arXiv subjects

S. Hailey-Dunsheath

Publications and source records attributed to S. Hailey-Dunsheath.

At least 19 recordsLinked to original sources

arXiv2026

Data reduction pipeline for the SuMAC millimeter-wave spectrometer at the LMT

We present the data reduction and analysis pipeline for the SuperSpec-MUSCAT Collaboration (SuMAC) along with several key science data products. In Summer 2025, SuperSpec on-chip spectrometers operating from $190-300$ GHz at $R\sim200$ were deployed in the MUSCAT cryostat at the Large Millimeter Telescope, obtaining several days of on-sky data. Analysis of these data has been used to characterize noise performance and study spectra of various astrophysical sources, establishing the viability of deploying SuperSpec detectors in future instruments. These proceedings discuss the modular data reduction pipeline which uses timestreams of the kinetic inductance detectors (KIDs) and auxiliary instrument data to generate a variety of data products. We present an on-sky calibration method for converting the KID fractional frequency shift to on-sky brightness temperature. The mapmaking module generates 3D data cubes of extended sources, while the spectrum module produces a millimeter-wave spectrum of an object. The observations all incorporate measurements of the atmosphere to model and correct for absorption. We also discuss data processing choices including detector weighting, despiking, and notch filtering. Finally, we present preliminary data products including detection of carbon monoxide in NGC 253 and spectral maps of the central region of the Orion KL nebula.

astro-ph.IM↗

arXiv2022

Design of The Kinetic Inductance Detector Based Focal Plane Assembly for The Terahertz Intensity Mapper

We report on the kinetic inductance detector (KID) array focal plane assembly design for the Terahertz Intensity Mapper (TIM). Each of the 2 arrays consists of 4 wafer-sized dies (quadrants), and the overall assembly must satisfy thermal and mechanical requirements, while maintaining high optical efficiency and a suitable electromagnetic environment for the KIDs. In particular, our design manages to strictly maintain a 50 $\mathrm{\mu m}$ air gap between the array and the horn block. We have prototyped and are now testing a sub-scale assembly which houses a single quadrant for characterization before integration into the full array. The initial test result shows a $>$95% yield, indicating a good performance of our TIM detector packaging design.

astro-ph.IM↗

arXiv2022

Design and testing of Kinetic Inductance Detector package for the Terahertz Intensity Mapper

The Terahertz Intensity Mapper (TIM) is designed to probe the star formation history in dust-obscured star-forming galaxies around the peak of cosmic star formation. This will be done via measurements of the redshifted 157.7 um line of singly ionized carbon ([CII]). TIM employs two R $\sim 250$ long-slit grating spectrometers covering 240-420 um. Each is equipped with a focal plane unit containing 4 wafer-sized subarrays of horn-coupled aluminum kinetic inductance detectors (KIDs). We present the design and performance of a prototype focal plane assembly for one of TIM's KID-based subarrays. Our design strictly maintain high optical efficiency and a suitable electromagnetic environment for the KIDs. The prototype detector housing in combination with the first flight-like quadrant are tested at 250 mK. Initial frequency scan shows that many resonances are affected by collisions and/or very shallow transmission dips as a result of a degraded internal quality factor (Q factor). This is attributed to the presence of an external magnetic field during cooldown. We report on a study of magnetic field dependence of the Q factor of our quadrant array. We implement a Helmholtz coil to vary the magnetic field at the detectors by (partially) nulling earth's. Our investigation shows that the earth magnetic field can significantly affect our KIDs' performance by degrading the Q factor by a factor of 2-5, well below those expected from the operational temperature or optical loading. We find that we can sufficiently recover our detectors' quality factor by tuning the current in the coils to generate a field that matches earth's magnetic field in magnitude to within a few uT. Therefore, it is necessary to employ a properly designed magnetic shield enclosing the TIM focal plane unit. Based on the results presented in this paper, we set a shielding requirement of |B| < 3 uT.

astro-ph.IM↗

arXiv2020

Full-Array Noise Performance of Deployment-Grade SuperSpec mm-wave On-Chip Spectrometers

SuperSpec is an on-chip filter-bank spectrometer designed for wideband moderate-resolution spectroscopy at millimeter wavelengths, employing TiN kinetic inductance detectors. SuperSpec technology will enable large-format spectroscopic integral field units suitable for high-redshift line intensity mapping and multi-object spectrographs. In previous results we have demonstrated noise performance in individual detectors suitable for photon noise limited ground-based observations at excellent mm-wave sites. In these proceedings we present the noise performance of a full $R\sim 275$ spectrometer measured using deployment-ready RF hardware and software. We report typical noise equivalent powers through the full device of $\sim 3 \times 10^{-16} \ \mathrm{W}/\sqrt{\mathrm{Hz}}$ at expected sky loadings, which are photon noise dominated. Based on these results, we plan to deploy a six-spectrometer demonstration instrument to the Large Millimeter Telescope in early 2020.

