[en] We present observations of NGC 839 made with the Wide Field Spectrograph on the ANU 2.3 m telescope. Our data cover a region 25'' x 60'' at a spatial resolution of ∼1.''5. The long axis of the field is aligned with the superwind we have discovered in this starburst galaxy. The data cover the range of 3700-7000 A, with a spectral resolution R ∼7000 in the red and R ∼3000 in the blue. We find that the stellar component of the galaxy is strongly dominated by a fast rotating intermediate-age (∼400 Myr) A-type stellar population, while the gas is concentrated in a bi-conical polar funnel. We have generated flux distributions, emission line ratio diagnostics, and velocity maps in both emission and absorption components. We interpret these in the context of a new grid of low-velocity shock models appropriate for galactic-scale outflows. These models fit the data remarkably well, providing for the first time model diagnostics for shocks in superwinds and strongly suggesting that shock excitation is largely responsible for the extended LINER emission in the outflowing gas in NGC 839. Our work may have important implications both for extended LINER emission seen in other galaxies and in the interpretation of objects with 'composite' spectra. Finally, we present a scenario for the formation of E+A galaxies based upon our observations of NGC 839 and its relation to M82.

[en] We have identified a complete, flux-limited (S₁₆₀>120 mJy) sample of 160 μm selected sources from Spitzer observations of the 1 deg² Infrared Space Observatory (ISO) Deep Field region in the Lockman Hole (LH). Ground-based UV, optical, and near-infrared (NIR) photometry and optical spectroscopy have been used to determine colors, redshifts, and masses for the complete sample of 40 galaxies. Spitzer-IRAC+MIPS photometry, supplemented by ISOPHOT data at 90 μm and 170 μm, has been used to calculate accurate total infrared luminosities, L_IR(8-1000 μm), and to determine the IR luminosity function (LF) of luminous infrared galaxies (LIRGs). The maximum observed redshift is z ∼ 0.80 and the maximum total infrared luminosity is log (L_IR/L_sun) = 12.74. Over the luminosity range log (L_IR/L_sun) = 10-12, the LF for LIRGs in the LH Deep Field is similar to that found previously for local sources at similar infrared luminosities. The mean host galaxy mass, log (M/M_sun) = 10.7, and dominance of H II-region spectral types, is also similar to what has been found for local LIRGs, suggesting that intense starbursts likely power the bulk of the infrared luminosity for sources in this range of L_IR. However for the most luminous sources, log (L_IR/L_sun)>12.0, we find evidence for strong evolution in the LF ∝(1 + z)^6±1, assuming pure number density evolution. These ultraluminous infrared galaxies (ULIRGs) have a larger mean host mass, log (M/M_sun) = 11.0, and exhibit disturbed morphologies consistent with strong interactions/mergers, and they are also more likely to be characterized by starburst-active galactic nucleus (AGN) composite or AGN spectral types.

[en] We report the results from a deep Hubble Space Telescope (HST) NICMOS H-band imaging survey of 28 z < 0.3 QSOs from the Palomar-Green (PG) sample. This program is part of QUEST (Quasar/ULIRG Evolution Study) and complements a similar set of data on 26 highly nucleated ULIRGs presented in Paper I. Our analysis indicates that the fraction of QSOs with elliptical hosts is higher among QSOs with undetected far-infrared (FIR) emission, small infrared excess (L _IR/L _B < 10), and luminous hosts. The hosts of FIR-faint QSOs show a tendency to have less pronounced merger-induced morphological anomalies and larger QSO-to-host luminosity ratios on average than the hosts of FIR-bright QSOs, consistent with late-merger evolution from FIR-bright to FIR-faint QSOs. The spheroid sizes (∼ 0.3-5.5 kpc) and total host luminosities (∼ 0.6-7.2 L* _H) of the radio-quiet PG QSOs in our sample are statistically indistinguishable from the ULIRG hosts presented in Paper I, while those of radio-loud PG QSOs are systematically larger and more luminous. ULIRGs and PG QSOs with elliptical hosts fall near, but not exactly on, the fundamental plane of inactive spheroids. We confirm the systematic trend noted in Paper I for objects with small (∼< 2 kpc) spheroids to be up to ∼ 1 mag brighter than inactive spheroids. The host colors and wavelength dependence of their sizes support the idea that these deviations are at least in part due to non-nuclear star formation. However, the amplitudes of these deviations depend mainly on host sizes, and possibly on infrared excess, but not on merger phase, QSO-to-host luminosity ratio, optical spectral type, active galactic nucleus fractional contribution to the bolometric luminosity, or host R - H color. Taken at face value (i.e., no correction for extinction or the presence of a young stellar population), the H-band spheroid-host luminosities imply black hole masses ∼ (5-200) x 10⁷ M _sun and sub-Eddington mass accretion rates for both QSOs and ULIRGs. These results are compared with published black hole mass estimates derived from other methods.

