X-Ray Emission of Active Galactic Nuclei with Circumnuclear Star-forming Rings: NGC 1097 and NGC 7469

Abstract

view Abstract Citations (43) References (70) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS X-Ray Emission of Active Galactic Nuclei with Circumnuclear Star-forming Rings: NGC 1097 and NGC 7469 Perez-Olea, Diego E. ; Colina, Luis Abstract ROSAT high-resolution imager (HRI) observations of the active galaxies NGC 1097 (Liner/Seyfert) and NGC 7469 (Seyfert 1), known to have a circumnuclear star-forming ring, are presented. An extended X-ray emission associated with ring of NGC 1097 is detected in the HRI image of this galaxy. The X-ray luminosity emitted by the ring is L_x_ = 3.6 x 10^40^ ergs s^-1^ and accounts for about 20% of the integrated X-ray luminosity of NGC 1097, L_x_ = 2 x 10^41^ ergs s^-1^. Circumnuclear star-forming rings in active galaxies like NGC 1097 and NGC 1068 have X-rays to radio and Hα luminosities ratios similar to those of pure starburst galaxies like M82, NGC 253, and NGC 1808. On average, starbursts are characterized by L_x_/L_5 GHz_ ~ 400, and L_x_/L_Hα_ ~ 0.14. The HRI image of NGC 7469 shows no structure, and the X-ray emission emitted by the circumnuclear ring cannot be disentangled from that of the nucleus. However, assuming the star-forming ring in NGC 7469 radiates with the average L_x_/L_5 GHz_ = 400 of starbursts, a X-ray luminosity L_x_ = 5.6 x 1O^41^ ergs s^-1^ is inferred. The ring contributes therefore to only about 4% of the integrated X-ray luminosity, L_x_ = 1.1 x 10^43^ ergs s^-1^. Pure active galactic nuclei (AGNs) are well differentiated from pure starbursts in the L-x_/L_Hα_ ratio, independent of their absolute luminosity and activity level. For a given Hα luminosity, AGNs produce 100 times more X-rays than pure starbursts do. The weak X-ray sources detected in some high-luminosity and ultraluminous infrared galaxies are characterized by X-ray to Hα and to radio luminosity ratios L_x_/L_Hα_ ~ 0.05 and L_x_/L_5 GHz_ ~ 20, respectively. These values are consistent with the ratios measured in nearly edge-on starbursts but about 100 times smaller than those of composite AGNs plus circumnuclear star-forming galaxies like NGC 1097 and NGC 7469. Publication: The Astrophysical Journal Pub Date: September 1996 DOI: 10.1086/177681 Bibcode: 1996ApJ...468..191P Keywords: GALAXIES: INDIVIDUAL NGC NUMBER: NGC 1097; GALAXIES: INDIVIDUAL NGC NUMBER: NGC 7469; GALAXIES: ACTIVE; GALAXIES: STARBURST; X-RAYS: GALAXIES; GALAXIES: SEYFERT; GALAXIES: STRUCTURE full text sources ADS | data products SIMBAD (28) NED (18) HEASARC (1)