arXiv subjects

Enrique Lopez-Rodriguez

Publications and source records attributed to Enrique Lopez-Rodriguez.

At least 37 records · Page 2Linked to original sources

arXiv2025

PRIMA Vista: far-infrared polarimetry to unveil small-scale magnetohydrodynamics in extragalactic observations

Magnetic fields are a fundamental part of the interstellar medium (ISM) and remain a challenge for building a comprehensive understanding of galactic properties. Their study requires far-infrared polarimetric observations, which provide an unrivaled probe of the dynamics, magnetization, and structure of the coldest and densest interstellar gas and dust at small scales in galaxies, where mass and star formation reside. We use high-resolution magnetohydrodynamical simulations of a face-on Milky Way-like galaxy and show that the alignment of magnetic fields with ISM structures and the turbulence at 100 pc scales decrease with increasing magnetization. We make predictions for extragalactic observations by the proposed PRobefarInfrared Mission for Astrophysics (PRIMA) telescope, comparing them with Stratospheric Observatory For Infrared Astronomy (SOFIA) observations similar to those of the Survey of extragALactic magnetiSm with SOFIA (SALSA). PRIMA will be able to better measure magnetic alignment trends inaccessible by SOFIA. We find that PRIMA will better sample magnetic turbulence, especially in dense environments, and will be able to measure the unresolved intrinsic magnetic field orientations to approximately 6 deg precision. PRIMA will also be capable of resolving observables such as the polarized fraction or the magnetic alignment down to scales comparable to the resolution of our simulations (about 10 pc) for galaxies up to 0.5 Mpc away. The polarization-dispersion relation shows that PRIMA observations will suffer from significantly reduced beam depolarization. Furthermore, PRIMA will recover the correlation between increasing the magnetic alignment parameter and local polarization fraction. Overall, observations of local galaxies with PRIMA will better characterize interstellar magnetism and constrain ISM and galaxy models, advancing our understanding of magnetism in the universe.

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arXiv2025

Mapping Magnetic Fields from Clouds to Cores with PRIMAger

High-resolution, wide-area mapping of magnetic field geometries within molecular clouds, and the star-forming filaments and cores within them, is crucial in order to understand the role of magnetic fields in the star formation process. We therefore propose an unbiased survey of star-forming molecular clouds within 0.5 kpc of the Earth in polarized light with the PRIMAger Polarimetry Imager. We will map magnetic fields over entire molecular clouds at linear resolutions of $\sim10^{-3}-10^{-2}$ pc ($\sim10^{3}-10^{4}$ au) in PRIMAger Bands PPI1 - PPI4, thereby resolving magnetic field structure both within individual star-forming filaments and cores, and in the most diffuse regions of molecular clouds. These multi-wavelength polarimetric observations will allow us to systematically investigate both the wide range of open questions about the role of magnetic fields in star formation and the evolution of the interstellar medium, and interstellar dust grain properties. The time required to map the area observed by the \textit{Herschel} Gould Belt Survey (160 deg$^{2}$) to the cirrus confusion limit in polarized light is 170 hours. This will give a 5-$σ$ detection of 20% polarized low-density cirrus emission, with surface brightnesses in polarized intensity of 1.0-2.4\,MJy/sr across the PRIMAger bands, and will ensure detection of polarized emission at all higher column densities. This time estimate can be simply scaled up in order to map magnetic fields in a larger sample of molecular clouds, including more distant regions of higher-mass star formation.

