Kevin N. Hainline

A DIRECT MEASUREMENT OF THE LINEAR BIAS OF MID-INFRARED-SELECTED QUASARS AT z ≈ 1 USING COSMIC MICROWAVE BACKGROUND LENSING

We measure the cross-power spectrum of the projected mass density as traced by the convergence of the cosmic microwave background lensing field from the South Pole Telescope (SPT) and a sample of Type 1 and 2 (unobscured and obscured) quasars at 〈z〉 ~ 1 selected with the Wide-field Infrared Survey Explorer, over 2500 deg^2. The cross-power spectrum is detected at ≈7σ, and we measure a linear bias b = 1.61 ± 0.22, consistent with clustering analyses. Using an independent lensing map, derived from Planck observations, to measure the cross-spectrum, we find excellent agreement with the SPT analysis. The bias of the combined sample of Type 1 and 2 quasars determined in this work is similar to that previously determined for Type 1 quasars alone; we conclude that obscured and unobscured quasars trace the matter field in a similar way. This result has implications for our understanding of quasar unification and evolution schemes.

THE REST-FRAME ULTRAVIOLET SPECTRA OF UV-SELECTED ACTIVE GALACTIC NUCLEI AT z ∼ 2-3 ∗

We present new results for a sample of 33 narrow-lined UV-selected active galactic nuclei (AGNs), identified in the course of a spectroscopic survey for star-forming galaxies at z ~ 2-3. The rest-frame UV composite spectrum for our AGN sample shows several emission lines characteristic of AGNs, as well as interstellar absorption features detected in star-forming Lyman break galaxies (LBGs). We report a detection of N iv] λ1486, which has been observed in high-redshift radio galaxies, as well as in rare optically selected quasars. The UV continuum slope of the composite spectrum is significantly redder than that of a sample of non-AGN UV-selected star-forming galaxies. Blueshifted Si iv absorption provides evidence for outflowing highly ionized gas in these objects at speeds of ~10^3 km s^(–1), quantitatively different from what is seen in the outflows of non-AGN LBGs. Grouping the individual AGNs by parameters such as the Lyα equivalent width, redshift, and UV continuum magnitude allows for an analysis of the major spectroscopic trends within the sample. Stronger Lyα emission is coupled with weaker low-ionization absorption, which is similar to what is seen in the non-AGN LBGs, and highlights the role that cool interstellar gas plays in the escape of Lyα photons. However, the AGN composite does not show the same trends between Lyα strength and extinction seen in the non-AGN LBGs. These results represent the first such comparison at high redshift between star-forming galaxies and similar galaxies that host AGN activity.

SALT Long-slit Spectroscopy of Luminous Obscured Quasars: An Upper Limit on the Size of the Narrow-line Region?

We present spatially resolved long-slit spectroscopy from the Southern African Large Telescope to examine the spatial extent of the narrow-line regions (NLRs) of a sample of eight luminous obscured quasars at 0.10 < z < 0.43. Our results are consistent with an observed shallow slope in the relationship between NLR size and L [O III], which has been interpreted to indicate that NLR size is limited by the density and ionization state of the NLR gas rather than the availability of ionizing photons. We also explore how the NLR size scales with a more direct measure of instantaneous active galactic nucleus power using mid-IR photometry from the Wide Field Infrared Explorer, which probes warm to hot dust near the central black hole and so, unlike [O III], does not depend on the properties of the NLR. Using our results as well as samples from the literature, we obtain a power-law relationship between NLR size and L 8 μm that is significantly steeper than that observed for NLR size and L [O III]. We find that the size of the NLR goes approximately as , as expected from the simple scenario of constant-density clouds illuminated by a central ionizing source. We further see tentative evidence for a flattening of the relationship between NLR size and L 8 μm at the high-luminosity end, and propose that we are seeing a limiting NLR size of 10-20 kpc, beyond which the availability of gas to ionize becomes too low. We find that , consistent with a picture in which the L [O III] is dependent on the volume of the NLR. These results indicate that high-luminosity quasars have a strong effect in ionizing the available gas in a galaxy.

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 [O III] λ5007 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 Sersic or Voigt profiles convolved with the seeing. These data, which span a full order of magnitude in IR luminosity (log (L 8 μm/erg s–1) = 44.4-45.4), also provide strong evidence that there is a flattening of the relationship between NLR size and active galactic nucleus luminosity at a seeing-corrected size of ~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 NLR around luminous quasars; beyond this size, there is either not enough gas or the gas is over-ionized and does not produce enough [O III] λ5007 emission.

