M 31 circum-nuclear region: A molecular survey with the IRAM interferometer

We analysed molecular observations performed at IRAM interferometer in CO(1-0) of the circum-nuclear region (within 250 pc) of Andromeda with 2.9″ = 11 pc resolution. We detected 12 molecular clumps in this region, corresponding to a total molecular mass of (8.4 ± 0.4)×104 M⊙. These clumps follow Larson’s mass-size relation, but lie well above the velocity-size relation. We discuss the possibility that these clumps are probably not virialised, but are transient agglomerations of smaller entities that might be virialised. Three of these clumps have been detected in CO(2-1) in a previous work, and we find a temperature line ratio below 0.5 in this work. With a radiative transfer analysis, we show that this gas is in non-local thermal equilibrium with a low excitation temperature (Tex = 5 − 9 K). We find a surface beam filling factor of order 5% and a gas density in the range 60 − 650 cm−3, which is well below the critical density. With a gas-to-stellar mass fraction of 4 × 10−4 and dust-to-gas ratio of 0.01, this quiescent region has exhausted its gas budget. Its spectral energy distribution is compatible with passive templates assembled from elliptical galaxies. While weak dust emission is present in the region, we show that no star formation is present and support the previous results that the dust is heated by the old and intermediate stellar population. We study the possibility that this region lies formally in the low-density part of the Kennicutt-Schmidt law in a regime where the star formation rate estimators are not completely reliable. We confirm the quiescence of the inner part of this galaxy known to lie on the green valley.

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High-resolution, 3D radiative transfer modelling

Astronomy and Astrophysics ◽

10.1051/0004-6361/202037476 ◽

2020 ◽

Vol 638 ◽

pp. A150

Author(s):

S. Viaene ◽

A. Nersesian ◽

J. Fritz ◽

S. Verstocken ◽

M. Baes ◽

...

Keyword(s):

Star Formation ◽

Radiative Transfer ◽

Spectral Energy Distribution ◽

Formation Rate ◽

Dust Emission ◽

Realistic Model ◽

Spectral Energy ◽

Nearby Star ◽

Future Evolution ◽

Ngc 1068

The star formation rate and the mass of interstellar medium (ISM) have a high predictive power for the future evolution of a galaxy. Nevertheless, deriving such properties is not straightforward. Dust emission, an important diagnostic of star formation and ISM mass throughout the Universe, can be powered by sources unrelated to ongoing star formation. In the framework of the DustPedia project we set out to disentangle the radiation of the ongoing star formation from that of the older stellar populations. This is done through detailed 3D radiative transfer simulations of face-on spiral galaxies. We take special care in modelling the morphological features present for each source of radiation. In this particular study, we focus on NGC 1068, which in addition contains an active galactic nucleus (AGN). The effect of diffuse dust heating by an AGN (beyond the torus) has so far only been investigated for quasars. This additional dust heating source further contaminates the broadband fluxes that are used by classic galaxy modelling tools to derive physical properties. We aim to fit a realistic model to the observations of NGC 1068 and quantify the contribution of the several dust-heating sources. Our model is able to reproduce the global spectral energy distribution of the galaxy. It matches the resolved optical and infrared images fairly well, but deviates in the UV and the submillimetre (submm). This is partly due to beam smearing effects, but also because the input dust distribution is not sufficiently peaked in the centre. We find that AGN contamination of the broadband fluxes has a strong dependency on wavelength. It peaks in the mid-infrared, drops in the far-infrared, and then rises again at submm wavelengths. We quantify the contribution of the dust-heating sources in each 3D dust cell and find a median value of 83% for the star formation component. The AGN contribution is measurable at the percentage level in the disc, but quickly increases in the inner few hundred parsecs, peaking above 90%. This is the first time the phenomenon of an AGN heating the diffuse dust beyond its torus is quantified in a nearby star-forming galaxy. NGC 1068 only contains a weak AGN, meaning this effect could be stronger in galaxies with a more luminous AGN. This could significantly impact the derived star formation rates and ISM masses for such systems.

