Sylvain Veilleux | University of Maryland, College Park (original) (raw)

Papers by Sylvain Veilleux

The Astronomical Journal, 2003

We report the results from a pilot study of 10 nearby starburst and active galaxies conducted wit... more We report the results from a pilot study of 10 nearby starburst and active galaxies conducted with the Taurus Tunable Filter (TTF) on the Anglo-Australian and William Herschel Telescopes. The main purpose of this imaging survey is to search for warm emission-line gas on the outskirts (galactocentric distances R 10 kpc) of galaxies to provide direct constraints on the size and geometry of the "zone of influence" of these galaxies on their environment. Gaseous complexes or filaments larger than ∼ 20 kpc are discovered or confirmed in six of the galaxies in the sample (NGC 1068, NGC 1482, NGC 4388, NGC 6240, NGC 7213, and MR 2251-178). Slightly smaller structures are seen for the first time in the ionization cones and galactic winds of NGC 1365, NGC 1705, Circinus galaxy, and ESO484-G036. The TTF data are combined with new optical long-slit spectra as well as published and archived radio and X-ray maps to constrain the origin and source of ionization of these filaments. A broad range of phenomena is observed, including large-scale ionization cones and galactic winds, tidal interaction, and ram-pressure stripping by an intracluster medium. The source of ionization in this gas ranges from shock ionization to photoionization by the central AGN or in-situ hot young stars. The sample is too small to draw statistically meaningful conclusions about the extent and properties of the warm ionized medium on large scale and its relevance to galaxy formation and evolution. The next generation of tunable filters on large telescopes promises to improve the sensitivity to faint emission-line fluxes at least tenfold and allow systematic surveys of a large sample of emission-line galaxies.

The Astrophysical Journal, 2002

Using Chandra and HST we show that X-ray and Hα filaments that form the 1.3-kpc diameter superbub... more Using Chandra and HST we show that X-ray and Hα filaments that form the 1.3-kpc diameter superbubble of NGC 3079 have strikingly similar patterns at ∼0. ′′ 8 resolution. This tight optical line/X-ray match seems to arise from cool disk gas that has been driven by the wind, with X-rays being emitted from upstream, stand-off bowshocks or by conductive cooling at the cloud/wind interfaces. We find that the soft X-ray plasma has thermal and kinetic energies E TH ∼ 2 × 10 56 η 0.5

Scientific American sp, 2007

Millions of galaxies shine in the night sky, mostmade visible by the combined light of their bill... more Millions of galaxies shine in the night sky, mostmade visible by the combined light of their billions of stars. In a few, however, a pointlike region in the central core dwarfs the brightness of the rest of the galaxy. The details of such galactic dynamos are too small to be resolved even with ...

Scientific American, 1996

Millions of galaxies shine in the night sky, mostmade visible by the combined light of their bill... more Millions of galaxies shine in the night sky, mostmade visible by the combined light of their billions of stars. In a few, however, a pointlike region in the central core dwarfs the brightness of the rest of the galaxy. The details of such galactic dynamos are too small to be resolved even with ...

Monthly Notices of the Royal Astronomical Society, 1998

The Smith high velocity cloud (V LSR = 98 km s −1 ) has been observed at two locations in the emi... more The Smith high velocity cloud (V LSR = 98 km s −1 ) has been observed at two locations in the emission lines [OIII]λ5007, [NII]λ6548 and Hα. Both the [NII] and Hα profiles show bright cores due to the Reynolds layer, and red wings with emission extending to V LSR ≈ 130 km s −1 . This is the first simultaneous detection of two emission lines towards a high velocity cloud, allowing us to form the ratio of these line profiles as a function of LSR velocity. At both cloud positions, we see a clear distinction between emission at the cloud velocity, and the Reynolds layer emission (V LSR ≈ 0). The [NII]/Hα ratio (≈0.25) for the Reynolds layer is typical of the warm ionised medium. At the cloud velocity, this ratio is enhanced by a factor of 3 − 4 compared to emission at rest with respect to the LSR. A moderately deep upper limit at [OIII] (0.12R at 3σ) was derived from our data.

Astrophysical Journal, 2002

Using Chandra and HST we show that X-ray and H$\alpha$ filaments that form the 1.3-kpc diameter s... more Using Chandra and HST we show that X-ray and H$\alpha$ filaments that form the 1.3-kpc diameter superbubble of NGC 3079 have strikingly similar patterns at 0."8 resolution. This tight match seems to arise from cool disk gas that has been driven by the wind, with X-rays being emitted from upstream, stand-off bowshocks or by conductive cooling at the cloud/wind interfaces.

