Showing papers by "Dieter Lutz published in 2018"

PHIBSS: Unified Scaling Relations of Gas Depletion Time and Molecular Gas Fractions

Abstract: This paper provides an update of our previous scaling relations between galaxy-integrated molecular gas masses, stellar masses, and star formation rates (SFRs), in the framework of the star formation main sequence (MS), with the main goal of testing for possible systematic effects. For this purpose our new study combines three independent methods of determining molecular gas masses from CO line fluxes, far-infrared dust spectral energy distributions, and ∼1 mm dust photometry, in a large sample of 1444 star-forming galaxies between z=0 and 4. The sample covers the stellar mass range log(M * /M e)=9.0-11.8, and SFRs relative to that on the MS, δMS=SFR/SFR (MS), from 10 −1.3 to 10 2.2. Our most important finding is that all data sets, despite the different techniques and analysis methods used, follow the same scaling trends, once method-to-method zero-point offsets are minimized and uncertainties are properly taken into account. The molecular gas depletion time t depl , defined as the ratio of molecular gas mass to SFR, scales as (1+z) −0.6 ×(δMS) −0.44 and is only weakly dependent on stellar mass. The ratio of molecular to stellar mass μ gas depends on (* d +´´-) () () z M 1 M S 2.5 0.52 0.36 , which tracks the evolution of the specific SFR. The redshift dependence of μ gas requires a curvature term, as may the mass dependences of t depl and μ gas. We find no or only weak correlations of t depl and μ gas with optical size R or surface density once one removes the above scalings, but we caution that optical sizes may not be appropriate for the high gas and dust columns at high z.

Spatially resolved rotation of the broad-line region of a quasar at sub-parsec scale

Abstract: The broadening of atomic emission lines by high-velocity motion of gas near accreting supermassive black holes is an observational hallmark of quasars. Observations of broad emission lines could potentially constrain the mechanism for transporting gas inwards through accretion disks or outwards through winds. The size of this broad-line region has been estimated by measuring the light travel time delay between the variable nuclear continuum and the emission lines - a method known as reverberation mapping. In some models the emission lines arise from a continuous outflow, whereas in others they are produced by orbiting gas clouds. Directly imaging such regions has not hitherto been possible because of their small angular sizes (< 0.1 milli-arcseconds). Here we report a spatial offset (with a spatial resolution of ten micro-arcseconds or about 0.03 parsecs for a distance of 550 million parsecs) between the red and blue photo-centres of the broad Paschen-α line of the quasar 3C 273 perpendicular to the direction of its radio jet. This spatial offset corresponds to a gradient in the velocity of the gas and thus implies that the gas is orbiting the central supermassive black hole. The data are well fitted by a broad-line-region model of a thick disk of gravitationally bound material orbiting a black hole of 300 million solar masses. We infer a disk radius of 150 light days; a radius of 100-400 light days was found previously using reverberation mapping. The rotation axis of the disk aligns in inclination and position angle with the radio jet. Our results support the methods that are often used to estimate the masses of accreting supermassive black holes and to study their evolution over cosmic time.

Spatially resolved rotation of the broad-line region of a quasar at sub-parsec scale

Abstract: The broadening of atomic emission lines by high-velocity motion of gas near accreting supermassive black holes is an observational hallmark of quasars. Observations of broad emission lines could potentially constrain the mechanism for transporting gas inwards through accretion disks or outwards through winds. The size of this broad-line region has been estimated by measuring the light travel time delay between the variable nuclear continuum and the emission lines - a method known as reverberation mapping. In some models the emission lines arise from a continuous outflow, whereas in others they are produced by orbiting gas clouds. Directly imaging such regions has not hitherto been possible because of their small angular sizes (< 0.1 milli-arcseconds). Here we report a spatial offset (with a spatial resolution of ten micro-arcseconds or about 0.03 parsecs for a distance of 550 million parsecs) between the red and blue photo-centres of the broad Paschen-{\alpha} line of the quasar 3C 273 perpendicular to the direction of its radio jet. This spatial offset corresponds to a gradient in the velocity of the gas and thus implies that the gas is orbiting the central supermassive black hole. The data are well fitted by a broad-line-region model of a thick disk of gravitationally bound material orbiting a black hole of 300 million solar masses. We infer a disk radius of 150 light days; a radius of 100-400 light days was found previously using reverberation mapping. The rotation axis of the disk aligns in inclination and position angle with the radio jet. Our results support the methods that are often used to estimate the masses of accreting supermassive black holes and to study their evolution over cosmic time.

