- ID:
- ivo://CDS.VizieR/J/A+A/494/799
- Title:
- Large Quasar Astrometric Catalogue (LQAC)
- Short Name:
- J/A+A/494/799
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The very large and increasing number of quasars reckoned from various sky surveys leads to a large quantity of data which brings various and inhomogeneous information in the fields of astrometry, photometry, radioastronomy and spectroscopy. In this paper, we describe our work that aims to make available a general compilation of the largest number of recorded quasars obtained from all the available catalogues, with their best position estimates, and providing physical information at both optical and radio wavelengths.
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- ID:
- ivo://CDS.VizieR/J/A+A/642/A166
- Title:
- Large scale mechanical heating in NGC4945
- Short Name:
- J/A+A/642/A166
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Understanding the dominant heating mechanism in the nuclei of galaxies is crucial to understand star formation in starbursts (SB), active galactic nuclei (AGN) phenomena and the relationship between the star formation and AGN activity in galaxies. The analysis of the carbon monoxide (^12^CO) rotational ladder versus the infrared continuum emission (hereafter, ^12^CO/IR) in galaxies with different type of activity have shown important differences between them. We aim at carrying out a comprehensive study of the nearby composite AGN-SB galaxy, NGC 4945, using spectroscopic and photometric data from the Herschel satellite. In particular, we want to characterize the thermal structure in this galaxy by a multi-transitions analysis of the spatial distribution of the ^12^CO emission at different spatial scales. We also want to establish the dominant heating mechanism at work in the inner region of this object at smaller spatial scales (<~200pc). We present far-infrared (FIR) and sub-millimeter (sub-mm) ^12^CO line maps and single spectra (from J_up_=3 to 20) using the Heterodyne Instrument for the Far Infrared (HIFI), the Photoconductor Array Camera and Spectrometer (PACS), and the Spectral and Photometric Imaging REceiver (SPIRE) onboard Herschel, and the Atacama Pathfinder EXperiment (APEX). We combined the ^12^CO/IR flux ratios and the local thermodynamic equilibrium (LTE) analysis of the ^12^CO images to derive the thermal structure of the Interstellar Medium (ISM) for spatial scales raging from <~200pc to 2kpc. In addition, we also present single spectra of low (^12^CO, ^13^CO and [CI]) and high density (HCN, HNC, HCO^+^, CS and CH) molecular gas tracers obtained with APEX and HIFI applying LTE and non-LTE analyses. Furthermore, the Spectral Energy Distribution (SED) of the continuum emission from the far-IR to sub-mm wavelengths is also presented. From the non-LTE analysis of the low and high density tracers we derive in NGC 4945 gas volume densities (10^3^-10^6^cm^-3^) similar to those found in other galaxies with different type of activity. From the ^12^CO analysis we found clear trend in the distribution of the derived temperatures and the ^12^CO/IR ratios. It is remarkable that at intermediate scales (360pc-1kpc, or 19"-57") we see large temperatures in the direction of the X-ray outflow while at smaller scales (<~200pc-360pc, or 9"-19"), the highest temperature, derived from the high-J lines, is not found toward the nucleus, but toward the galaxy plane. The thermal structure derived from the ^12^CO multi-transition analysis suggests that mechanical heating, like shocks or turbulence, dominates the heating of the ISM in the nucleus of NGC4945 located beyond 100 pc (&500) from the center of the galaxy. This result is further supported by the Kazandjian et al. (2015, Cat. J/AJ/133/504) models, which are able to reproduce the emission observed at high-J (PACS) ^12^CO transitions when mechanical heating mechanisms are included. Shocks and/or turbulence are likely produced by the barred potential and the outflow, observed in X-rays.
- ID:
- ivo://CDS.VizieR/J/ApJ/868/55
- Title:
- Large-scale structure of M31 halo. II. PAndAS
- Short Name:
- J/ApJ/868/55
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Pan-Andromeda Archaeological Survey is a survey of >400deg^2^ centered on the Andromeda (M31) and Triangulum (M33) galaxies that has provided the most extensive panorama of an L* galaxy group to large projected galactocentric radii. Here, we collate and summarize the current status of our knowledge of the substructures in the stellar halo of M31, and discuss connections between these features. We estimate that the 13 most distinctive substructures were produced by at least 5 different accretion events, all in the last 3 or 4Gyr. We suggest that a few of the substructures farthest from M31 may be shells from a single accretion event. We calculate the luminosities of some prominent substructures for which previous estimates were not available, and we estimate the stellar mass budget of the outer halo of M31. We revisit the problem of quantifying the properties of a highly structured data set; specifically, we use the OPTICS clustering algorithm to quantify the hierarchical structure of M31's stellar halo and identify three new faint structures. M31's halo, in projection, appears to be dominated by two "mega-structures", which can be considered as the two most significant branches of a merger tree produced by breaking M31's stellar halo into increasingly smaller structures based on the stellar spatial clustering. We conclude that OPTICS is a powerful algorithm that could be used in any astronomical application involving the hierarchical clustering of points.