Using Chandra and HST we show that X-ray and H laments that form the 1.3-kpc diameter superbubble... more Using Chandra and HST we show that X-ray and H laments that form the 1.3-kpc diameter superbubble of NGC 3079 have strikingly similar patterns at 0 8 resolution. This tight optical line/X-ray match seems to arise from cool disk gas that has been driven by the wind, with X-rays being emitted from upstream, stand-off bowshocks or by conductive cooling at

The Astrophysical Journal, 1995

... Printed in USA SPECTRAL EVIDENCE FOR SHOCK-IONIZED GAS ALONG THE JETS OF NGC 4258 GERALD CECI... more ... Printed in USA SPECTRAL EVIDENCE FOR SHOCK-IONIZED GAS ALONG THE JETS OF NGC 4258 GERALD CECIL, A. MORSE, SYLVAIN VEILLEUX Received 1995 February 15; accepted 1995 May 5 We use Fabry-Perot and long-slit spectra with radio, molecular, and X ...

The Astrophysical Journal, 2001

HST WFPC2 images are presented that span the inner ∼19 kpc diameter of the edge-on galaxy NGC 307... more HST WFPC2 images are presented that span the inner ∼19 kpc diameter of the edge-on galaxy NGC 3079; they are combined with optical, emission-line imaging spectrophotometry and VLA images of radio polarization vectors and rotation measures. Ionized gas filaments within 9-kpc diameter project up to 3 kpc above the disk, with the brightest forming the ≈ 1 kpc diameter superbubble. They are often resolved into strands ≈ 0. ′′ 3 (25 pc) wide, which emerge from the nuclear CO ring as five distinct streams with large velocities and velocity dispersions (FWHM ≈450 km s −1 ). The brightest stream emits ≈ 10% of the superbubble Hα flux and extends for 250 pc along the axis of the VLBI radio jet to one corner of the base of the superbubble. The other four streams are not connected to the jet, instead curving up to the vertical ≈ 0.6 kpc above the galaxy disk, then dispersing as a spray of droplets each with ≈ 10 3 √ f M of ionized gas (the volume filling factor f > 3 × 10 −3 ). Shredded clumps of disk gas form a similar structure in hydrodynamical models of a galaxy-scale wind. The pattern of magnetic fields and the gaseous kinematics also suggest that a wind of mechanical luminosity L w ≈ 10 43 ergs s −1 has stagnated in the galaxy disk at a radius of ∼ 800 pc, has flared to larger radii with increasing height as the balancing ISM pressure reduces above the disk, and has entrained dense clouds into a "mushroom vortex" above the disk. Hα emissivity of the filaments limits densities to n e > 4.3 f −1/2 cm −3 , hence kinetic energy and momentum to (0.4 − 5) × 10 55 √ f ergs and (1.6 − 6) × 10 47 √ f dyne s, respectively; the ranges result from uncertain space velocities. A prominent star-forming complex elsewhere in the galaxy shows a striking spray of linear filaments that extend for hundreds of parsecs to end in unresolved "bullets."

Annual Review of Astronomy and Astrophysics, 2005

Galactic winds are the primary mechanism by which energy and metals are recycled in galaxies and ... more Galactic winds are the primary mechanism by which energy and metals are recycled in galaxies and are deposited into the intergalactic medium. New observations are revealing the ubiquity of this process, particularly at high redshift. We describe the physics behind these winds, discuss the observational evidence for them in nearby star-forming and active galaxies and in the high-redshift universe, and consider the implications of energetic winds for the formation and evolution of galaxies and the intergalactic medium. To inspire future research, we conclude with a set of observational and theoretical challenges.

The Swift Gamma-Ray Burst satellite has detected a largely unbiased towards absorption sample of ... more The Swift Gamma-Ray Burst satellite has detected a largely unbiased towards absorption sample of local (< z >≈ 0.03) AGN, based solely on their 14-195 keV flux. In the first 9 months of the survey, 153 AGN sources were detected. The X-ray properties in the 0.3-10 keV band have been compiled and presented based on analyses with XMM-Newton, Chandra, Suzaku, and the Swift XRT ). Additionally, we have compiled a sub-sample of sources with medium resolution optical ground-based spectra from the SDSS or our own observations at KPNO. In this sample of 60 sources, we have classified the sources using standard emission line diagnostic plots, obtained masses for the broad line sources through measurement of the broad Hβ emission line, and measured the [OIII] 5007Å luminosity of this sample. Based on continuum fits to the intrinsic absorption features, we have obtained clues about the stellar populations of the host galaxies. We now present the highlights of our X-ray and optical studies of this unique sample of local AGNs, including a comparison of the 2-10 keV and 14-195 keV X-ray luminosities with the [OIII] 5007Å luminosity and the implications of our results towards measurements of bolometric luminosities.

