We use the SPace Infrared telescope for Cosmology and Astrophysics (SPICA) project as a template to demonstrate how deep spectrophotometric surveys covering large cosmological volumes over extended fields (1– $15\, \rm{deg^2}$ ) with a mid-IR imaging spectrometer (17– $36\, \rm{\rm{\upmu m}}$ ) in conjunction with deep $70\, \rm{\rm{\upmu m}}$ photometry with a far-IR camera, at wavelengths which are not affected by dust extinction can answer the most crucial questions in current galaxy evolution studies. A SPICA-like mission will be able for the first time to provide an unobscured three-dimensional (3D, i.e. x, y, and redshift z) view of galaxy evolution back to an age of the universe of less than $\sim$ 2 Gyrs, in the mid-IR rest frame. This survey strategy will produce a full census of the Star Formation Rate (SFR) in the universe, using polycyclic aromatic hydrocarbons (PAH) bands and fine-structure ionic lines, reaching the characteristic knee of the galaxy luminosity function, where the bulk of the population is distributed, at any redshift up to $z \sim 3.5$ . Deep follow-up pointed spectroscopic observations with grating spectrometers onboard the satellite, across the full IR spectral range (17– $210\, \rm{\rm{\upmu m}}$ ), would simultaneously measure Black Hole Accretion Rate (BHAR), from high-ionisation fine-structure lines, and SFR, from PAH and low- to mid-ionisation lines in thousands of galaxies from solar to low metallicities, down to the knee of their luminosity functions. The analysis of the resulting atlas of IR spectra will reveal the physical processes at play in evolving galaxies across cosmic time, especially its heavily dust-embedded phase during the activity peak at the cosmic noon ( $z \sim 1$ –3), through IR emission lines and features that are insensitive to the dust obscuration.

To sustain star formation rates (SFRs) of hundreds to thousands of solar masses per year over millions of years, a galaxy must efficiently cool its gas. At z ∼ 2, the peak epoch for stellar mass assembly, tracers of gas heating and cooling remain largely unexplored. For one z ∼ 2 starburst galaxy GS IRS20, we present Spitzer IRS spectroscopy of Polycyclic Aromatic Hydrocarbon (PAH) emission, and ALMA observations of [C II] 158 μm fine-structure emission which we use to probe ISM heating/cooling. Coupled with an unusually warm dust component, the ratio of [C II] /PAH emission suggests a low photolelectric efficiency, and/or the importance of cooling from other far-IR lines in this galaxy. A low photoelectric efficiency at z ∼ 2 could be key for the peak in the SFR density of the universe by decoupling stellar radiation from ISM gas temperatures.

We illustrate the extraordinary potential of the (far-IR) Origins Survey Spectrometer (OSS) on board the Origins Space Telescope (OST) to address a variety of open issues on the co-evolution of galaxies and AGNs. We present predictions for blind surveys, each of 1000 h, with different mapped areas (a shallow survey covering an area of 10 deg2 and a deep survey of 1 deg2) and two different concepts of the OST/OSS: with a 5.9 m telescope (Concept 2, our reference configuration) and with a 9.1 m telescope (Concept 1, previous configuration). In 1 000 h, surveys with the reference concept will detect from ∼1.9×106 to ∼8.7×106 lines from ∼4.8×105 to 2.7×106 star-forming galaxies and from ∼1.4×104 to ∼3.8×104 lines from ∼1.3×104 to 3.5×104 AGNs. The shallow survey will detect substantially more sources than the deep one; the advantage of the latter in pushing detections to lower luminosities/higher redshifts turns out to be quite limited. The OST/OSS will reach, in the same observing time, line fluxes more than one order of magnitude fainter than the SPICA/SMI and will cover a much broader redshift range. In particular it will detect tens of thousands of galaxies at z ≥ 5, beyond the reach of that instrument. The polycyclic aromatic hydrocarbons lines are potentially bright enough to allow the detection of hundreds of thousands of star-forming galaxies up to z ∼ 8.5, i.e. all the way through the reionisation epoch. The proposed surveys will allow us to explore the galaxy–AGN co-evolution up to z ∼ 5.5−6 with very good statistics. OST Concept 1 does not offer significant advantages for the scientific goals presented here.