astro-ph.IM↗

arXiv2018

Development of Aluminum LEKIDs for Balloon-Borne Far-IR Spectroscopy

We are developing lumped-element kinetic inductance detectors (LEKIDs) designed to achieve background-limited sensitivity for far-infrared (FIR) spectroscopy on a stratospheric balloon. The Spectroscopic Terahertz Airborne Receiver for Far-InfraRed Exploration (STARFIRE) will study the evolution of dusty galaxies with observations of the [CII] 158 $μ$m and other atomic fine-structure transitions at $z=0.5-1.5$, both through direct observations of individual luminous infrared galaxies, and in blind surveys using the technique of line intensity mapping. The spectrometer will require large format ($\sim$1800 detectors) arrays of dual-polarization sensitive detectors with NEPs of $1 \times 10^{-17}$ W Hz$^{-1/2}$. The low-volume LEKIDs are fabricated with a single layer of aluminum (20 nm thick) deposited on a crystalline silicon wafer, with resonance frequencies of $100-250$ MHz. The inductor is a single meander with a linewidth of 0.4 $μ$m, patterned in a grid to absorb optical power in both polarizations. The meander is coupled to a circular waveguide, fed by a conical feedhorn. Initial testing of a small array prototype has demonstrated good yield, and a median NEP of $4 \times 10^{-18}$ W Hz$^{-1/2}$.

astro-ph.IM↗

arXiv2017

ISM conditions in z~0.2 Lyman-Break Analogs

We present an analysis of far--infrared (FIR) [CII] and [OI] fine structure line and continuum observations obtained with $Herschel$/PACS, and CO(1-0) observations obtained with the IRAM Plateau de Bure Interferometer, of Lyman Break Analogs (LBAs) at $z\sim 0.2$. The principal aim of this work is to determine the typical ISM properties of $z\sim 1-2$ Main Sequence (MS) galaxies, with stellar masses between $10^{9.5}$ and $10^{11}$ $M_{\odot}$, which are currently not easily detectable in all these lines even with ALMA and NOEMA. We perform PDR modeling and apply different IR diagnostics to derive the main physical parameters of the FIR emitting gas and dust and we compare the derived ISM properties to those of galaxies on and above the MS at different redshifts. We find that the ISM properties of LBAs are quite extreme (low gas temperature, high density and thermal pressure) with respect to those found in local normal spirals and more active local galaxies. LBAs have no [CII] deficit despite having the high specific star formation rates (sSFRs) typical of starbursts. Although LBAs lie above the local MS, we show that their ISM properties are more similar to those of high-redshift MS galaxies than of local galaxies above the main sequence. This data set represents an important reference for planning future ALMA [CII] observations of relatively low-mass MS galaxies at the epoch of the peak of the cosmic star formation.

astro-ph.GA↗

arXiv2017

CO-Dark Star Formation and Black Hole Activity in 3C 368 at z = 1.131: Coeval Growth of Stellar and Supermassive Black Hole Masses

We present the detection of four far-infrared fine-structure oxygen lines, as well as strong upper limits for the CO(2-1) and [N II] 205 um lines, in 3C 368, a well-studied radio-loud galaxy at z = 1.131. These new oxygen lines, taken in conjunction with previously observed neon and carbon fine-structure lines, suggest a powerful active galactic nucleus (AGN), accompanied by vigorous and extended star formation. A starburst dominated by O8 stars, with an age of ~6.5 Myr, provides a good fit to the fine-structure line data. This estimated age of the starburst makes it nearly concurrent with the latest episode of AGN activity, suggesting a link between the growth of the supermassive black hole and stellar population in this source. We do not detect the CO(2-1) line, down to a level twelve times lower than the expected value for star forming galaxies. This lack of CO line emission is consistent with recent star formation activity if the star-forming molecular gas has low metallicity, is highly fractionated (such that CO is photodissociated through much of the clouds), or is chemically very young (such that CO has not yet had time to form). It is also possible, though we argue unlikely, that the ensemble of fine structure lines are emitted from the region heated by the AGN.