The Astrophysical Journal, 2011

We have assembled the largest sample of ultra hard X-ray selected (14-195 keV) AGN with host gala... more We have assembled the largest sample of ultra hard X-ray selected (14-195 keV) AGN with host galaxy optical data to date, with 185 nearby (z<0.05), moderate luminosity AGN from the Swif t BAT sample. The BAT AGN host galaxies have intermediate optical colors (u − r and g − r) that are bluer than a comparison sample of inactive galaxies and optically selected AGN from the Sloan Digital Sky Survey (SDSS) which are chosen to have the same stellar mass. Based on morphological classifications from the RC3 and the Galaxy Zoo, the bluer colors of BAT AGN are mainly due to a higher fraction of mergers and massive spirals than in the comparison samples. BAT AGN in massive galaxies (log M * >10.5) have a 5 to 10 times higher rate of spiral morphologies than in SDSS AGN or inactive galaxies. We also see enhanced far-IR emission in BAT AGN suggestive of higher levels of star formation compared to the comparison samples. BAT AGN are preferentially found in the most massive host galaxies with high concentration indexes indicative of large bulge-to-disk ratios and large supermassive black holes. The narrow-line (NL) BAT AGN have similar intrinsic luminosities as the SDSS NL Seyferts based on measurements of [O III] λ5007. There is also a correlation between the stellar mass and X-ray emission. The BAT AGN in mergers have bluer colors and greater ultra hard X-ray emission compared to the BAT sample as whole. In agreement with the Unified Model of AGN, and the relatively unbiased nature of the BAT sources, the host galaxy colors and morphologies are independent of measures of obscuration such as X-ray column density or Seyfert type. The high fraction of massive spiral galaxies and galaxy mergers in BAT AGN suggest that host galaxy morphology is related to the activation and fueling of local AGN.

The Astrophysical Journal, 2012

We present the first scientific results from the Sydney-AAO Multi-Object IFS (SAMI) at the Anglo-... more We present the first scientific results from the Sydney-AAO Multi-Object IFS (SAMI) at the Anglo-Australian Telescope. This unique instrument deploys 13 fused fibre bundles (hexabundles) across a one-degree field of view allowing simultaneous spatially-resolved spectroscopy of 13 galaxies. During the first SAMI commissioning run, targeting a single galaxy field, one object (ESO 185-G031) was found to have extended minor axis emission with ionisation and kinematic properties consistent with a large-scale galactic wind. The importance of this result is two-fold: (i) fibre bundle spectrographs are able to identify low-surface brightness emission arising from extranuclear activity; (ii) such activity may be more common than presently assumed because conventional multi-object spectrographs use single-aperture fibres and spectra from these are nearly always dominated by nuclear emission. These early results demonstrate the extraordinary potential of multi-object hexabundle spectroscopy in future galaxy surveys.

The Astrophysical Journal, 2010

The Swift Burst Alert Telescope survey of active galactic nuclei (AGNs) is providing an unprecede... more The Swift Burst Alert Telescope survey of active galactic nuclei (AGNs) is providing an unprecedented view of local AGNs (lang z rang??? 0.03) and their host galaxy properties. In this paper, we present an analysis of the optical spectra of a sample of 64 AGNs from the ...

The Astrophysical Journal, 2002

In this paper, we present moderately-high resolution (∼ 65 km s −1 ) spectroscopy, acquired with ... more In this paper, we present moderately-high resolution (∼ 65 km s −1 ) spectroscopy, acquired with ESI on Keck II, of 11 ultraluminous infrared galaxies at z < 0.3 from the IRAS 1 Jy sample. The targets were chosen as good candidates to host galaxy-scale outflows, and most have infrared luminosities dominated by star formation. We use a χ 2 minimization to fit one-to three-component profiles to the Na I D interstellar absorption doublet in each object. Assuming that gas blueshifted by more than 70 km s −1 relative to the systemic velocity of the host is outflowing, we detect outflows in 73% of these objects. We adopt a simple model of a mass-conserving free wind to infer mass outflow rates in the rangeṀ tot (H) = 13 − 133 M ⊙ yr −1 for galaxies hosting a wind. These values ofṀ tot , normalized to the corresponding global star formation rates inferred from infrared luminosities, are in the range η ≡Ṁ tot /SFR = 0.1 − 0.7. This is on average a factor of only 10 less than η from recent measurements of nearby dwarfs, edge-on spirals, and lower-luminosity infrared galaxies. Within our sample, we conclude that η has no dependence on the mass of the host (parameterized by host galaxy kinematics and absolute R-and K ′ -band magnitudes). We also attempt to estimate the average escape fraction f esc ≡ Ṁ i esc / Ṁ i tot and "ejection efficiency" δ ≡ Ṁ i esc / SFR i for our sample, which we find to be ∼ 0.4 − 0.5 and ∼ 0.1, respectively. The complex absorption-line properties of Mrk 231, an ultraluminous infrared galaxy which is optically classified as a Seyfert 1, are discussed separately in an appendix.

