Browsing by Author "Treister, E."

Now showing 1 - 5 of 5
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    A hard X-ray view of luminous and ultra-luminous infrared galaxies in GOALS - I. AGN obscuration along the merger sequence
    (2021) Ricci, C.; Privon, G. C.; Pfeifle, R. W.; Armus, L.; Iwasawa, K.; Torres-Albà, N.; Satyapal, S.; Bauer, F. E.; Treister, E.; Ho, L. C.; Aalto, S.; Arévalo, P.; Barcos-Muñoz, L.; Charmandaris, V.; Diaz-Santos, T.; Evans, A. S.; Gao, T.; Inami, H.; Koss, M. J.; Lansbury, G.; Linden, S. T.; Medling, A.; Sanders, D. B.; Song, Y.; Stern, D.; U, V.; Ueda, Y.; Yamada, S.
    The merger of two or more galaxies can enhance the inflow of material from galactic scales into the close environments of active galactic nuclei (AGNs), obscuring and feeding the supermassive black hole (SMBH). Both recent simulations and observations of AGN in mergers have confirmed that mergers are related to strong nuclear obscuration. However, it is still unclear how AGN obscuration evolves in the last phases of the merger process. We study a sample of 60 luminous and ultra-luminous IR galaxies (U/LIRGs) from the GOALS sample observed by NuSTAR. We find that the fraction of AGNs that are Compton thick (CT;N-H >= 10(24)cm(-2) ) peaks at at a late merger stage, prior to coalescence, when the nuclei have projected separations (d(sep)) of 0.4-6 kpc. A similar peak is also observed in the median N-H [[(1.6 +/- 0.5) x 10(24) cm(-2)].]. The vast majority (85(-9)(+7) per cent)) of the AGNs in the final merger stages (d(sep) less than or similar to 10 kpc) are heavily obscured (N-H = 10(23) cm(-2)), and the median N-H of the accreting SMBHs in our sample is systematically higher than that of local hard X-ray-selected AGN, regardless of the merger stage. This implies that these objects have very obscured nuclear environments, with the gas almost completely covering the AGN in late mergers. CT AGNs tend to have systematically higher absorption-corrected X-ray luminosities than less obscured sources. This could either be due to an evolutionary effect, with more obscured sources accreting more rapidly because they have more gas available in their surroundings, or to a selection bias. The latter scenario would imply that we are still missing a large fraction of heavily obscured, lower luminosity (L2-10 less than or similar to 10(43) erg s(-1)) AGNs in U/LIRGs.
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    BASS XXXI: Outflow scaling relations in low redshift X-ray AGN host galaxies with MUSE
    (2022) Kakkad, D.; Sani, E.; Rojas, A. F.; Mallmann, Nicolas D.; Veilleux, S.; Bauer, Franz E.; Ricci, F.; Mushotzky, R.; Koss, M.; Ricci, C.; Treister, E.; Privon, George C.; Nguyen, N.; Bär, R.; Harrison, F.; Oh, K.; Powell, M.; Riffel, R.; Stern, D.; Trakhtenbrot, B.; Urry, C. M.
    Ionized gas kinematics provide crucial evidence of the impact that active galactic nuclei (AGNs) have in regulating star formation in their host galaxies. Although the presence of outflows in AGN host galaxies has been firmly established, the calculation of outflow properties such as mass outflow rates and kinetic energy remains challenging. We present the [O iii]lambda 5007 ionized gas outflow properties of 22 z<0.1 X-ray AGN, derived from the BAT AGN Spectroscopic Survey using MUSE/VLT. With an average spatial resolution of 1 arcsec (0.1-1.2 kpc), the observations resolve the ionized gas clouds down to sub-kiloparsec scales. Resolved maps show that the [O iii] velocity dispersion is, on average, higher in regions ionized by the AGN, compared to star formation. We calculate the instantaneous outflow rates in individual MUSE spaxels by constructing resolved mass outflow rate maps, incorporating variable outflow density and velocity. We compare the instantaneous values with time-averaged outflow rates by placing mock fibres and slits on the MUSE field-of-view, a method often used in the literature. The instantaneous outflow rates (0.2-275 M-circle dot yr(-1)) tend to be two orders of magnitude higher than the time-averaged outflow rates (0.001-40 M-circle dot yr(-1)). The outflow rates correlate with the AGN bolometric luminosity (L-bol similar to 10(42.71)-10(45.62) erg s(-1)) but we find no correlations with black hole mass (10(6.1)-10(8.9) M-circle dot), Eddington ratio (0.002-1.1), and radio luminosity (10(21)-10(26) W Hz(-1)). We find the median coupling between the kinetic energy and L-bol to be 1 per cent, consistent with the theoretical predictions for an AGN-driven outflow.
