Herschel-pacs observations of far-ir co line emission in NGC 1068: Highly excited molecular gas in the circumnuclear disk
Astrophysical Journal 755:1 (2012)
Abstract:
We report the detection of far-IR CO rotational emission from the prototypical Seyfert 2 galaxy NGC 1068. Using Herschel-PACS, we have detected 11 transitions in the J upper = 14-30 (E upper/kB = 580-2565K) range, all of which are consistent with arising from within the central 10″ (700pc). The detected transitions are modeled as arising from two different components: a moderate-excitation (ME) component close to the galaxy systemic velocity and a high-excitation (HE) component that is blueshifted by 80kms-1. We employ a large velocity gradient model and derive n H2 105.6cm-3, T kin 170K, and M H2 106.7 M ⊙ for the ME component and n H2 106.4cm-3, T kin 570K, and M H2 105.6 M ⊙ for the HE component, although for both components the uncertainties in the density and mass are ±(0.6-0.9)dex. Both components arise from denser and possibly warmer gas than traced by low-J CO transitions, and the ME component likely makes a significant contribution to the mass budget in the nuclear region. We compare the CO line profiles with those of other molecular tracers observed at higher spatial and spectral resolution and find that the ME transitions are consistent with these lines arising in the200pc diameter ring of material traced by H 2 1-0 S(1) observations. The blueshift of the HE lines may also be consistent with the bluest regions of this H2 ring, but a better kinematic match is found with a clump of infalling gas 40pc north of the active galactic nucleus (AGN). We consider potential heating mechanisms and conclude that X-ray- or shock heating of both components is viable, while far-UV heating is unlikely. We discuss the prospects of placing the HE component near the AGN and conclude that while the moderate thermal pressure precludes an association with the 1pc radius H2O maser disk, the HE component could potentially be located only a few parsecs more distant from the AGN and might then provide the N H 1025cm-2 column obscuring the nuclear hard X-rays. Finally, we also report sensitive upper limits extending up to J upper = 50, which place constraints on a previous model prediction for the CO emission from the X-ray obscuring torus. © 2012 The American Astronomical Society. All rights reserved.The progenitor mass of the Type IIP supernova SN 2004et from late-time spectral modeling
(2012)
Future Science Prospects for AMI
ArXiv 1208.1966 (2012)
Abstract:
The Arcminute Microkelvin Imager (AMI) is a telescope specifically designed for high sensitivity measurements of low-surface-brightness features at cm-wavelength and has unique, important capabilities. It consists of two interferometer arrays operating over 13.5-18 GHz that image structures on scales of 0.5-10 arcmin with very low systematics. The Small Array (AMI-SA; ten 3.7-m antennas) couples very well to Sunyaev-Zel'dovich features from galaxy clusters and to many Galactic features. The Large Array (AMI-LA; eight 13-m antennas) has a collecting area ten times that of the AMI-SA and longer baselines, crucially allowing the removal of the effects of confusing radio point sources from regions of low surface-brightness, extended emission. Moreover AMI provides fast, deep object surveying and allows monitoring of large numbers of objects. In this White Paper we review the new science - both Galactic and extragalactic - already achieved with AMI and outline the prospects for much more.Search for charged Higgs bosons decaying via H± → τν in tt̄ events using pp collision data at √s = 7 TeV with the ATLAS detector
Journal of High Energy Physics 2012:6 (2012)