Range Of Star Formation Rates Research Articles

The Contribution of Host Galaxy Properties in X-Ray Active Galactic Nuclei Clusters

In this study, the influence of host galaxy properties on X-ray active galactic nuclei (AGN) clusters was investigated using multiwavelength data. X-ray data from the eFEDS main catalog, optical and near-infrared data from the fourth data release of KiDS/VIKING, and mid-infrared data from WISE were utilized. By integrating these datasets and employing the CIGALE code, the star formation rate, luminosity, and stellar mass of the host galaxies were estimated. The analysis reveals significant associations between luminosity, stellar mass, and star formation rate, providing valuable insights into AGN activity. Furthermore, AGN clusters were compared with non-AGN clusters to uncover distinctive characteristics. AGN clusters exhibit differences in their population across various luminosity levels. Interestingly, a significant proportion of AGN clusters is concentrated in the middle range of luminosity (45-46 measured in logL<sub>(0.5-2.0 keV)</sub>) for both low and high redshift classifications. Additionally, galaxies hosting AGNs detected in X-ray emission tend to fall within a specific range of stellar mass (10-11 measured in log(M<sub>⋆</sub>(M<sub>⊚</sub>)). This stellar mass range is populated by a substantial number of AGN galaxies, irrespective of their redshift classification. Moreover, a significant population of X-ray AGN is concentrated within the star formation rate range of 1.5-2.5 (expressed in log(M<sub>⊚</sub> yr<sup>-1</sup>)) in both low and high redshift regions. By analyzing the dependencies on luminosity, stellar mass, and star formation rate, this study provides valuable insights into the correlation and relationship between AGN clusters and their host galaxies. The comparison with non-AGN clusters and the integration of multiwavelength data from eFEDS, KiDS/VIKING, and WISE enhance the depth of analysis, contributing to a comprehensive evaluation of AGN clusters. These findings advance our understanding of the complex relationship between AGN clusters and host galaxy properties in the field of astrophysics.

The Lockman–SpReSO project

Context. The Lockman–SpReSO project is an optical spectroscopic survey of 956 far-infrared (FIR) objects within the Lockman Hole field limited by magnitude RC(AB) < 24.5. Fe II and Mg II absorption lines have been detected in 21 out of 456 objects with a determined spectroscopic redshift in the catalogue. The redshifts of these objects are in the range 0.5 ≲ z ≲ 1.44. Aims. The aim of this study is to investigate material ejection from star-forming regions and material infall into galaxies by analysing the Fe II and Mg II absorption lines. Additionally, we explore whether the correlations found in previous studies between these galactic wind velocities, line equivalent widths (EWs), and galaxy properties such as stellar mass (M*), star formation rate (SFR), and specific star formation rate (sSFR) are valid for a sample with FIR-selected objects. The objects analysed span an M* range of 9.89 < log(M*/M⊙) < 11.50 and an SFR range of 1.01 < log(SFR) < 2.70. Methods. We performed measurements of the Mg IIλλ2796, 2803, Mg Iλ2852, Fe IIλλ2374, 82, Fe IIλλ2586, 2600, and Fe IIλ2344 spectral lines present in the spectra of the selected sample to determine the EW and velocity of the flows observed in the star-forming galaxies. Subsequently, we conducted 107 bootstrap simulations using the Spearman’s rank correlation coefficient (ρs) to explore correlations with galaxy properties. Furthermore, we calculated the covering factor, gas density, and optical depth for the measured Fe II doublets. Results. Our analysis reveals strong correlations between the EW of Mg II lines and both M* (ρs = 0.43, 4.5σ) and SFR (ρs = 0.42, 4.4σ). For the Fe II lines, we observed strong correlations between the EW and SFR (ρs ∼ 0.65, > 3.9σ), with a weaker correlation for M* (ρs ∼ 0.35, > 1.9σ). No notable correlations were found between velocity measurements of the Mg II line and M*, SFR, or sSFR of the objects (ρs ∼ 0.1). However, a strong negative correlation was found between the velocity of the Fe II lines and the SFR of the galaxies (ρs ∼ −0.45, ∼3σ). Our results align with those of previous studies, although only FIR-selected objects are investigated here. Finally, we detect a candidate ‘loitering outflow’, a recently discovered subtype of the iron low-ionisation broad absorption line (FeLoBAL) quasars, at a redshift of z = 1.4399, exhibiting emission in C III] and low line velocities (|v|≲200 km s−1).