The SINS/zC-SINF Survey of z ∼2 Galaxy Kinematics: SINFONI Adaptive Optics-assisted Data and Kiloparsec-scale Emission-line Properties

Abstract: We present the "SINS/zC-SINF AO survey" of 35 star-forming galaxies, the largest sample with deep adaptive optics (AO)-assisted near-infrared integral field spectroscopy at z similar to 2. The observations, taken with SINFONI at the Very Large Telescope, resolve the Ha and [N II] emission and kinematics on scales of similar to 1.5 kpc. The sample probes the massive (M star similar to 2 x 10(9) - 3 x 10(11) M-circle dot), actively star-forming (SFR similar to 10-600 M-circle dot yr(-1)) part of the z similar to 2 galaxy population over a wide range of colors ((U-V)(rest) similar to 0.15-1.5 mag) and half-light radii (R-e,(H) similar to 1-8.5 kpc). The sample overlaps largely with the "main sequence" of star-forming galaxies in the same redshift range to a similar K-AB = 23 mag limit;it has similar to 0.3 dex higher median specific SFR, similar to 0.1 mag bluer median (U - V)(rest) color, and similar to 10% larger median rest-optical size. We describe the observations, data reduction, and extraction of basic flux and kinematic properties. With typically 3-4 times higher resolution and 4-5 times longer integrations (up to 23 hr) than the seeing-limited data sets of the same objects, the AO data reveal much more detail in morphology and kinematics. The complete AO observations confirm the majority of kinematically classified disks and the typically elevated disk velocity dispersions previously reported based on subsets of the data. We derive typically flat or slightly negative radial [N II]/H alpha gradients, with no significant trend with global galaxy properties, kinematic nature, or the presence of an AGN. Azimuthal variations in [N II]/H alpha are seen in several sources and are associated with ionized gas outflows and possibly more metal-poor star-forming clumps or small companions.

SHINING, a survey of far-infrared lines in nearby galaxies. II. Line-deficit models, AGN impact, [C ii]–SFR scaling relations, and mass–metallicity relation in (U)LIRGs

Abstract: The SHINING survey offers a great opportunity to study the properties of the ionized and neutral media of galaxies from prototypical starbursts and active galactic nuclei (AGNs) to heavily obscured objects. Based on Herschel/PACS observations of the main far-infrared (FIR) fine-structure lines, in this paper, we analyze the physical mechanisms behind the observed line deficits in galaxies, the apparent offset of luminous infrared galaxies (LIRGs) from the mass–metallicity relation, and the scaling relations between [C ii] 158 μm line emission and star formation rate (SFR). Based on a toy model and the Cloudy code, we conclude that the increase in the ionization parameter with FIR surface brightness can explain the observed decrease in the line-to-FIR continuum ratio of galaxies. In the case of the [C ii] line, the increase in the ionization parameter is accompanied by a reduction in the photoelectric heating efficiency and the inability of the line to track the increase in the FUV radiation field as galaxies become more compact and luminous. In the central approximately kiloparsec regions of AGN galaxies, we observe a significant increase in the [O i] 63 μm/[C ii] line ratio; the AGN impact on the line-to-FIR ratios fades on global scales. Based on extinction-insensitive metallicity measurements of LIRGs, we confirm that they lie below the mass–metallicity relation, but the offset is smaller than those reported in studies that use optical-based metal abundances. Finally, we present scaling relations between [C ii] emission and SFR in the context of the main sequence of star-forming galaxies.

The SINS/zC-SINF survey of z~2 galaxy kinematics: SINFONI adaptive optics-assisted data and kiloparsec-scale emission line properties