We present first results from the Intermediate Redshift OSIRIS Chemo-Kinematic Survey (IROCKS) of z ∼ 1 star forming galaxies (Mieda et al. in prep). We have targeted Hα and [NII] emission lines in J-band and have spatially resolved the galaxies at sub-kilo parsec scale. We have combined our sample with deep HST continuum images, and are able to reveal the dynamics, morphologies, metallicity distribution, emission-line diagnostics, and star formation rates of galaxies spanning this crucial z ∼ 1 epoch.

Galaxy outflows are a vital mechanism in the regulation of galaxy evolution through feedback and enrichment. NGC 2146, a nearby infrared luminous galaxy (LIRG), presents evidence for outflows along the disk minor axis in all gas phases (ionized, neutral atomic and molecular). We present new far-IR Herschel imaging and spectroscopy of this galaxy from the Key Insights on Nearby Galaxies: a Far-Infrared Survey with Herschel (KINGFISH) project, as well as new optical integral field unit spectroscopy, to map the kinematics and gas excitation in the central 5 kpc and trace the dust distribution (Kreckel et al.2014). We observe an increased velocity dispersion in the [OI] 62 um, [OIII] 88 um, [NII] 122 um and [CII] 158 um fine-structure lines that is spatially coincident with shocked gas above and below the disk.

Templates and models of galaxy spectra are often essential for determining the physical properties of galaxies. Many commonly used templates have large systematic errors, which significantly impact photometric redshifts and k-corrections. We present a new library of 110 galaxy template spectra spanning from the ultraviolet to the mid-infrared. The templates combine optical, Spitzer and Akari spectra with MAGPHYS models, all normalised and verified with matched aperture photometry. Our library contains more galaxies, spans a broader range of colours and has smaller systematic errors than previous libraries of galaxy spectra.

Interactions and mergers are important drivers of galaxy evolution, transform spiral galaxies into massive ellipticals, and fuel both powerful starbursts and massive nuclear black holes. In particular one galaxy population, namely Luminous Infrared Galaxies (LIRGs), are believed to be responsible for most of the star formation that happened in the history of the universe (see e.g. Le Floch et al. 2005, Caputi et al. 2007, Magnelli et al. 2009), and hence represent a critical phase in the evolution of galaxies where most of the galaxies mass is building up. During a merger process, violent relaxation acts on stars present in gas-rich progenitor disks, while the centers are structured by the relics of dissipational, compact starbursts, imprinting a central “extra light” component or “cusp” into the surface brightness profiles of merger remnants. Our HST NICMOS/WFC3 imaging program of the 88 most luminous LIRGs in the Great Observatories Allsky LIRG Survey (GOALS, see Armus et al. 2009) shows that the central luminosity surface density in nearby LIRGs increases significantly along the merger sequence, indicating that the gas inflow fuels a central starburst and subsequently builds a compact stellar cusp (Haan et al. 2011). A large fraction of all galaxies in our sample possess double or multiple nuclei (~63%). Half of these double nuclei are not visible in the HST B-band images due to dust obscuration, which implies strong limitations on the ability to detect the true nuclear structures of luminous infrared galaxies at high-redshift (z >2) and may explain some of the apparent discrepancy of the LIRG population and merger ratio between local and high-redshift galaxies. We find that ULIRGs (log[LIR/L⊙] > 12.0) have significantly smaller nuclear separations than LIRGs (log[LIR/L⊙] = 11.4 — 12.0) with a median value of 1.2 kpc and 6.7 kpc, respectively. In our sample, merger (regardless of whether LIRG or ULIRG) seem to be prevalent at two time scales (based on the projected nuclear separation and mass ratio of the nuclei): First, at a remaining merger time scale of 0.3<[t-tmerg]<1.3 Gyr (53% of mergers in our sample), and second, at [t-tmerg]~ 0 (26%), likely representing the first passage of interacting galaxies and the final nuclear coalescence, respectively, with a post-merger time (starburst phase after the nuclei merged) of roughly 300 Myrs.

