scholarly journals Lyman continuum leakage versus quenching with the James Webb Space Telescope: the spectral signatures of quenched star formation activity in reionization-epoch galaxies

2018 ◽  
Vol 479 (1) ◽  
pp. 368-376 ◽  
Author(s):  
Christian Binggeli ◽  
Erik Zackrisson ◽  
Kristiaan Pelckmans ◽  
Rubén Cubo ◽  
Hannes Jensen ◽  
...  
Keyword(s):  
Star Formation ◽  
Formation Rate ◽  
Classification Algorithm ◽  
Space Telescope ◽  
Spectral Signatures ◽  
Synthetic Spectra ◽  
Lyman Continuum ◽  
James Webb Space Telescope ◽  
Star Formation Activity ◽  
Balmer Lines

ABSTRACT In this paper, we study the effects of a recent drop in star formation rate (SFR) on the spectra of epoch of reionization (EoR) galaxies, and the resulting degeneracy with the spectral features produced by extreme Lyman continuum leakage. In order to study these effects in the wavelength range relevant for the upcoming James Webb Space Telescope (JWST), we utilize synthetic spectra of simulated EoR galaxies from cosmological simulations together with synthetic spectra of partially quenched mock galaxies. We find that rapid declines in the SFR of EoR galaxies could seriously affect the applicability of methods that utilize the equivalent width of Balmer lines and the ultraviolet spectral slope to assess the escape fraction of EoR galaxies. In order to determine if the aforementioned degeneracy can be avoided by using the overall shape of the spectrum, we generate mock NIRCam observations and utilize a classification algorithm to identify galaxies that have undergone quenching. We find that while there are problematic cases, JWST/NIRCam or NIRSpec should be able to reliably identify galaxies with redshifts z∼ 7 that have experienced a significant decrease in the SFR (by a factor of 10–100) in the past  50–100 Myr with a success rate ${\gtrsim } 85\,{per\,cent}$. We also find that uncertainties in the dust-reddening effects on EoR galaxies significantly affect the performance of the results of the classification algorithm. We argue that studies that aim to characterize the dust extinction law most representative in the EoR would be extremely useful.

scholarly journals Calibrating the James Webb Space Telescope Filters as Star Formation Rate Indicators

2018 ◽  
Vol 869 (2) ◽  
pp. L26 ◽  
Author(s):  
Madhooshi R. Senarath ◽  
Michael J. I. Brown ◽  
Michelle E. Cluver ◽  
John Moustakas ◽  
Lee Armus ◽  
...  
Keyword(s):  
Star Formation ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Space Telescope ◽  
James Webb Space Telescope

Extreme variations in star formation activity in the first galaxies

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 ◽  
Star Formation Histories

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.

scholarly journals Satellites and central galaxies in SDSS: the influence of interactions on their properties

2020 ◽  
Vol 501 (1) ◽  
pp. 1046-1058
Author(s):  
Valeria Mesa ◽  
Sol Alonso ◽  
Georgina Coldwell ◽  
Diego García Lambas ◽  
J L Nilo Castellon
Keyword(s):  
Star Formation ◽  
Stellar Population ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Control Sample ◽  
Stellar Populations ◽  
Control Sets ◽  
Central Galaxy ◽  
Star Formation Activity ◽  
Projected Distance

ABSTRACT We use SDSS-DR14 to construct a sample of galaxy systems consisting of a central object and two satellites. We adopt projected distance and radial velocity difference criteria and impose an isolation criterion to avoid membership in larger structures. We also classify the interaction between the members of each system through a visual inspection of galaxy images, finding ${\sim}80{{\ \rm per\ cent}}$ of the systems lack evidence of interactions whilst the remaining ${\sim}20{{\ \rm per\ cent}}$ involve some kind of interaction, as inferred from their observed distorted morphology. We have considered separately, samples of satellites and central galaxies, and each of these samples were tested against suitable control sets to analyse the results. We find that central galaxies showing signs of interactions present evidence of enhanced star formation activity and younger stellar populations. As a counterpart, satellite samples show these galaxies presenting older stellar populations with a lower star formation rate than the control sample. The observed trends correlate with the stellar mass content of the galaxies and with the projected distance between the members involved in the interaction. The most massive systems are less affected since they show no star formation excess, possibly due to their more evolved stage and less gas available to form new stars. Our results suggest that it is arguably a transfer of material during interactions, with satellites acting as donors to the central galaxy. As a consequence of the interactions, satellite stellar population ages rapidly and new bursts of star formation may frequently occur in the central galaxy.