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The effects of star formation history in the SFR–M* relation of H ii galaxies

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa3333 ◽

2020 ◽

Vol 500 (3) ◽

pp. 3240-3253

Author(s):

Amanda R Lopes ◽

Eduardo Telles ◽

Jorge Melnick

Keyword(s):

Star Formation ◽

Spectral Energy Distribution ◽

Formation Rate ◽

Star Formation History ◽

Spectral Energy ◽

Distribution Fitting ◽

Good Tool ◽

Star Forming ◽

Additional Information ◽

Star Formation Histories

ABSTRACT We discuss the implications of assuming different star formation histories (SFH) in the relation between star formation rate (SFR) and mass derived by the spectral energy distribution fitting (SED). Our analysis focuses on a sample of H ii galaxies, dwarf starburst galaxies spectroscopically selected through their strong narrow emission lines in SDSS DR13 at z < 0.4, cross-matched with photometric catalogues from GALEX, SDSS, UKIDSS, and WISE. We modelled and fitted the SEDs with the code CIGALE adopting different descriptions of SFH. By adding information from different independent studies, we find that H ii galaxies are best described by episodic SFHs including an old (10 Gyr), an intermediate age (100−1000 Myr) and a recent population with ages < 10 Myr. H ii galaxies agree with the SFR−M* relation from local star-forming galaxies, and only lie above such relation when the current SFR is adopted as opposed to the average over the entire SFH. The SFR−M* demonstrated not to be a good tool to provide additional information about the SFH of H ii galaxies, as different SFH present a similar behaviour with a spread of <0.1 dex.

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Probing changes of dust properties along a chain of solar-type prestellar and protostellar cores in Taurus with NIKA

Astronomy and Astrophysics ◽

10.1051/0004-6361/201731117 ◽

2017 ◽

Vol 604 ◽

pp. A52 ◽

Cited By ~ 20

Author(s):

A. Bracco ◽

P. Palmeirim ◽

Ph. André ◽

R. Adam ◽

P. Ade ◽

...

Keyword(s):

Star Formation ◽

Spectral Energy Distribution ◽

Dust Emission ◽

Class Ii ◽

Spectral Energy ◽

Relevant Parameter ◽

Mass Star ◽

Radial Temperature ◽

Dust Temperature ◽

Prestellar Cores

The characterization of dust properties in the interstellar medium is key for understanding the physics and chemistry of star formation. Mass estimates are crucial to determine gravitational collapse conditions for the birth of new stellar objects in molecular clouds. However, most of these estimates rely on dust models that need further observational constraints to capture the relevant parameter variations depending on the local environment: from clouds to prestellar and protostellar cores. We present results of a new study of dust emissivity changes based on millimeter continuum data obtained with the NIKA camera at the IRAM-30 m telescope. Observing dust emission at 1.15 mm and 2 mm allows us to constrain the dust emissivity index, β, in the Rayleigh-Jeans tail of the dust spectral energy distribution far from its peak emission, where the contribution of other parameters (i.e. dust temperature) is more important. Focusing on the Taurus molecular cloud, one of the most famous low-mass star-forming regions in the Gould Belt, we analyze the emission properties of several distinct objects in the B213 filament. This subparsec-sized region is of particular interest since it is characterized by a collection ofevolutionary stages of early star formation: three prestellar cores, two Class 0/I protostellar cores and one Class II object. We are therefore able to compare dust properties among a sequence of sources that likely derive from the same parent filament. By means of the ratio of the two NIKA channel maps, we show that in the Rayleigh-Jeans approximation, βRJ varies among the objects: it decreases from prestellar cores (βRJ ~ 2) to protostellar cores (βRJ ~ 1) and the Class II object (βRJ ~ 0). For one prestellar and two protostellar cores, we produce a robust study using available Herschel data to constrain the dust temperature of the sources. By using the Abel transform inversion technique we derive accurate radial temperature profiles that allow us to obtain radial β profiles. We find systematic spatial variations of β in the protostellar cores that are not observed in the prestellar core. While in the former case β decreases toward the center (with β varying between 1 and 2), in the latter it remains constant (β = 2.4 ± 0.3). Moreover, the dust emissivity index appears anticorrelated with the dust temperature. We discuss the implication of these results in terms of dust grain evolution between pre- and protostellar cores.

