Carbon monoxide (CO) observations show a luminosity−line width correlation that evolves with redshift. We present a method to use CO measurements alone to infer the molecular gas fraction (fmol) and ...constrain the CO−H2 conversion factor ( CO). We compile from the literature spatially integrated low-J CO observations of six galaxy populations, including a total of 449 galaxies between 0.01 ≤ z ≤ 3.26. The CO data of each population provide an estimate of the -normalized mean molecular gas fraction (fmol/ CO). The redshift evolution of the luminosity−line width correlation thus indicates an evolution of fmol/ CO. We use a Bayesian-based Monte Carlo Markov Chain sampler to derive the posterior probability distribution functions of fmol/ CO for these galaxy populations, accounting for random inclination angles and measurement errors in the likelihood function. We find that the molecular gas fraction evolves rapidly with redshift, with β 2, for both normal star-forming and starburst galaxies. Furthermore, the evolution trend agrees well with that inferred from the Kennicutt-Schmidt relation and the star-forming main sequence. Finally, at z < 0.1 normal star-forming galaxies (SFGs) require a ∼5× larger CO than starburst galaxies to match their molecular gas fractions, but at z > 1 both star-forming types exhibit sub-Galactic CO values and normal SFGs appear more gas rich than starbursts. Future applications of this method include calibrating Tully-Fisher relations without inclination correction and inferring the evolution of the atomic gas fraction with H i observations.
We have identified 105 galaxy pairs at z ∼ 0.04 with the MaNGA integral-field spectroscopic data. The pairs have projected separations between 1 and 30 kpc, and are selected to have radial velocity ...offsets less than 600 km s−1 and stellar mass ratio between 0.1 and 1. The pair fraction increases with both the physical size of the integral-field unit and the stellar mass, consistent with theoretical expectations. We provide the best-fit analytical function of the pair fraction and find that ∼3% of M* galaxies are in close pairs. For both isolated galaxies and paired galaxies, active galactic nuclei (AGNs) are selected using emission-line ratios and H equivalent widths measured inside apertures at a fixed physical size. We find AGNs in ∼24% of the paired galaxies and binary AGNs in ∼13% of the pairs. To account for the selection biases in both the pair sample and the MaNGA sample, we compare the AGN comoving volume densities with those expected from the mass- and redshift-dependent AGN fractions. We find a strong (∼5×) excess of binary AGNs over random pairing and a mild (∼20%) deficit of single AGNs. The binary AGN excess increases from ∼2× to ∼6× as the projected separation decreases from 10-30 to 1-10 kpc. Our results indicate that the pairing of galaxies preserves the AGN duty cycle in individual galaxies but increases the population of binary AGNs through correlated activities. We suggest tidally induced galactic-scale shocks and AGN cross-ionization as two plausible channels to produce low-luminosity narrow-line-selected binary AGNs.
Abstract
We present the largest currently existing subarcsecond 3–5
μ
m atlas of 119 local (
z
< 0.3) active galactic nuclei (AGNs). This atlas includes AGNs of five subtypes: 22 are Seyfert 1; five ...are intermediate Seyferts; 46 are Seyfert 2; 26 are low-ionization nuclear emission regions; and 20 are composites/starbursts. Each active galactic nucleus was observed with the Very Large Telescope Infrared Spectrometer and Array Camera (ISAAC) in the
L
and/or
M
bands between 2000 and 2013. We detected at 3
σ
confidence 92 sources in the
L
band and 83 sources in the
M
band. We separated the flux into unresolved nuclear flux and resolved the flux through two-Gaussian fitting. We report the nuclear flux, extended flux, apparent size, and position angle of each source, giving 3
σ
upper limits for sources that are undetected. Using Wide-field Infrared Survey Explorer (WISE)
W1
- and
W2
-band photometry we derived relations predicting the nuclear
L
and
M
fluxes for Sy1 and Sy2 AGNs based on their
W1–W2
color and WISE fluxes. Lastly, we compare the measured mid-infrared colors to those predicted by dusty torus models SKIRTOR, CLUMPY, CAT3D, and CAT3D-WIND, finding the best agreement with the latter. We find that models including polar winds best reproduce the 3–5
μ
m colors, indicating that it is an important component of dusty torus models. We found that several AGNs are bluer than models predict. We discuss several explanations for this and find that it is most plausibly stellar light contamination within the ISAAC
L
-band nuclear fluxes.
