THE QSO HE 0450-2958: SCANTILY DRESSED OR HEAVILY ROBED? A NORMAL QUASAR AS PART OF AN UNUSUAL ULIRG
- Max-Planck-Institut fuer Astronomie, Koenigstuhl 17, D-69117 Heidelberg (Germany)
- CEA Saclay/Service d'Astrophysique, Laboratoire AIM, CEA/DSM/IRFU-CNRS-Universite Paris Diderot, F-91191 Gif-sur-Yvette Cedex (France)
- Astrophysikalisches Institut Potsdam, An der Sternwarte 16, D-14482 Potsdam (Germany)
- Institut d'Astrophysique et Geophysique, Universite de Liege, Allee du 6 Aout, 17 Sart Tilman (Bat. B5C), B-4000 Liege (Belgium)
The luminous z = 0.286 quasar HE 0450-2958 is interacting with a companion galaxy at 6.5 kpc distance and the whole system radiates in the infrared (IR) at the level of an ultraluminous infrared galaxy (ULIRG). A so far undetected host galaxy triggered the hypothesis of a mostly 'naked' black hole (BH) ejected from the companion by three-body interaction. We present new Hubble Space Telescope (HST)/NICMOS 1.6 {mu}m imaging data at 0.''1 resolution and VLT/VISIR 11.3 {mu}m images at 0.''35 resolution that are for the first time resolving the system in the near- and mid-infrared. We combine these data with existing optical HST and CO maps. (1) At 1.6 {mu}m we find an extension NE of the quasar nucleus that is likely a part of the host galaxy, though not its main body. If true, a combination with upper limits on a main body co-centered with the quasar brackets the host-galaxy luminosity to within a factor of {approx}4 and places HE 0450-2958 directly onto the M{sub BH} - M{sub bulge} relation for nearby galaxies. (2) A dust-free line of sight to the quasar suggests a low dust obscuration of the host galaxy, but the formal upper limit for star formation (SF) lies at 60 M{sub sun} yr{sup -1}. HE 0450-2958 is consistent with lying at the high-luminosity end of Narrow-Line Seyfert 1 Galaxies, and more exotic explanations like a 'naked quasar' are unlikely. (3) All 11.3 {mu}m radiation in the system is emitted by the quasar nucleus. It has warm ULIRG-strength IR emission powered by BH accretion and is radiating at super-Eddington rate, L/L{sub Edd} = 6.2{sup +3.8}{sub -1.8}, or 12 M{sub sun} yr{sup -1}. (4) The companion galaxy is covered in optically thick dust and is not a collisional ring galaxy. It emits in the far-infrared at ULIRG strength, powered by Arp220-like SF (strong starburst-like). An M82-like SED is ruled out. (5) With its BH accretion rate, HE 0450-2958 produces not enough new stars to maintain its position on the M{sub BH} - M{sub bulge} relation, and SF and BH accretion are spatially disjoint. This relation can either only be maintained averaging over a longer timescale ({approx}<500 Myr) and/or the bulge has to grow by redistribution of pre-existing stars. (6) Systems similar to HE 0450-2958 with spatially disjoint ULIRG-strength star formation and quasar activity might be common at high redshifts but at z < 0.43 we only find <4% (3/77) candidates for a similar configuration.
- OSTI ID:
- 21313746
- Journal Information:
- Astrophysical Journal, Vol. 700, Issue 2; Other Information: DOI: 10.1088/0004-637X/700/2/1820; Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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