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Dust properties and star formation of approximately a thousand local galaxies

Astronomy and Astrophysics ◽

10.1051/0004-6361/201834553 ◽

2019 ◽

Vol 631 ◽

pp. A38 ◽

Cited By ~ 1

Author(s):

S. Lianou ◽

P. Barmby ◽

A. A. Mosenkov ◽

M. Lehnert ◽

O. Karczewski

Keyword(s):

Star Formation ◽

Spectral Energy Distribution ◽

Dust Emission ◽

Distribution Functions ◽

Spectral Energy ◽

Emission Properties ◽

Galaxy Type ◽

Dust Mass ◽

The Galaxy ◽

Stellar Masses

Aims. We derived the dust properties for 753 local galaxies and examine how these relate to some of their physical properties. We present the derived dust emission properties, including model spectral energy distribution (SEDs), star formation rates (SFRs) and stellar masses, as well as their relations. Methods. We modelled the global dust-SEDs for 753 galaxies, treated statistically as an ensemble within a hierarchical Bayesian dust-SED modelling approach, so as to derive their infrared (IR) emission properties. To create the observed dust-SEDs, we used a multi-wavelength set of observations, ranging from near-IR to far-IR-to-submillimeter wavelengths. The model-derived properties are the dust masses (Mdust), the average interstellar radiation field intensities (Uav), the mass fraction of very small dust grains (“QPAH” fraction), as well as their standard deviations. In addition, we used mid-IR observations to derive SFR and stellar masses, quantities independent of the dust-SED modelling. Results. We derive distribution functions of the properties for the galaxy ensemble and as a function of galaxy type. The mean value of Mdust for the early-type galaxies (ETGs) is lower than that for the late-type and irregular galaxies (LTGs and Irs, respectively), despite ETGs and LTGs having stellar masses spanning across the whole range observed. The Uav and “QPAH” fraction show no difference among different galaxy types. When fixing Uav to the Galactic value, the derived “QPAH” fraction varies across the Galactic value (0.071). The specific SFR increases with galaxy type, while this is not the case for the dust-specific SFR (SFR/Mdust), showing an almost constant star formation efficiency per galaxy type. The galaxy sample is characterised by a tight relationship between the dust mass and the stellar mass for the LTGs and Irs, while ETGs scatter around this relation and tend towards smaller dust masses. While the relation indicates that Mdust may fundamentally be linked to M⋆, metallicity and Uav are the second parameter driving the scatter, which we investigate in a forthcoming work. We used the extended Kennicutt–Schmidt (KS) law to estimate the gas mass and the gas-to-dust mass ratio (GDR). The gas mass derived from the extended KS law is on average ∼20% higher than that derived from the KS law, and a large standard deviation indicates the importance of the average star formation present to regulate star formation and gas supply. The average GDR for the LTGs and Irs is 370, and including the ETGs gives an average of 550.

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The star formation properties of the observed and simulated AGN Universe: BAT versus EAGLE

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa2414 ◽

2020 ◽

Vol 498 (2) ◽

pp. 2323-2338

Author(s):

Thomas M Jackson ◽

D J Rosario ◽

D M Alexander ◽

J Scholtz ◽

Stuart McAlpine ◽

...

Keyword(s):

Star Formation ◽

High Redshift ◽

Spectral Energy Distribution ◽

Formation Rate ◽

Host Galaxy ◽

Spectral Energy ◽

Host Galaxies ◽

X Ray ◽

Two Samples ◽

Stellar Masses

ABSTRACT In this paper, we present data from 72 low-redshift, hard X-ray selected active galactic nucleus (AGN) taken from the Swift–BAT 58 month catalogue. We utilize spectral energy distribution fitting to the optical to infrared photometry in order to estimate host galaxy properties. We compare this observational sample to a volume- and flux-matched sample of AGN from the Evolution and Assembly of GaLaxies and their Environments (EAGLE) hydrodynamical simulations in order to verify how accurately the simulations can reproduce observed AGN host galaxy properties. After correcting for the known +0.2 dex offset in the SFRs between EAGLE and previous observations, we find agreement in the star formation rate (SFR) and X-ray luminosity distributions; however, we find that the stellar masses in EAGLE are 0.2–0.4 dex greater than the observational sample, which consequently leads to lower specific star formation rates (sSFRs). We compare these results to our previous study at high redshift, finding agreement in both the observations and simulations, whereby the widths of sSFR distributions are similar (∼0.4–0.6 dex) and the median of the SFR distributions lie below the star-forming main sequence by ∼0.3–0.5 dex across all samples. We also use EAGLE to select a sample of AGN host galaxies at high and low redshift and follow their characteristic evolution from z = 8 to z = 0. We find similar behaviour between these two samples, whereby star formation is quenched when the black hole goes through its phase of most rapid growth. Utilizing EAGLE we find that 23 per cent of AGN selected at z ∼ 0 are also AGN at high redshift, and that their host galaxies are among the most massive objects in the simulation. Overall, we find EAGLE reproduces the observations well, with some minor inconsistencies (∼0.2 dex in stellar masses and ∼0.4 dex in sSFRs).

