Browsing by Author "Koss, Michael"
Now showing 1 - 6 of 6
Results Per Page
Sort Options
- ItemBAT AGN Spectroscopic Survey - XVII. The parsec-scale jet properties of the ultrahard X-ray-selected local AGNs(2019) Baek, Junhyun; Chung, Aeree; Schawinski, Kevin; Oh, Kyuseok; Wong, O. Ivy; Koss, Michael; Ricci, Claudio; Trakhtenbrot, Benny; Smith, Krista Lynne; Ueda, Yoshihiro
- ItemBAT AGN Spectroscopic Survey. VIII. Type 1 AGN with Massive Absorbing Columns(2018) Shimizu, T. Taro; Davies, Richard I.; Koss, Michael; Ricci, Claudio; Lamperti, Isabella; Oh, Kyuseok; Schawinski, Kevin; Trakhtenbrot, Benny; Burtscher, Leonard; Genzel, Reinhard; Lin, Ming-yi; Lutz, Dieter; Rosario, David; Sturm, Eckhard; T
- ItemSignatures of feedback in the spectacular extended emission region of NGC 5972(2023) Harvey, Thomas; Maksym, W. Peter; Keel, William; Koss, Michael; Bennert, Vardha N.; Chojnowski, S. Drew; Treister, Ezequiel; Finlez, Carolina; Lintott, Chris J.; Moiseev, Alexei; Simmons, Brooke D.; Sartori, Lia F.; Urry, MeganWe present Chandra X-ray Observatory observations and Space Telescope Imaging Spectrograph spectra of NGC 5972, one of the 19 ‘Voorwerpjes’ galaxies. This galaxy contains an extended emission-line region (EELR) and an arcsecond scale nuclear bubble. NGC 5972 is a faded active galactic nucleus (AGN), with EELR luminosity suggesting a 2.1 dex decrease in Lbol in the last ∼5 × 104 yr. We investigate the role of AGN feedback in exciting the EELR and bubble given the long-term variability and potential accretion state changes. We detect broad-band (0.3–8 keV) X-ray emission in the near-nuclear regions, coincident with the [O III] bubble, as well as diffuse soft X-ray emission coincident with the EELR. The soft nuclear (0.5–1.5 keV) emission is spatially extended and the spectra are consistent with two APEC thermal populations (∼0.80 and ∼0.10 keV). We find a bubble age >2.2 Myr, suggesting formation before the current variability. We find evidence for efficient feedback with Pkin/Lbol ∼ 0.8 per cent, which may be overestimated given the recent Lbol variation. [O III] kinematics show a 300 km s−1 high-ionization velocity consistent with disturbed rotation or potentially the line-of-sight component of a ∼780 km s−1 thermal X-ray outflow capable of driving strong shocks to photoionize the precursor material. We explore possibilities to explain the overall jet, radio lobe and EELR misalignment including evidence for a double supermassive black hole which could support a complex misaligned system.
- ItemThe 105-month swift-BAT all-sky hard X-ray survey(2018) Kyuseok, O.H.; Koss, Michael; Markwardt, Craig B.; Schawinski, Kevin; Baumgartner, Wayne H.; Barthelmy, Scott D.; Bradley Cenko, S.; Gehrels, Neil; Mushotzky, Richard; Ricci, Claudio
- ItemThe Accretion History of AGN: The Spectral Energy Distributions of X-Ray-luminous Active Galactic Nuclei(2023) Auge, Connor; Sanders, David; Treister, Ezequiel; Urry, C. Megan; Kirkpatrick, Allison; Cappelluti, Nico; Ananna, Tonima Tasnim; Boquien, Médéric; Baloković, Mislav; Civano, Francesca; Coleman, Brandon; Ghosh, Aritra; Kartaltepe, Jeyhan; Koss, Michael; LaMassa, Stephanie; Marchesi, Stefano; Peca, Alessandro; Powell, Meredith; Trakhtenbrot, Benny; Turner, Tracey JaneSpectral energy distributions (SEDs) from X-ray to far-infrared (FIR) wavelengths are presented for a sample of 1246 X-ray-luminous active galactic nuclei (AGNs; L0.5–10 keV > 1043 erg s−1), with zspec < 1.2, selected from Stripe 82X, COSMOS, and GOODS-N/S. The rest-frame SEDs show a wide spread (∼2.5 dex) in the relative strengths of broad continuum features at X-ray, ultraviolet (UV), mid-infrared (MIR), and FIR wavelengths. A linear correlation (log–log slope of 0.7 ± 0.04) is found between LMIR and LX. There is significant scatter in the relation between the LUV and LX owing to heavy obscuration; however, the most luminous and unobscured AGNs show a linear correlation (log–log slope of 0.8 ± 0.06) in the relation above this scatter. The relation between LFIR and LX is predominantly flat, but with decreasing dispersion at LX > 1044 erg s−1. The ratio between the "galaxy-subtracted" bolometric luminosity and the intrinsic LX increases from a factor of ∼10 to 70 from log Lbol/(erg s−1) = 44.5 to 46.5. Characteristic SED shapes have been determined by grouping AGNs based on relative strengths of the UV and MIR emission. The average L1μm is constant for the majority of these SED shapes, while AGNs with the strongest UV and MIR emission have elevated L1μm, consistent with the AGN emission dominating their SEDs at optical and near-infrared wavelengths. A strong correlation is found between the SED shape and both the LX and Lbol, such that Lbol/LX = 20.4 ± 1.8, independent of the SED shape. This is consistent with an evolutionary scenario of increasing Lbol with decreasing obscuration as the AGN blows away circumnuclear gas.
- ItemThe CO(3–2)/CO(1–0) Luminosity Line Ratio in Nearby Star-forming Galaxies and Active Galactic Nuclei from xCOLD GASS, BASS, and SLUGS(2020) Lamperti, Isabella; Saintonge, Amélie; Koss, Michael; Viti, Serena; Wilson, Christine D.; He, Hao; Shimizu, T. Taro; Greve, Thomas R; Mushotzky, Richard; Treister, Ezequiel