Submillimetre line spectrum of the Seyfert galaxy NGC1068 from the Herschel-SPIRE Fourier Transform Spectrometer

The first complete submillimetre spectrum (190-670um) of the Seyfert 2 galaxy NGC1068 has been observed with the SPIRE Fourier Transform Spectrometer onboard the {\it Herschel} Space Observatory. The sequence of CO lines (Jup=4-13), lines from water, the fundamental rotational transition of HF, two o-H_2O+ lines and one line each from CH+ and OH+ have been detected, together with the two [CI] lines and the [NII]205um line. The observations in both single pointing mode with sparse image sampling and in mapping mode with full image sampling allow us to disentangle two molecular emission components, one due to the compact circum-nuclear disk (CND) and one from the extended region encompassing the star forming ring (SF-ring). Radiative transfer models show that the two CO components are characterized by density of n(H_2)=10^4.5 and 10^2.9 cm^-3 and temperature of T=100K and 127K, respectively. The comparison of the CO line intensities with photodissociation region (PDR) and X-ray dominated region (XDR) models, together with other observational constraints, such as the observed CO surface brightness and the radiation field, indicate that the best explanation for the CO excitation of the CND is an XDR with density of n(H_2) 10^4 cm^-3 and X-ray flux of 9 erg s^-1 cm^-2, consistent with illumination by the active galactic nucleus, while the CO lines in the SF-ring are better modeled by a PDR. The detected water transitions, together with those observed with the \her \sim PACS Spectrometer, can be modeled by an LVG model with low temperature (T_kin \sim 40K) and high density (n(H_2) in the range 10^6.7-10^7.9 cm^-3).Comment: Accepted for publication on the Astrophysical Journal, 30 August 201

Herschel SPIRE-FTS Observations of Excited CO and [CI] in the Antennae (NGC 4038/39): Warm and Cold Molecular Gas

We present Herschel SPIRE-FTS observations of the Antennae (NGC 4038/39), a well studied, nearby ($22$ Mpc) ongoing merger between two gas rich spiral galaxies. We detect 5 CO transitions ($J=4-3$ to $J=8-7$), both [CI] transitions and the [NII]$205\mu m$ transition across the entire system, which we supplement with ground based observations of the CO $J=1-0$, $J=2-1$ and $J=3-2$ transitions, and Herschel PACS observations of [CII] and [OI]$63\mu m$. Using the CO and [CI] transitions, we perform both a LTE analysis of [CI], and a non-LTE radiative transfer analysis of CO and [CI] using the radiative transfer code RADEX along with a Bayesian likelihood analysis. We find that there are two components to the molecular gas: a cold ($T_{kin}\sim 10-30$ K) and a warm ($T_{kin} \gtrsim 100$ K) component. By comparing the warm gas mass to previously observed values, we determine a CO abundance in the warm gas of $x_{CO} \sim 5\times 10^{-5}$. If the CO abundance is the same in the warm and cold gas phases, this abundance corresponds to a CO $J=1-0$ luminosity-to-mass conversion factor of $\alpha_{CO} \sim 7 \ M_{\odot}{pc^{-2} \ (K \ km \ s^{-1})^{-1}}$in the cold component, similar to the value for normal spiral galaxies. We estimate the cooling from H$_2$, [CII], CO and [OI]$63\mu m$to be$\sim 0.01 L_{\odot}/M_{\odot}$. We compare PDR models to the ratio of the flux of various CO transitions, along with the ratio of the CO flux to the far-infrared flux in NGC 4038, NGC 4039 and the overlap region. We find that the densities recovered from our non-LTE analysis are consistent with a background far-ultraviolet field of strength$G_0\sim 1000$. Finally, we find that a combination of turbulent heating, due to the ongoing merger, and supernova and stellar winds are sufficient to heat the molecular gas.Comment: 50 pages, 15 figures, 8 tables, Accepted for publication in The Astrophysical Journa

Spectral and morphological analysis of the remnant of Supernova 1987A with ALMA & ATCA

We present a comprehensive spectral and morphological analysis of the remnant of Supernova (SN) 1987A with the Australia Telescope Compact Array (ATCA) and the Atacama Large Millimeter/submillimeter Array (ALMA). The non-thermal and thermal components of the radio emission are investigated in images from 94 to 672 GHz ($\lambda$ 3.2 mm to 450 $\mu$m), with the assistance of a high-resolution 44 GHz synchrotron template from the ATCA, and a dust template from ALMA observations at 672 GHz. An analysis of the emission distribution over the equatorial ring in images from 44 to 345 GHz highlights a gradual decrease of the east-to-west asymmetry ratio with frequency. We attribute this to the shorter synchrotron lifetime at high frequencies. Across the transition from radio to far infrared, both the synchrotron/dust-subtracted images and the spectral energy distribution (SED) suggest additional emission beside the main synchrotron component ($S_{\nu}\propto\nu^{-0.73}$) and the thermal component originating from dust grains at $T\sim22$ K. This excess could be due to free-free flux or emission from grains of colder dust. However, a second flat-spectrum synchrotron component appears to better fit the SED, implying that the emission could be attributed to a pulsar wind nebula (PWN). The residual emission is mainly localised west of the SN site, as the spectral analysis yields $-0.4\lesssim\alpha\lesssim-0.1$ across the western regions, with $\alpha\sim0$ around the central region. If there is a PWN in the remnant interior, these data suggest that the pulsar may be offset westward from the SN position.Comment: ApJ accepted. 21 pages, emulateapj. References update