ABSTRACT
Single dish observations of NGC 1068 have shown the presence of a 3.4 μm aliphatic hydrocarbon absorption feature similar to diffuse lines of sight towards the Galactic Centre. Both, the ...single dish spectra and the correlated fluxes obtained by MATISSE, present a broad absorption profile in the L band as well, that vary from baseline to baseline. A new CRIRES spectrum with a slit width comparable to the MATISSE aperture also reveals a wide feature around 3.4 μm. We aim to analyse these features to learn about their origin and the distribution of the carriers across the source. We argue that all these features are caused by absorption of aliphatic hydrocarbons. The 3.4 μm absorption features in the interferometric MATISSE correlated fluxes vary in optical depth over scales of 0.2-1.4 parsec in the plane of the sky, although probably placed at a larger distance from the AGN along the line of sight. The absorption in the extended areas seems to peak in the direction of the inner jet, close to the center of the ionization cone. These results support the theory of a clumpy torus. In comparing our results to the N-band surface density previously reported, we have discovered a mass ratio of carbonaceous to silicate olivine dust at ∼2 - 3.6 per cent, which is similar to those found in several lines of sight in the diffuse interstellar medium of our Galaxy.
During the last two decades, the first generation of beam combiners at the Very Large Telescope Interferometer has proved the importance of optical interferometry for high-angular resolution ...astrophysical studies in the near- and mid-infrared. With the advent of 4-beam combiners at the VLTI, the
u
−
v
coverage per pointing increases significantly, providing an opportunity to use reconstructed images as powerful scientific tools. Therefore, interferometric imaging is already a key feature of the new generation of VLTI instruments, as well as for other interferometric facilities like CHARA and JWST. It is thus imperative to account for the current image reconstruction capabilities and their expected evolutions in the coming years. Here, we present a general overview of the current situation of optical interferometric image reconstruction with a focus on new wavelength-dependent information, highlighting its main advantages and limitations. As an
Appendix
we include several cookbooks describing the usage and installation of several state-of-the art image reconstruction packages. To illustrate the current capabilities of the software available to the community, we recovered chromatic images, from simulated MATISSE data, using the MCMC software SQUEEZE. With these images, we aim at showing the importance of selecting good regularization functions and their impact on the reconstruction.
Context.
Asymptotic giant branch (AGB) stars are one of the main sources of dust production in the Galaxy. However, it is not yet clear what this process looks like and where the dust happens to be ...condensing in the circumstellar environment.
Aims.
By characterizing the location of the dust and the molecules in the close environment of an AGB star, we aim to achieve a better understanding the history of the dust formation process.
Methods.
We observed the carbon star R Scl with the thermal-infrared VLTI/MATISSE instrument in
L
- and
N
-bands. The high angular resolution of the VLTI observations (as small as 4.4 mas in the
L
-band and 15 mas in the
N
-band with ATs), combined with a large
uv
-plane coverage allowed us to use image reconstruction methods. To constrain the dust and molecules’ location, we used two different methods: one using MIRA image reconstruction algorithm and the second using the 1D code RHAPSODY.
Results.
We found evidence of C
2
H
2
and HCN molecules between 1 and 3.4
R
*
which is much closer to the star than the location of the dust (between 3.8 and 17.0
R
*
). We also estimated a mass-loss rate of 1.2 ± 0.4 × 10
−6
M
⊙
yr
−1
. In the meantime, we confirmed the previously published characteristics of a thin dust shell, composed of amorphous carbon (amC) and silicon carbide (SiC). However, no clear SiC feature has been detected in the MATISSE visibilities. This might be caused by molecular absorption that can affect the shape of the SiC band at 11.3 µm.
Conclusions.
The appearance of the molecular shells is in good agreement with predictions from dynamical atmosphere models. For the first time, we co-located dust and molecules in the environment of an AGB star. We confirm that the molecules are located closer to the star than the dust. The MIRA images unveil the presence of a clumpy environment in the fuzzy emission region beyond 4.0
R
*
. Furthermore, with the available dynamic range and angular resolution, we did not detect the presence of a binary companion. To solve this problem, additional observations combining MATISSE and SAM-VISIR instrument should enable this detection in future studies.
