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611. 1D Lya forest power spectrum
ID:
ivo://CDS.VizieR/J/A+A/559/A85
Title:
1D Lya forest power spectrum
Short Name:
J/A+A/559/A85
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have developed two independent methods to measure the one-dimensional power spectrum of the transmitted flux in the Lyman-{alpha} forest. The first method is based on a Fourier transform, and the second on a maximum likelihood estimator. The two methods are independent and have different systematic uncertainties. The determination of the noise level in the data spectra was subject to a novel treatment, because of its significant impact on the derived power spectrum. We applied the two methods to 13,821 quasar spectra from SDSS-III/BOSS DR9 (Baryon Oscillation Spectroscopic Survey, BOSS, 2013AJ....145...10D) selected from a larger sample of over 60,000 spectra on the basis of their high quality, large signal-to-noise ratio, and good spectral resolution. The power spectra measured using either approach are in good agreement over all twelve redshift bins from <z>=2.2 to <z>=4.4, and scales from 0.001(km/s)^-1^ to 0.02(km/s)^-1^. We determine the methodological and instrumental systematic uncertainties of our measurements.
612. 3D non-LTE Balmer line formation
ID:
ivo://CDS.VizieR/J/A+A/615/A139
Title:
3D non-LTE Balmer line formation
Short Name:
J/A+A/615/A139
Date:
21 Oct 2021
Publisher:
CDS
Description:
Hydrogen Balmer lines are commonly used as spectroscopic effective temperature diagnostics of late-type stars. However, reliable inferences require accurate model spectra, and the absolute accuracy of classical methods that are based on one-dimensional (1D) hydrostatic model atmospheres and local thermodynamic equilibrium (LTE) is still unclear. To investigate this, we carry out 3D non-LTE calculations for the Balmer lines, performed, for the first time, over an extensive grid of 3D hydrodynamic STAGGER model atmospheres. For H{alpha}, H{beta}, and H{gamma} we find significant 1D non-LTE versus 3D non-LTE differences (3D effects): the outer wings tend to be stronger in 3D models, particularly for H{gamma}, while the inner wings can be weaker in 3D models, particularly for H{alpha}. For H{alpha}, we also find significant 3D LTE versus 3D non-LTE differences (non-LTE effects): in warmer stars (Teff~~6500K) the inner wings tend to be weaker in non-LTE models, while at lower effective temperatures (Teff~~4500K) the inner wings can be stronger in non-LTE models; the non-LTE effects are more severe at lower metallicities. We test our 3D non-LTE models against observations of well-studied benchmark stars. For the Sun, we infer concordant effective temperatures from H{alpha}, H{beta}, and H{gamma}; however the value is too low by around 50K which could signal residual modelling shortcomings. For other benchmark stars, our 3D non-LTE models generally reproduce the effective temperatures to within 1{sigma} uncertainties. For H{alpha}, the absolute 3D effects and non-LTE effects can separately reach around 100K, in terms of inferred effective temperatures. For metal-poor turn-off stars, 1D LTE models of H{alpha} can underestimate effective temperatures by around 150K. Our 3D non-LTE model spectra are publicly available, and can be used for more reliable spectroscopic effective temperature determinations.
613. 1-D optical spectra for IRAS19135+3937
ID:
ivo://CDS.VizieR/J/A+A/631/A53
Title:
1-D optical spectra for IRAS19135+3937
Short Name:
J/A+A/631/A53
Date:
21 Oct 2021
Publisher:
CDS
Description:
We aim to determine the geometry, density gradient, and velocity structure of jets in post-asymptotic giant branch (post-AGB) binaries. Our high cadence time series of high-resolution optical spectra of jet-creating post-AGB binary systems provide us with a unique tomography of the jet. We determine the spatio-kinematic structure of the jets based on these data by fitting the synthetic spectral line profiles created by our model to the observed, orbital phase-resolved, H{alpha}-line profiles of these systems. The fitting routine is provided with an initial spectrum and is allowed to test three configurations, derived from three specific jet launching models: a stellar jet launched by the star, an X-wind, and a disk wind configuration. We apply a Markov-chain Monte Carlo routine in order to fit our model to the observations. Our fitting code is tested on the post-AGB binary IRAS19135+3937. We find that a model using the stellar jet configuration gives a marginally better fit to our observations. The jet has a wide half-opening angle of about 76 degrees and reaches velocities up to 870km/s. Our methodology is successful in determining some parameters for jets in post-AGB binaries. The model for IRAS19135+3937 includes a transparent, low density inner region (for a half-opening angle <40{deg}). The source feeding the accretion disk around the companion is most likely the circumbinary disk. We will apply this jet fitting routine to other jet-creating post-AGB stars in order to provide a more complete description of these objects. We aim at describing and understanding binary interaction processes in systems with very evolved companions. Here, we focus on understanding the origin and determining the properties of the high-velocity outflow observed in one such system.