[en] We report the results from a comprehensive study of 74 ultraluminous infrared galaxies (ULIRGs) and 34 Palomar-Green (PG) quasars within z ∼ 0.3 observed with the Spitzer Infrared Spectrograph (IRS). The contribution of nuclear activity to the bolometric luminosity in these systems is quantified using six independent methods that span a range in wavelength and give consistent results within ∼±10%-15% on average. This agreement suggests that deeply buried active galactic nuclei (AGNs) invisible to Spitzer IRS but bright in the far-infrared are not common in this sample. The average derived AGN contribution in ULIRGs is ∼35%-40%, ranging from ∼15%-35% among 'cool' (f ₂₅/f ₆₀ ≤ 0.2) optically classified H II-like and LINER ULIRGs to ∼50 and ∼75% among warm Seyfert 2 and Seyfert 1 ULIRGs, respectively. This number exceeds ∼80% in PG QSOs. ULIRGs fall in one of three distinct AGN classes: (1) objects with small extinctions and large polycyclic aromatic hydrocarbon (PAH) equivalent widths are highly starburst-dominated; (2) systems with large extinctions and modest PAH equivalent widths have larger AGN contributions, but still tend to be starburst-dominated; and (3) ULIRGs with both small extinctions and small PAH equivalent widths host AGN that are at least as powerful as the starbursts. The AGN contributions in class 2 ULIRGs are more uncertain than in the other objects, and we cannot formally rule out the possibility that these objects represent a physically distinct type of ULIRGs. A morphological trend is seen along the sequence (1)-(2)-(3), in general agreement with the standard ULIRG-QSO evolution scenario and suggestive of a broad peak in extinction during the intermediate stages of merger evolution. However, the scatter in this sequence, including the presence of a significant number of AGN-dominated systems prior to coalescence and starburst-dominated but fully merged systems, implies that black hole accretion, in addition to depending on the merger phase, also has a strong chaotic/random component, as in local AGNs.

[en] This paper describes the Maryland-Magellan Tunable Filter (MMTF) on the Magellan-Baade 6.5 m telescope. MMTF is based on a 150 mm clear aperture Fabry-Perot (FP) etalon that operates in low orders and provides transmission bandpass and central wavelength adjustable from ∼5 A to ∼15 A and from ∼5000 A to over ∼9200 A, respectively. It is installed in the Inamori Magellan Areal Camera and Spectrograph and delivers an image quality of ∼0.''5 over a field of view of 27' in diameter (monochromatic over ∼10'). This versatile and easy-to-operate instrument has been used over the past three years for a wide variety of projects. This paper first reviews the basic principles of FP tunable filters, and then provides a detailed description of the hardware and software associated with MMTF and the techniques developed to observe with this instrument and reduce the data. The main lessons learned in the course of the commissioning and implementation of MMTF are highlighted next, before concluding with a brief outlook on the future of MMTF and of similar facilities which are soon coming on line.

[en] We present for the first time metallicity maps generated using data from the Wide Field Spectrograph on the ANU 2.3 m of 10 luminous infrared galaxies (LIRGs) and discuss the abundance gradients and distribution of metals in these systems. We have carried out optical integral field spectroscopy (IFS) of several LIRGs in various merger phases to investigate the merger process. In a major merger of two spiral galaxies with preexisting disk abundance gradients, the changing distribution of metals can be used as a tracer of gas flows in the merging system as low-metallicity gas is transported from the outskirts of each galaxy to their nuclei. We employ this fact to probe merger properties by using the emission lines in our IFS data to calculate the gas-phase metallicity in each system. We create abundance maps and subsequently derive a metallicity gradient from each map. We compare our measured gradients to merger stage as well as several possible tracers of merger progress and observed nuclear abundances. We discuss our work in the context of previous abundance gradient observations and compare our results to new galaxy merger models that trace metallicity gradient. Our results agree with the observed flattening of metallicity gradients as a merger progresses. We compare our results with new theoretical predictions that include chemical enrichment. Our data show remarkable agreement with these simulations.

[en] New near- and far-ultraviolet (NUV and FUV) Hubble Space Telescope spectra of Mrk 231, the nearest quasar known, are combined with ground-based optical spectra to study the remarkable dichotomy between the FUV and NUV–optical spectral regions in this object. The FUV emission-line features are faint, broad, and highly blueshifted (up to ∼7000 km s⁻¹), with no significant accompanying absorption. In contrast, the profiles of the NUV absorption features resemble those of the optical Na i D, He i, and Ca ii H and K lines, exhibiting broad blueshifted troughs that overlap in velocity space with the FUV emission-line features and indicate a dusty, high-density and patchy broad absorption line (BAL) screen covering ∼90% of the observed continuum source at a distance ≲2–20 pc. The FUV continuum emission does not show the presence of any obvious stellar features and is remarkably flat compared with the steeply declining NUV continuum. The NUV (FUV) features and continuum emission have not varied significantly over the past ∼22 (3) years and are unresolved on scales ∼40 (170) pc. These results favor an active galactic nucleus origin for the NUV–FUV line and continuum emission. The observed FUV line emission is produced in the outflowing BAL cloud system, while the Balmer lines arise primarily from the standard broad line region seen through the dusty BAL screen. Our data are inconsistent with the recently proposed binary black hole model. We argue instead that Mrk 231 is the nearest example of weak-lined “wind-dominated” quasars with high Eddington ratios and geometrically thick (“slim”) accretion disks; these quasars are likely more common in the early universe.

