MEGA Mass Assembly with JWST: The MIRI EGS Galaxy and Active Galactic Nucleus Survey

We review results from cosmic X-ray surveys of active galactic nuclei (AGNs) over the past ~ 15 yr that have dramatically improved our understanding of growing supermassive black holes in the distant universe. First, we discuss the utility of such surveys for AGN investigations and the capabilities of the missions making these surveys, emphasizing Chandra, XMM-Newton, and NuSTAR. Second, we briefly describe the main cosmic X-ray surveys, the essential roles of complementary multiwavelength data, and how AGNs are selected from these surveys. We then review key results from these surveys on the AGN population and its evolution ("demographics"), the physical processes operating in AGNs ("physics"), and the interactions between AGNs and their environments ("ecology"). We conclude by describing some significant unresolved questions and prospects for advancing the field.

Massive black hole binaries (MBHBs) could be the loudest gravitational-wave (GW) sources in the millihertz (mHz) GW band, but their dynamical evolution may stall when the black holes reach the innermost parsec of a galaxy. Such a “final-parsec problem” could be solved if an MBHB forms in a gas-rich environment, such as an active galactic nucleus (AGN), but other solutions not involving AGNs also exist. Testing the correlation between these mHz GW sources and AGNs is difficult in real observation because AGNs are ubiquitous. To overcome this difficulty, we use a statistical method, first designed to constrain the host galaxies of stellar-mass binary black holes, to search for the MBHB–AGN correlation in different astrophysical scenarios. We find that by detecting only one MBHB at z ≲ 0.5, a mHz GW detector, such as the Laser Interferometer Space Antenna, can already distinguish different merger scenarios thanks to the precise localization of the source. Future detector networks and deeper AGNs surveys can further testify to the MBHB–AGN correlation up to a redshift of z ∼ 2 even if only a small fraction of MBHBs merge inside AGNs. These constraints will help settle the long-standing debate on the possible solutions to the final-parsec problem.

We report the detection of H2O maser emission in 4 out of 77 (5.2%) mid-IR red galaxies that meet the color criteria of W1 − W2 > 0.5 and W1 − W4 > 7 and are classified as Type 2 active galactic nuclei (AGNs) based on optical, near-IR, and mid-IR spectral energy distribution (SED) fitting. Here, W1, W2, and W4 represent the IR magnitudes at 3.4, 4.6, and 22 μm, respectively, as measured by the Wide-field Infrared Survey Explorer. Three of the four newly identified maser galaxies are classified as either Seyfert 2 or low-ionization nuclear emission-line region systems, but none are disk maser systems. Our analysis indicates that AGN identifications based solely on SED fitting are unreliable, resulting in an unexpectedly low megamaser detection rate. By restricting our sample to optically classified Type 2 AGNs that satisfy the mid-IR color criteria, we achieve a maser detection rate of ∼13%–18%, aligning with previous predictions for mid-IR red sources. These selection criteria are one of the most effective methods to date for facilitating new maser detections, particularly in light of the recent identification of additional Type 2 AGNs identified from ongoing galaxy and AGN surveys.

Local low-metallicity galaxies with signatures of possible accretion activity are ideal laboratories in which to search for the lowest-mass black holes and study their impact on the host galaxy. Here we present the first JWST NIRSpec IFS observations of SDSS J120122.30+021108.3, a nearby (z = 0.00354) extremely metal-poor dwarf galaxy with no optical signatures of accretion activity but identified by the Wide-field Infrared Survey Explorer to have red mid-infrared (MIR) colors consistent with active galactic nuclei (AGNs). We identify over 100 lines between ∼1.7 and 5.2 μm, an unresolved nuclear continuum source with an extremely steep spectral slope consistent with hot dust from an AGN (F ν ≈ ν −1.5), and a plethora of H i, He i, and H2 lines, with no lines from heavier elements, CO or ice absorption features, or polycyclic aromatic hydrocarbons (PAHs). While the bright central unresolved source (≲5 pc) is suggestive of an AGN, there are no He ii lines or coronal lines identified in the spectrum, and, importantly, there is no evidence that the radiation field is harder in the nuclear source compared with surrounding regions. The emission-line spectrum can be explained by a young (<5 Myr) nuclear star cluster with stellar mass ∼3 × 104 M ⊙, but the unresolved continuum source is more typical for a deeply embedded AGN powered by a black hole of minimum mass ∼1450 M ⊙. These observations reveal that either a metal-poor stellar population can heat the dust to extremely high temperatures, a result that would have significant impact on the reliability of MIR color selection in AGN surveys and our understanding of the properties of the interstellar medium and young stars in metal-poor galaxies, or an accreting intermediate-mass black hole is deeply embedded and hidden even at near-infrared wavelengths.

