scholarly journals A radio perspective on star-formation in distant galaxies

1999 ◽  
Author(s):  
Eric A. Richards
Keyword(s):  
Star Formation ◽  
Distant Galaxies

scholarly journals HII regions and star formation in the Magellanic Clouds

1991 ◽  
Vol 148 ◽  
pp. 139-144 ◽  
Author(s):  
Robert C. Kennicutt
Keyword(s):  
Star Formation ◽  
Interstellar Medium ◽  
Massive Star ◽  
Massive Stars ◽  
Hii Regions ◽  
Magellanic Clouds ◽  
H Ii Regions ◽  
Distant Galaxies ◽  
Close Range ◽  
Mass Functions

The H II regions in the Magellanic Clouds provide an opportunity to characterize the global star formation properties of a galaxy at close range. They also provide a unique laboratory for testing empirical tracers of the massive star formation rates and initial mass functions in more distant galaxies, and for studying the dynamical interactions between massive stars and the interstellar medium. This paper discusses several current studies in these areas.

scholarly journals Widespread star formation inside galactic outflows

2019 ◽  
Vol 485 (3) ◽  
pp. 3409-3429 ◽  
Author(s):  
R Gallagher ◽  
R Maiolino ◽  
F Belfiore ◽  
N Drory ◽  
R Riffel ◽  
...  
Keyword(s):  
Star Formation ◽  
Galaxy Evolution ◽  
Scaling Relations ◽  
Molecular Gas ◽  
Distant Galaxies ◽  
Major Mode ◽  
Galactic Outflows ◽  
The Universe ◽  
Integral Field

Abstract Several models have predicted that stars could form inside galactic outflows and that this would be a new major mode of galaxy evolution. Observations of galactic outflows have revealed that they host large amounts of dense and clumpy molecular gas, which provide conditions suitable for star formation. We have investigated the properties of the outflows in a large sample of galaxies by exploiting the integral field spectroscopic data of the large MaNGA-SDSS4 galaxy survey. We find evidence for prominent star formation occurring inside at least 30 per cent of the galactic outflows in our sample, whilst signs of star formation are seen in up to half of the outflows. We also show that even if star formation is prominent inside many other galactic outflows, this may have not been revealed as the diagnostics are easily dominated by the presence of even faint active galactic nucleus and shocks. If very massive outflows typical of distant galaxies and quasars follow the same scaling relations observed locally, then the star formation inside high-z outflows can be up to several 100 $\rm M_{\odot }~yr^{-1}$ and could contribute substantially to the early formation of the spheroidal component of galaxies. Star formation in outflows can also potentially contribute to establishing the scaling relations between black holes and their host spheroids. Moreover, supernovae exploding on large orbits can chemically enrich in situ and heat the circumgalactic and intergalactic medium. Finally, young stars ejected on large orbits may also contribute to the reionization of the Universe.

scholarly journals Giant H II Regions in M81

1986 ◽  
Vol 116 ◽  
pp. 503-504 ◽  
Author(s):  
Michele Kaufman ◽  
R. C. Kennicutt ◽  
F. N. Bash
Keyword(s):  
Star Formation ◽  
Hii Regions ◽  
Radio Continuum ◽  
H Ii Regions ◽  
Hii Region ◽  
Distant Galaxies ◽  
Flux Measurements ◽  
Selection Of

Giant HII regions are important tracers of recent star formation in distant galaxies. For a selection of HII regions in our galaxy where the exciting stars can be identified, Rumstay (1985) finds that the measured Hα and radio continuum luminosities of an HII region correlate with the stellar ionizing flux derived from model atmospheres and the known exciting stars. Therefore, we use flux measurements of giant HII regions as an index of the distribution of O stars in M81.

scholarly journals Evolutionary Studies of Galaxies at Intermediate Redshifts

1990 ◽  
Vol 43 (2) ◽  
pp. 271
Author(s):  
WJ Couch
Keyword(s):  
Star Formation ◽  
Spectroscopic Studies ◽  
Density Field ◽  
Low Density ◽  
Triggering Mechanism ◽  
Evolution Of Galaxies ◽  
Distant Galaxies ◽  
Evolutionary Studies ◽  
Intermediate Redshifts

Photometric and spectroscopic studies of cluster and field galaxies out to redshifts of -0�5 have provided clear evidence for strong evolution over recent epochs. The development of this picture is reviewed by contrasting and comparing the investigations of distant galaxies in rich clusters and the low density field. A common link is found in that the evolution of galaxies in both environments is related to short-lived bursts of star formation. The triggering mechanism for these bursts is discussed with special attention being paid to the role of galaxy merging

scholarly journals The VIMOS Ultra Deep Survey: Nature, ISM properties, and ionizing spectra of CIII]λ1909 emitters at z = 2–4

2018 ◽  
Vol 612 ◽  
pp. A94 ◽  
Author(s):  
K. Nakajima ◽  
D. Schaerer ◽  
O. Le Fèvre ◽  
R. Amorín ◽  
M. Talia ◽  
...  
Keyword(s):  
Star Formation ◽  
Physical Properties ◽  
Radiation Field ◽  
High Redshift ◽  
Star Forming ◽  
Uv Emission ◽  
Distant Galaxies ◽  
Deep Survey ◽  
Ionization Parameter ◽  
Large Grid