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Serendipitous discovery of an “ALMA-only” galaxy at 5 < z < 6 in an ALMA 3-mm survey

Proceedings of the International Astronomical Union ◽

10.1017/s1743921320000605 ◽

2019 ◽

Vol 15 (S352) ◽

pp. 194-198

Author(s):

Christina C. Williams

Keyword(s):

Star Formation ◽

Energy Distribution ◽

Star Formation Rate ◽

High Redshift ◽

Spectral Energy Distribution ◽

Formation Rate ◽

Spectral Energy ◽

Large Contribution ◽

Massive Galaxies ◽

Multi Wavelength

AbstractWe discuss the serendipitous discovery of a dusty high-redshift galaxy in a small (8 arcmin2) ALMA 3-mm survey Williams et al. (2019). The galaxy was previously unknown and is absent from existing multi-wavelength catalogs (“ALMA-only”). Using the ALMA position as prior, we perform forced deblended photometry to constrain its spectral energy distribution. The spectral energy distribution is well described by a massive (M* = 1010.8 M⊙) and highly obscured (AV ∼ 4) galaxy at redshift z = 5.5 ± 1.1 with star formation rate ∼ 300 M⊙yr−1. Our small survey area implies an uncertain but large contribution to the cosmic star formation rate density, similar to the contribution from all ultraviolet-selected galaxies combined at this redshift. This galaxy likely traces an abundant population of massive galaxies absent from current samples of infrared-selected or sub-millimeter galaxies, but with larger space densities, higher duty cycles, and significant contribution to the cosmic star-formation rate and stellar mass densities.

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Simulating JWST deep extragalactic imaging surveys and physical parameter recovery

Astronomy and Astrophysics ◽

10.1051/0004-6361/202037450 ◽

2020 ◽

Vol 640 ◽

pp. A67

Author(s):

O. B. Kauffmann ◽

O. Le Fèvre ◽

O. Ilbert ◽

J. Chevallard ◽

C. C. Williams ◽

...

Keyword(s):

Star Formation ◽

Near Infrared ◽

High Redshift ◽

Spectral Energy Distribution ◽

Formation Rate ◽

Spectral Energy ◽

Photometric Redshifts ◽

The Galaxy ◽

Stellar Masses ◽

The Impact

We present a new prospective analysis of deep multi-band imaging with the James Webb Space Telescope (JWST). In this work, we investigate the recovery of high-redshift 5 < z < 12 galaxies through extensive image simulations of accepted JWST programs, including the Early Release Science in the EGS field and the Guaranteed Time Observations in the HUDF. We introduced complete samples of ∼300 000 galaxies with stellar masses of log(M*/M⊙) > 6 and redshifts of 0 < z < 15, as well as galactic stars, into realistic mock NIRCam, MIRI, and HST images to properly describe the impact of source blending. We extracted the photometry of the detected sources, as in real images, and estimated the physical properties of galaxies through spectral energy distribution fitting. We find that the photometric redshifts are primarily limited by the availability of blue-band and near-infrared medium-band imaging. The stellar masses and star formation rates are recovered within 0.25 and 0.3 dex, respectively, for galaxies with accurate photometric redshifts. Brown dwarfs contaminating the z > 5 galaxy samples can be reduced to < 0.01 arcmin−2 with a limited impact on galaxy completeness. We investigate multiple high-redshift galaxy selection techniques and find that the best compromise between completeness and purity at 5 < z < 10 using the full redshift posterior probability distributions. In the EGS field, the galaxy completeness remains higher than 50% at magnitudes mUV < 27.5 and at all redshifts, and the purity is maintained above 80 and 60% at z ≤ 7 and 10, respectively. The faint-end slope of the galaxy UV luminosity function is recovered with a precision of 0.1–0.25, and the cosmic star formation rate density within 0.1 dex. We argue in favor of additional observing programs covering larger areas to better constrain the bright end.