We present a study of the X-ray properties of a volume-limited sample of optically selected emission-line galaxies. The sample is derived from a correlation between the KPNO International Spectroscopic Survey (KISS), an Hα-selected objective-prism survey of active galactic nuclei (AGNs) and starbursting galaxies, and the ROSAT All-Sky Survey (RASS). After elimination of all spurious matches, we identify 18 ROSAT-detected X-ray sources within the KISS sample in the 0.1–2.4 keV band. Because of soft X-ray selection effects, the majority of the ROSAT sources are Seyfert 1 galaxies. The majority (54%) of the ROSAT-KISS Seyfert galaxies are classified as narrow-line Seyfert 1 objects, a relatively high percentage compared with previous objective-prism–selected Seyfert galaxy samples. We estimate the X-ray luminosities of the ROSAT-detected KISS objects and derive volume emissivities of 6.63 × 1038 and 1.45 × 1038 ergs s-1 Mpc-3 for the 30° and 43° survey strips, respectively. For those KISS AGNs not detected by the RASS, we use the median LX/LHα ratio derived from a previous study to estimate LX. The total 0.5–2 keV volume emissivity we predict for the overall KISS AGN sample is sufficient to account for 22.1% ± 8.9% of the soft X-ray background, averaged over both survey strips. The KISS AGN sample is made up predominantly of intermediate-luminosity Seyfert 2's and LINERs, which tend to be weak sources of soft X-rays. They may, however, represent a much more significant contribution to the hard X-ray background.

In recent years, large radio surveys of active galactic nuclei, comprising millions of sources, have become available where one could investigate dipole asymmetries, assumedly arising due to a peculiar motion of the Solar system. Investigations of such dipoles have yielded in past much larger amplitudes than the cosmic microwave background (CMB) dipole, though their directions seem to lie close to the CMB dipole. Here we investigate dipole asymmetries in two recent large radio surveys, Very Large Array sky survey (VLASS) containing 1.9 million sources, covering the sky north of −40° declination, and the Rapid ASKAP Continuum Survey (RACS) containing 2.1 million sources, covering the sky south of +30° declination We find dipoles determined from the VLASS and RACS surveys to be significantly larger than the CMB dipole. Dipole directions from the VLASS and RACS data differ significantly from each other. Nevertheless, along with a number of other previously determined dipoles, including the CMB, they all appear to lie in a narrow sky region, which argues for the various dipoles to be related somehow. However, significant differences in their derived peculiar velocities, including that of the CMB, cannot be explained by a peculiar motion of the Solar system, which should necessarily be a single value. Instead, their discordant peculiar velocities may be indicating that different cosmic reference frames are moving relative to each other or that the matter distribution on cosmic scales is not homogeneous and isotropic, either scenario being in contravention of what expected from the cosmological principle.

We describe data release 3 (DR3) of the Galaxy And Mass Assembly (GAMA) survey. The GAMA survey is a spectroscopic redshift and multi-wavelength photometric survey in three equatorial regions each of 60.0 deg^2 (G09, G12, G15), and two southern regions of 55.7 deg^2 (G02) and 50.6 deg^2 (G23). DR3 consists of: the first release of data covering the G02 region and of data on H-ATLAS sources in the equatorial regions; and updates to data on sources released in DR2. DR3 includes 154809 sources with secure redshifts across four regions. A subset of the G02 region is 95.5% redshift complete to r<19.8 over an area of 19.5 deg^2, with 20086 galaxy redshifts, that overlaps substantially with the XXL survey (X-ray) and VIPERS (redshift survey). In the equatorial regions, the main survey has even higher completeness (98.5%), and spectra for about 75% of H-ATLAS filler targets were also obtained. This filler sample extends spectroscopic redshifts, for probable optical counterparts to H-ATLAS sub-mm sources, to 0.8 mag deeper (r<20.6) than the GAMA main survey. There are 25814 galaxy redshifts for H-ATLAS sources from the GAMA main or filler surveys. GAMA DR3 is available at the survey website (www.gama-survey.org/dr3/).