Context. Ultraviolet (UV) emission-line spectra are used to spectroscopically confirm high-z galaxies and increasingly also to determine their physical properties. Aims. We construct photoionization models to interpret the observed UV spectra of distant galaxies in terms of the dominant radiation field and the physical condition of the interstellar medium (ISM). These models are applied to new spectroscopic observations from the VIMOS Ultra Deep Survey (VUDS). Methods. We construct a large grid of photoionization models, which use several incident radiation fields (stellar populations, active galactic nuclei (AGNs), mix of stars and AGNs, blackbodies, and others), and cover a wide range of metallicities and ionization parameters. From these models we derive new spectral UV line diagnostics using equivalent widths (EWs) of [CIII]λ1909 doublet, CIVλ1549 doublet and the line ratios of [CIII], CIV, and He IIλ1640 recombination lines. We apply these diagnostics to a sample of 450 [CIII]-emitting galaxies at redshifts z = 2–4 previously identified in VUDS. Results. We demonstrate that our photoionization models successfully reproduce observations of nearby and high-redshift sources with known radiation field and/or metallicity. For star-forming galaxies our models predict that [CIII] EW peaks at sub-solar metallicities, whereas CIV EW peaks at even lower metallicity. Using the UV diagnostics, we show that the average star-forming galaxy (EW([CIII]) ~ 2 Å) based on the composite of the 450 UV-selected galaxies’ spectra The inferred metallicity and ionization parameter is typically Z = 0.3–0.5 Z⊙ and logU = −2.7 to − 3, in agreement with earlier works at similar redshifts. The models also indicate an average age of 50–200 Myr since the beginning of the current star-formation, and an ionizing photon production rate, ξion, of logξion/erg−1 Hz = 25.3–25.4. Among the sources with EW([CIII]) >= 10 Å, approximately 30% are likely dominated by AGNs. The metallicity derived for galaxies with EW(CIII) = 10–20 Å is low, Z = 0.02–0.2 Z⊙, and the ionization parameter higher (logU ~−1.7) than the average star-forming galaxy. To explain the average UV observations of the strongest but rarest [CIII] emitters (EW([CIII]) > 20 Å), we find that stellar photoionization is clearly insufficient. A radiation field consisting of a mix of a young stellar population (logξion/erg−1 Hz ~ 25.7) plus an AGN component is required. Furthermore an enhanced C/O abundance ratio (up to the solar value) is needed for metallicities Z = 0.1–0.2 Z⊙ and logU = −1.7 to − 1.5. Conclusions. A large grid of photoionization models has allowed us to propose new diagnostic diagrams to classify the nature of the ionizing radiation field (star formation or AGN) of distant galaxies using UV emission lines, and to constrain their ISM properties. We have applied this grid to a sample of [CIII]-emitting galaxies at z = 2–4 detected in VUDS, finding a range of physical properties and clear evidence for significant AGN contribution in rare sources with very strong [CIII] emission. The UV diagnostics we propose should also serve as an important basis for the interpretation of upcoming observations of high-redshift galaxies.

scholarly journals Molecular gas across cosmic time

2019 ◽  
Vol 15 (S352) ◽  
pp. 205-209
Author(s):  
Georgios E. Magdis
Keyword(s):  
Star Formation ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Cosmic Time ◽  
Continuum Emission ◽  
Molecular Gas ◽  
Direct Observations ◽  
Distant Galaxies ◽  
Ir Emission

AbstractWe have entered an era where the gas mass estimates of distant galaxies do not rely on a single tracer but rather on an inventory of different and independent methods, much like the case for the determination of the star formation rate (SFR) of the galaxies. This is crucial as the traditional Mgas tracers, i.e. low-J CO transition lines and dust continuum emission are becoming highly uncertain as we move to higher redshifts due to metallicity and CMB effects. Here, we present a homogeneous and statistically significant investigation of the use of atomic carbon as an alternative Mgas tracer (Valentino et al.2018) and provide evidence of optically thick far-IR emission in high−z starbursts that point towards higher dust temperatures and lower dust and gas mass estimates than previously inferred (Cortzen et al.2019, submitted). Finally, we present direct observations of the effect of the CMB on the far-IR SEDs of high-z SBs, manifested by unphyscally large (β = 2.5–3.5) apparent spectral indexes in R-J tail (Jin et al. 2019, submitted).

scholarly journals The rising star formation histories of distant galaxies and implications for gas accretion with time

2010 ◽  
pp. no-no ◽  
Author(s):  
Casey Papovich ◽  
Steven L. Finkelstein ◽  
Henry C. Ferguson ◽  
Jennifer M. Lotz ◽  
Mauro Giavalisco
Keyword(s):  
Star Formation ◽  
Distant Galaxies ◽  
Gas Accretion ◽  
Star Formation Histories
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