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arXiv2025

JWST interferometric imaging reveals the dusty disk obscuring the supermassive black hole of the Circinus galaxy

The dusty and molecular torus is one of the most elusive structures surrounding supermassive black holes, yet its importance is unequivocal for understanding feedback and accretion mechanisms. The torus and accretion disk feed the inspiraling gas onto the supermassive black hole (SMBH) and launch outflows, fundamentally connecting the SMBH activity to the host galaxy. This scenario situates the torus as the interface between the AGN and its host galaxy with a flow cycle of molecular gas and dust of a few parsecs in size. Here, we utilize a novel aperture-masking interferometric mode onboard the JWST, achieving twice the previously possible resolution, and bringing out the fainter features that clearly show the torus being the critical interface for feeding material from galaxy scales into the SMBH. We also identify that $<1$% of the emission arises from an arc structure composed of hot dust entrained in a molecular and ionized outflow. The rest of the emission, $12$%, is associated with dust heated by the AGN and/or radio-jet at large scales. Combined with continuum data, gas tracers, and torus models, our study shows that most of the dust mass is located in the equatorial axis in the form of a disk feeding the AGN.

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arXiv2025

The fallibility of equipartition magnetic field strengths from synchrotron emission using synthetically observed galaxies

Understanding the role that magnetic fields play on the stage of galaxy formation requires accurate methods for inferring the properties of extragalactic magnetic fields. Radio synchrotron emission has been the most promising avenue to infer magnetic field strengths across galaxies, with the application of a central assumption: that galactic cosmic rays are in energy equipartition with the magnetic field. In this work, we leverage flexible synthetic observations of a high-resolution magnetohydrodynamic simulation of a Milky Way-like galaxy to review whether true equipartition is capable of reproducing radio observations of galaxies, and investigate its impact on the inference of magnetic field strengths when varying the properties and density distribution of the cosmic rays. We find that imposing equipartition (regardless of scale length) results in cosmic ray electron densities that are unable to generate either the amplitude or the shape of the radio intensity profiles typically observed in spiral galaxies. Instead, observationally motivated smooth distributions of cosmic ray electrons across the galaxy provide a remarkable match to observations. We further demonstrate that assuming equipartition with those mock observations can lead to significant overestimation of the magnetic field strength. This misestimation varies with cosmic ray electron densities, cosmic ray spectrum power-law index, and galactic environment, aggravated in inter-arm regions and attenuated in star-forming regions. Our results promote caution when assuming equipartition in observations, and suggest that additional theoretical and numerical work is required to leverage the upcoming generation of radio observations poised to revolutionize our understanding of astrophysical magnetic fields.

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arXiv2024

The Galaxy Activity, Torus, and Outflow Survey (GATOS). VII. The 20-214 $μ$m imaging atlas of active galactic nuclei using SOFIA

We present a 19.7 - 214 $μ$m imaging atlas of local (4 - 181 Mpc; median 43 Mpc) active galactic nuclei (AGN) observed with FORCAST and HAWC+ on board the SOFIA telescope with angular resolutions ~ 3"- 20". This atlas comprises 22 Seyferts (17 Type 2 and 5 Type 1) with a total of 69 images, 41 of which have not been previously published. The AGN span a range of luminosities of log$_{10}$ ($L_{bol}$ [erg/s]) = [42, 46] with a median of log$_{10}$ ($L_{bol}$ [erg/s]) = 44.1 $\pm$ 1.0. We provide total fluxes of our sample using aperture photometry for point source objects and a 2-D Gaussian fitting for objects with extended host galaxy emission, which was used to estimate the unresolved nuclear component. Most galaxies in our sample are point-like sources, however, four sources (Centaurus A, Circinus, NGC 1068, and NGC 4388) show extended emission in all wavelengths. The 30 - 40 $μ$m extended emission in NGC 4388 is coincident with the narrow line region at PA ~ 50$^{\circ}$, while the dusty extension at longer wavelengths arises from the host galaxy at PA ~ 90$^{\circ}$. Our new observations allow us to construct the best sampled spectral energy distributions (SEDs) available between 30 - 500 $μ$m for a sample of nearby AGN. We estimate that the average peak wavelength of the nuclear SEDs is ~ 40 $μ$m in $ν$F$_ν$ , which we associate with an unresolved extended dusty region heated by the AGN.