X-Ray Constraints on the Hot Gaseous Corona of Edge-on Late-type Galaxies in Virgo

We present a systematic study of the putative hot gas corona around late-type galaxies (LTGs) residing in the Virgo cluster, based on archival Chandra observations. Our sample consists of 21 nearly edge-on galaxies representing a range of star formation rate (SFR) of 0.2–3 M ⊙ yr−1 and a range of stellar mass (M *) of (0.2–10) × 1010 M ⊙, the majority of which have not been explored with high-sensitivity X-ray observations so far. Significant extraplanar diffuse X-ray (0.5–2 keV) emission is detected in only three LTGs, which are also the three galaxies with the highest SFR. A stacking analysis is performed for the remaining galaxies without individual detection, dividing the whole sample into two subsets based on SFR, stellar mass, or specific SFR. Only the high-SFR bin yields a significant detection, which has a value of L X ∼ 3 × 1038 erg s−1 per galaxy. The stacked extraplanar X-ray signals of the Virgo LTGs are consistent with the empirical L X–SFR and L X–M * relations found among highly inclined disk galaxies in the field, but appear to be systematically lower than those of a comparison sample of simulated star-forming galaxies in clusters identified from the Illustris-TNG100 simulation. The apparent paucity of hot gas coronae in the sampled Virgo LTGs might be understood as the net outcome of the long-lasting effect of ram pressure stripping exerted by the hot intracluster medium and in-disk star-forming activity acting on shorter timescales. A better understanding of the roles of environmental effects in regulating the hot gas content of cluster galaxies invites sensitive X-ray observations for a large sample of galaxies.

Searching for the Role of Mergers in Fast and Early SMBH Growth: Morphological Decomposition of Quasars and Their Hosts at z ∼ 4.8

We present rest-frame ultraviolet images of six luminous quasars at z ∼ 4.8 obtained with the Hubble Space Telescope (HST). These quasars exhibit a wide range of star formation rates (SFRs) and lie in a wide range of environments. We carefully model and subtract the point-like quasar emission and investigate the morphology of the underlying host galaxies at kpc scales. The residual images allowed identification of potential companion sources, which enabled us to explore the role of galaxy merger scenarios in the coevolution of the quasars and their hosts. We also search for the mechanism driving extreme SFRs in three of the six quasars. We find that the rate of detection of potential companions to the host galaxies does not follow trends between high- and low-SFR sources; i.e., the HST imaging suggests that both high- and low-SFR sources are found in both dense and sparse galactic environments. The suggested role of major mergers driving extreme SFRs cannot be supported by the multiwavelength data in hand. Three of four companion sources, previously revealed by submillimeter observations, are not detected in the HST images of three of our quasars. An adapted high-resolution imaging strategy focused on high-SFR sources and extended to a larger quasar sample is required in order to determine the role of mergers in the processes of star formation and supermassive black hole growth at high redshift.

Mapping circumgalactic medium observations to theory using machine learning

ABSTRACT We present a random forest (RF) framework for predicting circumgalactic medium (CGM) physical conditions from quasar absorption line observables, trained on a sample of Voigt profile-fit synthetic absorbers from the simba cosmological simulation. Traditionally, extracting physical conditions from CGM absorber observations involves simplifying assumptions such as uniform single-phase clouds, but by using a cosmological simulation we bypass such assumptions to better capture the complex relationship between CGM observables and underlying gas conditions. We train RF models on synthetic spectra for H i and selected metal lines around galaxies across a range of star formation rates, stellar masses, and impact parameters, to predict absorber overdensities, temperatures, and metallicities. The models reproduce the true values from simba well, with normalized transverse standard deviations of 0.50–0.54 dex in overdensity, 0.32–0.54 dex in temperature, and 0.49–0.53 dex in metallicity predicted from metal lines (not H i), across all ions. Examining the feature importance, the RF indicates that the overdensity is most informed by the absorber column density, the temperature is driven by the line width, and the metallicity is most sensitive to the specific star formation rate. Alternatively examining feature importance by removing one observable at a time, the overdensity and metallicity appear to be more driven by the impact parameter. We introduce a normalizing flow approach in order to ensure the scatter in the true physical conditions is accurately spanned by the network. The trained models are available online.

