Discovery of a Binary Active Galactic Nucleus in the Ultraluminous Infrared Galaxy NGC 6240 Using Chandra

By S. Komossa, V. Burwitz, G. Hasinger, P. Predehl, J. Kaastra, Y. Ikebe. 2002

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Ultraluminous infrared galaxies (ULIRGs) are outstanding due to their huge luminosity output in the infrared, which is predominantly powered by superstarbursts and/or hidden active galactic nuclei (AGNs). NGC 6240 is one of the nearest ULIRGs and is considered a key representative of its class. Here we report the first high-resolution imaging spectroscopy of NGC 6240 in X-rays. The observation, performed with the ACIS-S detector aboard the Chandra X-Ray Observatory, led to the discovery of two hard nuclei, coincident with the optical-IR nuclei of NGC 6240. The AGN character of both nuclei is revealed by the detection of absorbed, hard, luminous X-ray emission and two strong neutral Fe Kα lines. In addition, extended X-ray emission components are present, changing their rich structure in dependence of energy. The close correlation of the extended emission with the optical Hα emission of NGC 6240, in combination with the softness of its spectrum, clearly indicates its relation to starburst-driven superwind activity.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/5628a9258209d1ef8bd86c3142566cd44a58f441

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Citations in the corpus

Quasar feedback: more bang for your buck (2009, background): “For example, in dense nuclear star-forming regions in e.g. ultraluminous infrared galaxies (ULIRGs), the column densities are so high (NH 1023 cm−2; see e.g. Komossa et al. 2003; Li et al. 2008) that the quasar can do little until star formation exhausts more of the gas supply.”
Dynamics of triple black hole systems in hierarchically merging massive galaxies (2006, background): “The most famous example is NGC 6240, an Ultraluminous Infrared Galaxy (ULIRG) in which two distinct active galactic nuclei (AGN) are clearly seen in hard X-rays at a projected separation of ∼1 kpc (Komossa et al. 2003).”
A LARGE SYSTEMATIC SEARCH FOR CLOSE SUPERMASSIVE BINARY AND RAPIDLY RECOILING BLACK HOLES (2011, neutral): “Observational Searches for Close Binary and Recoiling Holes in Historical Perspective Until recently, direct imaging had resolved very few (presumably unbound) wide BH pairs, such as NGC6240 (Komossa et al. 2003), and a close pair, CSO 0402+379 (Maness et al. 2004; Rodriguez et al. 2006, 2009).”
Doing Science with eLISA: Astrophysics and Cosmology in the Millihertz Regime (2012, background): “X-ray view of NGC6240 (lower left panel) an ultra luminous infrared galaxy considered to be a merger in a well advanced phase (Komossa et al., 2003).”
Supermassive black hole binaries in gaseous and stellar circumnuclear discs: orbital dynamics and gas accretion (2006, background): “Buried in a wide–spread star burst, these two hard X–ray sources have been identified as a pair of accreting massive black holes (MBHs) (Komossa et al. 2003; Risaliti et al. 2006).”
Supermassive Black Holes in Galactic Nuclei: Past, Present and Future Research (2004, methodology): “The presence of two SBHs (about 1 kpc apart and therefore not strictly yet forming a binary system) in the Ultraluminous Infrared Galaxy NGC 6240 is betrayed by the Chandra X-ray detection of two optical/IR nuclei (Komossa et al. 2003).”
Massive Black Hole Binary Evolution (2004, background): “One clear exception is NGC 6240 (Figure 2), for which both nuclei exhibit the flat X-ray spectra characteristic of AGNs [105].”
BAT AGN Spectroscopic Survey. V. X-Ray Properties of the Swift/BAT 70-month AGN Catalog (2017, background): “The luminous infrared galaxy NGC6240 is known to host two Compton-thick AGN separated by 0.7 kpc (1.8′′): NGC6240N and NGC6240S (Komossa et al. 2003).”
The Relation between Quasar and Merging Galaxy Luminosity Functions and the Merger-driven Star Formation History of the Universe (2006, background): “…(SEDs), suggesting that they harbor buried quasars (Sanders et al. 1988b), as implied byX-ray observations of growing black holes in NGC 6240 (Komossa et al. 2003) and other ULIRGs, which are heavily obscured at optical and infrared wavelengths (Gerssen et al. 2004; Max et al. 2005;…”
Physics, Astrophysics and Cosmology with Gravitational Waves (2009, background): “The recent discovery of an SMBH binary [222] and the association of X-shaped radio lobes with the merger of SMBH binaries [254] has further raised the optimism concerning SMBH merger rates, as has the suggestion that an SMBH has been observed to have been expelled from the center of its galaxy, an e”
A systematic search for close supermassive black hole binaries in the Catalina Real-time Transient Survey (2015, background): “G A ] SMBH binary pairs have been detected at kiloparsec separations, e.g., NGC 6240 at a separation of 1.4 kpc by Chandra (Komossa et al. 2003), but the observational evidence for close (subparsec) pairs is tentative.”
Black-hole binaries, gravitational waves, and numerical relativity (2010, background): “However, due to the vast cosmic distances involved, and the small angular separations on the sky expected for MBH binaries, only a few candidates are currently known through electromagnetic observations (Komossa, 2003; Komossa et al., 2003; Rodriguez et al., 2006).”
The Link between Submillimetre Galaxies and Luminous Ellipticals: Near-Infrared IFU Spectroscopy of Submillimetre Galaxies (2006, background): “Since the chance of a false association is <∼ 1%, it may be that we are witnessing the interaction or merging of AGNs in these sources (a low redshift example of this binary AGN activity is seen in the ULIRG NGC 6240; Komossa et al. 2003).”
A Population of Short-Period Variable Quasars from PTF as Supermassive Black Hole Binary Candidates (2016, background): “Several wide binaries (at kpc separation) have been spatially resolved in different bands, from X-rays to radio (Owen et al. 1985; Komossa et al. 2003; Bianchi et al. 2008; Green et al. 2010; Koss et al. 2011; Fabbiano et al. 2011; Comerford et al. 2011; Fu et al. 2015), including a few in triple…”
Evolution of binary black holes in self gravitating discs. Dissecting the torques (2012, background): “…et al. 2006; Myers et al. 2007, 2008; Foreman et al. 2009; Shen et al. 2011), and by few ∼< kpc dual accreting BHs embedded in the same galaxy (e.g. Komossa et al. 2003; Fabbiano et al. 2011), identification of gravitationally bound BHBs in galaxy centres remains elusive (for an up-to-date…”
The Murmur of the Sleeping Black Hole: Detection of Nuclear Ultraviolet Variability in LINER Galaxies (2005, background): “Both nuclei of NGC 6240 are probably LINERs (Raffanelli et al. 1997), both are compact radio sources at 1.4 and 5 GHz (Colbert et al. 1994; Gallimore & Beswick 2004), and both emit hard X-ray continua and Fe K lines (Komossa et al. 2003).”