The Astrophysical Journal, 2010

The Great Observatories All-sky LIRG Survey (GOALS) consists of a complete sample of 202 Luminous... more The Great Observatories All-sky LIRG Survey (GOALS) consists of a complete sample of 202 Luminous Infrared Galaxies (LIRGs) selected from the IRAS Revised Bright Galaxy Sample (RBGS). The galaxies span the full range of interaction stages, from isolated galaxies to interacting pairs to late stage mergers. We present a comparison of the UV and infrared properties of 135 galaxies in GOALS observed by GALEX and Spitzer. For interacting galaxies with separations greater than the resolution of GALEX and Spitzer (∼ 2 − 6 ′′ ), we assess the UV and IR properties of each galaxy individually. The contribution of the FUV to the measured SFR ranges from 0.2% to 17.9%, with a median of 2.8% and a mean of 4.0 ± 0.4%. The specific star formation rate of the

New Astronomy Reviews, 2006

We present a study of the dynamical evolution of Ultraluminous Infrared Galaxies (ULIRGs), mergin... more We present a study of the dynamical evolution of Ultraluminous Infrared Galaxies (ULIRGs), merging galaxies of infrared luminosity > 10 12 L⊙. During our Very Large Telescope large program, we have obtained ISAAC nearinfrared, high-resolution spectra of 54 ULIRGs (at several merger phases) and 12 local Palomar-Green QSOs, to investigate whether ULIRGs go through a QSO phase during their evolution. One possible evolutionary scenario is that after nuclear coalescence, the black hole radiates close to Eddington to produce QSO luminosities. The mean stellar velocity dispersion that we measure from our spectra is similar (∼160 km/s) for 30 post-coalescence ULIRGs and 7 IR-bright QSOs. The black holes in both populations have masses of order 10 7 -10 8 M⊙ (calculated from the relation to the host dispersion) and accrete at rates > 0.5 Eddington. Placing ULIRGs and IR-bright QSOs on the fundamental plane of early-type galaxies shows that they are located on a similar region (that of moderate-mass ellipticals), in contrast to giant ellipticals and radio-loud QSOs. While this preliminary comparison of the ULIRG and QSO host kinematical properties indicates that (some) ULIRGs may undergo a QSO phase in their evolutionary history before they settle down as ellipticals, further data on non-IR excess QSOs are necessary to test this scenario.

The Astrophysical Journal, 2010

We discuss the merger rate, close galaxy environment, and clustering on scales up to a Mpc of the... more We discuss the merger rate, close galaxy environment, and clustering on scales up to a Mpc of the SW IF T BAT hard X-ray sample of nearby (z <0.05), moderate-luminosity active galactic nuclei (AGN). We find a higher incidence of galaxies with signs of disruption compared to a matched control sample (18% versus 1%) and of close pairs within 30 kpc (24% versus 1%). We also find a larger fraction with companions compared to normal galaxies and optical emission line selected AGN at scales up to 250 kpc. We hypothesize that these merging AGN may not be identified using optical emission line diagnostics because of optical extinction and dilution by star formation. In support of this hypothesis, in merging systems we find a higher hard X-ray to [O III] flux ratio, as well as emission line diagnostics characteristic of composite or star-forming galaxies, and a larger IRAS 60 µm to stellar mass ratio.

The Astrophysical Journal, 2010

We present a high spatial resolution Hα survey of 23 cooling flow clusters using the Maryland Mag... more We present a high spatial resolution Hα survey of 23 cooling flow clusters using the Maryland Magellan Tunable Filter (MMTF), covering 1-2 orders of magnitude in cooling rate, dM/dt, temperature and entropy. We find 8/23 (35%) of our clusters have complex, filamentary morphologies at Hα, while an additional 7/23 (30%) have marginally extended or nuclear Hα emission, in general agreement with previous studies of line emission in cooling flow cluster BCGs. A weak correlation between the integrated near-UV luminosity and the Hα luminosity is also found for our complete sample, with a large amount of scatter about the expected relation for photoionization by young stars. We detect Hα emission out to the X-ray cooling radius, but no further, in several clusters and find a strong correlation between the Hα luminosity contained in filaments and the X-ray cooling flow rate of the cluster, suggesting that the warm ionized gas is linked to the cooling flow. Furthermore, we detect a strong enhancement in the cooling properties of the ICM coincident with the Hα emission, compared to the surrounding ICM at the same radius. While the filaments in a few clusters may be entrained by buoyant radio bubbles, in general, the radially-infalling cooling flow model provides a better explanation for the observed trends. The correlation of the Hα and X-ray properties suggests that conduction may be important in keeping the filaments ionized. The thinness of the filaments suggests that magnetic fields are an important part of channeling the gas and shielding it from the surrounding hot ICM.

