Similarity of ionized gas nebulae around unobscured and obscured quasars

Quasar feedback is suspected to play a key role in the evolution of massive galaxies, by removing or reheating gas in quasar host galaxies and thus limiting the amount of star formation. In this paper we continue our investigation of quasar-driven winds on galaxy-wide scales. We conduct Gemini Integral Field Unit spectroscopy of a sample of luminous unobscured (type 1) quasars, to determine the morphology and kinematics of ionized gas around these objects, predominantly via observations of the [O III]5007 emission line. We find that ionized gas nebulae extend out to ~13 kpc from the quasar, that they are smooth and round, and that their kinematics are inconsistent with gas in dynamical equilibrium with the host galaxy. The observed morphological and kinematic properties are strikingly similar to those of ionized gas around obscured (type 2) quasars with matched [O III] luminosity, with marginal evidence that nebulae around unobscured quasars are slightly more compact. Therefore in samples of obscured and unobscured quasars carefully matched in [O III] luminosity we find support for the standard geometry-based unification model of active galactic nuclei, in that the intrinsic properties of quasars, of their hosts and of their ionized gas appear to be very similar. Given the apparent ubiquity of extended ionized regions, we are forced to conclude that either the quasar is at least partially illuminating pre-existing gas or that both samples of quasars are seen during advanced stages of quasar feedback. In the latter case, we may be biased by our [O III]-based selection against quasars in the early "blow-out" phase, for example due to dust obscuration.Comment: 17 pages, 10 figures, 2 tables. Published in MNRAS, 201

Observations of Feedback from Radio-Quiet Quasars: I. Extents and Morphologies of Ionized Gas Nebulae

Black hole feedback -- the strong interaction between the energy output of supermassive black holes and their surrounding environments -- is routinely invoked to explain the absence of overly luminous galaxies, the black hole vs. bulge correlations and the similarity of black hole accretion and star formation histories. Yet direct probes of this process in action are scarce and limited to small samples of active nuclei. We present Gemini IFU observations of the distribution of ionized gas around luminous, obscured, radio-quiet (RQ) quasars at z~0.5. We detect extended ionized gas nebulae via [O III]5007 emission in every case, with a mean diameter of 28 kpc. These nebulae are nearly perfectly round. The regular morphologies of nebulae around RQ quasars are in striking contrast with lumpy or elongated nebulae seen around radio galaxies at low and high redshifts. We present the uniformly measured size-luminosity relationship of [O III] nebulae around Seyfert 2 galaxies and type 2 quasars spanning 6 orders of magnitude in luminosity and confirm the flat slope of the correlation (R ~ L^{0.25+/-0.02}). We find a universal behavior of the [O III]/H-beta ratio in our entire RQ quasar sample: it persists at a constant value (~10) in the central regions, until reaching a "break" isophotal radius ranging from 4 to 11 kpc where it starts to decrease. We propose a model of clumpy nebulae in which clouds that produce line emission transition from being ionization-bounded at small distances from the quasar to being matter-bounded in the outer parts of the nebula, which qualitatively explains the observed line ratio and surface brightness profiles. It is striking that we see such smooth and round large-scale gas nebulosities in this sample, which are inconsistent with illuminated merger debris and which we suggest may be the signature of accretion energy from the nucleus reaching gas at large scales.Comment: 44 pages, 11 figures, 3 tables. Accepted for publication in MNRA

Observations of Feedback from Radio-Quiet Quasars - II. Kinematics of Ionized Gas Nebulae

The prevalence and energetics of quasar feedback is a major unresolved problem in galaxy formation theory. In this paper, we present Gemini Integral Field Unit observations of ionized gas around eleven luminous, obscured, radio-quiet quasars at z~0.5 out to ~15 kpc from the quasar; specifically, we measure the kinematics and morphology of [O III]5007 emission. The round morphologies of the nebulae and the large line-of-sight velocity widths (with velocities containing 80% of the emission as high as 1000 km/s combined with relatively small velocity difference across them (from 90 to 520 km/s) point toward wide-angle quasi-spherical outflows. We use the observed velocity widths to estimate a median outflow velocity of 760 km/s, similar to or above the escape velocities from the host galaxies. The line-of-sight velocity dispersion declines slightly toward outer parts of the nebulae (by 3% per kpc on average). The majority of nebulae show blueshifted excesses in their line profiles across most of their extents, signifying gas outflows. For the median outflow velocity, we find a kinetic energy flow between 4x10^{44} and 3x10^{45} erg/s and mass outflow rate between 2000 and 20000 Msun/yr. These values are large enough for the observed quasar winds to have a significant impact on their host galaxies. The median rate of converting bolometric luminosity to kinetic energy of ionized gas clouds is ~2%. We report four new candidates for "super-bubbles" -- outflows that may have broken out of the denser regions of the host galaxy.Comment: 23 pages, 10 figures, 2 tables, accepted for publication in MNRA

Gemini Long-slit Observations of Luminous Obscured Quasars: Further Evidence for an Upper Limit on the Size of the Narrow-Line Region

We examine the spatial extent of the narrow-line regions (NLRs) of a sample of 30 luminous obscured quasars at $0.4 < z < 0.7$ observed with spatially resolved Gemini-N GMOS long-slit spectroscopy. Using the [OIII]$\lambda5007$ emission feature, we estimate the size of the NLR using a cosmology-independent measurement: the radius where the surface brightness falls to 10$^{-15}$ erg s$^{-1}$ cm$^{-2}$ arcsec$^{-2}$. We then explore the effects of atmospheric seeing on NLR size measurements and conclude that direct measurements of the NLR size from observed profiles are too large by 0.1 - 0.2 dex on average, as compared to measurements made to best-fit S\'{e}rsic or Voigt profiles convolved with the seeing. These data, which span a full order of magnitude in IR luminosity ($\log{(L_{8 \mu \mathrm{m}} / \mathrm{erg\, s}^{-1})} = 44.4 - 45.4$) also provide strong evidence that there is a flattening of the relationship between NLR size and AGN luminosity at a seeing-corrected size of $\sim 7$ kpc. The objects in this sample have high luminosities which place them in a previously under-explored portion of the size-luminosity relationship. These results support the existence of a maximal size of the narrow-line region around luminous quasars; beyond this size either there is not enough gas, or the gas is over-ionized and does not produce enough [OIII]$\lambda5007$ emission.Comment: 10 pages, 6 figures, accepted for publication in the Astrophysical Journa

Understanding alternatives in data analysis activities

Data workers are non-professional data scientists who engage in data analysis activities as part of their daily work. In this position paper, we share past and on-going work to understand data workers’ sense-making practices. We use multidisciplinary approaches to explore their human-tool partnerships. We introduce our current research on the role of alternatives in data analysis activities. Finally, we conclude with open questions and research directions