Fermi-LAT Detection of a New Starburst Galaxy Candidate: IRAS 13052-5711

A likely starburst galaxy (SBG), IRAS 13052–5711, which is the most distant SBG candidates discovered to date, was found by analyzing 14.4 yr of data from the Fermi large-area telescope. This SBG’s significance level is approximately 6.55σ in the 0.1–500 GeV band. Its spatial position is close to that of 4FGL J1308.9–5730, determined from the Fermi large telescope fourth-source Catalog (4FGL). Its power-law spectral index is approximately 2.1, and its light curve for 14.4 yr has no significant variability. These characteristics are highly similar to those of SBGs found in the past. We calculate the SBG’s star formation rate (SFR) to be 29.38 M ⊙ yr−1, which is within the SFR range of SBGs found to date. Therefore, IRAS 13052-5711 is considered to be a likely SBG. In addition, its 0.1–500 GeV luminosity is (3.28 ± 0.67) × 1042 erg s−1, which deviates from the empirical relationship of the γ-ray luminosity and the total infrared luminosity. We considered a hadronic model to explain the GeV spectrum of IRAS 13052-5711.

The relationship between the incidence of X-ray selected AGN in nearby galaxies & star-formation rate

ABSTRACT We present the identification and analysis of an X-ray selected AGN sample that lie within the local (z < 0.35) galaxy population. From a parent sample of 22 079 MPA-JHU (based on SDSS DR8) galaxies, we identified 917 galaxies with central, excess X-ray emission (from 3XMM-DR7) likely originating from an AGN. We measured the host galaxies’ star formation rates and classified them as either star-forming or quiescent based on their position relative to main sequence of star formation. Only 72 per cent of the X-ray selected sample were identified as AGN using BPT selection; this technique is much less effective in quiescent hosts, only identifying 50 per cent of the X-ray AGN. We also calculated the growth rates of the black holes powering these AGN in terms of their specific accretion rate (∝ LX/M*) and found quiescent galaxies, on average, accrete at a lower rate than star-forming galaxies. Finally, we measured the sensitivity function of 3XMM so we could correct for observational bias and construct probability distributions as a function of accretion rate. AGN were found in galaxies across the full range of star formation rates ($\log _{10} \, \mathrm{SFR/M_\odot \ yr^{-1}} = -3\ \mathrm{to}\ 2$) in both star-forming and quiescent galaxies. The incidence of AGN was enhanced by a factor 2 (at a 3.5σ significance) in star-forming galaxies compared to quiescent galaxies of equivalent stellar mass and redshift, but we also found a significant population of AGN hosted by quiescent galaxies.

Star formation rate and stellar mass calibrations based on infrared photometry and their dependence on stellar population age and extinction

Context. The stellar mass (M⋆) and the star formation rate (SFR) are among the most important features that characterize galaxies. Measuring these fundamental properties accurately is critical for understanding the present state of galaxies, their history, and future evolution. Infrared (IR) photometry is widely used to measure the M⋆ and SFR of galaxies because the near-IR traces the continuum emission of the majority of their stellar populations (SPs), and the mid/far-IR traces the dust emission powered by star-forming activity. Aims. This work explores the dependence of the IR emission of galaxies on their extinction, and the age of their SPs. It aims to provide accurate and precise IR-photometry SFR and M⋆ calibrations that account for SP age and extinction while providing quantification of their scatter. Methods. We used the CIGALE spectral energy distribution (SED) fitting code to create model SEDs of galaxies with a wide range of star formation histories, dust content, and interstellar medium properties. We fit the relations between M⋆ and SFR with IR and optical photometry of the model-galaxy SEDs with the Markov chain Monte Carlo (MCMC) method. As an independent confirmation of the MCMC fitting method, we performed a machine-learning random forest (RF) analysis on the same data set. The RF model yields similar results to the MCMC fits, thus validating the latter. Results. This work provides calibrations for the SFR using a combination of the WISE bands 1 and 3, or the JWST NIR-F200W and MIRI-F2100W. It also provides mass-to-light ratio calibrations based on the WISE band-1, the JWST NIR-F200W, and the optical u − r or g − r colors. These calibrations account for the biases attributed to the SP age, while they are given in the form of extinction-dependent and extinction-independent relations. Conclusions. The proposed calibrations show robust estimations while minimizing the scatter and biases throughout a wide range of SFRs and stellar masses. The SFR calibration offers better results, especially in dust-free or passive galaxies where the contributions of old SPs or biases from the lack of dust are significant. Similarly, the M⋆ calibration yields significantly better results for dusty and high-SFR galaxies where dust emission can otherwise bias the estimations.

