is that MACS1149-JD1 exhibits a significant Balmer break at around rest-frame 4000 Å, which may indicate that the galaxy has experienced large variations in star formation rate prior to z ∼ 9, with a rather long period of low star formation activity. While some simulations predict large variations in star formation activity in high-redshift galaxies, it is unclear whether the simulations can reproduce the kind of variations seen in MACS1149-JD1. Here, we utilize synthetic spectra of simulated galaxies from two simulation suites in order to study to what extent these can accurately reproduce the spectral features (specifically the Balmer break) observed in MACS1149-JD1. We show that while the simulations used in this study produce galaxies with varying star formation histories, galaxies such as MACS1149-JD1 would be very rare in the simulations. In principle, future observations with the James Webb Space Telescope may tell us if MACS1149-JD1 represents something rare, or if such galaxies are more common than predicted by current simulations.

The diversity and variability of star formation histories in models of galaxy evolution

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa2150 ◽

2020 ◽

Vol 498 (1) ◽

pp. 430-463 ◽

Cited By ~ 2

Author(s):

Kartheik G Iyer ◽

Sandro Tacchella ◽

Shy Genel ◽

Christopher C Hayward ◽

Lars Hernquist ◽

...

Keyword(s):

Star Formation ◽

Galaxy Evolution ◽

Time Scales ◽

Formation Rate ◽

Power Laws ◽

Stellar Mass ◽

Physical Processes ◽

Long Time ◽

Hydrodynamical Simulations ◽

ABSTRACT Understanding the variability of galaxy star formation histories (SFHs) across a range of time-scales provides insight into the underlying physical processes that regulate star formation within galaxies. We compile the SFHs of galaxies at z = 0 from an extensive set of models, ranging from cosmological hydrodynamical simulations (Illustris, IllustrisTNG, Mufasa, Simba, EAGLE), zoom simulations (FIRE-2, g14, and Marvel/Justice League), semi-analytic models (Santa Cruz SAM) and empirical models (UniverseMachine), and quantify the variability of these SFHs on different time-scales using the power spectral density (PSD) formalism. We find that the PSDs are well described by broken power laws, and variability on long time-scales (≳1 Gyr) accounts for most of the power in galaxy SFHs. Most hydrodynamical models show increased variability on shorter time-scales (≲300 Myr) with decreasing stellar mass. Quenching can induce ∼0.4−1 dex of additional power on time-scales >1 Gyr. The dark matter accretion histories of galaxies have remarkably self-similar PSDs and are coherent with the in situ star formation on time-scales >3 Gyr. There is considerable diversity among the different models in their (i) power due to star formation rate variability at a given time-scale, (ii) amount of correlation with adjacent time-scales (PSD slope), (iii) evolution of median PSDs with stellar mass, and (iv) presence and locations of breaks in the PSDs. The PSD framework is a useful space to study the SFHs of galaxies since model predictions vary widely. Observational constraints in this space will help constrain the relative strengths of the physical processes responsible for this variability.

Cloud-Particle Dynamics and Star Formation in Spiral Galaxies

Symposium - International Astronomical Union ◽

10.1017/s0074180900032617 ◽

1983 ◽

Vol 100 ◽

pp. 131-132

Author(s):

W. W. Roberts ◽

M. A. Hausman ◽

F. H. Levinson

Keyword(s):

Star Formation ◽

Spiral Galaxies ◽

Particle Dynamics ◽

Particle Model ◽

Computational Simulations ◽

Physical Processes ◽

Cloud Particle ◽

Stellar Association ◽

New Associations ◽

Stellar Associations

We study the gas in a spiral galaxy with a cloud-dominated “stellar association-perturbed” interstellar medium from the standpoint of a cloud-particle model. Through N-body computational simulations, we follow the time evolution of the system of gas clouds and the corresponding system of young stellar associations forming from the clouds. Basic physical processes are modeled in a three-step cyclic procedure: (1) dynamical propagation of the clouds and young stellar associations, (2) simulation of cloud-cloud collisions, and (3) formation of new associations of protostars that are triggered by the local mechanisms of cloud-cloud collisions and cloud interactions with existing young stellar associations.

Tidal Dwarf Galaxies and Missing Baryons

Advances in Astronomy ◽

10.1155/2010/735284 ◽

2010 ◽

Vol 2010 ◽

pp. 1-7 ◽

Cited By ~ 19

Author(s):

Frederic Bournaud

Keyword(s):

Dark Matter ◽

Spiral Galaxies ◽

Dwarf Galaxies ◽

High Redshift ◽

Rotation Curves ◽

Cosmological Problem ◽

Flat Rotation Curves ◽

Mass Size ◽

Merger Rate ◽

The Universe

Tidal dwarf galaxies form during the interaction, collision, or merger of massive spiral galaxies. They can resemble “normal” dwarf galaxies in terms of mass, size, and become dwarf satellites orbiting around their massive progenitor. They nevertheless keep some signatures from their origin, making them interesting targets for cosmological studies. In particular, they should be free from dark matter from a spheroidal halo. Flat rotation curves and high dynamical masses may then indicate the presence of an unseen component, and constrain the properties of the “missing baryons,” known to exist but not directly observed. The number of dwarf galaxies in the Universe is another cosmological problem for which it is important to ascertain if tidal dwarf galaxies formed frequently at high redshift, when the merger rate was high, and many of them survived until today. In this paper, “dark matter” is used to refer to the nonbaryonic matter, mostly located in large dark halos, that is, CDM in the standard paradigm, and “missing baryons” or “dark baryons” is used to refer to the baryons known to exist but hardly observed at redshift zero, and are a baryonic dark component that is additional to “dark matter”.