- ID:
- ivo://CDS.VizieR/J/ApJ/842/120
- Title:
- Large spectrosc. survey of Palomar 5 stellar stream
- Short Name:
- J/ApJ/842/120
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present two spectroscopic surveys of the tidal stellar stream of the Palomar 5 globular cluster undertaken with the VLT/FLAMES and AAT/AAOmega instruments. We use these data in conjunction with photometric data presented in the previous contribution in this series to classify the survey stars in terms of their probability of belonging to the Palomar 5 stellar stream. We find that high-probability candidates are only found in a very narrow spatial interval surrounding the locus of the stream on the sky. PanSTARRS RRLyrae stars in this region of the sky are also distributed in a similar manner. The absence of significant "fanning" of this stellar stream confirms that Palomar 5 does not follow a chaotic orbit. Previous studies have found that Palomar 5 is largely devoid of low-mass stars, and we show that this is true also of the stellar populations along the trailing arm out to 6{deg}. Within this region, which contains 73% of the detected stars, the population is statistically identical to the core, implying that the ejection of the low-mass stars occurred before the formation of the stream. We also present an updated structural model fit to the bound remnant, which yields a total mass of 4297+/-98M_{sun}_ and a tidal radius 0.145+/-0.009kpc. We estimate the mass of the observed system including the stream to be 12200+/-400M_{sun}_, and the initial mass to have been ~47000+/-1500M_{sun}_.
3425. LARGESS survey
- ID:
- ivo://CDS.VizieR/J/MNRAS/464/1306
- Title:
- LARGESS survey
- Short Name:
- J/MNRAS/464/1306
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the Large Area Radio Galaxy Evolution Spectroscopic Survey (LARGESS), a spectroscopic catalogue of radio sources designed to include the full range of radio AGN populations out to redshift z~0.8. The catalogue covers ~800deg^2^ of sky, and provides optical identifications for 19179 radio sources from the 1.4GHz Faint Images of the Radio Sky at Twenty-cm (FIRST) survey down to an optical magnitude limit of i_mod_<20.5 in Sloan Digital Sky Survey (SDSS) images. Both galaxies and point-like objects are included, and no colour cuts are applied. In collaboration with the WiggleZ and Galaxy And Mass Assembly (GAMA) spectroscopic survey teams, we have obtained new spectra for over 5000 objects in the LARGESS sample. Combining these new spectra with data from earlier surveys provides spectroscopic data for 12329 radio sources in the survey area, of which 10 856 have reliable redshifts. 85 per cent of the LARGESS spectroscopic sample are radio AGN (median redshift z=0.44), and 15 per cent are nearby star-forming galaxies (median z=0.08). Low-excitation radio galaxies (LERGs) comprise the majority (83 per cent) of LARGESS radio AGN at z<0.8, with 12 per cent being high-excitation radio galaxies (HERGs) and 5 per cent radio-loud QSOs. Unlike the more homogeneous LERG and QSO sub-populations, HERGs are a heterogeneous class of objects with relatively blue optical colours and a wide dispersion in mid-infrared colours. This is consistent with a picture in which most HERGs are hosted by galaxies with recent or ongoing star formation as well as a classical accretion disc.
- ID:
- ivo://CDS.VizieR/VII/228
- Title:
- Las Campanas Infrared Survey
- Short Name:
- VII/228
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Las Campanas Infrared Survey, based on broadband optical and near-infrared photometry, is designed to robustly identify a statistically significant and representative sample of evolved galaxies at redshifts z>1. We have completed an H-band imaging survey over 1.1{deg}^2^ of sky in six separate fields. The average 5{sigma} detection limit in a 4" diameter aperture is H~20.8. Here we describe the design of the survey, the observation strategies, data-reduction techniques, and object identification procedures. We present sample near-infrared and optical photometric catalogs for objects identified in two survey fields. The optical images of the Hubble Deep Field-South region obtained from the literature reach 5{sigma} detection thresholds in a 4" diameter aperture of U~24.6, B~26.1, V~25.6, R~25.1, and I~24.2mag. The optical images of the Chandra Deep Field-South region obtained from our own observations reach 5 {sigma} detection thresholds in a 4" diameter aperture of V~26.8, R~26.2, I~25.3, and z'~23.7mag. We perform object detection in all bandpasses and identify>~54000 galaxies over 1408 arcmin^2^ of sky in the two fields. Of these galaxies, ~14000 are detected in the H band and ~2000 have the colors of evolved galaxies, I-H >~3, at z>~1.
- ID:
- ivo://CDS.VizieR/J/MNRAS/361/525
- Title:
- Las Campanas Infrared Survey. V.
