Browsing by Author "Stern, D."
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- ItemA 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.
- ItemA New Compton-thick AGN in Our Cosmic Backyard: Unveiling the Buried Nucleus in NGC 1448 with NuSTAR(2017) Annuar, A.; Alexander, D.; Gandhi, P.; Lansbury, G.; Asmus, D.; Ballantyne, D.; Bauer, Franz Erik; Boggs, S.; Boorman, P.; Brandt W.; Brightman, M.|Christensen, F.; Craig, W.; Farrah, D.; Goulding, A.; Hailey, C.; Harrison, F.; Koss, M.; Lamassa, S.; Murray, S.; Ricci, Claudio; Rosario, D.; Stanley, F.; Stern, D.; Zhang, W.
- ItemAn extragalactic spectroscopic survey of the SSA22 field(2015) Saez, C.; Lehmer, B. D.; Bauer, Franz Erik; Stern, D.; Gonzales, A.; Rreza, I.; Alexander, D. M.; Matsuda, Y.; Geach, J. E.; Harrison, F. A.
- ItemAn extremely luminous and variable ultraluminous X-ray source in the outskirts of circinus observed with nustar(2013) Walton, D. J.; Fürst, F.; Harrison, F. A.; Stern, D.; Bachetti, Matteo; Barret, Didier; Bauer, Franz Erik; Boggs, S. E.
- ItemBASS 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.
- ItemBASS. XLII. The Relation between the Covering Factor of Dusty Gas and the Eddington Ratio in Nearby Active Galactic Nuclei(Wiley, 2023) Ricci, C.; Ichikawa, K.; Stalevski, M.; Kawamuro, T.; Yamada, S.; Ueda, Y.; Mushotzky, R.; Privon, G. C.; Koss, M. J.; Trakhtenbrot, B.; Fabian, A. C.; Ho, L. C.; Asmus, D.; Bauer, Franz Erik; Chang, C. S.; Gupta, K. K.; Oh, K.; Powell, M.; Pfeifle, R. W.; Rojas, A.; Ricci, F.; Temple, M. J.; Toba, Y.; Tortosa, A.; Treister, Ezequiel; Harrison, F.; Stern, D.; Urry, C. M.Accreting supermassive black holes (SMBHs) located at the centers of galaxies are typically surrounded by large quantities of gas and dust. The structure and evolution of this circumnuclear material can be studied at different wavelengths, from the submillimeter to the X-ray. Recent X-ray studies have shown that the covering factor of the obscuring material tends to decrease with increasing Eddington ratio, likely due to radiative feedback on dusty gas. Here we study a sample of 549 nearby (z less than or similar to 0.1) hard X-ray (14-195 keV) selected nonblazar active galactic nuclei (AGN) and use the ratio between the AGN infrared and bolometric luminosity as a proxy of the covering factor. We find that, in agreement with what has been found by X-ray studies of the same sample, the covering factor decreases with increasing Eddington ratio. We also confirm previous findings that showed that obscured AGN typically have larger covering factors than unobscured sources. Finally, we find that the median covering factors of AGN located in different regions of the column density-Eddington ratio diagram are in good agreement with what would be expected from a radiation-regulated growth of SMBHs.
- ItemBASS. XLII. The Relation between the Covering Factor of Dusty Gas and the Eddington Ratio in Nearby Active Galactic Nuclei(2023) Ricci, C.; Ichikawa, K.; Stalevski, M.; Kawamuro, T.; Yamada, S.; Ueda, Y.; Mushotzky, R.; Privon, G. C.; Koss, M. J.; Trakhtenbrot, B.; Fabian, A. C.; Ho, L. C.; Asmus, D.; Bauer, Franz Erik; Chang, C. S.; Gupta, K. K.; Oh, K.; Powell, M.; Pfeifle, R. W.; Rojas, A.; Ricci, F.; Temple, M. J.; Toba, Y.; Tortosa, A.; Treister, Ezequiel; Harrison, F.; Stern, D.; Urry, C. M.Accreting supermassive black holes (SMBHs) located at the centers of galaxies are typically surrounded by large quantities of gas and dust. The structure and evolution of this circumnuclear material can be studied at different wavelengths, from the submillimeter to the X-ray. Recent X-ray studies have shown that the covering factor of the obscuring material tends to decrease with increasing Eddington ratio, likely due to radiative feedback on dusty gas. Here we study a sample of 549 nearby (z less than or similar to 0.1) hard X-ray (14-195 keV) selected nonblazar active galactic nuclei (AGN) and use the ratio between the AGN infrared and bolometric luminosity as a proxy of the covering factor. We find that, in agreement with what has been found by X-ray studies of the same sample, the covering factor decreases with increasing Eddington ratio. We also confirm previous findings that showed that obscured AGN typically have larger covering factors than unobscured sources. Finally, we find that the median covering factors of AGN located in different regions of the column density-Eddington ratio diagram are in good agreement with what would be expected from a radiation-regulated growth of SMBHs.
- ItemBAT AGN spectroscopic survey – XV: the high frequency radio cores of ultra-hard X-ray selected AGN(OUP, 2019) Smith, K. L.; Mushotzky, R. F.; Koss, M.; Trakhtenbrot, B.; Ricci, Claudio; Wong, O. I.; Bauer, F. E.; Ricci, F.; Vogel, S.; Stern, D.; Powell, M. C.; Urry, C. M.; Harrison, F.; Mejia-Restrepo, J.; Oh, K.; Baek, J.; Chun, A.We have conducted 22 GHz radio imaging at 1 arcsec resolution of 100 low-redshift AGN selected at 14–195 keV by the Swift-BAT. We find a radio core detection fraction of 96 per cent, much higher than lower frequency radio surveys. Of the 96 radio-detected AGN, 55 have compact morphologies, 30 have morphologies consistent with nuclear star formation, and 11 have sub-kpc to kpc-scale jets. We find that the total radio power does not distinguish between nuclear star formation and jets as the origin of the radio emission. For 87 objects, we use optical spectroscopy to test whether AGN physical parameters are distinct between radio morphological types. We find that X-ray luminosities tend to be higher if the 22 GHz morphology is jet-like, but find no significant difference in other physical parameters. We find that the relationship between the X-ray and core radio luminosities is consistent with the LR/LX ∼ 10−5 of coronally active stars. We further find that the canonical fundamental planes of black hole activity systematically overpredict our radio luminosities, particularly for objects with star formation morphologies.