Abstract: We present the "SINS/zC-SINF AO survey" of 35 star-forming galaxies, the largest sample with deep adaptive optics-assisted (AO) near-infrared integral field spectroscopy at z~2. The observations, taken with SINFONI at the Very Large Telescope, resolve the Ha and [NII] line emission and kinematics on scales of ~1.5 kpc. In stellar mass, star formation rate, rest-optical colors and size, the AO sample is representative of its parent seeing-limited sample and probes the massive (M* ~ 2x10^9 - 3x10^11 Msun), actively star-forming (SFR ~ 10-600 Msun/yr) part of the z~2 galaxy population over a wide range in colors ((U-V)_rest ~ 0.15-1.5 mag) and half-light radii (R_e,H ~ 1-8.5 kpc). The sample overlaps largely with the "main sequence" of star-forming galaxies in the same redshift range to a similar K_AB = 23 magnitude limit; it has ~0.3 dex higher median specific SFR, ~0.1 mag bluer median (U-V)_rest color, and ~10% larger median rest-optical size. We describe the observations, data reduction, and extraction of basic flux and kinematic properties. With typically 3-4 times higher resolution and 4-5 times longer integrations (up to 23hr) than the seeing-limited datasets of the same objects, the AO data reveal much more detail in morphology and kinematics. The now complete AO observations confirm the majority of kinematically-classified disks and the typically elevated disk velocity dispersions previously reported based on subsets of the data. We derive typically flat or slightly negative radial [NII]/Ha gradients, with no significant trend with global galaxy properties, kinematic nature, or the presence of an AGN. Azimuthal variations in [NII]/Ha are seen in several sources and are associated with ionized gas outflows, and possible more metal-poor star-forming clumps or small companions. [Abridged]

Molecular outflow and feedback in the obscured quasar XID2028 revealed by ALMA

Abstract: We imaged, with ALMA and ARGOS/LUCI, the molecular gas and dust and stellar continuum in XID2028, which is an obscured quasi-stellar object (QSO) at z = 1.593, where the presence of a massive outflow in the ionised gas component traced by the [OIII]5007 emission has been resolved up to 10 kpc. This target represents a unique test case to study QSO feedback in action at the peak epoch of AGN-galaxy co-evolution. The QSO was detected in the CO(5 − 4) transition and in the 1.3 mm continuum at ~30 and ~20σ significance, respectively; both emissions are confined in the central (<2 kpc) radius area. Our analysis suggests the presence of a fast rotating molecular disc (v ~ 400 km s^(−1)) on very compact scales well inside the galaxy extent seen in the rest-frame optical light (~10 kpc, as inferred from the LUCI data). Adding available measurements in additional two CO transitions, CO(2 − 1) and CO(3 − 2), we could derive a total gas mass of ~10^(10) M⊙, thanks to a critical assessment of CO excitation and the comparison with the Rayleigh–Jeans continuum estimate. This translates into a very low gas fraction (<5%) and depletion timescales of 40–75 Myr, reinforcing the result of atypical gas consumption conditions in XID2028, possibly because of feedback effects on the host galaxy. Finally, we also detect the presence of high velocity CO gas at ~5σ, which we interpret as a signature of galaxy-scale molecular outflow that is spatially coincident with the ionised gas outflow. XID2028 therefore represents a unique case in which the measurement of total outflowing mass, of ~500–800 M⊙ yr^(−1) including the molecular and atomic components in both the ionised and neutral phases, was attempted for a high-z QSO.

The KMOS^3D Survey: Demographics and Properties of Galactic Outflows at z = 0.6 - 2.7

Abstract: We present a census of ionized gas outflows in 599 normal galaxies at redshift 06 112 galaxies The incidence, strength, and velocity of AGN-driven winds strongly correlates with stellar mass and central concentration Their outflowing ionized gas appears denser (n_e~1000 cm^-3), and possibly compressed and shock-excited These winds have comparable mass loading factors as the SF-driven winds but carry ~10 (~50) times more momentum (energy) The results confirm our previous findings of high duty cycle, energy-driven outflows powered by AGN above the Schechter mass, which may contribute to star formation quenching

LLAMA: normal star formation efficiencies of molecular gas in the centres of luminous Seyfert galaxies