Large optical surveys provide an unprecedsCeented census of galaxies in the local Universe, forming an invaluable framework into which more detailed studies of objects can be placed. But how useful are optical surveys for understanding the co-evolution of black holes and galaxies, given their limited wavelength coverage, selection criteria, and depth? Here we present work-in-progress comparing optical and mid-IR diagnostics of three “unusual” low-z populations (luminous Seyferts, dusty Balmer-strong AGN, ULIRGs) with a set of ordinary star-forming galaxies from the SDSS. We address the questions “how well do the mid-IR and optical diagnostics of star formation and AGN strength agree?” and “to what extent do optical surveys allow us to include extreme, dusty, morphologically disturbed galaxies in our ‘complete’ census of BH-galaxy co-evolution?

We present results from infrared spectroscopic projects that aim to test the relation between the mass of a black hole MBH and the velocity dispersion of the stars in its host-galaxy bulge. We demonstrate that near-infrared, high-resolution spectroscopy assisted by adaptive optics is key in populating the high-luminosity end of the relation. We show that the velocity dispersions of mid-infrared, high-ionization lines originating from gas in the narrow-line region of the active galactic nucleus follow the same relation. This result provides a way of inferring MBH estimates for the cosmologically significant population of obscured, type 2 AGN that can be applicable to data from spectrographs on next-generation infrared telescopes.

We discuss our program of narrow-band (Hα + [Nil]) imaging of a sample of 30 powerful far-infrared galaxies (FIRG’s) chosen to have far-infrared spectral energy distributions similar to the prototype FIRG’s Arp 220, NGC 3690, NGC 6240, and M82. The emission-line nebulae of these IR color-selected sample (ICSS) galaxies as a class are both impressively large (mean half light radius, r ~1.3 Kpc, and mean diameter, D ~16 Kpc) and luminous (LTOT ~108 Lo; uncorrected for internal extinction). The mean total Hα + [Nil] luminosity of the FIRG’s is comparable to that found for pairs of optically selected interacting galaxies (Bushouse, Lamb, and Werner 1988), but is a factor of ~5 greater than that of isolated spirals (Kennicutt and Kent 1983). Only ~25% of the nearby (z ≤ 0.10) FIRG’s have morphologies suggesting that large HII~regions contribuí significantly to their emission-line appearance. The broad-band morphologies of our IR color-selected galaxies fall into three major categories. Nearly 75% are single galaxy systems, with the remaining FIRG’s being either multiple nuclei systems, or members of interacting pairs. Since we see few (10%) currently interacting FIRG’s, yet many (80%) with highly distorted continuum morphologies, our IR color criteria may be preferentially selecting galaxies that have undergone highly inelastic, rapidly merging interactions.

It has been known since the IRAS mission that there exist galaxies with far-infrared luminosities of 1011–1012Lo, and LFTR/LB = 10–100. Through extensive modelling and observations of HII-region/molecular cloud complexes in the Galaxy, this infrared radiation is believed to be thermal emission from heated dust grains (c.f. review by Stein and Soifer 1983). While starburst models are consistent with the data over a large range in wavelength, direct evidence for sizeable populations of young stars is scarce, and in many cases the presence of an active nucleus either cannot be ruled out, or is required on the basis of energy considerations. In order to better understand the energy source responsible for heating the dust, we have undertaken a spectroscopic survey of galaxies chosen to have far-infrared spectral energy distributions similar to the prototypical class members Arp 220, NGC 6240, NGC 3690, and Mrk 231. It was required that between 25μ and 60μ, α ≤ −1.5, and that between 60μ and 100μ, α ≥ −0.5, where Sv α vα.