Ultraviolet‐Optical Pixel Maps of Face‐on Spiral Galaxies: Clues for Dynamics and Star Formation Histories

The Astrophysical Journal ◽

10.1086/367820 ◽

2003 ◽

Vol 586 (2) ◽

pp. 923-938 ◽

Cited By ~ 14

Author(s):

Paul B. Eskridge ◽

Jay A. Frogel ◽

Violet A. Taylor ◽

Rogier A. Windhorst ◽

Stephen C. Odewahn ◽

...

Keyword(s):

Star Formation ◽

Spiral Galaxies ◽

Outflows in low-mass galaxies at z >1

Proceedings of the International Astronomical Union ◽

10.1017/s1743921316011686 ◽

2016 ◽

Vol 11 (S321) ◽

pp. 339-341

Author(s):

Michael V. Maseda ◽

Keyword(s):

Star Formation ◽

High Redshift ◽

Theoretical Models ◽

Potential Wells ◽

Low Mass ◽

Hydrodynamical Simulations ◽

Gas Accretion ◽

Stellar Masses ◽

Cold Gas

AbstractStar formation histories of local dwarf galaxies, derived through resolved stellar populations, appear complex and varied. The general picture derived from hydrodynamical simulations is one of cold gas accretion and bursty star formation, followed by feedback from supernovae and winds that heat and eject the central gas reservoirs. This ejection halts star formation until the material cools and re-accretes, resulting in an episodic SFH, particularly at stellar masses below ~ 109 M⊙. Such feedback has often been cited as the driving force behind the observed slowly-rising rotation curves in local dwarfs, due to an under-density of dark matter compared to theoretical models, which is one of the primary challenges to LCDM cosmology. However, these events have not yet been directly observed at high-redshift. Recently, using HST imaging and grism spectroscopy, we have uncovered an abundant population of low-mass galaxies (M* < 109 M⊙) at z = 1 - 2 that are undergoing strong bursts of star formation, in agreement with the theoretical predictions. These Extreme Emission Line Galaxies, with high specific SFRs and shallow gravitational potential wells, are ideal places to test the theoretical prediction of strong feedback-driven outflows. Here we use deep MUSE spectroscopy to search these galaxies for signatures of outflowing material, namely kinematic offsets between absorption lines (in the restframe optical and UV), which trace cool gas, and the nebular emission lines, which define the systemic redshift of the galaxy. Although the EELGs are intrinsically very faint, stacked spectra reveal blueshifted velocity centroids for Fe II absorption, which is indicative of outflowing cold gas. This represents the first constraint on outflows in M* < 109 M⊙ galaxies at z = 1 - 2. These outflows should regulate the star formation histories of low-mass galaxies at early cosmic times and thus play a crucial role in galaxy growth and evolution.

Red and dead CANDELS: massive passive galaxies at the dawn of the Universe

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz2615 ◽

2019 ◽

Vol 490 (3) ◽

pp. 3309-3328 ◽

Cited By ~ 10

Author(s):

E Merlin ◽

F Fortuni ◽

M Torelli ◽

P Santini ◽

M Castellano ◽

...

Keyword(s):

Star Formation ◽

High Redshift ◽

Formation Rate ◽

Probabilistic Approach ◽

Big Bang ◽

Spectral Lines ◽

Massive Galaxies ◽

Star Formation Activity ◽

The Big Bang

ABSTRACT We search the five CANDELS fields (COSMOS, EGS, GOODS-North, GOODS-South, and UDS) for passively evolving a.k.a. ‘red and dead’ massive galaxies in the first 2 Gyr after the big bang, integrating and updating the work on GOODS-South presented in a previous paper. We perform SED-fitting on photometric data, with top-hat star-formation histories to model an early and abrupt quenching, and using a probabilistic approach to select only robust candidates. Using libraries without (with) spectral lines emission, starting from a total of more than 20 000 z > 3 sources we end up with 102 (40) candidates, including one at z = 6.7. This implies a minimal number density of 1.73 ± 0.17 × 10−5 (6.69 ± 1.08 × 10−6) Mpc−3 for 3 < z < 5; applying a correction factor to account for incompleteness yields 2.30 ± 0.20 × 10−5. We compare these values with those from five recent hydrodynamical cosmological simulations, finding a reasonable agreement at z < 4; tensions arise at earlier epochs. Finally, we use the star-formation histories from the best-fitting models to estimate the contribution of the high-redshift passive galaxies to the global star formation rate density during their phase of activity, finding that they account for ∼5–10 per cent of the total star formation at 3 < z < 8, despite being only $\sim 0.5{{\ \rm per\ cent}}$ of the total in number. The resulting picture is that early and strong star formation activity, building massive galaxies on short time-scales and followed by a quick and abrupt quenching, is a rare but crucial phenomenon in the early Universe: the evolution of the cosmos must be heavily influenced by the short but powerful activity of these pristine monsters.