The Astronomical Journal, 2003

We report the results from a pilot study of 10 nearby starburst and active galaxies conducted wit... more We report the results from a pilot study of 10 nearby starburst and active galaxies conducted with the Taurus Tunable Filter (TTF) on the Anglo-Australian and William Herschel Telescopes. The main purpose of this imaging survey is to search for warm emission-line gas on the outskirts (galactocentric distances R 10 kpc) of galaxies to provide direct constraints on the size and geometry of the "zone of influence" of these galaxies on their environment. Gaseous complexes or filaments larger than ∼ 20 kpc are discovered or confirmed in six of the galaxies in the sample (NGC 1068, NGC 1482, NGC 4388, NGC 6240, NGC 7213, and MR 2251-178). Slightly smaller structures are seen for the first time in the ionization cones and galactic winds of NGC 1365, NGC 1705, Circinus galaxy, and ESO484-G036. The TTF data are combined with new optical long-slit spectra as well as published and archived radio and X-ray maps to constrain the origin and source of ionization of these filaments. A broad range of phenomena is observed, including large-scale ionization cones and galactic winds, tidal interaction, and ram-pressure stripping by an intracluster medium. The source of ionization in this gas ranges from shock ionization to photoionization by the central AGN or in-situ hot young stars. The sample is too small to draw statistically meaningful conclusions about the extent and properties of the warm ionized medium on large scale and its relevance to galaxy formation and evolution. The next generation of tunable filters on large telescopes promises to improve the sensitivity to faint emission-line fluxes at least tenfold and allow systematic surveys of a large sample of emission-line galaxies.

The Astrophysical Journal, 2002

Using Chandra and HST we show that X-ray and Hα filaments that form the 1.3-kpc diameter superbub... more Using Chandra and HST we show that X-ray and Hα filaments that form the 1.3-kpc diameter superbubble of NGC 3079 have strikingly similar patterns at ∼0. ′′ 8 resolution. This tight optical line/X-ray match seems to arise from cool disk gas that has been driven by the wind, with X-rays being emitted from upstream, stand-off bowshocks or by conductive cooling at the cloud/wind interfaces. We find that the soft X-ray plasma has thermal and kinetic energies E TH ∼ 2 × 10 56 η 0.5

Scientific American sp, 2007

Millions of galaxies shine in the night sky, mostmade visible by the combined light of their bill... more Millions of galaxies shine in the night sky, mostmade visible by the combined light of their billions of stars. In a few, however, a pointlike region in the central core dwarfs the brightness of the rest of the galaxy. The details of such galactic dynamos are too small to be resolved even with ...

Scientific American, 1996

Millions of galaxies shine in the night sky, mostmade visible by the combined light of their bill... more Millions of galaxies shine in the night sky, mostmade visible by the combined light of their billions of stars. In a few, however, a pointlike region in the central core dwarfs the brightness of the rest of the galaxy. The details of such galactic dynamos are too small to be resolved even with ...

Monthly Notices of the Royal Astronomical Society, 1998

The Smith high velocity cloud (V LSR = 98 km s −1 ) has been observed at two locations in the emi... more The Smith high velocity cloud (V LSR = 98 km s −1 ) has been observed at two locations in the emission lines [OIII]λ5007, [NII]λ6548 and Hα. Both the [NII] and Hα profiles show bright cores due to the Reynolds layer, and red wings with emission extending to V LSR ≈ 130 km s −1 . This is the first simultaneous detection of two emission lines towards a high velocity cloud, allowing us to form the ratio of these line profiles as a function of LSR velocity. At both cloud positions, we see a clear distinction between emission at the cloud velocity, and the Reynolds layer emission (V LSR ≈ 0). The [NII]/Hα ratio (≈0.25) for the Reynolds layer is typical of the warm ionised medium. At the cloud velocity, this ratio is enhanced by a factor of 3 − 4 compared to emission at rest with respect to the LSR. A moderately deep upper limit at [OIII] (0.12R at 3σ) was derived from our data.

Astrophysical Journal, 2002

Using Chandra and HST we show that X-ray and H$\alpha$ filaments that form the 1.3-kpc diameter s... more Using Chandra and HST we show that X-ray and H$\alpha$ filaments that form the 1.3-kpc diameter superbubble of NGC 3079 have strikingly similar patterns at 0."8 resolution. This tight match seems to arise from cool disk gas that has been driven by the wind, with X-rays being emitted from upstream, stand-off bowshocks or by conductive cooling at the cloud/wind interfaces.