The dust-to-gas mass ratio of luminous galaxies as a function of their metallicity at cosmic noon

Aims. We aim to quantify the relation between the dust-to-gas mass ratio (DTG) and gas-phase metallicity of z = 2.1 − 2.5 luminous galaxies and contrast this high-redshift relation against analogous constraints at z = 0. Methods. We present a sample of ten star-forming main-sequence galaxies in the redshift range 2.1 < z < 2.5 with rest-optical emission-line information available from the MOSDEF survey and with ALMA 1.2 millimetre and CO J = 3 − 2 follow-up observations. The galaxies have stellar masses ranging from 1010.3 to 1010.6 M⊙ and cover a range in star-formation rate from 35 to 145 M⊙ yr−1. We calculated the gas-phase oxygen abundance of these galaxies from rest-optical nebular emission lines (8.4 < 12 + log(O/H) < 8.8, corresponding to 0.5−1.25 Z⊙). We estimated the dust and H2 masses of the galaxies (using a metallicity-dependent CO-to-H2 conversion factor) from the 1.2 mm and CO J = 3 − 2 observations, respectively, from which we estimated a DTG. Results. We find that the galaxies in this sample follow the trends already observed between CO line luminosity and dust-continuum luminosity from z = 0 to z = 3, extending such trends to fainter galaxies at 2.1 < z < 2.5 than observed to date. We find no second-order metallicity dependence in the CO – dust-continuum luminosity relation for the galaxies presented in this work. The DTGs of main-sequence galaxies at 2.1 < z < 2.5 are consistent with an increase in the DTG with gas-phase metallicity. The metallicity dependence of the DTG is driven by the metallicity dependence of the CO-to-H2 conversion factor. Galaxies at z = 2.1 − 2.5 are furthermore consistent with the DTG-metallicity relation found at z = 0 (i.e. with no significant evolution), providing relevant constraints for galaxy formation models. These results furthermore imply that the metallicity of galaxies should be taken into account when estimating cold-gas masses from dust-continuum emission, which is especially relevant when studying metal-poor low-mass or high-redshift galaxies.

GECKOS: Turning galaxy evolution on its side with deep observations of edge-on galaxies

AbstractWe present GECKOS (Generalising Edge-on galaxies and their Chemical bimodalities, Kinematics, and Outflows out to Solar environments), a new ESO VLT/MUSE large program. The main aim of GECKOS is to reveal the variation in key physical processes of disk formation by connecting Galactic Archaeology with integral field spectroscopic observations of nearby galaxies. Edge-on galaxies are ideal for this task: they allow us to disentangle the assembly history imprinted in thick disks and provide the greatest insights into outflows. The GECKOS sample of 35 nearby edge-on disk galaxies is designed to trace the assembly histories and properties of galaxies across a large range of star formation rates, bulge-to-total ratios, and boxy and non-boxy bulges. GECKOS will deliver spatially resolved measurements of stellar abundances, ages, and kinematics, as well as ionised gas metallicities, ionisation param- eters, pressure, and inflow and outflow kinematics; all key parameters for building a complete chemodynamical picture of disk galaxies. With these data, we aim to extend Galactic analysis methods to the wider galaxy population, reaping the benefits of detailed Milky Way studies, while probing the diverse mechanisms of galaxy evolution.

