TY - JOUR
T1 - X-ray nuclear activity in s4g barred galaxies
T2 - No link between bar strength and co-occurrent supermassive black hole fueling
AU - Cisternas, Mauricio
AU - Gadotti, Dimitri A.
AU - Knapen, Johan H.
AU - Kim, Taehyun
AU - Díaz-García, Simón
AU - Laurikainen, Eija
AU - Salo, Heikki
AU - González-Martín, Omaira
AU - Ho, Luis C.
AU - Elmegreen, Bruce G.
AU - Zaritsky, Dennis
AU - Sheth, Kartik
AU - Athanassoula, E.
AU - Bosma, Albert
AU - Comerón, Sébastien
AU - Erroz-Ferrer, Santiago
AU - Gil De Paz, Armando
AU - Hinz, Joannah L.
AU - Holwerda, Benne W.
AU - Laine, Jarkko
AU - Meidt, Sharon
AU - Menéndez-Delmestre, Karín
AU - Mizusawa, Trisha
AU - Muñoz-Mateos, Juan Carlos
AU - Regan, Michael W.
AU - Seibert, Mark
PY - 2013/10/10
Y1 - 2013/10/10
N2 - Stellar bars can lead to gas inflow toward the center of a galaxy and stimulate nuclear star formation. However, there is no compelling evidence on whether they also feed a central supermassive black hole: by measuring the fractions of barred active and inactive galaxies, previous studies have yielded conflicting results. In this paper, we aim to understand the lack of observational evidence for bar-driven active galactic nucleus (AGN) activity by studying a sample of 41 nearby (d < 35 Mpc) barred galaxies from the Spitzer Survey for Stellar Structure in Galaxies. We use Chandra observations to measure nuclear 2-10 keV X-ray luminosities and estimate Eddington ratios, together with Spitzer 3.6 μm imaging to quantify the strength of the stellar bar in two independent ways: (1) from its structure, as traced by its ellipticity and boxiness, and (2) from its gravitational torque Qb , taken as the maximum ratio of the tangential force to the mean background radial force. In this way, rather than discretizing the presence of both stellar bars and nuclear activity, we are able to account for the continuum of bar strengths and degrees of AGN activity. We find nuclear X-ray sources in 31 out of 41 galaxies with median X-ray luminosity and Eddington ratio of L X = 4.3 × 1038 erg s-1 and L bol/L Edd = 6.9 × 10-6, respectively, consistent with low-luminosity AGN activity. Including upper limits for those galaxies without nuclear detections, we find no significant correlation between any of the bar strength indicators and the degree of nuclear activity, irrespective of galaxy luminosity, stellar mass, Hubble type, or bulge size. Strong bars do not favor brighter or more efficient nuclear activity, implying that at least for the low-luminosity regime, supermassive black hole fueling is not closely connected to large-scale features.
AB - Stellar bars can lead to gas inflow toward the center of a galaxy and stimulate nuclear star formation. However, there is no compelling evidence on whether they also feed a central supermassive black hole: by measuring the fractions of barred active and inactive galaxies, previous studies have yielded conflicting results. In this paper, we aim to understand the lack of observational evidence for bar-driven active galactic nucleus (AGN) activity by studying a sample of 41 nearby (d < 35 Mpc) barred galaxies from the Spitzer Survey for Stellar Structure in Galaxies. We use Chandra observations to measure nuclear 2-10 keV X-ray luminosities and estimate Eddington ratios, together with Spitzer 3.6 μm imaging to quantify the strength of the stellar bar in two independent ways: (1) from its structure, as traced by its ellipticity and boxiness, and (2) from its gravitational torque Qb , taken as the maximum ratio of the tangential force to the mean background radial force. In this way, rather than discretizing the presence of both stellar bars and nuclear activity, we are able to account for the continuum of bar strengths and degrees of AGN activity. We find nuclear X-ray sources in 31 out of 41 galaxies with median X-ray luminosity and Eddington ratio of L X = 4.3 × 1038 erg s-1 and L bol/L Edd = 6.9 × 10-6, respectively, consistent with low-luminosity AGN activity. Including upper limits for those galaxies without nuclear detections, we find no significant correlation between any of the bar strength indicators and the degree of nuclear activity, irrespective of galaxy luminosity, stellar mass, Hubble type, or bulge size. Strong bars do not favor brighter or more efficient nuclear activity, implying that at least for the low-luminosity regime, supermassive black hole fueling is not closely connected to large-scale features.
KW - galaxies: active
KW - galaxies: evolution
KW - galaxies: nuclei
KW - galaxies: structure
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UR - http://www.scopus.com/inward/citedby.url?scp=84884849753&partnerID=8YFLogxK
U2 - 10.1088/0004-637X/776/1/50
DO - 10.1088/0004-637X/776/1/50
M3 - Article
AN - SCOPUS:84884849753
SN - 0004-637X
VL - 776
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 1
M1 - 50
ER -