Using Chandra and HST we show that X-ray and H laments that form the 1.3-kpc diameter superbubble... more Using Chandra and HST we show that X-ray and H laments that form the 1.3-kpc diameter superbubble of NGC 3079 have strikingly similar patterns at 0 8 resolution. This tight optical line/X-ray match seems to arise from cool disk gas that has been driven by the wind, with X-rays being emitted from upstream, stand-off bowshocks or by conductive cooling at

The Astrophysical Journal, 1995

... Printed in USA SPECTRAL EVIDENCE FOR SHOCK-IONIZED GAS ALONG THE JETS OF NGC 4258 GERALD CECI... more ... Printed in USA SPECTRAL EVIDENCE FOR SHOCK-IONIZED GAS ALONG THE JETS OF NGC 4258 GERALD CECIL, A. MORSE, SYLVAIN VEILLEUX Received 1995 February 15; accepted 1995 May 5 We use Fabry-Perot and long-slit spectra with radio, molecular, and X ...

The Astrophysical Journal, 2001

HST WFPC2 images are presented that span the inner ∼19 kpc diameter of the edge-on galaxy NGC 307... more HST WFPC2 images are presented that span the inner ∼19 kpc diameter of the edge-on galaxy NGC 3079; they are combined with optical, emission-line imaging spectrophotometry and VLA images of radio polarization vectors and rotation measures. Ionized gas filaments within 9-kpc diameter project up to 3 kpc above the disk, with the brightest forming the ≈ 1 kpc diameter superbubble. They are often resolved into strands ≈ 0. ′′ 3 (25 pc) wide, which emerge from the nuclear CO ring as five distinct streams with large velocities and velocity dispersions (FWHM ≈450 km s −1 ). The brightest stream emits ≈ 10% of the superbubble Hα flux and extends for 250 pc along the axis of the VLBI radio jet to one corner of the base of the superbubble. The other four streams are not connected to the jet, instead curving up to the vertical ≈ 0.6 kpc above the galaxy disk, then dispersing as a spray of droplets each with ≈ 10 3 √ f M of ionized gas (the volume filling factor f > 3 × 10 −3 ). Shredded clumps of disk gas form a similar structure in hydrodynamical models of a galaxy-scale wind. The pattern of magnetic fields and the gaseous kinematics also suggest that a wind of mechanical luminosity L w ≈ 10 43 ergs s −1 has stagnated in the galaxy disk at a radius of ∼ 800 pc, has flared to larger radii with increasing height as the balancing ISM pressure reduces above the disk, and has entrained dense clouds into a "mushroom vortex" above the disk. Hα emissivity of the filaments limits densities to n e > 4.3 f −1/2 cm −3 , hence kinetic energy and momentum to (0.4 − 5) × 10 55 √ f ergs and (1.6 − 6) × 10 47 √ f dyne s, respectively; the ranges result from uncertain space velocities. A prominent star-forming complex elsewhere in the galaxy shows a striking spray of linear filaments that extend for hundreds of parsecs to end in unresolved "bullets."

Annual Review of Astronomy and Astrophysics, 2005

Galactic winds are the primary mechanism by which energy and metals are recycled in galaxies and ... more Galactic winds are the primary mechanism by which energy and metals are recycled in galaxies and are deposited into the intergalactic medium. New observations are revealing the ubiquity of this process, particularly at high redshift. We describe the physics behind these winds, discuss the observational evidence for them in nearby star-forming and active galaxies and in the high-redshift universe, and consider the implications of energetic winds for the formation and evolution of galaxies and the intergalactic medium. To inspire future research, we conclude with a set of observational and theoretical challenges.

The Swift Gamma-Ray Burst satellite has detected a largely unbiased towards absorption sample of ... more The Swift Gamma-Ray Burst satellite has detected a largely unbiased towards absorption sample of local (< z >≈ 0.03) AGN, based solely on their 14-195 keV flux. In the first 9 months of the survey, 153 AGN sources were detected. The X-ray properties in the 0.3-10 keV band have been compiled and presented based on analyses with XMM-Newton, Chandra, Suzaku, and the Swift XRT ). Additionally, we have compiled a sub-sample of sources with medium resolution optical ground-based spectra from the SDSS or our own observations at KPNO. In this sample of 60 sources, we have classified the sources using standard emission line diagnostic plots, obtained masses for the broad line sources through measurement of the broad Hβ emission line, and measured the [OIII] 5007Å luminosity of this sample. Based on continuum fits to the intrinsic absorption features, we have obtained clues about the stellar populations of the host galaxies. We now present the highlights of our X-ray and optical studies of this unique sample of local AGNs, including a comparison of the 2-10 keV and 14-195 keV X-ray luminosities with the [OIII] 5007Å luminosity and the implications of our results towards measurements of bolometric luminosities.