The ALMaQUEST Survey X: what powers merger induced star formation?

ABSTRACT Galaxy mergers are known to trigger both extended and central star formation. However, what remains to be understood is whether this triggered star formation is facilitated by enhanced star formation efficiencies (SFEs), or an abundance of molecular gas fuel. This work presents spatially resolved measurements of CO emission collected with the Atacama Large Millimetre Array (ALMA) for 20 merging galaxies (either pairs or post-mergers) selected from the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey. Eleven additional merging galaxies are selected from the ALMA MaNGA QUEnching and STar formation (ALMaQUEST) survey, resulting in a set of 31 mergers at various stages of interaction and covering a broad range of star formation rates (SFRs). We investigate galaxy-to-galaxy variations in the resolved Kennicutt–Schmidt relation, (rKS: $\Sigma _{\textrm {H}_2}$ versus ΣSFR), the resolved molecular gas main sequence (rMGMS: Σ⋆ versus $\Sigma _{\textrm {H}_2}$), and the resolved star-forming main sequence (rSFMS: Σ⋆ versus ΣSFR). We quantify offsets from these resolved relations to determine if SFR, molecular gas fraction, or/and SFE is/are enhanced in different regions of an individual galaxy. By comparing offsets in all three parameters, we can discern whether gas fraction or SFE powers an enhanced ΣSFR. We find that merger-induced star formation can be driven by a variety of mechanisms, both within a galaxy and between different mergers, regardless of interaction stage.

The Westerbork Coma Survey

We present the blind Westerbork Coma Survey probing the H I content of the Coma galaxy cluster with the Westerbork Synthesis Radio Telescope. The survey covers the inner ∼1 Mpc around the cluster centre, extending out to 1.5 Mpc towards the south-western NGC 4839 group. The survey probes the atomic gas in the entire Coma volume down to a sensitivity of ∼1019 cm−2 and 108 M⊙. Combining automated source finding with source extraction at optical redshifts and visual verification, we obtained 40 H I detections of which 24 are new. Over half of the sample displays perturbed H I morphologies indicative of an ongoing interaction with the cluster environment. With the use of ancillary UV and mid-IR, data we measured their stellar masses and star formation rates and compared the H I properties to a set of field galaxies spanning a similar stellar mass and star formation rate range. We find that ∼75% of H I-selected Coma galaxies have simultaneously enhanced star formation rates (by ∼0.2 dex) and are H I deficient (by ∼0.5 dex) compared to field galaxies of the same stellar mass. According to our toy model, the simultaneous H I deficiency and enhanced star formation activity can be attributed to either H I stripping of already highly star forming galaxies on a very short timescale, while their H2 content remains largely unaffected, or to H I stripping coupled to a temporary boost of the H I-to-H2 conversion, causing a brief starburst phase triggered by ram pressure before eventually quenching the galaxy.

Exploring the physics behind the non-thermal emission from star-forming galaxies detected in γ rays

Context. Star-forming galaxies emit non-thermal radiation from radio to γ rays. Observations show that their radio and γ-ray luminosities scale with their star formation rates, supporting the hypothesis that non-thermal radiation is emitted by cosmic rays produced by their stellar populations. However, the nature of the main cosmic-ray transport processes that shape the emission in these galaxies is still poorly understood, especially at low star formation rates. Aims. Our aim is to investigate the main mechanisms of global cosmic-ray transport and cooling in star-forming galaxies. The way they contribute to shaping the relations between non-thermal luminosities and star formation rates could shed light onto their nature, and allow us to quantify their relative importance at different star formation rates. Methods. We developed a model to compute the cosmic-ray populations of star-forming galaxies, taking into account their production, transport, and cooling. The model is parametrised only through global galaxy properties, and describes the non-thermal emission in radio (at 1.4 GHz and 150 MHz) and γ rays (in the 0.1−100 GeV band). We focused on the role of diffusive and advective transport by galactic winds, either driven by turbulent or thermal instabilities. We compared model predictions to observations, for which we compiled a homogeneous set of luminosities in these radio bands, and updated those available in γ rays. Results. Our model reproduces reasonably well the observed relations between the γ-ray or 1.4 GHz radio luminosities and the star formation rate, assuming a single power-law scaling of the magnetic field (with index β = 0.3) and winds blowing either at Alfvenic speeds (∼tens of km s−1, for ≲5 M⊙ yr−1) or typical starburst wind velocities (∼hundreds of km s−1, for ≳5 M⊙ yr−1). Escape of cosmic rays is negligible for ≳30 M⊙ yr−1. A constant ionisation fraction of the interstellar medium fails to reproduce the 150 MHz radio luminosity throughout the whole star formation rate range. Conclusions. Our results reinforce the idea that galaxies with high star formation rates are cosmic-ray calorimeters, and that the main mechanism driving proton escape is diffusion, whereas electron escape also proceeds via wind advection. They also suggest that these winds should be cosmic-ray or thermally driven at low and intermediate star formation rates, respectively. Our results globally support that magneto-hydrodynamic turbulence is responsible for the dependence of the magnetic field strength on the star formation rate and that the ionisation fraction is strongly disfavoured to be constant throughout the whole range of star formation rates.