Abstract: Using new Atacama Pathfinder Experiment and James Clerk Maxwell Telescope spectroscopy of the CO 2→1 line, we undertake a controlled study of cold molecular gas in moderately luminous (Lbol = 1043–44.5 erg s−1) active galactic nuclei (AGN) and inactive galaxies from the Luminous Local AGN with Matched Analogs (LLAMA) survey. We use spatially resolved infrared photometry of the LLAMA galaxies from 2MASS, the Wide-field Infrared Survey Explorer the Infrared Astronomical Satellite and the Herschel Space Observatory (Herschel), corrected for nuclear emission using multicomponent spectral energy distribution fits, to examine the dust-reprocessed star formation rates, molecular gas fractions and star formation efficiencies (SFEs) over their central 1–3 kpc. We find that the gas fractions and central SFEs of both active and inactive galaxies are similar when controlling for host stellar mass and morphology (Hubble type). The equivalent central molecular gas depletion times are consistent with the discs of normal spiral galaxies in the local Universe. Despite energetic arguments that the AGN in LLAMA should be capable of disrupting the observable cold molecular gas in their central environments, our results indicate that nuclear radiation only couples weakly with this phase. We find a mild preference for obscured AGN to contain higher amounts of central molecular gas, which suggests connection between AGN obscuration and the gaseous environment of the nucleus. Systems with depressed SFEs are not found among the LLAMA AGN. We speculate that the processes that sustain the collapse of molecular gas into dense pre-stellar cores may also be a prerequisite for the inflow of material on to AGN accretion discs.

SHINING, a survey of far-infrared lines in nearby galaxies. - I. Survey description, observational trends, and line diagnostics

Abstract: We use the Herschel/PACS spectrometer to study the global and spatially resolved far-infrared (FIR) fine-structure line emission in a sample of 52 galaxies that constitute the SHINING survey. These galaxies include star-forming, active-galactic nuclei (AGNs), and luminous infrared galaxies (LIRGs). We find an increasing number of galaxies (and kiloparsec-size regions within galaxies) with low line-to-FIR continuum ratios as a function of increasing FIR luminosity (L FIR), dust infrared color, L FIR to molecular gas mass ratio (L FIR/M mol), and FIR surface brightness (ΣFIR). The correlations between the [C ii]/FIR or [O i]/FIR ratios with ΣFIR are remarkably tight (~0.3 dex scatter over almost four orders of magnitude in ΣFIR). We observe that galaxies with ${L}_{\mathrm{FIR}}/{M}_{\mathrm{mol}}\gtrsim 80\,{L}_{\odot }\,{M}_{\odot }^{-1}$ and ΣFIR gsim 1011 L ⊙ kpc−2 tend to have weak fine-structure line-to-FIR continuum ratios, and that LIRGs with infrared sizes gsim1 kpc have line-to-FIR ratios comparable to those observed in typical star-forming galaxies. We analyze the physical mechanisms driving these trends in Paper II. The combined analysis of the [C ii], [N ii] 122 μm, and [O iii] 88 μm lines reveals that the fraction of the [C ii] line emission that arises from neutral gas increases from 60% to 90% in the most active star-forming regions and that the emission originating in the ionized gas is associated with low-ionization, diffuse gas rather than with dense gas in H ii regions. Finally, we report the global and spatially resolved line fluxes of the SHINING galaxies to enable the comparison and planning of future local and high-z studies.

Ionized and Molecular Gas Kinematics in a z=1.4 Star-forming Galaxy

Abstract: We present deep observations of a $z=1.4$ massive, star-forming galaxy in molecular and ionized gas at comparable spatial resolution (CO 3-2, NOEMA; H$\\alpha$, LBT). The kinematic tracers agree well, indicating that both gas phases are subject to the same gravitational potential and physical processes affecting the gas dynamics. We combine the one-dimensional velocity and velocity dispersion profiles in CO and H$\\alpha$ to forward-model the galaxy in a Bayesian framework, combining a thick exponential disk, a bulge, and a dark matter halo. We determine the dynamical support due to baryons and dark matter, and find a dark matter fraction within one effective radius of $f_{\\rm DM}(\\leq$$R_{e})=0.18^{+0.06}_{-0.04}$. Our result strengthens the evidence for strong baryon-dominance on galactic scales of massive $z\\sim1-3$ star-forming galaxies recently found based on ionized gas kinematics alone.

The Molecular and Ionized Gas Phases of an AGN-driven Outflow in a Typical Massive Galaxy at z=2

Abstract: Nuclear outflows driven by accreting massive black holes are one of the main feedback mechanisms invoked at high-z to reproduce the distinct separation between star-forming, disk galaxies and quiescent spheroidal systems. Yet, our knowledge of feedback at high-z remains limited by the lack of observations of the multiple gas phases in galaxy outflows. In this work we use new deep, high-spatial resolution ALMA CO(3-2) and archival VLT/SINFONI H$\alpha$ observations to study the molecular and ionized components of the AGN-driven outflow in zC400528 ---a massive, main sequence galaxy at z=2.3 in the process of quenching. We detect a powerful molecular outflow that shows a positive velocity gradient and extends for at least ~10 kpc from the nuclear region, about three times the projected size of the ionized wind. The molecular gas in the outflow does not reach velocities high enough to escape the galaxy and is therefore expected to be reaccreted. Keeping in mind the various assumptions involved in the analysis, we find that the mass and energetics of the outflow are dominated by the molecular phase. The AGN-driven outflow in zC400528 is powerful enough to deplete the molecular gas reservoir on a timescale at least twice shorter than that needed to exhaust it by star formation. This suggests that the nuclear outflow is one of the main quenching engines at work in the observed suppression of the central star-formation activity in zC400528.