Stellar Populations of UV-Selected Active Galactic Nuclei Host Galaxies at z ~ 2 - 3

We use stellar population synthesis modeling to analyze the host galaxy properties of a sample of 33 UV-selected, narrow-lined active galactic nuclei (AGNs) at z ~ 2 - 3. In order to quantify the contribution of AGN emission to host galaxy broadband spectral energy distributions (SEDs), we use the subsample of 11 AGNs with photometric coverage spanning from rest-frame UV through near-IR wavelengths. Modeling the SEDs of these objects with a linear combination of stellar population and AGN templates, we infer the effect of the AGN on derived stellar population parameters. We also estimate the typical bias in derived stellar populations for AGNs lacking rest-frame near-IR wavelength coverage, and develop a method for inferring the true host galaxy properties. We compare AGN host galaxy properties to those of a sample of UV-selected, star-forming non-AGNs in the same redshift range, including a subsample carefully matched in stellar mass. Although the AGNs have higher masses and SFRs than the full non-active sample, their stellar population properties are consistent with those of the mass-selected sample, suggesting that the presence of an AGN is not connected with the cessation of star-formation activity in star-forming galaxies at z ~ 2 - 3. We suggest that a correlation between M_BH and galaxy stellar mass is already in place at this epoch. Assuming a roughly constant Eddington ratio for AGNs at all stellar masses, we are unable to detect the AGNs in low-mass galaxies because they are simply too faint.

SN 2012au: A Golden Link Between Superluminous Supernovae and Their Lower-Luminosity Counterparts

We present optical and near-infrared observations of SN?2012au, a slow-evolving supernova (SN) with properties that suggest a link between subsets of energetic and H-poor SNe and superluminous SNe. SN?2012au exhibited conspicuous Type-Ib-like He I lines and other absorption features at velocities reaching 2 ? 104?km?s?1 in its early spectra, and a broad light curve that peaked at MB = ?18.1?mag. Models of these data indicate a large explosion kinetic energy of ~1052?erg and 56Ni mass ejection of M Ni 0.3 M ? on par with SN?1998bw. SN?2012aus spectra almost one year after explosion show a blend of persistent Fe II P-Cyg absorptions and nebular emissions originating from two distinct velocity regions. These late-time emissions include strong [Fe II], [Ca II], [O I], Mg I], and Na I lines at velocities 4500?km?s?1, as well as O I and Mg I lines at noticeably smaller velocities 2000?km?s?1. Many of the late-time properties of SN?2012au are similar to the slow-evolving hypernovae SN?1997dq and SN?1997ef, and the superluminous SN?2007bi. Our observations suggest that a single explosion mechanism may unify all of these events that span ?21 MB ?17 mag. The aspherical and possibly jetted explosion was most likely initiated by the core collapse of a massive progenitor star and created substantial high-density, low-velocity Ni-rich material.

SPECTROSCOPIC CONFIRMATION OF AN ULTRAMASSIVE AND COMPACT GALAXY AT z = 3.35: A DETAILED LOOK AT AN EARLY PROGENITOR OF LOCAL GIANT ELLIPTICALS

We present the first spectroscopic confirmation of an ultramassive galaxy at redshift using data from Keck-NIRSPEC, VLT-X-shooter, and GTC-Osiris. We detect strong [O iii] and Ly? emission, and weak [O ii], C iv, and He ii, placing C1-23152 at a spectroscopic redshift of . The modeling of the emission-line-corrected spectral energy distribution (SED) results in a best-fit stellar mass of , a star formation rate of <7 yr?1, and negligible dust extinction. The stars appear to have formed in a short intense burst ?300?500 Myr prior to the observation epoch, setting the formation redshift of this galaxy at z ? 4.1. From the analysis of the line ratios and widths and the observed flux at 24 ?m, we confirm the presence of a luminous hidden active galactic nucleus (AGN), with bolometric luminosity of erg s?1. Potential contamination of the observed SED from the AGN continuum is constrained, placing a lower limit on the stellar mass of . HST/WFC3 and ACS images are modeled, resulting in an effective radius of kpc in the band and a S?rsic index . This object may be a prototype of the progenitors of local most massive elliptical galaxies in the first 2 Gyr of cosmic history, having formed most of its stars at in a highly dissipative, intense, and short burst of star formation. C1-23152 is completing its transition to a post-starburst phase while hosting a powerful AGN, potentially responsible for the quenching of the star formation activity.

A spectroscopic survey of WISE-selected obscured quasars with the southern african large telescope

We present the results of an optical spectroscopic survey of a sample of 40 candidate obscured quasars identified on the basis of their mid-infrared emission detected by the Wide-Field Infrared Survey Explorer (WISE). Optical spectra for this survey were obtained using the Robert Stobie Spectrograph (RSS) on the Southern African Large Telescope (SALT). Our sample was selected with WISE colors characteristic of AGNs, as well as red optical to mid-IR colors indicating that the optical/UV AGN continuum is obscured by dust. We obtain secure redshifts for the majority of the objects that comprise our sample (35/40), and find that sources that are bright in the WISE W4 (22

Weighing obscured and unobscured quasar hosts with the cosmic microwave background

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MID-INFRARED COLORS OF DWARF GALAXIES: YOUNG STARBURSTS MIMICKING ACTIVE GALACTIC NUCLEI

m) band are typically at moderate redshift ( = 0.35