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arXiv2024

A kiloparsec-scale ordered magnetic field in a galaxy at z=5.6

Magnetic fields are widely observed in various astronomical contexts, yet much remains unknown about their significance across different systems and cosmic epochs. Our current knowledge of the evolution of magnetic fields is limited by scarce observations in the distant Universe, where galaxies have recently been found to be more evolved than most model predictions. To address this gap, we conducted rest-frame 131 um full-polarisation observations of dust emission in a strongly lensed dusty star-forming galaxy, SPT0346-52, at z=5.6, when the Universe was only 1 Gyr old. Dust grains can become aligned with local magnetic fields, resulting in the emission of linearly polarised thermal infrared radiation. Our observations have revealed a median polarisation level of $0.9\pm0.2$ percent with a variation of $\pm0.4$ percent across the 3 kpc extention, indicating the presence of large-scale ordered magnetic fields. The polarised dust emission is patchy, offset from the total dust emission and mostly overlaps with the [C II] emission at a velocity of about -150 km/s. The bimodal distribution of field orientations, their spatial distribution, and the connection with the cold gas kinematics further emphasise the complexity of the magnetic environment in this galaxy and the potential role of mergers in shaping its magnetic fields. Such early formation of ordered galactic magnetic fields also suggests that both small-scale and large-scale dynamos could be efficient in early galaxies. Continued observations of magnetic fields in early galaxies, as well as expanding surveys to a wider galaxy population, are essential for a comprehensive understanding of the prevalence and impact of magnetic fields in the evolving Universe.

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arXiv2024

Thirty Meter Telescope International Observatory Detailed Science Case 2024

The Thirty Meter Telescope (TMT) International Observatory (TIO) will be a revolutionary leap forward in astronomical observing capabilities, enabling us to address some of the most profound questions about the universe. From unraveling the mysteries of dark matter and dark energy to exploring the origins of stars and planets, TMT will transform our understanding of the cosmos. The TIO Detailed Science Case (DSC) presents science goals that inform the top-level requirements for the observatory's design and operations, including the telescope, enclosure, instruments, and adaptive optics system.

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arXiv2024

Confusion of extragalactic sources in the far infrared: a baseline assessment of the performance of PRIMAger in intensity and polarization

Because of their limited angular resolution, far-infrared telescopes are usually affected by confusion phenomenon. Since several galaxies can be located in the same instrumental beam, only the brightest objects emerge from the fluctuations caused by fainter sources. The probe far-infrared mission for astrophysics imager (PRIMAger) will observe the mid- and far-infrared (25-235 $μ$m) sky both in intensity and polarization. We aim to provide predictions of the confusion level and its consequences for future surveys. We produced simulated PRIMAger maps affected only by the confusion noise using the simulated infrared extragalactic sky (SIDES) semi-empirical simulation. We then estimated the confusion limit in these maps and extracted the sources using a basic blind extractor. By comparing the input galaxy catalog and the extracted source catalog, we derived various performance metrics as completeness, purity, and the accuracy of various measurements. In intensity, we predict that the confusion limit increases rapidly with increasing wavelength. The confusion limit in polarization is more than 100x lower. The measured flux density is dominated by the brightest galaxy in the beam, but other objects also contribute at longer wavelength (~30% at 235 $μ$m). We also show that galaxy clustering has a mild impact on confusion in intensity (up to 25%), while it is negligible in polarization. In intensity, a basic blind extraction will be sufficient to detect galaxies at the knee of the luminosity function up to z~3 and 10$^{11}$ M$_\odot$ main-sequence galaxies up to z~5. In polarization for a conservative sensitivity, we expect ~8 000 detections up to z=2.5 opening a totally new window on the high-z dust polarization. Finally, we show that intensity surveys at short wavelength and polarization surveys at long wavelength tend to reach confusion at similar depth. There is thus a strong synergy.