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    GOODS-ALMA 2.0: Source catalog, number counts, and prevailing compact sizes in 1.1 mm galaxies
    (2022) Gómez-Guijarro, C.; Elbaz, D.; Xiao, M.; Béthermin, M.; Franco, M.; Magnelli, B.; Daddi, E.; Dickinson, M.; Demarco, R.; Inami, H.; Rujopakarn, W.; Magdis, G. E.; Shu, X.; Chary, R.; Zhou, L.; Alexander, D. M.; Bournaud, F.; Ciesla, L.; Ferguson, H. C.; Finkelstein, S. L.; Giavalisco, M.; Iono, D.; Juneau, S.; Kartaltepe, J. S.; Lagache, G.; Le Floc'h, E.; Leiton, R.; Lin, L.; Motohara, K.; Mullaney, J.; Okumura, K.; Pannella, M.; Papovich, C.; Pope, A.; Sargent, M. T.; Silverman, J. D.; Treister, E.; Wang, T.
    Submillimeter/millimeter observations of dusty star-forming galaxies with the Atacama Large Millimeter/submillimeter Array (ALMA) have shown that dust continuum emission generally occurs in compact regions smaller than the stellar distribution. However, it remains to be understood how systematic these findings are. Studies often lack homogeneity in the sample selection, target discontinuous areas with inhomogeneous sensitivities, and suffer from modest uv coverage coming from single array configurations. GOODS-ALMA is a 1.1 mm galaxy survey over a continuous area of 72.42 arcmin(2) at a homogeneous sensitivity. In this version 2.0, we present a new low resolution dataset and its combination with the previous high resolution dataset from the survey, improving the uv coverage and sensitivity reaching an average of sigma = 68.4 mu Jy beam(-1). A total of 88 galaxies are detected in a blind search (compared to 35 in the high resolution dataset alone), 50% at S/N-peak >= 5 and 50% at 3.5 <= S/N-peak <= 5 aided by priors. Among them, 13 out of the 88 are optically dark or faint sources (H- or K-band dropouts). The sample dust continuum sizes at 1.1 mm are generally compact, with a median effective radius of R-e = 0 ''.10 +/- 0 ''.5 (a physical size of R-e = 0.73 +/- 0.29 kpc at the redshift of each source). Dust continuum sizes evolve with redshift and stellar mass resembling the trends of the stellar sizes measured at optical wavelengths, albeit a lower normalization compared to those of late-type galaxies. We conclude that for sources with flux densities S-1.1mm > 1 mJy, compact dust continuum emission at 1.1 mm prevails, and sizes as extended as typical star-forming stellar disks are rare. The S-1.1mm < 1 mJy sources appear slightly more extended at 1.1 mm, although they are still generally compact below the sizes of typical star-forming stellar disks.
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    MAGNUM survey: Compact jets causing large turmoil in galaxies. Enhanced line widths perpendicular to radio jets as tracers of jet-ISM interaction
    (2021) Venturi, G.; Cresci, G.; Marconi, A.; Mingozzi, M.; Nardini, E.; Carniani, S.; Mannucci, F.; Marasco, A.; Maiolino, R.; Perna, M.; Treister, E.; Bland-Hawthorn, J.; Gallimore, J.