614. Double-peaked AGN. I. Dual AGN candidates
ID:
ivo://CDS.VizieR/J/ApJ/753/42
Title:
Double-peaked AGN. I. Dual AGN candidates
Short Name:
J/ApJ/753/42
Date:
21 Oct 2021
Publisher:
CDS
Description:
Merger-remnant galaxies with kiloparsec (kpc) scale separation dual active galactic nuclei (AGNs) should be widespread as a consequence of galaxy mergers and triggered gas accretion onto supermassive black holes, yet very few dual AGNs have been observed. Galaxies with double-peaked narrow AGN emission lines in the Sloan Digital Sky Survey (SDSS) are plausible dual AGN candidates, but their double-peaked profiles could also be the result of gas kinematics or AGN-driven outflows and jets on small or large scales. To help distinguish between these scenarios, we have obtained spatial profiles of the AGN emission via follow-up long-slit spectroscopy of 81 double-peaked narrow-line AGNs in SDSS at 0.03<=z<=0.36 using Lick, Palomar, and MMT Observatories. We find that all 81 systems exhibit double AGN emission components with ~kpc projected spatial separations on the sky (0.2h^-1^_70_kpc<{Delta}x<5.5h^-1^_70_kpc; median {Delta}x=1.1h^-1^_70_kpc), which suggests that they are produced by kiloparsec-scale dual AGNs or kiloparsec-scale outflows, jets, or rotating gaseous disks.
615. Double-peaked narrow lines in AGN. II. z<0.1
ID:
ivo://CDS.VizieR/J/ApJ/832/67
Title:
Double-peaked narrow lines in AGN. II. z<0.1
Short Name:
J/ApJ/832/67
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present optical long-slit observations of the complete sample of 71 Type 2 active galactic nuclei (AGNs) with double-peaked narrow emission lines at z<0.1 in the Sloan Digital Sky Survey. Double-peaked emission lines are produced by a variety of mechanisms including disk rotation, kiloparsec-scale dual AGNs, and narrow-line region (NLR) kinematics (outflows or inflows). We develop a novel kinematic classification technique to determine the nature of these objects using long-slit spectroscopy alone. We determine that 86% of the double-peaked profiles are produced by moderate-luminosity AGN outflows, 6% are produced by rotation, and 8% are ambiguous. While we are unable to directly identify dual AGNs with long-slit data alone, we explore their potential kinematic classifications with this method. We also find a positive correlation between the NLR size and luminosity of the AGN NLRs (R_NLR_{propto}L_[OIII]_^0.21+/-0.05^), indicating a clumpy two-zone ionization model for the NLR.
616. Double-peaked narrow lines in AGN. IV. Mergers
ID:
ivo://CDS.VizieR/J/ApJ/867/66
Title:
Double-peaked narrow lines in AGN. IV. Mergers
Short Name:
J/ApJ/867/66
Date:
21 Oct 2021
Publisher:
CDS
Description:
Double-peaked narrow emission lines in active galactic nucleus (AGN) spectra can be produced by AGN outflows, rotation, or dual AGNs, which are AGN pairs in ongoing galaxy mergers. Consequently, double-peaked narrow AGN emission lines are useful tracers of the coevolution of galaxies and their supermassive black holes, as driven by AGN feedback and AGN fueling. We investigate this concept further with follow-up optical longslit observations of a sample of 95 Sloan Digital Sky Survey (SDSS) galaxies that have double-peaked narrow AGN emission lines. Based on a kinematic analysis of the longslit spectra, we confirm previous work that finds that the majority of double-peaked narrow AGN emission lines are associated with outflows. We also find that eight of the galaxies have companion galaxies with line-of-sight velocity separations <500km/s and physical separations <30kpc. Since we find evidence of AGNs in both galaxies, all eight of these systems are compelling dual AGN candidates. Galaxies with double-peaked narrow AGN emission lines occur in such galaxy mergers at least twice as often as typical active galaxies. Finally, we conclude that at least 3% of SDSS galaxies with double-peaked narrow AGN emission lines are found in galaxy mergers where both galaxies are resolved in SDSS imaging.