We combine IR, optical, and X-ray data from the overlapping, 9.3 deg2 NOAO Deep Wide-Field Survey, AGN and Galaxy Evolution Survey (AGES), and XBoötes Survey to measure the X-ray evolution of 6146 normal galaxies as a function of absolute optical luminosity, redshift, and spectral type over the largely unexplored redshift range 0.1 ≲ z ≲ 0.5. Because only the closest or brightest of the galaxies are individually detected in X-rays, we use a stacking analysis to determine the mean properties of the sample. Our results suggest that X-ray emission from spectroscopically late-type galaxies is dominated by star formation, while that from early-type galaxies is dominated by a combination of hot gas and active galactic nucleus (AGN) emission. We find that the mean star formation and supermassive black hole accretion rate densities evolve like ∼(1 + z)3±1, in agreement with the trends found for samples of bright, individually detectable starburst galaxies and AGN. Our work also corroborates the results of many previous stacking analyses of faint source populations, with improved statistics.

The Galaxy And Mass Assembly (GAMA) survey furnishes a deep redshift catalog that, when combined with the Wide-field Infrared Survey Explorer (WISE), allows us to explore for the first time the mid-infrared properties of &gt;110, 000 galaxies over 120 deg2 to z ≃ 0.5. In this paper we detail the procedure for producing the matched GAMA-WISE catalog for the G12 and G15 fields, in particular characterizing and measuring resolved sources; the complete catalogs for all three GAMA equatorial fields will be made available through the GAMA public releases. The wealth of multiwavelength photometry and optical spectroscopy allows us to explore empirical relations between optically determined stellar mass (derived from synthetic stellar population models) and 3.4 μm and 4.6 μm WISE measurements. Similarly dust-corrected Hα-derived star formation rates can be compared to 12 μm and 22 μm luminosities to quantify correlations that can be applied to large samples to z &lt; 0.5. To illustrate the applications of these relations, we use the 12 μm star formation prescription to investigate the behavior of specific star formation within the GAMA-WISE sample and underscore the ability of WISE to detect star-forming systems at z 0.5. Within galaxy groups (determined by a sophisticated friends-of-friends scheme), results suggest that galaxies with a neighbor within 100 h -1 kpc have, on average, lower specific star formation rates than typical GAMA galaxies with the same stellar mass. © 2014. The American Astronomical Society. All rights reserved.

Aims. We study the environment in which a galaxy lies (i.e. field or group) and its connection with the morphology of the galaxy. This is done by examining the distribution of parametric and non-parametric statistics across the star-formation rate (SFR) – stellar mass (M⋆) plane and studying how these distributions change with the environment in the local universe (z &lt; 0.15). Methods. We determine the concentration (C), Gini, M20, asymmetry, Gini-M20 bulge statistic (GMB), 50% light radius (r50), total Sérsic index, and bulge Sérsic index (nBulge) for galaxies from the Galaxy and Mass Assembly (GAMA) survey using optical images from the Kilo Degree Survey. We determine the galaxy environment using the GAMA group catalogue and split the galaxies into field or group galaxies. The group galaxies are further divided by the group halo mass (Mh)−11 ≤ log(Mh/M⊙) &lt; 12, 12 ≤ log(Mh/M⊙) &lt; 13, and 13 ≤ log(Mh/M⊙) &lt; 14 – and into central and satellite galaxies. The galaxies in each of these samples are then placed onto the SFR-M⋆ plane, and each parameter is used as a third dimension. We fit the resulting distributions for each parameter in each sample using two two-dimensional Gaussian distributions: one for star-forming galaxies and one for quiescent galaxies. The coefficients of these Gaussian fits are then compared between environments. Results. Using C and r50, we find that galaxies typically become larger as the group mass increases. This change is greater for larger galaxies. There is no indication that galaxies are typically more or less clumpy as the environment changes. Using GMB and nBulge, we see that the star-forming galaxies do not become more bulge or disk dominated as the group mass changes. Asymmetry does not appear to be greatly influenced by environment.