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Mapping Obscuration to Reionization with ALMA (MORA): 2 mm Efficiently Selects the Highest-redshift Obscured Galaxies

The Astrophysical Journal ◽

10.3847/1538-4357/ac2eb4 ◽

2021 ◽

Vol 923 (2) ◽

pp. 215

Author(s):

Caitlin M. Casey ◽

Jorge A. Zavala ◽

Sinclaire M. Manning ◽

Manuel Aravena ◽

Matthieu Béthermin ◽

...

Keyword(s):

Star Formation ◽

Near Infrared ◽

Formation Rate ◽

Dust Emission ◽

Volume Density ◽

Drop Out ◽

Spectral Energy ◽

Photometric Redshifts ◽

Star Forming ◽

Dusty Galaxies

Abstract We present the characteristics of 2 mm selected sources from the largest Atacama Large Millimeter/submillimeter Array (ALMA) blank-field contiguous survey conducted to date, the Mapping Obscuration to Reionization with ALMA (MORA) survey covering 184 arcmin2 at 2 mm. Twelve of 13 detections above 5σ are attributed to emission from galaxies, 11 of which are dominated by cold dust emission. These sources have a median redshift of 〈 z 2 mm 〉 = 3.6 − 0.3 + 0.4 primarily based on optical/near-infrared photometric redshifts with some spectroscopic redshifts, with 77% ± 11% of sources at z > 3 and 38% ± 12% of sources at z > 4. This implies that 2 mm selection is an efficient method for identifying the highest-redshift dusty star-forming galaxies (DSFGs). Lower-redshift DSFGs (z < 3) are far more numerous than those at z > 3 yet are likely to drop out at 2 mm. MORA shows that DSFGs with star formation rates in excess of 300 M ⊙ yr−1 and a relative rarity of ∼10−5 Mpc−3 contribute ∼30% to the integrated star formation rate density at 3 < z < 6. The volume density of 2 mm selected DSFGs is consistent with predictions from some cosmological simulations and is similar to the volume density of their hypothesized descendants: massive, quiescent galaxies at z > 2. Analysis of MORA sources’ spectral energy distributions hint at steeper empirically measured dust emissivity indices than reported in typical literature studies, with 〈 β 〉 = 2.2 − 0.4 + 0.5 . The MORA survey represents an important step in taking census of obscured star formation in the universe’s first few billion years, but larger area 2 mm surveys are needed to more fully characterize this rare population and push to the detection of the universe’s first dusty galaxies.

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CIGALE: a python Code Investigating GALaxy Emission

Astronomy and Astrophysics ◽

10.1051/0004-6361/201834156 ◽

2019 ◽

Vol 622 ◽

pp. A103 ◽

Cited By ~ 129

Author(s):

M. Boquien ◽

D. Burgarella ◽

Y. Roehlly ◽

V. Buat ◽

L. Ciesla ◽

...

Keyword(s):

Star Formation ◽

Physical Properties ◽

High Speed ◽

Spectral Energy Distribution ◽

Formation Rate ◽

Stellar Populations ◽

Radio Spectrum ◽

Spectral Energy ◽

Spectral Models ◽

Formation And Evolution

Context. Measuring how the physical properties of galaxies change across cosmic times is essential to understand galaxy formation and evolution. With the advent of numerous ground-based and space-borne instruments launched over the past few decades we now have exquisite multi-wavelength observations of galaxies from the far-ultraviolet (FUV) to the radio domain. To tap into this mine of data and obtain new insight into the formation and evolution of galaxies, it is essential that we are able to extract information from their spectral energy distribution (SED). Aims. We present a completely new implementation of Code Investigating GALaxy Emission (CIGALE). Written in python, its main aims are to easily and efficiently model the FUV to radio spectrum of galaxies and estimate their physical properties such as star formation rate, attenuation, dust luminosity, stellar mass, and many other physical quantities. Methods. To compute the spectral models, CIGALE builds composite stellar populations from simple stellar populations combined with highly flexible star formation histories, calculates the emission from gas ionised by massive stars, and attenuates both the stars and the ionised gas with a highly flexible attenuation curve. Based on an energy balance principle, the absorbed energy is then re-emitted by the dust in the mid- and far-infrared domains while thermal and non-thermal components are also included, extending the spectrum far into the radio range. A large grid of models is then fitted to the data and the physical properties are estimated through the analysis of the likelihood distribution. Results. CIGALE is a versatile and easy-to-use tool that makes full use of the architecture of multi-core computers, building grids of millions of models and analysing samples of thousands of galaxies, both at high speed. Beyond fitting the SEDs of galaxies and parameter estimations, it can also be used as a model-generation tool or serve as a library to build new applications.