The Astrophysical Journal, 2011

We have assembled the largest sample of ultra hard X-ray selected (14-195 keV) AGN with host gala... more We have assembled the largest sample of ultra hard X-ray selected (14-195 keV) AGN with host galaxy optical data to date, with 185 nearby (z<0.05), moderate luminosity AGN from the Swif t BAT sample. The BAT AGN host galaxies have intermediate optical colors (u − r and g − r) that are bluer than a comparison sample of inactive galaxies and optically selected AGN from the Sloan Digital Sky Survey (SDSS) which are chosen to have the same stellar mass. Based on morphological classifications from the RC3 and the Galaxy Zoo, the bluer colors of BAT AGN are mainly due to a higher fraction of mergers and massive spirals than in the comparison samples. BAT AGN in massive galaxies (log M * >10.5) have a 5 to 10 times higher rate of spiral morphologies than in SDSS AGN or inactive galaxies. We also see enhanced far-IR emission in BAT AGN suggestive of higher levels of star formation compared to the comparison samples. BAT AGN are preferentially found in the most massive host galaxies with high concentration indexes indicative of large bulge-to-disk ratios and large supermassive black holes. The narrow-line (NL) BAT AGN have similar intrinsic luminosities as the SDSS NL Seyferts based on measurements of [O III] λ5007. There is also a correlation between the stellar mass and X-ray emission. The BAT AGN in mergers have bluer colors and greater ultra hard X-ray emission compared to the BAT sample as whole. In agreement with the Unified Model of AGN, and the relatively unbiased nature of the BAT sources, the host galaxy colors and morphologies are independent of measures of obscuration such as X-ray column density or Seyfert type. The high fraction of massive spiral galaxies and galaxy mergers in BAT AGN suggest that host galaxy morphology is related to the activation and fueling of local AGN.

The Astrophysical Journal, 2012

We present the first scientific results from the Sydney-AAO Multi-Object IFS (SAMI) at the Anglo-... more We present the first scientific results from the Sydney-AAO Multi-Object IFS (SAMI) at the Anglo-Australian Telescope. This unique instrument deploys 13 fused fibre bundles (hexabundles) across a one-degree field of view allowing simultaneous spatially-resolved spectroscopy of 13 galaxies. During the first SAMI commissioning run, targeting a single galaxy field, one object (ESO 185-G031) was found to have extended minor axis emission with ionisation and kinematic properties consistent with a large-scale galactic wind. The importance of this result is two-fold: (i) fibre bundle spectrographs are able to identify low-surface brightness emission arising from extranuclear activity; (ii) such activity may be more common than presently assumed because conventional multi-object spectrographs use single-aperture fibres and spectra from these are nearly always dominated by nuclear emission. These early results demonstrate the extraordinary potential of multi-object hexabundle spectroscopy in future galaxy surveys.

The Astrophysical Journal, 2010

The Swift Burst Alert Telescope survey of active galactic nuclei (AGNs) is providing an unprecede... more The Swift Burst Alert Telescope survey of active galactic nuclei (AGNs) is providing an unprecedented view of local AGNs (lang z rang??? 0.03) and their host galaxy properties. In this paper, we present an analysis of the optical spectra of a sample of 64 AGNs from the ...

The Astrophysical Journal, 2002

In this paper, we present moderately-high resolution (∼ 65 km s −1 ) spectroscopy, acquired with ... more In this paper, we present moderately-high resolution (∼ 65 km s −1 ) spectroscopy, acquired with ESI on Keck II, of 11 ultraluminous infrared galaxies at z < 0.3 from the IRAS 1 Jy sample. The targets were chosen as good candidates to host galaxy-scale outflows, and most have infrared luminosities dominated by star formation. We use a χ 2 minimization to fit one-to three-component profiles to the Na I D interstellar absorption doublet in each object. Assuming that gas blueshifted by more than 70 km s −1 relative to the systemic velocity of the host is outflowing, we detect outflows in 73% of these objects. We adopt a simple model of a mass-conserving free wind to infer mass outflow rates in the rangeṀ tot (H) = 13 − 133 M ⊙ yr −1 for galaxies hosting a wind. These values ofṀ tot , normalized to the corresponding global star formation rates inferred from infrared luminosities, are in the range η ≡Ṁ tot /SFR = 0.1 − 0.7. This is on average a factor of only 10 less than η from recent measurements of nearby dwarfs, edge-on spirals, and lower-luminosity infrared galaxies. Within our sample, we conclude that η has no dependence on the mass of the host (parameterized by host galaxy kinematics and absolute R-and K ′ -band magnitudes). We also attempt to estimate the average escape fraction f esc ≡ Ṁ i esc / Ṁ i tot and "ejection efficiency" δ ≡ Ṁ i esc / SFR i for our sample, which we find to be ∼ 0.4 − 0.5 and ∼ 0.1, respectively. The complex absorption-line properties of Mrk 231, an ultraluminous infrared galaxy which is optically classified as a Seyfert 1, are discussed separately in an appendix.