    Context. Outflows accelerated by active galactic nuclei (AGN) are commonly observed in the form of coherent, mildly collimated high-velocity gas directed along the AGN ionisation cones and kinetically powerful (greater than or similar to 10(44-45) erg s(-1)) jets. Recent works found that outflows can also be accelerated by low-power (less than or similar to 10(44) erg s(-1)) jets, and the most recent cosmological simulations indicate that these are the dominant source of feedback on sub-kiloparsec scales, but little is known about their effect on the galaxy host.Aims. We study the relation between radio jets and the distribution and kinematics of the ionised gas in IC 5063, NGC 5643, NGC 1068, and NGC 1386 as part of our survey of nearby Seyfert galaxies called Measuring Active Galactic Nuclei Under MUSE Microscope (MAGNUM). All these objects host a small-scale (less than or similar to 1 kpc) low-power (less than or similar to 10(44) erg s(-1)) radio jet that has small inclinations (less than or similar to 45 degrees) with respect to the galaxy disc.Methods. We employed seeing-limited optical integral field spectroscopic observations from the Multi Unit Spectroscopic Explorer (MUSE) at the Very Large Telescope to obtain flux, kinematic, and excitation maps of the extended ionised gas. We compared these maps with archival radio images and in one case, with Chandra X-ray observations.Results. We detect a strong (up to greater than or similar to 800-1000 km s(-1)) and extended (greater than or similar to 1 kpc) emission-line velocity spread perpendicular to the direction of the AGN ionisation cones and jets in all four targets. The gas excitation in this region of line-width enhancement is entirely compatible with shock ionisation. These broad and symmetric line profiles are not associated with a single coherent velocity of the gas. A 'classical' outflow component with net blueshifted and redshifted motions is also present, but is directed along the ionisation cones and jets.Conclusions. We interpret the observed phenomenon as due to the action of the jets perturbing the gas in the galaxy disc. These intense and extended velocity spreads perpendicular to AGN jets and cones are indeed currently only observed in galaxies hosting a low-power jet whose inclination is sufficiently low with respect to the galaxy disc to impact on and strongly affect its material. In line with cosmological simulations, our results demonstrate that low-power jets are indeed capable of affecting the host galaxy.
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    The Evolution of the IR Luminosity Function and Dust-obscured Star Formation over the Past 13 Billion Years
    (2021) Zavala, J. A.; Casey, C. M.; Manning, S. M.; Aravena, M.; Bethermin, M.; Caputi, K. I.; Clements, D. L.; Cunha, E. da; Drew, P.; Finkelstein, S. L.; Fujimoto, S.; Hayward, C.; Hodge, J.; Kartaltepe, J. S.; Knudsen, K.; Koekemoer, A. M.; Long, A. S.; Magdis, G. E.; Man, A. W. S.; Popping, G.; Sanders, D.; Scoville, N.; Sheth, K.; Staguhn, J.; Toft, S.; Treister, E.; Vieira, J. D.; Yun, M. S.
    We present the first results from the Mapping Obscuration to Reionization with ALMA (MORA) survey, the largest Atacama Large Millimeter/submillimeter Array (ALMA) blank-field contiguous survey to date (184 arcmin(2)) and the only at 2 mm to search for dusty star-forming galaxies (DSFGs). We use the 13 sources detected above 5 sigma to estimate the first ALMA galaxy number counts at this wavelength. These number counts are then combined with the state-of-the-art galaxy number counts at 1.2 and 3 mm and with a backward evolution model to place constraints on the evolution of the IR luminosity function and dust-obscured star formation in the past 13 billion years. Our results suggest a steep redshift evolution on the space density of DSFGs and confirm the flattening of the IR luminosity function at faint luminosities, with a slope of alpha(LF) = -0.42(-0.04)(+0.02). We conclude that the dust-obscured component, which peaks at z approximate to 2-2.5, has dominated the cosmic history of star formation for the past similar to 12 billion years, back to z similar to 4. At z = 5, the dust-obscured star formation is estimated to be similar to 35% of the total star formation rate density and decreases to 25%-20% at z = 6-7, implying a minor contribution of dusten-shrouded star formation in the first billion years of the universe. With the dust-obscured star formation history constrained up to the end of the epoch of reionization, our results provide a benchmark to test galaxy formation models, to study the galaxy mass assembly history, and to understand the dust and metal enrichment of the universe at early times.