Structural and stellar-population properties versus bulge types in Sloan Digital Sky Survey central galaxies

ABSTRACT This paper studies pseudo-bulges (P-bulges) and classical bulges (C-bulges) in Sloan Digital Sky Survey (SDSS) central galaxies using the new bulge indicator ΔΣ1, which measures relative central stellar-mass surface density within 1 kpc. We compare ΔΣ1 to the established bulge-type indicator Δ〈μe〉 from Gadotti (2009) and show that classifying by ΔΣ1 agrees well with Δ〈μe〉. ΔΣ1 requires no bulge–disc decomposition and can be measured on SDSS images out to z = 0.07. Bulge types using it are mapped on to 20 different structural and stellar-population properties for 12 000 SDSS central galaxies with masses 10.0 < log M*/M⊙ < 10.4. New trends emerge from this large sample. Structural parameters show fairly linear log–log relations versus ΔΣ1 and Δ〈μe〉 with only moderate scatter, while stellar-population parameters show a highly non-linear ‘elbow’ in which specific star formation rate remains roughly flat with increasing central density and then falls rapidly at the elbow, where galaxies begin to quench. P-bulges occupy the low-density end of the horizontal arm of the elbow and are universally star forming, while C-bulges occupy the elbow and the vertical branch and exhibit a wide range of star formation rates at a fixed density. The non-linear relation between central density and star formation rate has been seen before, but this mapping on to bulge class is new. The wide range of star formation rates in C-bulges helps to explain why bulge classifications using different parameters have sometimes disagreed in the past. The elbow-shaped relation between density and stellar indices suggests that central structure and stellar populations evolve at different rates as galaxies begin to quench.

Star-forming Clumps in Local Luminous Infrared Galaxies

Abstract We present HST narrowband near-infrared imaging of Paα and Paβ emission of 48 local luminous infrared galaxies (LIRGs) from the Great Observatories All-Sky LIRG Survey. These data allow us to measure the properties of 810 spatially resolved star-forming regions (59 nuclei and 751 extranuclear clumps) and directly compare their properties to those found in both local and high-redshift star-forming galaxies. We find that in LIRGs the star-forming clumps have radii ranging from ∼90 to 900 pc and star formation rates (SFRs) of ∼1 × 10−3 to 10 M ⊙ yr−1, with median values for extranuclear clumps of 170 pc and 0.03 M ⊙ yr−1. The detected star-forming clumps are young, with a median stellar age of 8.7 Myr, and have a median stellar mass of 5 × 105 M ⊙. The SFRs span the range of those found in normal local star-forming galaxies to those found in high-redshift star-forming galaxies at z = 1–3. The luminosity function of the LIRG clumps has a flatter slope than found in lower-luminosity, star-forming galaxies, indicating a relative excess of luminous star-forming clumps. In order to predict the possible range of star-forming histories and gas fractions, we compare the star-forming clumps to those measured in the MassiveFIRE high-resolution cosmological simulation. The star-forming clumps in MassiveFIRE cover the same range of SFRs and sizes found in the local LIRGs and have total gas fractions that extend from 10% to 90%. If local LIRGs are similar to these simulated galaxies, we expect that future observations with ALMA will find a large range of gas fractions, and corresponding star formation efficiencies, among the star-forming clumps in LIRGs.