We present a pilot study to assess the potential of Hyper Suprime-Cam Public Data Release 2 (HSC-PDR2) images for the analysis of extended faint structures within groups of galaxies. We examine the intragroup light (IGL) of the group 400138 (Mdyn = 1.3 ± 0.5 × 1013 M⊙, z ∼ 0.2) from the Galaxy And Mass Assembly (GAMA) survey using Hyper Suprime-Cam Subaru Strategic Program Public Data Release 2 (HSC-SSP PDR2) images in g, r, and i bands. We present the most extended IGL measurement to date, reaching down to $\mu _{g}^{\rm {lim}}=30.76$ mag arcsec−2 (3σ; 10 × 10 arcsec2) at a semimajor axis of 275 kpc. The IGL shows mean colour values of g − i = 0.92, g − r = 0.60, and r − i = 0.32 (±0.01). The IGL stellar populations are younger (2–2.5 Gyr) and less metal rich ([Fe/H] ∼ −0.4) than those of the host group galaxies. We find a range of IGL fractions as a function of total group luminosity of ${\sim} 2\!-\!36 {{\ \rm per\ cent}}$ depending on the definition of IGL, with larger fractions the bluer the observation wavelength. The early-type to late-type galaxy ratio suggests that 400138 is a more evolved group, dominated by early-type galaxies, and the IGL fraction agrees with that of other similarly evolved groups. These results are consistent with tidal stripping of the outer parts of Milky Way-like galaxies as the main driver of the IGL build-up. This is supported by the detection of substructure in the IGL towards the galaxy member 1660615 suggesting a recent interaction (&amp;lt;1 Gyr ago) of that galaxy with the core of the group.

A full appreciation of the role played by gas metallicity (Z), star-formation rate (SFR), and stellar mass is fundamental to understanding how galaxies form and evolve. The connections between these three parameters at different redshifts significantly affect galaxy evolution, and thus provide important constraints for galaxy evolution models. Using data from the Sloan Digital Sky Survey-Data Release 7 (SDSS-DR7) and the Galaxy and Mass Assembly (GAMA) surveys we study the relationships and dependencies between SFR, Z, and stellar mass, as well as the Fundamental Plane for star-forming galaxies. We combine both surveys using volume-limited samples up to a redshift of z ~ 0.36. The GAMA and SDSS surveys complement each other when analyzing the relationships between SFR, Mass and Z. We present evidence for SFR and metallicity evolution to z ~ 0.2. We study the dependencies between SFR, Mass, Z, and specific star-formation rate (SSFR) on the M-Z, M-SFR, M-SSFR, Z-SFR, and Z-SSFR relations, finding strong correlations between all. Based on those dependencies, we propose a simple model that allows us to explain the different behaviour observed between low and high mass galaxies. Finally, our analysis allows us to confirm the existence of a Fundamental Plane, for which Mass=f(Z, SFR) in star-forming galaxies.

Aims. We investigate how different mid-infrared (mid-IR) properties of galaxies are correlated with the environment in which the galaxies are located. For this purpose, we first study the dependence of galaxy clustering on the absolute magnitude at 3.4 μm and redshift. Then, we look into the environmental dependence of mid-IR luminosities and the galaxy properties derived from these luminosities. We also explore how various IR galaxy luminosity selections influence the galaxy clustering measurements. Methods. We used a set of W1 (3.4 μm) absolute magnitude (MW1) selected samples from the Galaxy and Mass Assembly (GAMA) survey matched with mid-IR properties from the Wide-field Infrared Survey Explorer (WISE) in the redshift range 0.07 ≤ z &lt; 0.43. We computed the galaxy two-point correlation function (2pCF) and compared the clustering lengths between subsamples binned in MW1 and in redshift. We also measured the marked correlation function (MCF), in which the galaxies are weighted by marks when measuring clustering statistics, using the luminosities in the WISE W1 to W4 (3.4 to 22 μm) bands as marks. Additionally, we compared the measurements of MCFs with different estimates of stellar mass and star formation rate (SFR) used as marks. Finally, we checked how different selections applied to the sample affect the clustering measurements. Results. We show strong clustering dependence on the W1 absolute magnitude: galaxies brighter in the W1 band are more strongly clustered than their fainter counterparts. We also observe a lack of significant redshift dependence of clustering in the redshift range 0.07 ≤ z &lt; 0.43. We show that although the W1 and W2 bands are direct indicators of stellar mass, a galaxy sample selected based on W1 or W2 bands does not perfectly show the clustering behaviour of a stellar mass-selected sample. The proxy relation between W3 and W4 bands and SFR is similar. We also demonstrate the influence of estimation techniques of stellar mass and SFR on the clustering measurements.