Carbon monoxide (CO) observations show a luminosity\(-\)line-width correlation that evolves with redshift. We present a method to use CO measurements alone to infer the molecular gas fraction ...(\(f_{\rm mol}\)) and constrain the CO\(-\)H\(_2\) conversion factor (\(\alpha_{\rm CO}\)). We compile from the literature spatially integrated low-\(J\) CO observations of six galaxy populations, including a total of 449 galaxies between \(0.01 \leq z \leq 3.26\). The CO data of each population provide an estimate of the \(\alpha_{\rm CO}\)-normalized mean molecular gas fraction (\(f_{\rm mol}/\alpha_{\rm CO}\)). The redshift evolution of the luminosity\(-\)line-width correlation thus indicates an evolution of \(f_{\rm mol}/\alpha_{\rm CO}\). We use a Bayesian-based Monte-Carlo Markov Chain sampler to derive the posterior probability distribution functions of \(f_{\rm mol}/\alpha_{\rm CO}\) for these galaxy populations, accounting for random inclination angles and measurement errors in the likelihood function. We find that the molecular gas fraction evolves rapidly with redshift, \(f_{\rm mol} \propto (1+z)^\beta\) with \(\beta \simeq 2\), for both normal star-forming and starburst galaxies. Furthermore, the evolution trend agrees well with that inferred from the Kennicutt-Schmidt relation and the star-forming main sequence. Finally, at \(z < 0.1\) normal star-forming galaxies require a \(\sim5\times\) larger \(\alpha_{\rm CO}\) than starburst galaxies to match their molecular gas fractions, but at \(z > 1\) both star-forming types exhibit sub-Galactic \(\alpha_{\rm CO}\) values and normal star-forming galaxies appear more gas-rich than starbursts. Future applications of this method include calibrating Tully-Fisher relations without inclination correction and inferring the evolution of the atomic gas fraction with HI observations.
In this paper we present the first-ever \(L\)- and \(M\)-band interferometric observations of Circinus, building upon a recent \(N\)-band analysis. We used these observations to reconstruct images ...and fit Gaussian models to the \(L\) and \(M\) bands. Our findings reveal a thin edge-on disk whose width is marginally resolved and is the spectral continuation of the disk imaged in the \(N\) band to shorter wavelengths. Additionally, we find a point-like source in the \(L\) and \(M\) bands that, based on the \(LMN\)-band spectral energy distribution fit, corresponds to the \(N\)-band point source. We also demonstrate that there is no trace of direct sightlines to hot dust surfaces in the circumnuclear dust structure of Circinus. By assuming the dust is present, we find that obscuration of A\(_{\rm V} \gtrsim 250\) mag is necessary to reproduce the measured fluxes. Hence, the imaged disk could play the role of the obscuring "torus" in the unified scheme of active galactic nuclei. Furthermore, we explored the parameter space of the disk + hyperbolic cone radiative transfer models and identify a simple modification at the base of the cone. Adding a cluster of clumps just above the disk and inside the base of the hyperbolic cone provides a much better match to the observed temperature distribution in the central aperture. This aligns well with the radiation-driven fountain models that have recently emerged. Only the unique combination of sensitivity and spatial resolution of the VLTI allows such models to be scrutinized and constrained in detail. We plan to test the applicability of this detailed dust structure to other MATISSE-observed active galactic nuclei in the future.
Profiling of circulating tumor DNA (ctDNA) in the bloodstream shows promise for noninvasive cancer detection. Chromatin fragmentation features have previously been explored to infer gene expression ...profiles from cell-free DNA (cfDNA), but current fragmentomic methods require high concentrations of tumor-derived DNA and provide limited resolution. Here we describe promoter fragmentation entropy as an epigenomic cfDNA feature that predicts RNA expression levels at individual genes. We developed 'epigenetic expression inference from cell-free DNA-sequencing' (EPIC-seq), a method that uses targeted sequencing of promoters of genes of interest. Profiling 329 blood samples from 201 patients with cancer and 87 healthy adults, we demonstrate classification of subtypes of lung carcinoma and diffuse large B cell lymphoma. Applying EPIC-seq to serial blood samples from patients treated with PD-(L)1 immune-checkpoint inhibitors, we show that gene expression profiles inferred by EPIC-seq are correlated with clinical response. Our results indicate that EPIC-seq could enable noninvasive, high-throughput tissue-of-origin characterization with diagnostic, prognostic and therapeutic potential.
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