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Self-consistent population spectral synthesis with FADO

Astronomy and Astrophysics ◽

10.1051/0004-6361/201833438 ◽

2019 ◽

Vol 622 ◽

pp. A56 ◽

Cited By ~ 2

Author(s):

Leandro S. M. Cardoso ◽

Jean Michel Gomes ◽

Polychronis Papaderos

Keyword(s):

Star Formation ◽

Galaxy Evolution ◽

Spectral Synthesis ◽

Spectral Energy Distribution ◽

Formation Rate ◽

Continuum Emission ◽

Spectral Energy ◽

Spectral Evolution ◽

Fitting Procedure ◽

Self Consistent

Context. Spectral population synthesis (PS) is a fundamental tool in extragalactic research that aims to decipher the assembly history of galaxies from their spectral energy distribution (SED). Whereas this technique has led to key insights into galaxy evolution in recent decades, star formation histories (SFHs) inferred therefrom have been plagued by considerable uncertainties stemming from inherent degeneracies and the fact that until recently all PS codes were restricted to purely stellar fits, neglecting the essential contribution of nebular emission (ne). With the advent of FADO (Fitting Analysis using Differential evolution Optimisation), the now possible self-consistent modelling of stellar and ne opens new routes to the exploration of galaxy SFHs. Aims. The main goal of this study is to quantitatively explore the accuracy to which FADO can recover physical and evolutionary properties of galaxies and compare its output with that from purely stellar PS codes. Methods. FADO and STARLIGHT were applied to synthetic SEDs that track the spectral evolution of stars and gas in extinction-free mock galaxies of solar metallicity that form their stellar mass (M⋆) according to different parametric SFHs. Spectral fits were computed for two different set-ups that approximate the spectral range of SDSS and CALIFA (V500) data, using up to seven libraries of simple stellar population spectra in the 0.005–2.5 Z⊙ metallicity range. Results. Our analysis indicates that FADO can recover the key physical and evolutionary properties of galaxies, such as M⋆ and mass- and light-weighted mean age and metallicity, with an accuracy better than 0.2 dex. This is the case even in phases of strongly elevated specific star formation rate (sSFR) and thus with considerable ne contamination (EW(Hα) > 103 Å). Likewise, population vectors from FADO adequately recover the mass fraction of stars younger than 10 Myr and older than 1 Gyr (M⋆<10Myr/M⋆total and M⋆>1Gyr/M⋆total, respectively) and reproduce with a high fidelity the observed Hα luminosity. As for STARLIGHT, our analysis documents a moderately good agreement with theoretical values only for evolutionary phases for which ne drops to low levels (EW(Hα) ≤ 60 Å) which, depending on the assumed SFH, correspond to an age between ∼0.1 Gyr and 2–4 Gyr. However, fits with STARLIGHT during phases of high sSFR severely overestimate both M⋆ and the mass-weighted stellar age, whereas strongly underestimate the light-weighted age and metallicity. Furthermore, our analysis suggests a subtle tendency of STARLIGHT to favour a bi-modal SFH, as well a slightly overestimated M⋆<10Myr/M⋆total, regardless of galaxy age. Whereas the amplitude of these biases can be reduced, depending on the specifics of the fitting procedure (e.g. accuracy and completeness of flagging emission lines, omission of the Balmer and Paschen jump from the fit), they persist even in the idealised case of a line-free SED comprising only stellar and nebular continuum emission. Conclusions. The insights from this study suggest that the neglect of nebular continuum emission in STARLIGHT and similar purely stellar PS codes could systematically impact M⋆ and SFH estimates for star-forming galaxies. We argue that these biases can be relevant in the study of a range of topics in extragalactic research, including the redshift-dependent slope of the star formation (SF) main sequence, the SF frosting hypothesis, and the regulatory role of supermassive black holes on the global SFH of galaxies.

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