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arXiv2024

Forgotten treasures in the HST/FOC UV imaging polarimetric archives of active galactic nuclei. II. Mrk 463E

The Mrk 463 system is known to host two powerful sources separated by about 4 kpc, both identified as active galactic nuclei (AGN). This makes the Mrk 463 system a unique laboratory to study the geometry and dynamics of galaxy merging and its relation to AGN duty cycles. The eastern nuclei, Mrk 463E, is the brightest of the two and thus a prime target for a polarimetric study. It is classified as a Seyfert 2 galaxy, meaning that one could expect large polarization degrees from scattering off electrons and dust in the polar winds. In the continuity of our series of papers, we reduced archived and previously unpublished polarization observations obtained with the Faint Object Camera (FOC) onboard the Hubble Space Telescope (HST), to obtain a high resolution near ultraviolet (near-UV) polarization map of the Mrk 463E nuclei. We coupled this map to near infrared (NIR) and X-ray observations to get a clear picture of the geometric arrangement of matter around the core of Mrk 463E. We found that the nucleus location is further South from the optical peak flux than previously estimated. The strongly polarized conical wind has a half-opening angle of ~15° and display three main periods of mass ejection. Its polarization allowed us to estimate the AGN inclination towards the observer (~55°) Finally, our maps revealed a streamer connecting Mrk 463E and Mrk 463W, with a tentative detection of a large kpc-scale ordered magnetic field connecting both galaxies. This unpublished observation turned out to offer more than the original proposal asked for and allowed to derive tight geometric and dynamical constraints for Mrk 463E. High resolution radio maps and IR polarimetry are now necessary to further study the jet and the newly discovered streamer.

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arXiv2024

AtLAST Science Overview Report

Submillimeter and millimeter wavelengths provide a unique view of the Universe, from the gas and dust that fills and surrounds galaxies to the chromosphere of our own Sun. Current single-dish facilities have presented a tantalising view of the brightest (sub-)mm sources, and interferometers have provided the exquisite resolution necessary to analyse the details in small fields, but there are still many open questions that cannot be answered with current facilities. In this report we summarise the science that is guiding the design of the Atacama Large Aperture Submillimeter Telescope (AtLAST). We demonstrate how tranformational advances in topics including star formation in high redshift galaxies, the diffuse circumgalactic medium, Galactic ecology, cometary compositions and solar flares motivate the need for a 50m, single-dish telescope with a 1-2 degree field of view and a new generation of highly multiplexed continuum and spectral cameras. AtLAST will have the resolution to drastically lower the confusion limit compared to current single-dish facilities, whilst also being able to rapidly map large areas of the sky and detect extended, diffuse structures. Its high sensitivity and large field of view will open up the field of submillimeter transient science by increasing the probability of serendipitous detections. Finally, the science cases listed here motivate the need for a highly flexible operations model capable of short observations of individual targets, large surveys, monitoring programmes, target of opportunity observations and coordinated observations with other observatories. AtLAST aims to be a sustainable, upgradeable, multipurpose facility that will deliver orders of magnitude increases in sensitivity and mapping speeds over current and planned submillimeter observatories.

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arXiv2024

SAUNAS II: Discovery of Cross-shaped X-ray Emission and a Rotating Circumnuclear Disk in the Supermassive S0 Galaxy NGC 5084

