- ID:
- ivo://CDS.VizieR/J/ApJ/725/842
- Title:
- New X-ray-selected SNRs detection with Chandra
- Short Name:
- J/ApJ/725/842
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results from a study of the supernova remnant (SNR) population in a sample of six nearby galaxies (NGC 2403, NGC 3077, NGC 4214, NGC 4449, NGC 4395, and NGC 5204) based on Chandra archival data. We have detected 244 discrete X-ray sources down to a limiting flux of 10^-15^ erg/s/cm^2^. We identify 37 X-ray-selected thermal SNRs based on their X-ray colors or spectra, 30 of which are new discoveries. In many cases, the X-ray classification is confirmed based on counterparts with SNRs identified in other wavelengths. Three of the galaxies in our sample (NGC 4214, NGC 4395, and NGC 5204) are studied for the first time, resulting in the discovery of 13 thermal SNRs. We discuss the properties (luminosity, temperature, and density) of the X-ray-detected SNRs in the galaxies of our sample in order to address their dependence on their environment. We find that X-ray-selected SNRs in irregular galaxies appear to be more luminous than those in spirals. We attribute this to the lower metallicities and therefore more massive progenitor stars of irregular galaxies or the higher local densities of the interstellar medium. We also discuss the X-ray-selected SNR populations in the context of the star formation rate of their host galaxies. A comparison of the numbers of observed luminous X-ray-selected SNRs with those expected based on the luminosity functions of X-ray SNRs in the Magellanic Clouds and M33 suggest different luminosity distributions between the SNRs in spiral and irregular galaxies with the latter tending to have flatter distributions.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/855/142
- Title:
- Next Generation Fornax Survey (NGFS) II.
- Short Name:
- J/ApJ/855/142
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a photometric study of the dwarf galaxy population in the core region (<~r_vir_/4) of the Fornax galaxy cluster based on deep u'g'i' photometry from the Next Generation Fornax Cluster Survey. All imaging data were obtained with the Dark Energy Camera mounted on the 4m Blanco telescope at the Cerro Tololo Interamerican Observatory. We identify 258 dwarf galaxy candidates with luminosities -17<~Mg'<~-8mag, corresponding to typical stellar masses of 9.5>~logM*/M_{sun}_>~5.5, reaching ~3mag deeper in point-source luminosity and ~4mag deeper in surface brightness sensitivity compared to the classic Fornax Cluster Catalog. Morphological analysis shows that the dwarf galaxy surface-brightness profiles are well represented by single-component Sersic models with average Sersic indices of <n>_u',g',i'_=(0.78-0.83)+/-0.02 and average effective radii of <r_e_>_u',g',i'_=(0.67-0.70+/-0.02kpc. Color-magnitude relations indicate a flattening of the galaxy red sequence at faint galaxy luminosities, similar to the one recently discovered in the Virgo cluster. A comparison with population synthesis models and the galaxy mass-metallicity relation reveals that the average faint dwarf galaxy is likely older than ~5Gyr. We study galaxy scaling relations between stellar mass, effective radius, and stellar mass surface density over a stellar mass range covering six orders of magnitude. We find that over the sampled stellar mass range several distinct mechanisms of galaxy mass assembly can be identified: (1) dwarf galaxies assemble mass inside the half-mass radius up to logM*~8.0, (2) isometric mass assembly occurs in the range 8.0<~logM*/M_{sun}_<~10.5, and (3) massive galaxies assemble stellar mass predominantly in their halos at logM*~10.5 and above.
2473. NGC 2000.0
- ID:
- ivo://CDS.VizieR/VII/118
- Title:
- NGC 2000.0
- Short Name:
- VII/118
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- NGC 2000.0 is a modern compilation of the New General Catalogue of Nebulae and Clusters of Stars (NGC), the Index Catalogue (IC), and the Second Index Catalogue compiled by J. L. E. Dreyer (1888, 1895, 1908). The new compilation of these classical catalogs is intended to meet the needs of present-day observers by reporting positions at equinox B2000.0 and by incorporating the corrections reported by Dreyer himself and by a host of other astronomers who have worked with the data and compiled lists of errata. The object types given are those known to modern astronomy. The catalog lists object ID, object type, positions in equinox B2000.0, source of modern data (see NGC 2000 paperback copy), constellation, object size, magnitude, and the description of the object as given by Dreyer. The order of the new catalog is strictly by right ascension, the NGC and IC objects being merged into one machine-readable file.