astro-ph.GA↗

arXiv2015

Low Noise Titanium Nitride KIDs for SuperSpec: A Millimeter-Wave On-Chip Spectrometer

SuperSpec is a novel on-chip spectrometer we are developing for multi-object, moderate resolution (R = 100 - 500), large bandwidth (~1.65:1) submillimeter and millimeter survey spectroscopy of high-redshift galaxies. The spectrometer employs a filter bank architecture, and consists of a series of half-wave resonators formed by lithographically-patterned superconducting transmission lines. The signal power admitted by each resonator is detected by a lumped element titanium nitride (TiN) kinetic inductance detector (KID) operating at 100 - 200 MHz. We have tested a new prototype device that achieves the targeted R = 100 resolving power, and has better detector sensitivity and optical efficiency than previous devices. We employ a new method for measuring photon noise using both coherent and thermal sources of radiation to cleanly separate the contributions of shot and wave noise. We report an upper limit to the detector NEP of $1.4\times10^{-17}$ W Hz$^{-1/2}$, within 10% of the photon noise limited NEP for a ground-based R=100 spectrometer.

astro-ph.IM↗

arXiv2015

A deep Herschel/PACS observation of CO(40-39) in NGC 1068: a search for the molecular torus

Emission from high-J CO lines in galaxies has long been proposed as a tracer of X-ray dominated regions (XDRs) produced by AGN. Of particular interest is the question of whether the obscuring torus, which is required by AGN unification models, can be observed via high-J CO cooling lines. Here we report on the analysis of a deep Herschel-PACS observation of an extremely high J CO transition (40-39) in the Seyfert 2 galaxy NGC 1068. The line was not detected, with a derived 3$σ$ upper limit of $2 \times 10^{-17}\,\text{W}\,\text{m}^{-2}$. We apply an XDR model in order to investigate whether the upper limit constrains the properties of a molecular torus in NGC 1068. The XDR model predicts the CO Spectral Line Energy Distributions for various gas densities and illuminating X-ray fluxes. In our model, the CO(40-39) upper limit is matched by gas with densities $\sim 10^{6}-10^{7}\,\text{cm}^{-3}$, located at $1.6-5\,\text{pc}$ from the AGN, with column densities of at least $10^{25}\,\text{cm}^{-2}$. At such high column densities, however, dust absorbs most of the CO(40-39) line emission at $λ= 65.69\, μ$m. Therefore, even if NGC 1068 has a molecular torus which radiates in the CO(40-39) line, the dust can attenuate the line emission to below the PACS detection limit. The upper limit is thus consistent with the existence of a molecular torus in NGC 1068. In general, we expect that the CO(40-39) is observable in only a few AGN nuclei (if at all), because of the required high gas column density, and absorption by dust.

astro-ph.GA↗

arXiv2015

High-J CO SLEDs in nearby infrared bright galaxies observed by Herschel-PACS

We report the detection of far-infrared (FIR) CO rotational emission from nearby active galactic nuclei (AGN) and starburst galaxies, as well as several merging systems and Ultra-Luminous Infrared Galaxies (ULIRGs). Using Herschel-PACS, we have detected transitions in the J$_{upp}$ = 14 - 20 range ($λ\sim$ 130 - 185 $μ$m, $ν\sim$ 1612 - 2300 GHz) with upper limits on (and in two cases, detections of) CO line fluxes up to J$_{upp}$ = 30. The PACS CO data obtained here provide the first well-sampled FIR extragalactic CO SLEDs for this range, and will be an essential reference for future high redshift studies. We find a large range in the overall SLED shape, even amongst galaxies of similar type, demonstrating the uncertainties in relying solely on high-J CO diagnostics to characterize the excitation source of a galaxy. Combining our data with low-J line intensities taken from the literature, we present a CO ratio-ratio diagram and discuss its potential diagnostic value in distinguishing excitation sources and physical properties of the molecular gas. The position of a galaxy on such a diagram is less a signature of its excitation mechanism, than an indicator of the presence (or absence) of warm, dense molecular gas. We then quantitatively analyze the CO emission from a subset of the detected sources with Large Velocity Gradient (LVG) radiative transfer models to fit the CO SLEDs. Using both single-component and two-component LVG models to fit the kinetic temperature, velocity gradient, number density and column density of the gas, we derive the molecular gas mass and the corresponding CO-to-H$_2$ conversion factor, $α_{CO}$, for each respective source. For the ULIRGs we find $α$ values in the canonical range 0.4 - 5 M$_\odot$/(K kms$^{-1}$pc$^2$), while for the other objects, $α$ varies between 0.2 and 14.} Finally, we compare our best-fit LVG model ..