Combining Chandra, ALMA, EVLA, and Hubble Space Telescope archival data and newly acquired APO/DIS spectroscopy, we detect a double-lobed 17~kpc X-ray emission with plumes oriented approximately perpendicular and parallel to the galactic plane of the massive lenticular galaxy NGC\,5084 at 0.3--2.0~keV. We detect a highly inclined ($i=71.2^{+1.8\circ}_{-1.7}$), molecular circumnuclear disk ($D=304^{+10}_{-11}$ pc) in the core of the galaxy rotating (V$^{\rm (2-1) CO}_{\rm rot}=242.7^{+9.6}_{-6.4}$ km s$^{-1}$) in a direction perpendicular to that of the galactic disk, implying a total mass of $\log_{10}\left( \frac{M_{\rm BH}}{M_{\odot}} \right) = 7.66^{+0.21}_{-0.15}$ for NGC\,5084's supermassive black hole. Archival EVLA radio observations at 6 cm and 20 cm reveal two symmetric radio lobes aligned with the galactic plane, extending to a distance of $\overline{R}=4.6\pm0.6$ kpc from the core, oriented with the polar axis of the circumnuclear disk. The spectral energy distribution lacks strong emission lines in the optical range. Three formation scenarios are considered to explain these multi-wavelength archival observations: 1) AGN re-orientation caused by accretion of surrounding material, 2) AGN-driven hot gas outflow directed along the galactic minor axis, or 3) a starburst / supernovae driven outflow at the core of the galaxy. This discovery is enabled by new imaging analysis tools including \SAUNAS\ (Selective Amplification of Ultra Noisy Astronomical Signal), demonstrating the abundance of information still to be exploited in the vast and growing astronomical archives.

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arXiv2024

Dust beyond the torus: Revealing the mid-infrared heart of local Seyfert ESO 428-G14 with JWST/MIRI

Polar dust has been discovered in a number of local Active Galactic Nuclei (AGN), with radiation-driven torus models predicting a wind to be its main driver. However, little is known about its characteristics, spatial extent, or connection to the larger scale outflows. We present the first JWST/MIRI study aimed at imaging polar dust by zooming onto the centre of ESO 428-G14, part of the Galaxy Activity, Torus, and Outflow Survey (GATOS) survey of local AGN. We detect extended mid-infrared (MIR) emission within 200 pc from the nucleus. This polar structure is co-linear with a radio jet and lies perpendicular to a molecular gas lane that feeds and obscures the nucleus. Its morphology bears a striking resemblance to that of gas ionised by the AGN in the narrow-line region. We demonstrate that part of this spatial correspondence is due to contamination within the JWST filter bands from strong emission lines. Correcting for the contamination, we find the morphology of the dust continuum to be more compact, though still clearly extended out to ~ 100 pc. We estimate the emitting dust has a temperature of ~ 120 K. Using simple models, we find that the heating of small dust grains by the radiation from the central AGN and/or radiative jet-induced shocks is responsible for the extended MIR emission. Radiation-driven dusty winds from the torus is unlikely to be important. This has important implications for scales to which AGN winds can carry dust and dense gas out into their host galaxies.

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arXiv2024

Towards an observationally motivated AGN dusty torus model. I. Dust chemical composition from the modeling of Spitzer spectra

Spectral energy distribution (SED) fitting is one of most commonly used techniques to study the dust properties in Active Galactic Nuclei (AGN). Works implementing this technique commonly use radiative transfer models that assume a variety of dust properties. Despite the key role of this aspect, limited effort has been put forward to explore the chemical composition, the role of different optical properties, and the grain size distribution of dust, all of which can have a substantial impact on the theoretical radiative transfer calculations. In this work, we explore the role of the dust chemical composition in the AGN dusty torus through SED fitting to \emph{Spitzer}/IRS spectra of a sample of 49 nearby AGN with silicate features in emission. We implement a mineralogy model including the popular astronomical silicates and a set of oxides and amorphous silicates with different grain sizes. We find that best fits use principally porous alumina, periclase, and olivine. In terms of mass fractions, $\sim99\%$ of the dust is composed of dust grains of size $\rm{0.1 μm}$, with a $<1\%$ contribution from $\rm{3 μm}$ grains. Moreover, the astronomical silicates have a very low occurrence in the best fits, suggesting that they are not the most suited dust species to reproduce the silicate features in our sample.