scholarly journals SDSS J114818.18-013823.7: Forming Compact Dwarf Galaxy through the Dwarf-Dwarf Merger

2021 ◽  
Vol 7 (2) ◽  
pp. 49-57
Author(s):  
D. N. Chhatkuli ◽  
S. Paudel ◽  
A. K. Gautam ◽  
B. Aryal
Keyword(s):  
Star Formation ◽  
Emission Line ◽  
Star Formation Rate ◽  
Dwarf Galaxy ◽  
Formation Rate ◽  
Absolute Magnitude ◽  
Spectroscopic Properties ◽  
Normal Galaxies ◽  
Star Formation Activity ◽  
The Galaxy

We studied the spectroscopic properties of the low redshift (z = 0.0130) interacting dwarf galaxy SDSS J114818.18-013823.7. It is a compact galaxy of half-light radius 521 parsec. It’s r-band absolute magnitude is -16.71 mag. Using a publicly available optical spectrum from the Sloan Sky Survey data archive, we calculated star-formation rate, emission line metallicity, and dust extinction of the galaxy. Star formation rate (SFR) due to Hα is found to be 0.118 Mʘ year-1 after extinction correction. The emission-line metallicity, 12+log(O/H), is 8.13 dex. Placing these values in the scaling relation of normal galaxies, we find that SDSS J114818.18-013823.7 is a significant outlier from both size-magnitude relation and SFR-B-band absolute relation. Although SDSS J114818.18-013823.7 possess enhance rate of star-formation, the current star-formation activity can persist several Giga years in the future at the current place and it remains compact.

scholarly journals Legacy of star formation in the pre-reionization universe

2019 ◽  
Vol 488 (2) ◽  
pp. 2202-2221 ◽  
Author(s):  
Jason Jaacks ◽  
Steven L Finkelstein ◽  
Volker Bromm
Keyword(s):  
Star Formation ◽  
Luminosity Function ◽  
Star Formation Rate ◽  
Direct Detection ◽  
Formation Rate ◽  
Mass Function ◽  
James Webb Space Telescope ◽  
Current Limiting ◽  
Molecular Cooling ◽  
Low Mass

ABSTRACT We utilize gizmo, coupled with newly developed sub-grid models for Population III (Pop III) and Population II (Pop II), to study the legacy of star formation in the pre-reionization Universe. We find that the Pop II star formation rate density (SFRD), produced in our simulation (${\sim } 10^{-2}\ \mathrm{M}_\odot \, {\rm yr^{-1}\, Mpc^{-3}}$ at z ≃ 10), matches the total SFRD inferred from observations within a factor of <2 at 7 ≲ z ≲ 10. The Pop III SFRD, however, reaches a plateau at ${\sim }10^{-3}\ \mathrm{M}_\odot \, {\rm yr^{-1}\, Mpc^{-3}}$ by z ≈ 10, remaining largely unaffected by the presence of Pop II feedback. At z  = 7.5, ${\sim } 20{{\ \rm per\ cent}}$ of Pop III star formation occurs in isolated haloes that have never experienced any Pop II star formation (i.e. primordial haloes). We predict that Pop III-only galaxies exist at magnitudes MUV ≳ −11, beyond the limits for direct detection with the James Webb Space Telescope. We assess that our stellar mass function (SMF) and UV luminosity function (UVLF) agree well with the observed low mass/faint-end behaviour at z = 8 and 10. However, beyond the current limiting magnitudes, we find that both our SMF and UVLF demonstrate a deviation/turnover from the expected power-law slope (MUV,turn = −13.4 ± 1.1 at z  = 10). This could impact observational estimates of the true SFRD by a factor of 2(10) when integrating to MUV = −12 (−8) at z ∼ 10, depending on integration limits. Our turnover correlates well with the transition from dark matter haloes dominated by molecular cooling to those dominated by atomic cooling, for a mass Mhalo ≈ 108 M⊙ at z ≃ 10.