The Astrophysical Journal, 2010

The Great Observatories All-sky LIRG Survey (GOALS) consists of a complete sample of 202 Luminous... more The Great Observatories All-sky LIRG Survey (GOALS) consists of a complete sample of 202 Luminous Infrared Galaxies (LIRGs) selected from the IRAS Revised Bright Galaxy Sample (RBGS). The galaxies span the full range of interaction stages, from isolated galaxies to interacting pairs to late stage mergers. We present a comparison of the UV and infrared properties of 135 galaxies in GOALS observed by GALEX and Spitzer. For interacting galaxies with separations greater than the resolution of GALEX and Spitzer (∼ 2 − 6 ′′ ), we assess the UV and IR properties of each galaxy individually. The contribution of the FUV to the measured SFR ranges from 0.2% to 17.9%, with a median of 2.8% and a mean of 4.0 ± 0.4%. The specific star formation rate of the

New Astronomy Reviews, 2006

We present a study of the dynamical evolution of Ultraluminous Infrared Galaxies (ULIRGs), mergin... more We present a study of the dynamical evolution of Ultraluminous Infrared Galaxies (ULIRGs), merging galaxies of infrared luminosity > 10 12 L⊙. During our Very Large Telescope large program, we have obtained ISAAC nearinfrared, high-resolution spectra of 54 ULIRGs (at several merger phases) and 12 local Palomar-Green QSOs, to investigate whether ULIRGs go through a QSO phase during their evolution. One possible evolutionary scenario is that after nuclear coalescence, the black hole radiates close to Eddington to produce QSO luminosities. The mean stellar velocity dispersion that we measure from our spectra is similar (∼160 km/s) for 30 post-coalescence ULIRGs and 7 IR-bright QSOs. The black holes in both populations have masses of order 10 7 -10 8 M⊙ (calculated from the relation to the host dispersion) and accrete at rates > 0.5 Eddington. Placing ULIRGs and IR-bright QSOs on the fundamental plane of early-type galaxies shows that they are located on a similar region (that of moderate-mass ellipticals), in contrast to giant ellipticals and radio-loud QSOs. While this preliminary comparison of the ULIRG and QSO host kinematical properties indicates that (some) ULIRGs may undergo a QSO phase in their evolutionary history before they settle down as ellipticals, further data on non-IR excess QSOs are necessary to test this scenario.

The Astrophysical Journal, 2010

We discuss the merger rate, close galaxy environment, and clustering on scales up to a Mpc of the... more We discuss the merger rate, close galaxy environment, and clustering on scales up to a Mpc of the SW IF T BAT hard X-ray sample of nearby (z <0.05), moderate-luminosity active galactic nuclei (AGN). We find a higher incidence of galaxies with signs of disruption compared to a matched control sample (18% versus 1%) and of close pairs within 30 kpc (24% versus 1%). We also find a larger fraction with companions compared to normal galaxies and optical emission line selected AGN at scales up to 250 kpc. We hypothesize that these merging AGN may not be identified using optical emission line diagnostics because of optical extinction and dilution by star formation. In support of this hypothesis, in merging systems we find a higher hard X-ray to [O III] flux ratio, as well as emission line diagnostics characteristic of composite or star-forming galaxies, and a larger IRAS 60 µm to stellar mass ratio.

The Astrophysical Journal, 2010

We present a high spatial resolution Hα survey of 23 cooling flow clusters using the Maryland Mag... more We present a high spatial resolution Hα survey of 23 cooling flow clusters using the Maryland Magellan Tunable Filter (MMTF), covering 1-2 orders of magnitude in cooling rate, dM/dt, temperature and entropy. We find 8/23 (35%) of our clusters have complex, filamentary morphologies at Hα, while an additional 7/23 (30%) have marginally extended or nuclear Hα emission, in general agreement with previous studies of line emission in cooling flow cluster BCGs. A weak correlation between the integrated near-UV luminosity and the Hα luminosity is also found for our complete sample, with a large amount of scatter about the expected relation for photoionization by young stars. We detect Hα emission out to the X-ray cooling radius, but no further, in several clusters and find a strong correlation between the Hα luminosity contained in filaments and the X-ray cooling flow rate of the cluster, suggesting that the warm ionized gas is linked to the cooling flow. Furthermore, we detect a strong enhancement in the cooling properties of the ICM coincident with the Hα emission, compared to the surrounding ICM at the same radius. While the filaments in a few clusters may be entrained by buoyant radio bubbles, in general, the radially-infalling cooling flow model provides a better explanation for the observed trends. The correlation of the Hα and X-ray properties suggests that conduction may be important in keeping the filaments ionized. The thinness of the filaments suggests that magnetic fields are an important part of channeling the gas and shielding it from the surrounding hot ICM.