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arXiv2024

SAUNAS I: Searching for Low Surface Brightness X-ray Emission with Chandra/ACIS

We present SAUNAS (Selective Amplification of Ultra Noisy Astronomical Signal), a pipeline designed for detecting diffuse X-ray emission in the data obtained with the Advanced CCD Imaging Spectrometer (ACIS) of the Chandra X-ray Observatory. SAUNAS queries the available observations in the Chandra archive, performs photometric calibration, PSF (point spread function) modeling, and deconvolution, point-source removal, adaptive smoothing, and background correction. This pipeline builds on existing and well-tested software including CIAO, VorBin, and LIRA. We characterize the performance of SAUNAS through several quality performance tests, and demonstrate the broad applications and capabilities of SAUNAS using two galaxies already known to show X-ray emitting structures. SAUNAS successfully detects the 30 kpc X-ray super-wind of NGC 3079 using Chandra/ACIS datasets, matching the spatial distribution detected with more sensitive XMM-Newton observations. The analysis performed by SAUNAS reveals an extended low surface brightness source in the field of UGC 5101 in the 0.3-1.0 keV and 1.0-2.0 keV bands. This source is potentially a background galaxy cluster or a hot gas plume associated with UGC 5101. SAUNAS demonstrates its ability to recover previously undetected structures in archival data, expanding exploration into the low surface brightness X-ray universe with Chandra/ACIS.

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arXiv2024

Extragalactic Magnetism with SOFIA (SALSA Legacy Program). VII. A Tomographic View of Far-infrared and Radio Polarimetric Observations through MHD Simulations of Galaxies

The structure of magnetic fields in galaxies remains poorly constrained, despite the importance of magnetism in the evolution of galaxies. Radio synchrotron and far-infrared (FIR) polarization and polarimetric observations are the best methods to measure galactic scale properties of magnetic fields in galaxies beyond the Milky Way. We use synthetic polarimetric observations of a simulated galaxy to identify and quantify the regions, scales, and interstellar medium (ISM) phases probed at FIR and radio wavelengths. Our studied suite of magnetohydrodynamical cosmological zoom-in simulations features high-resolutions (10 pc full-cell size) and multiple magnetization models. Our synthetic observations have a striking resemblance to those of observed galaxies. We find that the total and polarized radio emission extends to approximately double the altitude above the galactic disk (half-intensity disk thickness of $h_\text{I radio} \sim h_\text{PI radio} = 0.23 \pm 0.03$ kpc) relative to the total FIR and polarized emission that are concentrated in the disk midplane ($h_\text{I FIR} \sim h_\text{PI FIR} = 0.11 \pm 0.01$ kpc). Radio emission traces magnetic fields at scales of $\gtrsim 300$ pc, whereas FIR emission probes magnetic fields at the smallest scales of our simulations. These scales are comparable to our spatial resolution and well below the spatial resolution ($<300$ pc) of existing FIR polarimetric measurements. Finally, we confirm that synchrotron emission traces a combination of the warm neutral and cold neutral gas phases, whereas FIR emission follows the densest gas in the cold neutral phase in the simulation. These results are independent of the ISM magnetic field strength. The complementarity we measure between radio and FIR wavelengths motivates future multiwavelength polarimetric observations to advance our knowledge of extragalactic magnetism.

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arXiv2024

Atacama Large Aperture Submillimeter Telescope (AtLAST) science: Gas and dust in nearby galaxies