astro-ph.GA↗

arXiv2015

Status of SuperSpec: A Broadband, On-Chip Millimeter-Wave Spectrometer

SuperSpec is a novel on-chip spectrometer we are developing for multi-object, moderate resolution (R = 100 - 500), large bandwidth (~1.65:1) submillimeter and millimeter survey spectroscopy of high-redshift galaxies. The spectrometer employs a filter bank architecture, and consists of a series of half-wave resonators formed by lithographically-patterned superconducting transmission lines. The signal power admitted by each resonator is detected by a lumped element titanium nitride (TiN) kinetic inductance detector (KID) operating at 100-200 MHz. We have tested a new prototype device that is more sensitive than previous devices, and easier to fabricate. We present a characterization of a representative R=282 channel at f = 236 GHz, including measurements of the spectrometer detection efficiency, the detector responsivity over a large range of optical loading, and the full system optical efficiency. We outline future improvements to the current system that we expect will enable construction of a photon-noise-limited R=100 filter bank, appropriate for a line intensity mapping experiment targeting the [CII] 158 micron transition during the Epoch of Reionization

astro-ph.IM↗

arXiv2014

High-lying OH absorption, [C II] deficits, and extreme $L_{\mathrm{FIR}}/M_{\mathrm{H2}}$ ratios in galaxies

Herschel/PACS observations of 29 local (Ultra-)Luminous Infrared Galaxies, including both starburst and AGN-dominated sources as diagnosed in the mid-infrared/optical, show that the equivalent width of the absorbing OH 65 um Pi_{3/2} J=9/2-7/2 line (W_{eq}(OH65)) with lower level energy E_{low}~300 K, is anticorrelated with the [C ii]158 um line to far-infrared luminosity ratio, and correlated with the far-infrared luminosity per unit gas mass and with the 60-to-100 um far-infrared color. While all sources are in the active L_{IR}/M_{H2}>50 Lsun/Msun mode as derived from previous CO line studies, the OH65 absorption shows a bimodal distribution with a discontinuity at L_{FIR}/M_{H2}~100 Lsun/Msun. In the most buried sources, OH65 probes material partially responsible for the silicate 9.7 um absorption. Combined with observations of the OH 71 um Pi_{1/2} J=7/2-5/2 doublet (E_{low}~415 K), radiative transfer models characterized by the equivalent dust temperature, Tdust, and the continuum optical depth at 100 um, tau_{100}, indicate that strong [C ii]158 um deficits are associated with far-IR thick (tau_{100}>~0.7, N_{H}>~10^{24} cm^{-2}), warm (Tdust>~60 K) structures where the OH 65 um absorption is produced, most likely in circumnuclear disks/tori/cocoons. With their high L_{FIR}/M_{H2} ratios and columns, the presence of these structures is expected to give rise to strong [C ii] deficits. W_{eq}(OH65) probes the fraction of infrared luminosity arising from these compact/warm environments, which is >~30-50% in sources with high W_{eq}({OH65}). Sources with high W_{eq}({OH65}) have surface densities of both L_{IR} and M_{H2} higher than inferred from the half-light (CO or UV/optical) radius, tracing coherent structures that represent the most buried/active stage of (circum)nuclear starburst-AGN co-evolution.

astro-ph.GA↗

arXiv2014

Chemically Distinct Nuclei and Outflowing Shocked Molecular Gas in Arp 220

We present the results of interferometric spectral line observations of Arp 220 at 3.5mm and 1.2mm from the Plateau de Bure Interferometer (PdBI), imaging the two nuclear disks in H$^{13}$CN$(1 - 0)$ and $(3 - 2)$, H$^{13}$CO$^+(1 - 0)$ and $(3 - 2)$, and HN$^{13}$C$(3 - 2)$ as well as SiO$(2 - 1)$ and $(6 - 5)$, HC$^{15}$N$(3 - 2)$, and SO$(6_6 - 5_5)$. The gas traced by SiO$(6 - 5)$ has a complex and extended kinematic signature including a prominent P Cygni profile, almost identical to previous observations of HCO$^+(3 - 2)$. Spatial offsets $0.1''$ north and south of the continuum centre in the emission and absorption of the SiO$(6 - 5)$ P Cygni profile in the western nucleus (WN) imply a bipolar outflow, delineating the northern and southern edges of its disk and suggesting a disk radius of $\sim40$ pc, consistent with that found by ALMA observations of Arp 220. We address the blending of SiO$(6 - 5)$ and H$^{13}$CO$^+(3 - 2)$ by considering two limiting cases with regards to the H$^{13}$CO$^+$ emission throughout our analysis. Large velocity gradient (LVG) modelling is used to constrain the physical conditions of the gas and to infer abundance ratios in the two nuclei. Our most conservative lower limit on the [H$^{13}$CN]/[H$^{13}$CO$^+$] abundance ratio is 11 in the WN, cf. 0.10 in the eastern nucleus (EN). Comparing these ratios to the literature we argue on chemical grounds for an energetically significant AGN in the WN driving either X-ray or shock chemistry, and a dominant starburst in the EN.