- ItemBroad-band X-ray spectral analysis of the Seyfert 1 galaxy GRS 1734-292(2017) Tortosa, A.; Marinucci, A.; Matt, G.; Bianchi, S.; La Franca, F.; Ballantyne, D. R.; Boorman, P. G.; Fabian, A. C.; Farrah, D.; Ricci, Claudio; Fuerst, F.; Gandhi, P.; Harrison, F. A.; Koss, M. J.; Stern, D.; Ursini, F.; Walton, D. J.
- ItemConstraining X-ray reflection in the low-luminosity AGN NGC3718 using NuSTAR and XMM-Newton(2020) Diaz, Y.; Arevalo, P.; Hernandez Garcia, L.; Bassani, L.; Malizia, A.; Gonzalez Martin, O.; Ricci, Claudio; Matt, G.; Stern, D.; Bauer, Franz Erik; May, D.; Zezas, A .
- ItemDetermining the covering factor of compton-thick active galactic nuclei with NuSTAR(2015) Brightman, M.; Balokovic, M.; Stern, D.; Arevalo, P.; Ballantyne, D. R.; Bauer, Franz Erik; Bogg, S. E.; Craig, W. W.; Christensen, F. E.; Comastri, A.; Gandhi, P.; Hailey, C. J.; Harrison, F. A.; Hickox, R. C.; Koss, M.; Lamassa, S.; Fuerst, F.; Puccetti, S.; Rivers, E.; Vasudevan, R.; Walton, D. J.; Zhang, W. W.
- ItemDiscovery and Classification of Transients from CRTS-II(2016) Drake, A. J.; Djorgovski, S. G.; Mahabal, A. A.; Graham, M. J.; Stern, D.; Catelan, Márcio; Christensen, E.; Larson, S. M.Following on from the Catalina Real-time Transient Survey (CRTS), the CRTS-II project has begun to search for transients and highly variable sources. As with CRTS, all detections will be made public immediately following discovery....
- ItemDo some AGN lack X-ray emission?(2016) Simmonds, C.; Bauer, Franz Erik; Thuan, T.; Izotov, Y.; Stern, D.; Harrison, F.
- ItemHard X-ray emission of the luminous infrared galaxy NGC 6240 as observed by NuSTAR(2016) Puccetti, S.; Comastri, A.; Bauer, Franz Erik; Brandt, W.; Fiore, E.; Harrison, F.; Luo, B.; Stern, D.; Urry, C.; Alexander, D.; Annuar, A.; Arevalo, P.; Balokovic, M.; Boggs, S.; Brightman, M.; Craig, W.; Ricci, Claudio
- ItemHard X-Ray-selected AGNs in Low-mass Galaxies from the NuSTAR Serendipitous Survey(2017) Chen, C. T. J.; Brandt, W. N.; Reines, A. E.; Lansbury, G.; Stern, D.; Alexander, D. M.; Bauer, Franz Erik; Ricci, Claudio; Del Moro, A.; Gandhi, P.; Harrison, F. A.; Hickox, R. C.; Koss, M. J.; Lanz, L.; Koss, M. J.; Lanz, L.; Luo, B.; Ricci, Claudio
- ItemHOT DUST OBSCURED GALAXIES WITH EXCESS BLUE LIGHT : DUAL AGN OR SINGLE AGN UNDER EXTREME CONDITIONS?(2016) Assef, R.; Walton, D.; Brightman, M.; Stern, D.; Alexander, D.; Bauer, Franz Erik; Blain, A.; Diaz, T.; Eisenhardt, P.; Finkelstein, S.; Hickox, R.; Tsai, C.; Wu, J.
- ItemInitial results from NuSTAR observations of the Norma ARM(2014) Bodaghee, A.; Tomsick, J.; Krivonos, R.; Stern, D.; Bauer, Franz Erik; Fornasini, F.; Barriere, N.; Boggs, S.,
- ItemInvestigating the Evolution of the Dual AGN System ESO 509-IG066.(2017) Kosec, P.; Ricci, Claudio; Treister, Ezequiel; Privon, G. C.; Brightman, M.; Stern, D.; Müller-Sánchez, Francisco; Koss, M.; Oh, K.; Assef T., Roberto; Gandhi, P.
- ItemNew spectral model for constraining torus covering factors from broadband X-ray spectra of active galactic nuclei(2018) Baloković, M.; Brightman, M.; Harrison, F.A.; Comastri, A.; Ricci, Claudio; Buchner, J.; Gandhi, P.; Farrah, D.; Stern, D.
- ItemNustar and suzaku X-Ray spectroscopy of NGC 4151: evidence for reflection from the inner accretion disk(2015) Keck, M.; Brenneman, L.; Ballantyne, D.; Bauer, Franz Erik; Boggs, S.; Christensen, F.; Craig, W.; Dauser, T.; Elvis, M.; Fabian, A.; Fuerst, F.; García, J.; Grefenstette, B.; Hailey, C.; Harrison, F.; Madejski, G.; Marinucci, A.; Matt, G.; Reynolds, C.; Stern, D.; Walton, D.; Zoghbi, A.
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