Ionized and molecular gas kinematics in a z=1.4 star-forming galaxy

Abstract: We present deep observations of a $z=14$ massive, star-forming galaxy in molecular and ionized gas at comparable spatial resolution (CO 3-2, NOEMA; H$\alpha$, LBT) The kinematic tracers agree well, indicating that both gas phases are subject to the same gravitational potential and physical processes affecting the gas dynamics We combine the one-dimensional velocity and velocity dispersion profiles in CO and H$\alpha$ to forward-model the galaxy in a Bayesian framework, combining a thick exponential disk, a bulge, and a dark matter halo We determine the dynamical support due to baryons and dark matter, and find a dark matter fraction within one effective radius of $f_{\rm DM}(\leq$$R_{e})=018^{+006}_{-004}$ Our result strengthens the evidence for strong baryon-dominance on galactic scales of massive $z\sim1-3$ star-forming galaxies recently found based on ionized gas kinematics alone

Kiloparsec Scale Properties of Star-Formation Driven Outflows at z~2.3 in the SINS/zC-SINF AO Survey.

Abstract: We investigate the relationship between star formation activity and outflow properties on kiloparsec scales in a sample of 28 star forming galaxies at $z\sim$ 2-2.6, using adaptive optics assisted integral field observations from SINFONI on the VLT. The narrow and broad components of the H$\alpha$ emission are used to simultaneously determine the local star formation rate surface density ($\Sigma_{\rm SFR}$), and the outflow velocity $v_{\rm out}$ and mass outflow rate $\dot{M}_{\rm out}$, respectively. We find clear evidence for faster outflows with larger mass loading factors at higher $\Sigma_{\rm SFR}$. The outflow velocities scale as $v_{\rm out}$ $\propto$ $\Sigma_{\rm SFR}^{0.34 \pm 0.10}$, which suggests that the outflows may be driven by a combination of mechanical energy released by supernova explosions and stellar winds, as well as radiation pressure acting on dust grains. The majority of the outflowing material does not have sufficient velocity to escape from the galaxy halos, but will likely be re-accreted and contribute to the chemical enrichment of the galaxies. In the highest $\Sigma_{\rm SFR}$ regions the outflow component contains an average of $\sim$45% of the H$\alpha$ flux, while in the lower $\Sigma_{\rm SFR}$ regions only $\sim$10% of the H$\alpha$ flux is associated with outflows. The mass loading factor, $\eta$ = $\dot{M}_{\rm out}$/SFR, is positively correlated with $\Sigma_{\rm SFR}$ but is relatively low even at the highest $\Sigma_{\rm SFR}$: $\eta \lesssim$ 0.5 $\times$ (380 cm$^{-3}$/n$_e$). This may be in tension with the $\eta$ $\gtrsim$ 1 required by cosmological simulations, unless a significant fraction of the outflowing mass is in other gas phases and has sufficient velocity to escape the galaxy halos.

The KMOS3D Survey: Rotating Compact Star-forming Galaxies and the Decomposition of Integrated Line Widths