A Dynamical Study of Extraplanar Diffuse Ionized Gas in NGC 5775*

Abstract The structure and kinematics of gaseous, disk–halo interfaces are imprinted with the processes that transfer mass, metals, and energy between galactic disks and their environments. We study the extraplanar diffuse ionized gas (eDIG) layer in the interacting, star-forming galaxy NGC 5775 to better understand the consequences of star formation feedback on the dynamical state of the thick-disk interstellar medium. Combining emission-line spectroscopy from the Robert Stobie Spectrograph on the Southern African Large Telescope with radio continuum observations from Continuum Halos in Nearby Galaxies—an EVLA Survey, we ask whether thermal, turbulent, magnetic field, and cosmic-ray pressure gradients can stably support the eDIG layer in dynamical equilibrium. This model fails to reproduce the observed exponential electron scale heights of the eDIG thick disk and halo on the northeast ( kpc) and southwest ( kpc) sides of the galaxy at R < 11 kpc. We report the first definitive detection of an increasing eDIG velocity dispersion as a function of height above the disk. Blueshifted gas along the minor axis at large distances from the midplane hints at a disk–halo circulation and/or ram pressure effects caused by the ongoing interaction with NGC 5774. This work motivates further integral field unit and/or Fabry–Perot spectroscopy of galaxies with a range of star formation rates to develop a spatially resolved understanding of the role of star formation feedback in shaping the kinematics of the disk–halo interface.

Subaru High-z Exploration of Low-Luminosity Quasars (SHELLQs). VIII. A less biased view of the early co-evolution of black holes and host galaxies

Abstract We present ALMA [C ii] line and far-infrared (FIR) continuum observations of three $z \gt 6$ low-luminosity quasars ($M_{\rm 1450} \gt -25$ mag) discovered by our Subaru Hyper Suprime-Cam (HSC) survey. The [C ii] line was detected in all three targets with luminosities of $(2.4\mbox{--}9.5) \times 10^8\, L_{\odot }$, about one order of magnitude smaller than optically luminous ($M_{\rm 1450} \lesssim -25$ mag) quasars. The FIR continuum luminosities range from $\lt 9 \times 10^{10}\, L_{\odot }$ (3 $\sigma$ limit) to ${\sim } 2 \times 10^{12}\, L_{\odot }$, indicating a wide range in star formation rates in these galaxies. Most of the HSC quasars studied thus far show [C ii]/ FIR luminosity ratios similar to local star-forming galaxies. Using the [C ii]-based dynamical mass ($M_{\rm dyn}$) as a surrogate for bulge stellar mass ($M_{\rm\, bulge}$), we find that a significant fraction of low-luminosity quasars are located on or even below the local $M_{\rm\, BH}$–$M_{\rm\, bulge}$ relation, particularly at the massive end of the galaxy mass distribution. In contrast, previous studies of optically luminous quasars have found that black holes are overmassive relative to the local relation. Given the low luminosities of our targets, we are exploring the nature of the early co-evolution of supermassive black holes and their hosts in a less biased way. Almost all of the quasars presented in this work are growing their black hole mass at a much higher pace at $z \sim 6$ than the parallel growth model, in which supermassive black holes and their hosts grow simultaneously to match the local $M_{\rm\, BH}$–$M_{\rm\, bulge}$ relation at all redshifts. As the low-luminosity quasars appear to realize the local co-evolutionary relation even at $z \sim 6$, they should have experienced vigorous starbursts prior to the currently observed quasar phase to catch up with the relation.