astro-ph.GA↗

arXiv2013

Massive Molecular Outflows and Evidence for AGN Feedback from CO Observations

We study the properties of massive, galactic-scale outflows of molecular gas and investigate their impact on galaxy evolution. We present new IRAM PdBI CO(1-0) observations of local ULIRGs and QSO hosts: clear signature of massive and energetic molecular outflows, extending on kpc scales, is found in the CO(1-0) kinematics of four out of seven sources, with measured outflow rates of several 100 Msun/yr. We combine these new observations with data from the literature, and explore the nature and origin of massive molecular outflows within an extended sample of 19 local galaxies. We find that starburst-dominated galaxies have an outflow rate comparable to their SFR, or even higher by a factor of ~ 2-4, implying that starbursts can indeed be effective in removing cold gas from galaxies. Nevertheless, our results suggest that the presence of an AGN can boost the outflow rate by a large factor, which is found to increase with the L_AGN/L_bol ratio. The gas depletion time-scales due to molecular outflows are anti-correlated with the presence and luminosity of an AGN in these galaxies, and range from a few hundred million years in starburst galaxies, down to just a few million years in galaxies hosting powerful AGNs. In quasar hosts the depletion time-scales due to the outflow are much shorter than the depletion time-scales due to star formation. We estimate the outflow kinetic power and find that, for galaxies hosting powerful AGNs, it corresponds to about 5% of the AGN luminosity, as expected by models of AGN feedback. Moreover, we find that momentum rates of about 20 L_AGN/c are common among the AGN-dominated sources in our sample. For "pure" starburst galaxies our data tentatively support models in which outflows are mostly momentum-driven by the radiation pressure from young stars onto dusty clouds.

astro-ph.CO↗

arXiv2013

Fast Molecular Outflows in Luminous Galaxy Mergers: Evidence for Quasar Feedback from Herschel

We report the results from a systematic search for molecular (OH-119 um) outflows with Herschel-PACS in a sample of 43 nearby (z < 0.3) galaxy mergers, mostly ultraluminous infrared galaxies (ULIRGs) and QSOs. We find that the character of the OH feature (strength of the absorption relative to the emission) correlates with that of the 9.7-um silicate feature, a measure of obscuration in ULIRGs. Unambiguous evidence for molecular outflows, based on the detection of OH absorption profiles with median velocities more blueshifted than -50 km/sec, is seen in 26 (70%) of the 37 OH-detected targets, suggesting a wide-angle (~145 degrees) outflow geometry. Conversely, unambiguous evidence for molecular inflows, based on the detection of OH absorption profiles with median velocities more redshifted than +50 km/sec, is seen in only 4 objects, suggesting a planar or filamentary geometry for the inflowing gas. Terminal outflow velocities of ~-1000 km/sec are measured in several objects, but median outflow velocities are typically ~-200 km s^{-1}. While the outflow velocities show no statistically significant dependence on the star formation rate, they are distinctly more blueshifted among systems with large AGN fractions and luminosities [log (L_AGN / L_sun) > 11.8 +/- 0.3]. The quasars in these systems play a dominant role in driving the molecular outflows. In contrast, the most AGN dominated systems, where OH is seen purely in emission, show relatively modest OH line widths, despite their large AGN luminosities, perhaps indicating that molecular outflows subside once the quasar has cleared a path through the obscuring material.