Abstract: Using integral field spectroscopy, we investigate the kinematic properties of 35 massive centrally dense and compact star-forming galaxies (SFGs; $\mathrm{log}{\overline{M}}_{* }[{M}_{\odot }]=11.1$, $\mathrm{log}({{\rm{\Sigma }}}_{1\mathrm{kpc}}[{M}_{\odot }\,{\mathrm{kpc}}^{-2}])\gt 9.5$, $\mathrm{log}({M}_{* }/{r}_{e}^{1.5}[{M}_{\odot }\,{\mathrm{kpc}}^{-1.5}])\gt 10.3$) at z ~ 0.7–3.7 within the KMOS3D survey. We spatially resolve 23 compact SFGs and find that the majority are dominated by rotational motions with velocities ranging from 95 to 500 km s−1. The range of rotation velocities is reflected in a similar range of integrated Hα line widths, 75–400 km s−1, consistent with the kinematic properties of mass-matched extended galaxies from the full KMOS3D sample. The fraction of compact SFGs that are classified as "rotation-dominated" or "disklike" also mirrors the fractions of the full KMOS3D sample. We show that integrated line-of-sight gas velocity dispersions from KMOS3D are best approximated by a linear combination of their rotation and turbulent velocities with a lesser but still significant contribution from galactic-scale winds. The Hα exponential disk sizes of compact SFGs are, on average, 2.5 ± 0.2 kpc, 1–2× the continuum sizes, in agreement with previous work. The compact SFGs have a 1.4× higher active galactic nucleus (AGN) incidence than the full KMOS3D sample at fixed stellar mass with an average AGN fraction of 76%. Given their high and centrally concentrated stellar masses, as well as stellar-to-dynamical mass ratios close to unity, the compact SFGs are likely to have low molecular gas fractions and to quench on a short timescale unless replenished with inflowing gas. The rotation in these compact systems suggests that their direct descendants are rotating passive galaxies.

Cross-calibration of CO- versus dust-based gas masses and assessment of the dynamical mass budget in Herschel-SDSS Stripe82 galaxies.

Abstract: We present a cross-calibration of CO- and dust-based molecular gas masses at z ≤ 0.2. Our results are based on a survey with the IRAM 30-m telescope collecting CO(1–0) measurements of 78 massive (logM⋆/M⊙> 10) galaxies with known gas-phase metallicities and with IR photometric coverage from Wide-field Infrared Survey Explorer(WISE; 22 μ m) and Herschel Spectral and Photometric Imaging Receiver (SPIRE; 250, 350, 500 μ m). We find a tight relation (∼0.17 dex scatter) between the gas masses inferred from CO and dust continuum emission, with a minor systematic offset of 0.05 dex. The two methods can be brought into agreement by applying a metallicity-dependent adjustment factor (∼0.13 dex scatter). We illustrate that the observed offset is consistent with a scenario in which dust traces not only molecular gas but also part of the HI reservoir, residing in the H2-dominated region of the galaxy. Observations of the CO(2–1) to CO(1–0) line ratio for two-thirds of the sample indicate a narrow range in excitation properties, with a median ratio of luminosities ⟨R21⟩ ∼ 0.64. Finally, we find dynamical mass constraints from spectral line profile fitting to agree well with the anticipated mass budget enclosed within an effective radius, once all mass components (stars, gas, and dark matter) are accounted for.

BAT AGN Spectroscopic Survey. VIII. Type 1 AGN with Massive Absorbing Columns

Abstract: We explore the relationship between X-ray absorption and optical obscuration within the BAT AGN Spectroscopic Survey (BASS), which has been collecting and analyzing the optical and X-ray spectra for 641 hard X-ray selected (E > 14 keV) active galactic nuclei (AGNs). We use the deviation from a linear broad Hα-to-X-ray relationship as an estimate of the maximum optical obscuration toward the broad line region (BLR) and compare the A V to the hydrogen column densities (${N}_{{\rm{H}}}$) found through systematic modeling of their X-ray spectra. We find that the inferred columns implied by A V toward the BLR are often orders of magnitude less than the columns measured toward the X-ray emitting region, indicating a small-scale origin for the X-ray absorbing gas. After removing 30% of Sy 1.9s that potentially have been misclassified due to outflows, we find that 86% (164/190) of the Type 1 population (Sy 1–1.9) are X-ray unabsorbed as expected based on a single obscuring structure. However, 14% (26/190), of which 70% (18/26) are classified as Sy 1.9, are X-ray absorbed, suggesting that the BLR itself is providing extra obscuration toward the X-ray corona. The fraction of X-ray absorbed Type 1 AGNs remains relatively constant with AGN luminosity and Eddington ratio, indicating a stable BLR covering fraction.