The impact of star formation sampling effects on the spectra of lensed z > 6 galaxies detectable with JWST

2019 ◽  
Vol 492 (2) ◽  
pp. 1706-1712
Author(s):  
Anton Vikaeus ◽  
Erik Zackrisson ◽  
Christian Binggeli
Keyword(s):  
Star Formation ◽  
Spectral Synthesis ◽  
High Redshift ◽  
Formation Rate ◽  
Mass Function ◽  
Spectroscopic Studies ◽  
Initial Mass Function ◽  
James Webb Space Telescope ◽  
Population Iii Stars ◽  
The Impact

ABSTRACT The upcoming James Webb Space Telescope (JWST) will allow observations of high-redshift galaxies at fainter detection levels than ever before, and JWST surveys targeting gravitationally lensed fields are expected to bring z ≳ 6 objects with very low star formation rate (SFR) within reach of spectroscopic studies. As galaxies at lower and lower star formation activity are brought into view, many of the standard methods used in the analysis of integrated galaxy spectra are at some point bound to break down, due to violation of the assumptions of a well-sampled stellar initial mass function (IMF) and a slowly varying SFR. We argue that galaxies with SFR ∼ 0.1 M⊙ yr−1 are likely to turn up at the spectroscopic detection limit of JWST in lensed fields, and investigate to what extent star formation sampling may affect the spectral analysis of such objects. We use the slug spectral synthesis code to demonstrate that such effects are likely to have significant impacts on spectral diagnostics of, for example, the Balmer emission lines. These effects are found to stem primarily from SFRs varying rapidly on short (∼Myr) time-scales due to star formation in finite units (star clusters), whereas the effects of an undersampled IMF is deemed insignificant in comparison. In contrast, the ratio between the He ii- and H i-ionizing flux is found to be sensitive to IMF-sampling as well as ICMF-sampling (sampling of the initial cluster mass function), which may affect interpretations of galaxies containing Population III stars or other sources of hard ionizing radiation.

scholarly journals Star formation law in the epoch of reionization from [C ii] and C iii] lines

2020 ◽  
Vol 495 (1) ◽  
pp. L22-L26 ◽  
Author(s):  
L Vallini ◽  
A Ferrara ◽  
A Pallottini ◽  
S Carniani ◽  
S Gallerani
Keyword(s):  
Monte Carlo ◽  
Markov Chain ◽  
Star Formation ◽  
Markov Chain Monte Carlo ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Average Density ◽  
Monte Carlo Algorithm ◽  
James Webb Space Telescope ◽  
Novel Method

ABSTRACT We present a novel method to simultaneously characterize the star formation law and the interstellar medium properties of galaxies in the epoch of reionization (EoR) through the combination of [C ii] 158 μm (and its known relation with star formation rate) and C iii] λ1909 Å emission line data. The method, based on a Markov chain Monte Carlo algorithm, allows us to determine the target galaxy average density, n, gas metallicity, Z, and ‘burstiness’ parameter, κs, quantifying deviations from the Kennicutt–Schmidt relation. As an application, we consider COS-3018 (z = 6.854), the only EoR Lyman Break Galaxy so far detected in both [C ii] and C iii]. We show that COS-3018 is a moderate starburst (κs ≈ 3), with $Z \approx 0.4 \, \mathrm{Z}_{\odot }$, and $n \approx 500\, {\rm cm^{-3}}$. Our method will be optimally applied to joint ALMA and James Webb Space Telescope targets.