[en] A deep 400 ks ACIS-S observation of the nearest quasar known, Mrk 231, is combined with archival 120 ks data to carry out the first ever spatially resolved spectral analysis of a hot X-ray-emitting circumgalactic nebula around a quasar. The 65 × 50 kpc X-ray nebula shares no resemblance with the tidal debris seen at optical wavelengths. One notable exception is the small tidal arc ∼3.5 kpc south of the nucleus where excess soft X-ray continuum emission and Si XIII 1.8 keV line emission are detected, consistent with star formation and its associated alpha-element enhancement, respectively. An X-ray shadow is also detected at the location of the 15 kpc northern tidal tail. The hard X-ray continuum emission within ∼6 kpc of the center is consistent with being due entirely to the bright central active galactic nucleus. The soft X-ray spectrum of the outer (≳6 kpc) portion of the nebula is best described as the sum of two thermal components with temperatures ∼3 and ∼8 million K and spatially uniform super-solar alpha-element abundances, relative to iron. This result implies enhanced star formation activity over ∼10⁸ yr, accompanied by redistribution of the metals on a large scale. The low-temperature thermal component is not present within ∼6 kpc of the nucleus, suggesting extra heating in this region from the circumnuclear starburst, the central quasar, or the optically identified ≳3 kpc quasar-driven outflow. The soft X-ray emission is weaker in the western quadrant, coincident with a deficit of Hα and some of the largest columns of neutral gas outflowing from the nucleus. Shocks may heat the gas to high temperatures at this location, consistent with the tentative ∼2σ detection of extended Fe XXV 6.7 keV line emission.

[en] In Tombesi et al., we reported the first direct evidence for a quasar accretion disk wind driving a massive (>100 M _⊙ yr⁻¹) molecular outflow. The target was F11119+3257, an ultraluminous infrared galaxy (ULIRG) with unambiguous type 1 quasar optical broad emission lines. The energetics of the accretion disk wind and molecular outflow were found to be consistent with the predictions of quasar feedback models where the molecular outflow is driven by a hot energy-conserving bubble inflated by the inner quasar accretion disk wind. However, this conclusion was uncertain because the mass outflow rate, momentum flux, and mechanical power of the outflowing molecular gas were estimated from the optically thick OH 119 μm transition profile observed with Herschel. Here, we independently confirm the presence of the molecular outflow in F11119+3257, based on the detection of ∼±1000 km s⁻¹ blue- and redshifted wings in the CO(1−0) emission line profile derived from deep ALMA observations obtained in the compact array configuration (∼2.″8 resolution). The broad CO(1−0) line emission appears to be spatially extended on a scale of at least ∼7 kpc from the center. Mass outflow rate, momentum flux, and mechanical power of (80–200) $R_7^{-<!--\; ???\; -->1}$ M _⊙ yr⁻¹, (1.5–3.0) $R_7^{-<!--\; ???\; -->1}$ L _AGN/c, and (0.15–0.40)% $R_7^{-<!--\; ???\; -->1}$ $L_{\mathrm{A}\mathrm{G}\mathrm{N}}$, respectively, are inferred from these data, assuming a CO-to-H₂ conversion factor appropriate for a ULIRG (R ₇ is the radius of the outflow normalized to 7 kpc, and L _AGN is the AGN luminosity). These rates are time-averaged over a flow timescale of 7 × 10⁶ yr. They are similar to the OH-based rates time-averaged over a flow timescale of 4 × 10⁵ yr, but about a factor of 4 smaller than the local (“instantaneous”; ≲10⁵ yr) OH-based estimates cited in Tombesi et al. The implications of these new results are discussed in the context of time-variable quasar-mode feedback and galaxy evolution. The need for an energy-conserving bubble to explain the molecular outflow is also reexamined.

[en] Mrk 231, the nearest (z = 0.0422) quasar, hosts both a galactic-scale wind and a nuclear-scale iron low-ionization broad absorption line (FeLoBAL) outflow. We recently obtained a far-ultraviolet (FUV) spectrum of this object covering ∼1150-1470 Å with the Cosmic Origins Spectrograph on board the Hubble Space Telescope. This spectrum is highly peculiar, highlighted by the presence of faint (∼<2% of predictions based on Hα), broad (∼>10,000 km s^–1 at the base), and highly blueshifted (centroid at ∼ –3500 km s^–1) Lyα emission. The FUV continuum emission is slightly declining at shorter wavelengths (consistent with F _λ∝λ^1.7) and does not show the presence of any obvious photospheric or wind stellar features. Surprisingly, the FUV spectrum also does not show any unambiguous broad absorption features. It thus appears to be dominated by the AGN, rather than hot stars, and virtually unfiltered by the dusty FeLoBAL screen. The observed Lyα emission is best explained if it is produced in the outflowing BAL cloud system, while the Balmer lines arise primarily from the standard broad emission line region seen through the dusty (A_V ∼ 7 mag) broad absorption line region. Two possible geometric models are discussed in the context of these new results.