Millimeter mapping at z~1: dust-obscured bulge building and disk growth

Abstract: A randomly chosen star in today's Universe is most likely to live in a galaxy with a stellar mass between that of the Milky Way and Andromeda. Yet it remains uncertain how the structural evolution of these bulge-disk systems proceeded. Most of the unobscured star formation we observe building Andromdeda progenitors at 0.7 90% of their star formation is reprocessed by dust and remains unaccounted for. Here we map 500micron dust continuum emission in an Andromeda progenitor at z=1.25 to probe where it is growing through dust-obscured star formation. Combining resolved dust measurements from the NOEMA interferometer with Hubble Space Telescope Halpha maps and multicolor imaging (including new UV data from the HDUV survey), we find a bulge growing by dust-obscured star formation: while the unobscured star formation is centrally suppressed, the dust continuum is centrally concentrated, filling in the ring-like structures evident in the Halpha and UV emission. Reflecting this, the dust emission is more compact than the optical/UV tracers of star formation with r_e(dust)=3.4kpc, r_e(Halpha)/r_e(dust)=1.4, and r_e(UV)/r_e(dust)=1.8. Crucially, however, the bulge and disk of this galaxy are building simultaneously; although the dust emission is more compact than the rest-optical emission (r_e(optical)/r_e(dust)=1.4), it is somewhat less compact than the stellar mass (r_e(M_*)/r_e(dust)=0.9). Taking the 500micron emission as a tracer of star formation, the expected structural evolution of this galaxy can be accounted for by star formation: it will grow in size by Delta(r_e)/Delta(M_*)~0.3 and central surface density by Delta(Sigma_cen)/Delta(M_*)~0.9. Finally, our observations are consistent with a picture in which merging and disk instabilities drive gas to the center of galaxies, boosting global star formation rates above the main sequence and building bulges.

Local Swift-BAT active galactic nuclei prefer circumnuclear star formation

Abstract: We use Herschel data to analyze the size of the far-infrared 70 μ m emission for z Swift -BAT selected active galactic nuclei (AGN), and 515 comparison galaxies that are not detected by BAT. For modest far-infrared luminosities 8.5 L FIR [ L ⊙ ]) R e,70 for both populations, but a typical R e,70 ≲ 1 kpc for the BAT hosts that is only half that of comparison galaxies of same far-infrared luminosity. The result mostly reflects a more compact distribution of star formation (and hence gas) in the AGN hosts, but compact AGN heated dust may contribute in some extremely AGN dominated systems. Our findings are in support of an AGN-host coevolution where accretion onto the central black hole and star formation are fed from the same gas reservoir, with more efficient black hole feeding if that reservoir is more concentrated. The significant scatter in the far-infrared sizes emphasizes that we are mostly probing spatial scales much larger than those of actual accretion, and that rapid accretion variations can smear the distinction between the AGN and comparison categories. Large samples are hence needed to detect structural differences that favor feeding of the black hole. No size difference between AGN host and comparison galaxies is observed at higher far-infrared luminosities log( L FIR [ L ⊙ ]) > 10.5 (star formation rates ≳6 M ⊙ yr -1 ), possibly because these are typically reached in more compact regions.

LLAMA : nuclear stellar properties of Swift-BAT AGN and matched inactive galaxies.

Abstract: In a complete sample of local 14–195 keV selected active galactic nuclei (AGNs) and inactive galaxies, matched by their host galaxy properties, we study the spatially resolved stellar kinematics and luminosity distributions at near-infrared wavelengths on scales of 10–150 pc, using SINFONI on the VLT. In this paper, we present the first half of the sample, which comprises 13 galaxies, eight AGNs and five inactive galaxies. The stellar velocity fields show a disc-like rotating pattern, for which the kinematic position angle is in agreement with the photometric position angle obtained from large scale images. For this set of galaxies, the stellar surface brightness of the inactive galaxy sample is generally comparable to the matched sample of AGN, but extends to lower surface brightness. After removal of the bulge contribution, we find a nuclear stellar light excess with an extended nuclear disc structure, which exhibits a size-luminosity relation. While we expect the excess luminosity to be associated with a dynamically cooler young stellar population, we do not typically see a matching drop in dispersion. This may be because these galaxies have pseudo-bulges in which the intrinsic dispersion increases towards the centre. And although the young stars may have an impact in the observed kinematics, their fraction is too small to dominate over the bulge and compensate the increase in dispersion at small radii, so no dispersion drop is seen. Finally, we find no evidence for a difference in the stellar kinematics and nuclear stellar luminosity excess between these active and inactive galaxies.