617. Doubly ^13^C-substituted ethyl cyanide
ID:
ivo://CDS.VizieR/J/A+A/590/A93
Title:
Doubly ^13^C-substituted ethyl cyanide
Short Name:
J/A+A/590/A93
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have performed a spectral line survey called Exploring Molecular Complexity with ALMA (EMoCA) toward Sagittarius B2(N) between 84.1 and 114.4GHz with the Atacama Large Millimeter/submillimeter Array (ALMA) in its Cycles 0 and 1. Line intensities of the main isotopic species of ethyl cyanide and its singly ^13^C-substituted isotopomers observed toward the hot molecular core Sagittarius B2(N2) suggest that the doubly ^13^C-substituted isotopomers should also be detectable. We want to determine the spectroscopic parameters of all three doubly ^13^C-substituted isotopologues of ethyl cyanide to search for them in our ALMA data. We investigated the laboratory rotational spectra of the three species between 150GHz and 990GHz. We searched for emission lines produced by these species in the ALMA spectrum of Sagittarius B2(N2). We modeled their emission and the emission of the ^12^C and singly ^13^C-substituted isotopologues assuming local thermodynamic equilibrium.
618. DPOSS II compact group survey
ID:
ivo://CDS.VizieR/J/A+A/445/857
Title:
DPOSS II compact group survey
Short Name:
J/A+A/445/857
Date:
21 Oct 2021
Publisher:
CDS
Description:
This paper presents the results of a pilot redshift survey of 18 candidate compact groups from the distant DPOSS survey that extends to redshift 0.2 the available surveys of compact groups of galaxies, mainly Hickson Compact Groups and Southern Compact Groups. The goal of our survey was to confirm group membership via redshift information and to measure the characteristic parameters of a representative, albeit small, sample of DPOSS survey groups.
619. DPOSS II compact group survey. EMMI-NTT sample
ID:
ivo://CDS.VizieR/J/A+A/539/A106
Title:
DPOSS II compact group survey. EMMI-NTT sample
Short Name:
J/A+A/539/A106
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the results of a redshift survey of 138 candidate compact groups from the DPOSS II catalogue, which extends the available redshift range of spectroscopically confirmed compact groups of galaxies to redshift z~0.2. In this survey, we aim to confirm group membership via spectroscopic redshift information, to measure the characteristic properties of the confirmed groups, namely their mass, radius, luminosity, velocity dispersion, and crossing time, and to compare them with those of nearby compact groups. Using information available from the literature, we also studied the surrounding group environment and searched for additional, previously unknown, group members, or larger scale structures to whom the group might be associated.
620. 3D spectroscopy in 30 Dor
ID:
ivo://CDS.VizieR/J/ApJS/191/160
Title:
3D spectroscopy in 30 Dor
Short Name:
J/ApJS/191/160
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have completed a new optical imaging and spectrophotometric survey of a 140x80pc^2^ region of 30 Doradus centered on R136, covering key optical diagnostic emission lines including H{alpha}, H{beta}, H{gamma}, [OIII]4363, 4959, 5007, [NII]6548, 6584, [SII]6717, 6731 [SIII]6312, and in some locations [SIII]9069. We present maps of fluxes and intensity ratios for these lines, and catalogs of isolated ionizing stars, elephant-trunk pillars, and edge-on ionization fronts. The final science-quality spectroscopic data products are available to the public. Our analysis of the new data finds that, while stellar winds and supernovae undoubtedly produce shocks and are responsible for shaping the nebula, there are no global spectral signatures to indicate that shocks are currently an important source of ionization. We conclude that the considerable region covered by our survey is well described by photoionization from the central cluster where the ionizing continuum is dominated by the most massive O stars. We show that if 30 Dor were viewed at a cosmological distance, its integrated light would be dominated by its extensive regions of lower surface brightness rather than by the bright, eye-catching arcs.

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