astro-ph.CO↗

arXiv2012

Excited OH+, H2O+, and H3O+ in NGC 4418 and Arp 220

We report on Herschel/PACS observations of absorption lines of OH+, H2O+ and H3O+ in NGC 4418 and Arp 220. Excited lines of OH+ and H2O+ with E_lower of at least 285 and \sim200 K, respectively, are detected in both sources, indicating radiative pumping and location in the high radiation density environment of the nuclear regions. Abundance ratios OH+/H2O+ of 1-2.5 are estimated in the nuclei of both sources. The inferred OH+ column and abundance relative to H nuclei are (0.5-1)x10^{16} cm-2 and \sim2x10^{-8}, respectively. Additionally, in Arp 220, an extended low excitation component around the nuclear region is found to have OH+/H2O+\sim5-10. H3O+ is detected in both sources with N(H3O+)\sim(0.5-2)x10^{16} cm-2, and in Arp 220 the pure inversion, metastable lines indicate a high rotational temperature of ~500 K, indicative of formation pumping and/or hot gas. Simple chemical models favor an ionization sequence dominated by H+ - O+ - OH+ - H2O+ - H3O+, and we also argue that the H+ production is most likely dominated by X-ray/cosmic ray ionization. The full set of observations and models leads us to propose that the molecular ions arise in a relatively low density (\gtrsim10^4 cm-3) interclump medium, in which case the ionization rate per H nucleus (including secondary ionizations) is zeta>10^{-13} s-1, a lower limit that is severalx10^2 times the highest rate estimates for Galactic regions. In Arp 220, our lower limit for zeta is compatible with estimates for the cosmic ray energy density inferred previously from the supernova rate and synchrotron radio emission, and also with the expected ionization rate produced by X-rays. In NGC 4418, we argue that X-ray ionization due to an AGN is responsible for the molecular ion production.

astro-ph.GA↗

arXiv2012

Spectroscopic FIR mapping of the disk and galactic wind of M82 with Herschel-PACS

[Abridged] We present maps of the main cooling lines of the neutral atomic gas ([OI] at 63 and 145 micron and [CII] at 158 micron) and in the [OIII] 88 micron line of the starburst galaxy M82, carried out with the PACS spectrometer on board the Herschel satellite. By applying PDR modeling we derive maps of the main ISM physical parameters, including the [CII] optical depth, at unprecedented spatial resolution (~300 pc). We can clearly kinematically separate the disk from the outflow in all lines. The [CII] and [OI] distributions are consistent with PDR emission both in the disk and in the outflow. Surprisingly, in the outflow, the atomic and the ionized gas traced by the [OIII] line both have a deprojected velocity of ~75 km/s, very similar to the average velocity of the outflowing cold molecular gas (~ 100 km/s) and several times smaller than the outflowing material detected in Halpha (~ 600 km/s). This suggests that the cold molecular and neutral atomic gas and the ionized gas traced by the [OIII] 88 micron line are dynamically coupled to each other but decoupled from the Halpha emitting gas. We propose a scenario where cold clouds from the disk are entrained into the outflow by the winds where they likely evaporate, surviving as small, fairly dense cloudlets (n_H\sim 500-1000 cm^-3, G_0\sim 500- 1000, T_gas\sim300 K). We show that the UV photons provided by the starburst are sufficient to excite the PDR shells around the molecular cores. The mass of the neutral atomic gas in the outflow is \gtrsim 5-12x 10^7 M_sun to be compared with that of the molecular gas (3.3 x 10^8 M_sun) and of the Halpha emitting gas (5.8 x 10^6 M_sun). The mass loading factor, (dM/dt)/SFR, of the molecular plus neutral atomic gas in the outflow is ~ 2. Energy and momentum driven outflow models can explain the data equally well, if all the outflowing gas components are taken into account.

astro-ph.GA↗

arXiv2012

Herschel-PACS Observations of Far-IR CO Line Emission in NGC 1068: Highly Excited Molecular Gas in the Circumnuclear Disk

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/k_B = 580-2565 K) range, all of which are consistent with arising from within the central 10" (700 pc). The detected transitions are modeled as arising from 2 different components: a moderate excitation (ME) component close to the galaxy systemic velocity, and a high excitation (HE) component that is blueshifted by ~80 km s^{-1}. We employ a large velocity gradient (LVG) model and derive n_H2~10^{5.6} cm^{-3}, T_kin~170 K, and M_H2~10^{6.7} M_sun for the ME component, and n_H2~10^{6.4} cm^{-3}, T_kin~570 K, and M_H2~10^{5.6} M_sun for the HE component, although for both components the uncertainties in the density and mass are plus/minus (0.6-0.9) dex. 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 the ~200 pc 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 H_2 ring, but a better kinematic match is found with a clump of infalling gas ~40 pc north of the AGN. 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 ~1 pc radius H_2O 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~10^{25} cm^{-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. [Abridged]

astro-ph.GA↗