scholarly journals xGASS: the role of bulges along and across the local star-forming main sequence

2020 ◽  
Vol 493 (4) ◽  
pp. 5596-5605 ◽  
Author(s):  
Robin H W Cook ◽  
Luca Cortese ◽  
Barbara Catinella ◽  
Aaron Robotham
Keyword(s):  
Star Formation ◽  
Main Sequence ◽  
Formation Rate ◽  
Stellar Mass ◽  
Local Universe ◽  
Star Forming ◽  
Star Formation Activity ◽  
The Galaxy ◽  
Stellar Masses

ABSTRACT We use our catalogue of structural decomposition measurements for the extended GALEX Arecibo SDSS Survey (xGASS) to study the role of bulges both along and across the galaxy star-forming main sequence (SFMS). We show that the slope in the sSFR–M⋆ relation flattens by ∼0.1 dex per decade in M⋆ when re-normalizing specifice star formation rate (sSFR) by disc stellar mass instead of total stellar mass. However, recasting the sSFR–M⋆ relation into the framework of only disc-specific quantities shows that a residual trend remains against disc stellar mass with equivalent slope and comparable scatter to that of the total galaxy relation. This suggests that the residual declining slope of the SFMS is intrinsic to the disc components of galaxies. We further investigate the distribution of bulge-to-total ratios (B/T) as a function of distance from the SFMS (ΔSFRMS). At all stellar masses, the average B/T of local galaxies decreases monotonically with increasing ΔSFRMS. Contrary to previous works, we find that the upper envelope of the SFMS is not dominated by objects with a significant bulge component. This rules out a scenario in which, in the local Universe, objects with increased star formation activity are simultaneously experiencing a significant bulge growth. We suggest that much of the discrepancies between different works studying the role of bulges originate from differences in the methodology of structurally decomposing galaxies.

scholarly journals SDSS-IV MaNGA: effects of morphology in the global and local star formation main sequences

2019 ◽  
Vol 488 (3) ◽  
pp. 3929-3948 ◽  
Author(s):  
M Cano-Díaz ◽  
V Ávila-Reese ◽  
S F Sánchez ◽  
H M Hernández-Toledo ◽  
A Rodríguez-Puebla ◽  
...  
Keyword(s):  
Star Formation ◽  
Surface Density ◽  
Main Sequence ◽  
Formation Rate ◽  
Stellar Mass ◽  
Star Forming ◽  
Spatially Resolved ◽  
Star Formation Activity ◽  
Global And Local ◽  
Universal Mechanism

ABSTRACT We study the global star formation rate (SFR) versus stellar mass (M*) correlation, and the spatially resolved SFR surface density (ΣSFR) versus stellar mass surface density (Σ*) correlation, in a sample of ∼2000 galaxies from the MaNGA MPL-5 survey. We classify galaxies and spatially resolved areas into star forming and retired according to their ionization processes. We confirm the existence of a star-forming main sequence (SFMS) for galaxies and spatially resolved areas, and show that they have the same nature, with the global as a consequence of the local one. The latter presents a bend below a limit Σ* value, ≈3 × 107 M$\odot$ kpc−2, which is not physical. Using only star-forming areas (SFAs) above this limit, a slope and a scatter of ≈1 and ≈0.27 dex are determined. The retired galaxies/areas strongly segregate from their respective SFMSs, by ∼−1.5 dex on average. We explore how the global/local SFMSs depend on galaxy morphology, finding that for star-forming galaxies and SFAs, there is a trend to lower values of star formation activity with earlier morphological types, which is more pronounced for the local SFMS. The morphology not only affects the global SFR due to the diminish of SFAs with earlier types, but also affects the local SF process. Our results suggest that the local SF at all radii is established by some universal mechanism partially modulated by morphology. Morphology seems to be connected to the slow aging and sharp decline of the SF process, and on its own it may depend on other properties as the environment.

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