PHIBSS2: survey design and z=0.5-0.8 results. Molecular gas reservoirs during the winding-down of star formation

Abstract: Following the success of the Plateau de Bure high-z Blue Sequence Survey (PHIBSS), we present the PHIBSS2 legacy program, a survey of the molecular gas properties of star-forming galaxies on and around the star formation main sequence (MS) at different redshifts using NOEMA. This survey significantly extends the existing sample of star-forming galaxies with CO molecular gas measurements, probing the peak epoch of star formation (z=1-1.6) as well as its building-up (z=2-3) and winding-down (z=0.5-0.8) phases. The targets are drawn from the GOODS, COSMOS, and AEGIS deep fields and uniformly sample the MS in the stellar mass (M*) - star formation rate (SFR) plane with log(M*/Msun) = 10-11.8. We describe the survey strategy and sample selection before focusing on the results obtained at z=0.5-0.8, where we report 60 CO(2-1) detections out of 61 targets. We determine their molecular gas masses and separately obtain disc sizes and bulge-to-total (B/T) luminosity ratios from HST I-band images. The median molecular gas-to-stellar mass ratio, gas fraction, and depletion time as well as their dependence with M* and offset from the MS follow published scaling relations for a much larger sample of galaxies spanning a wider range of redshifts. The galaxy-averaged Kennicutt-Schmidt (KS) relation between molecular gas and SFR surface densities is strikingly linear, pointing towards similar star formation timescales within galaxies at any given epoch. In terms of morphology, the molecular gas content, the SFR, the disc stellar mass, and the disc molecular gas fraction do not seem to correlate with B/T and the stellar surface density, which suggests an ongoing supply of fresh molecular gas to compensate for the build-up of the bulge. Our measurements do not yield any significant variation of the depletion time with B/T and hence no strong evidence for morphological quenching within the scatter of the MS.

Witnessing the Early Growth and Life Cycle of Galaxies with KMOS3D

Abstract: These observations have established the broad scope of the equilibrium growth model, in which accretion from the cosmic web and minor mergers fairly continuously replenish the gas reservoirs of SFGs, and the balance between accretion, star formation, and outflows governs their evolution. Given the different conditions prevailing in early SFGs, detailed in-situ observations are necessary to understand which processes regulate their evolution, how the disc and spheroidal components of present-day galaxies arise, and why star formation shuts down at high masses.

SHINING, A Survey of Far Infrared Lines in Nearby Galaxies. I: Survey Description, Observational Trends, and Line Diagnostics

Abstract: We use the Herschel/PACS spectrometer to study the global and spatially resolved far-infrared (FIR) fine-structure line emission in a sample of 52 galaxies that constitute the SHINING survey. These galaxies include star-forming, active-galactic nuclei (AGN), and luminous infrared galaxies (LIRGs). We find an increasing number of galaxies (and kiloparsec size regions within galaxies) with low line-to-FIR continuum ratios as a function of increasing FIR luminosity ($L_{\mathrm{FIR}}$), dust infrared color, $L_{\mathrm{FIR}}$ to molecular gas mass ratio ($L_{\mathrm{FIR}}/M_{\mathrm{mol}}$), and FIR surface brightness ($\Sigma_{\mathrm{FIR}}$). The correlations between the [CII]/FIR or [OI]/FIR ratios with $\Sigma_{\mathrm{FIR}}$ are remarkably tight ($\sim0.3$ dex scatter over almost four orders of magnitude in $\Sigma_{\mathrm{FIR}}$). We observe that galaxies with $L_{\mathrm{FIR}}/M_{\mathrm{mol}} \gtrsim 80\,L_{\odot}\,M_{\odot}^{-1}$ and $\Sigma_{\mathrm{FIR}}\gtrsim10^{11}$ $L_{\odot}$ kpc$^{-2}$ tend to have weak fine-structure line-to-FIR continuum ratios, and that LIRGs with infrared sizes $\gtrsim1$ kpc have line-to-FIR ratios comparable to those observed in typical star-forming galaxies. We analyze the physical mechanisms driving these trends in Paper II (Herrera-Camus et al. 2018). The combined analysis of the [CII], [NII], and [OIII] lines reveals that the fraction of the [CII] line emission that arises from neutral gas increases from 60% to 90% in the most active star-forming regions and that the emission originating in the ionized gas is associated with low-ionization, diffuse gas rather than with dense gas in HII regions. Finally, we report the global and spatially resolved line fluxes of the SHINING galaxies to enable the comparison and planning of future local and high-$z$ studies.