- Short Name:
- J/MNRAS/361/525
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present deep Keck spectroscopy, using the Deep Imaging Multi-Object Spectrograph and the Low-Resolution Imaging Spectrometer spectrographs, of a large and representative sample of 67 extremely red objects (EROs) to H=20.5 in three fields (SSA22, Chandra Deep Field South and NTT Deep Field) drawn from the Las Campanas Infrared Survey (LCIRS). Using the colour cut (I-H)>3.0 (Vega magnitudes) adopted in earlier papers in this series, we verify the efficiency of this selection for locating and studying distant old sources. Spectroscopic redshifts are determined for 44 sources, of which only two are contaminating low-mass stars. When allowance is made for incompleteness, the spectroscopic redshift distribution closely matches that predicted earlier on the basis of photometric data.
- ID:
- ivo://CDS.VizieR/J/AJ/162/102
- Title:
- LASSO; Robo-AO observation of 444 young stars
- Short Name:
- J/AJ/162/102
- Date:
- 14 Mar 2022 06:43:15
- Publisher:
- CDS
- Description:
- We present results from the Large Adaptive optics Survey for Substellar Objects, where the goal is to directly image new substellar companions (<70M_Jup_) at wide orbital separations (>~50au) around young (<~300Myr), nearby (<100pc), low-mass (~0.1-0.8 M{odot}) stars. We report on 427 young stars imaged in the visible (i') and near-infrared (J or H ) simultaneously with Robo-AO on the Kitt Peak 2.1m telescope and later the Maunakea University of Hawaii 2.2m telescope. To undertake the observations, we commissioned a new infrared camera for Robo-AO that uses a low-noise high-speed SAPHIRA avalanche photodiode detector. We detected 121 companion candidates around 111 stars, of which 62 companions are physically associated based on Gaia DR2 parallaxes and proper motions, another 45 require follow-up observations to confirm physical association, and 14 are background objects. The companion separations range from 2 to 1101 au and reach contrast ratios of 7.7 mag in the near-infrared compared to the primary. The majority of confirmed and pending candidates are stellar companions, with ~5 being potentially substellar and requiring follow-up observations for confirmation. We also detected a 43{+/-}9 M_Jup_ and an 81{+/-}5M_Jup_ companion that were previously reported. We found 34 of our targets have acceleration measurements detected using Hipparcos-Gaia proper motions. Of those, 58_-14_^+12^% of the 12 stars with imaged companion candidates have significant accelerations ({chi}^2^>11.8), while only 23_-6_^+11^% of the remaining 22 stars with no detected companion have significant accelerations. The significance of the acceleration decreases with increasing companion separation. These young accelerating low-mass stars with companions will eventually yield dynamical masses with future orbit monitoring.
- ID:
- ivo://CDS.VizieR/J/AJ/107/1556
- Title:
- Late B-type stars classification
- Short Name:
- J/AJ/107/1556
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In the fourth and final of a series of papers on the late B to the early F type stars, we refine the MK spectral classification system for the late B type stars and consider the effect of rotation on both spectral classification and Stromgren photometry of these stars. We extend the work of Morgan by establishing self-consistent sequences of narrow and broadlined standards. We reclassify a number of Bp stars, compare these classifications with Stromgren photometry and consider the question of whether all Bp stars are main-sequence objects.
- ID:
- ivo://CDS.VizieR/J/ApJ/681/1163
- Title:
- Late-type galaxies in Chandra deep fields
- Short Name:
- J/ApJ/681/1163
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on the X-ray evolution over the last ~9Gyr of cosmic history (i.e., since z=1.4) of late-type galaxy populations in the Chandra Deep Field-North and Extended Chandra Deep Field-South (CDF-N and E-CDF-S, respectively; jointly CDFs) survey fields. Our late-type galaxy sample consists of 2568 galaxies, which were identified using rest-frame optical colors and HST morphologies. We utilized X-ray stacking analyses to investigate the X-ray emission from these galaxies, emphasizing the contributions from normal galaxies that are not dominated by active galactic nuclei (AGNs). Over this redshift range, we find significant increases (factors of ~5-10) in the X-ray-to-optical mean luminosity ratio (L_X_/L_B_) and the X-ray-to-stellar mass mean ratio (L_X_/M_*_) for galaxy populations selected by L_B_ and M_*_, respectively. When analyzing galaxy samples selected via SFR, we find that the mean X-ray-to-SFR ratio (L_X_/SFR) is consistent with being constant over the entire redshift range for galaxies with SFR=1-100M_{sun}_/yr, thus demonstrating that X-ray emission can be used as a robust indicator of star formation activity out to z~1.4. We find that the star formation activity (as traced by X-ray luminosity) per unit stellar mass in a given redshift bin increases with decreasing stellar mass over the redshift range z=0.2-1, which is consistent with previous studies of how star formation activity depends on stellar mass. Finally, we extend our X-ray analyses to Lyman break galaxies at z~3 and estimate that L_X_/L_B_ at z~3 is similar to its value at z=1.4.