The SAMI Galaxy Survey will observe 3400 galaxies with the Sydney-AAO Multi-object Integral-field spectrograph (SAMI) on the Anglo-Australian Telescope (AAT) in a 3-year survey which began in 2013. We present the throughput of the SAMI system, the science basis and specifications for the target selection, the survey observation plan and the combined properties of the selected galaxies. The survey includes four volume limited galaxy samples based on cuts in a proxy for stellar mass, along with low-stellar mass dwarf galaxies all selected from the Galaxy And Mass Assembly (GAMA) survey. The GAMA regions were selected because of the vast array of ancillary data available, including ultraviolet through to radio bands. These fields are on the celestial equator at 9, 12, and 14.5 hours, and cover a total of 144 square degrees (in GAMA-I). Higher density environments are also included with the addition of eight clusters. The clusters have spectroscopy from 2dFGRS and SDSS and photometry in regions covered by the Sloan Digital Sky Survey (SDSS) and/or VLT Survey Telescope/ATLAS. The aim is to cover a broad range in stellar mass and environment, and therefore the primary survey targets cover redshifts 0.004 < z < 0.095, magnitudes r$_{pet}$ < 19.4, stellar masses $10^{7} - 10^{12}$ M$_{sol}$, and environments from isolated field galaxies through groups to clusters of $10^{15}$ M$_{sol}$.

The purpose of this study is to understand the space density and properties of active galaxies to . We have invesz 0.8 tigated the frequency and nature of unresolved nuclei in galaxies at moderate redshift as indicators of nuclear activity such as active galactic nuclei (AGNs) or starbursts. Candidates are selected by fitting imaged galaxies with multicomponent models using maximum likelihood estimate techniques to determine the best model fit. We select those galaxies requiring an unresolved, point source component in the galaxy nucleus, in addition to a disk and/or bulge component, to adequately model the galaxy light. We have searched 70 WFPC2 images primarily from the Medium Deep Survey for galaxies containing compact nuclei. In our survey of 1033 galaxies, the fraction containing an unresolved nuclear component ≥3% of the total galaxy light is corrected for incompleteness. Most of the nuclei 16% 3% comprise less than 20% of the total galaxy light. The majority of the host galaxies are spirals with little or no bulge component having a distribution of Hubble types comparable to that for “dwarf” Seyfert nuclei in nearby galaxies (L. C. Ho, A. Fillipenko, & W. L. W. Sargent, ApJS, 112, 315 [1997]) and local starburst nuclei (V. Balzano, ApJ, 268, 602 [1983]). The colors of the nuclei are compared with synthetic colors V I for Seyferts and starburst nuclei to help differentiate between AGNs and starbursts in our sample. Spectroscopic redshifts have been obtained for 35 of our AGN/starburst candidates and photometric redshifts are estimated to an accuracy of for the remaining sample. j 0.1 z Figure 1 is the luminosity function for compact nuclei in our sample having colors consistent with those of Seyfert nuclei. This represents an upper limit LF for low-luminosity AGNs (LLAGNs) in two redshift bins to . We detect z 0.8 mild number density evolution of the form for 1.9 f ∝ (1 z) nuclei at . Our LF shows a smooth transition 18 M 14 B from the brighter Seyfert LF of J. Huchra and R. Burg (ApJ, 393, 90 [1992]) and flattens at . This flattening of M ≥ 16 B the LF at fainter magnitudes is inconsistent with models using pure luminosity or density evolution fitted to quasar LFs at similar redshifts. Based on the observed number density of compact nuclei in this study, we find that almost all presentday spiral galaxies may host an active LLAGN at some point in their lives.