Understanding the physical processes that regulate star formation and galaxy evolution are major areas of activity in modern astrophysics. Nearby galaxies offer unique opportunities to inspect interstellar medium (ISM), star formation (SF), radiative, dynamic and magnetic physics in great detail from sub-galactic (kpc) scales to sub-cloud (sub-pc) scales, from quiescent galaxies to starbursts, and from field galaxies to overdensities. In this case study, we discuss the major breakthroughs in this area of research that will be enabled by the Atacama Large Aperture Submillimeter Telescope (AtLAST), a proposed 50-m single-dish submillimeter telescope. The new discovery space of AtLAST comes from its exceptional sensitivity, in particular to extended low surface brightness emission, a very large 2 degree field of view, and correspondingly high mapping efficiency. This paper focuses on four themes which will particularly benefit from AtLAST: 1) the LMC and SMC, 2) extragalactic magnetic fields, 3) the physics and chemistry of the interstellar medium, and 4) star formation and galaxy evolution. With ~1000-2000h surveys each, AtLAST could deliver deep dust continuum maps of the entire LMC and SMC fields at parsec-scale resolution, high-resolution maps of the magnetic field structure, gas density, temperature and composition of the dense and diffuse ISM in ~100 nearby galaxies, as well as the first large-scale blind CO survey in the nearby Universe, delivering molecular gas masses for up to 10^6 galaxies (3 orders of magnitude more than current samples). Through such observing campaigns, AtLAST will have a profound impact on our understanding of the baryon cycle and star formation across a wide range of environments.

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arXiv2024

Probing the dust grain alignment mechanisms in spiral galaxies with M51 as the case study

Magnetic fields (B-fields) in galaxies have recently been traced using far-infrared and sub-mm polarimetric observations with SOFIA, JCMT, and ALMA. The main assumption is that dust grains are magnetically aligned with the local B-field in the interstellar medium (ISM). However, the range of physical conditions of the ISM, dust grain sizes, and B-field strengths in galaxies where this assumption is valid has not been characterized yet. Here, we use the well-studied spiral galaxy M51 as a case study. We find that the timescale for the alignment mechanism arising from magnetically aligned dust grains (B-RAT) dominates over other alignment mechanisms, including radiative precession (k-RAT) and mechanical alignment (v-MAT), as well as the randomization effect (gas damping). We estimate the sizes of the aligned dust grain to be in the range of 0.009-0.182 $μ$m and 0.019-0.452 $μ$m for arms and inter-arms, respectively. We show that the difference in the polarization fraction between arms and interarms can arise from the enhancement of small dust grain sizes in the arms as an effect of the grain alignment disruption (RAT-D). We argue that the RAT-D mechanism needs to have additional effects, e.g., intrinsic variations of the B-field structure and turbulence, in the galaxy's components to fully explain the polarization fraction variations within the arms and inter-arms.

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arXiv2023

Cygnus A Obscuring Torus: Ionized, Atomic or Molecular?

The prototypical powerful FR \Romannum{2} radio galaxy Cygnus A fits extremely well into the quasar/radio galaxy unified model: high polarization with an angle almost perpendicular to the radio jet and polarized flux showing broad permitted lines. It has been claimed that ionized gas in the torus reveals a very clear torus shape via Bremmstrahlung emission. We rule out the later with an energetic argument, and we constrain the molecular and atomic gas properties with existing observations. The atomic absorption against the core has been shown to match the X-ray column only if the spin temperature is an implausible $T_{\rm s} = 1\times 10^6$ K. This points to a molecular medium for the X-ray column $\log(N_{\rm H} ~[\rm{cm^{-2}}]) \sim 23.5$. Yet not low-J CO absorption is detected to sensitive limits. The non-detection is surprising given that this powerful radio galaxy hosts a luminous, dust-obscured active nucleus and copious warm molecular hydrogen. These conditions suggest a detectable level of emission. Furthermore, the torus X-ray column density suggests detectable absorption. We explore various possibilities to explain the lack of a signature from warm CO (200-250K). Specifically, that the radiative excitation by the radio core renders low-J CO absorption below current sensitivities, and that high-J levels are well populated and conducive to producing absorption. We test this hypothesis using archival \textit{Hershel}/SPIRE FTS observations of Cygnus A of high-J CO lines ($14 \geq J \geq 4$ transitions). Still high-J CO lines are not detected. We suggest that ALMA observations near its high frequency limit can be critical to obtain the signature of molecular line of the torus of Cygnus A.

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