The ALMA Spectroscopic Survey in the Hubble Ultra Deep Field: Evolution of the Molecular Gas in CO-selected Galaxies

Abstract We analyze the interstellar medium properties of a sample of 16 bright CO line emitting galaxies identified in the ALMA Spectroscopic Survey in the Hubble Ultra Deep Field (ASPECS) Large Program. This CO−selected galaxy sample is complemented by two additional CO line emitters in the UDF that are identified based on their Multi-Unit Spectroscopic Explorer (MUSE) optical spectroscopic redshifts. The ASPECS CO−selected galaxies cover a larger range of star formation rates (SFRs) and stellar masses compared to literature CO emitting galaxies at z > 1 for which scaling relations have been established previously. Most of ASPECS CO-selected galaxies follow these established relations in terms of gas depletion timescales and gas fractions as a function of redshift, as well as the SFR–stellar mass relation (“galaxy main sequence”). However, we find that ∼30% of the galaxies (5 out of 16) are offset from the galaxy main sequence at their respective redshift, with ∼12% (2 out of 16) falling below this relationship. Some CO-rich galaxies exhibit low SFRs, and yet show substantial molecular gas reservoirs, yielding long gas depletion timescales. Capitalizing on the well-defined cosmic volume probed by our observations, we measure the contribution of galaxies above, below, and on the galaxy main sequence to the total cosmic molecular gas density at different lookback times. We conclude that main-sequence galaxies are the largest contributors to the molecular gas density at any redshift probed by our observations (z ∼ 1−3). The respective contribution by starburst galaxies above the main sequence decreases from z ∼ 2.5 to z ∼ 1, whereas we find tentative evidence for an increased contribution to the cosmic molecular gas density from the passive galaxies below the main sequence.

Resolving on 100 pc-scales the UV-continuum in Lyman-emitters between redshift 2 to 3 with gravitational lensing

AbstractLyman-alpha emitting (LAE) galaxies are thought to be predominantly responsible for the re-ionisation of the Universe and are, as such, one of the most studied star-forming galaxy populations. Current optical and narrow-band studies are limited by the angular resolution of the observations and the considerable investment in telescope time. Strong gravitational lensing is an extremely powerful method that can be used to overcome these limitations. In my talk I will present a study on the first homogeneous sample of 17 lensed Lyman-alpha emitters at redshift 2 < z < 3. By taking advantage of the lensing magnification, I was able to access the detailed structure of this high redshift star-forming galaxies, finding that they have radii ranging from 0.2 to 1.8 kpc and have a complex and clumpy morphology, with a median ellipticity of 0.49. This is consistent with disk-like structures of star-formation, which would rule out models where the Lyman-alpha emission is only seen perpendicular to the disk, and favours those clumpy models for the escape lines of sight for Lyman-alpha photons. We also find that the star formation rates range from 0.3 to 8.5 Mȯ/yr and that these galaxies tend to be very compact. The lower limit to their intrinsic size is about a factor of two smaller than that found for non-lensed LAEs, which highlights the power of gravitational lensing and sophisticated lens modelling techniques for resolving such objects in the high redshift Universe.

IQ-Collaboratory 1.1: The Star-forming Sequence of Simulated Central Galaxies

Abstract A tightly correlated star formation rate (SFR)–stellar mass relation of star-forming galaxies, or star-forming sequence (SFS), is a key feature in galaxy property-space that is predicted by modern galaxy formation models. We present a flexible data-driven approach for identifying this SFS over a wide range of SFRs and stellar masses using Gaussian mixture modeling (GMM). Using this method, we present a consistent comparison of the z = 0 SFSs of central galaxies in the Illustris, Evolution and Assembly of GaLaxies and their Environment, and Mufasa hydrodynamic simulations and the Santa Cruz semianalytic model (SC-SAM), alongside data from the Sloan Digital Sky Survey. We find, surprisingly, that the amplitude of the SFS varies by up to ∼0.7 dex (factor of ∼5) among the simulations with power-law slopes ranging from 0.7 to 1.2. In addition to the SFS, our GMM method also identifies subcomponents in the SFR–stellar mass plane corresponding to starburst, transitioning, and quiescent subpopulations. The hydrodynamic simulations are similarly dominated by SFS and quiescent subpopulations unlike the SC-SAM, which predicts substantial fractions of transitioning and starburst galaxies at stellar masses above and below , respectively. All of the simulations also produce an abundance of low mass quiescent central galaxies in apparent tension with observations. These results illustrate that, even among models that well reproduce many observables of the galaxy population, the z = 0 SFS and other subpopulations still show marked differences that can provide strong constraints on galaxy formation models.