- ID:
- ivo://CDS.VizieR/J/A+A/629/A3
- Title:
- NGC1326A, 1425 and 4548 supergiants VI mags
- Short Name:
- J/A+A/629/A3
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Studies on the massive star population in galaxies beyond the Local Group are the key to understand the link between their numbers and modes of star formation in different environments. We present the analysis of the massive star population of the galaxies NGC1326A, NGC 1425 and NGC 4548 using archival Hubble Space Telescope Wide Field Planetary Camera 2 images in the F555W and F814W filters. Through high precision point spread function fitting photometry for all sources in the three fields we identified 7640 candidate blue supergiants, 2314 candidate yellow supergiants, and 4270 candidate red supergiants. We provide an estimation the ratio of blue to red supergiants for each field as a function of galactocentric radius. Using Modules for Experiments in Stellar Astrophysics (MESA) at solar metallicity, we defined the luminosity function and estimated the star formation history of each galaxy. We carried out a variability search in the V and I filters using three variability indexes: the median absolute deviation, the interquartile range, and the inverse von-Neumann ratio. This analysis yielded 243 new variable candidates with absolute magnitudes ranging from M_V_=-4 to -10mag. We classified the variable stars based on their absolute magnitude and their position on the color-magnitude diagram using the MESA evolutionary tracks at solar metallicity. Our analysis yielded 8 candidate variable blue supergiants, 12 candidate variable yellow supergiants, 21 candidate variable red supergiants, and 4 candidate periodic variables.
- ID:
- ivo://CDS.VizieR/J/A+A/537/A108
- Title:
- NGC 6822 AGB spectroscopic catalogue
- Short Name:
- J/A+A/537/A108
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We calibrate spectroscopically the C- versus (vs.) M-type asymptotic giant branch (AGB) star selection made using near-IR photometry, and investigate the spatial distribution of the C/M ratio in NGC 6822, based on low resolution spectroscopy and near-IR photometry.
- ID:
- ivo://CDS.VizieR/J/A+A/621/A83
- Title:
- NGC 1566 ALMA and Gemini-GMOS/IFU datacubes
- Short Name:
- J/A+A/621/A83
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Tracing nuclear inflows and outflows in AGNs, determining the mass of gas involved in them, and their impact on the host galaxy and nuclear black hole requires 3-D imaging studies of both the ionized and molecular gas. We map the distribution and kinematics of molecular and ionized gas in a sample of active galaxies to quantify the nuclear inflows and outflows. Here, we analyze the nuclear kinematics of NGC 1566 via ALMA observations of the CO J:2-1 emission at 24pc spatial and ~2.6km/s spectral resolution, and Gemini-GMOS/IFU observations of ionized gas emission lines and stellar absorption lines at similar spatial resolution, and 123km/s of intrinsic spectral resolution. The morphology and kinematics of stellar, molecular (CO), and ionized ([NII]) emission lines are compared to the expectations from rotation, outflows, and streaming inflows. While both ionized and molecular gas show rotation signatures, there are significant non-circular motions in the innermost 200pc and along spiral arms in the central kpc (CO). The nucleus shows a double-peaked CO profile (full width at zero intensity of 200km/s), and prominent (~80km/s) blue- and redshifted lobes are found along the minor axis in the inner arcseconds. Perturbations by the large-scale bar can qualitatively explain all features in the observed velocity field. We thus favor the presence of a molecular outflow in the disk with true velocities of ~180km/s in the nucleus and decelerating to 0 by ~72pc. The implied molecular outflow rate is 5.6M_{Sun}_/yr, with this gas accumulating in the nuclear 2" arms. The ionized gas kinematics support an interpretation of a similar but more spherical outflow in the inner 100pc, with no signs of deceleration. There is some evidence of streaming inflows of ~50km/s along specific spiral arms, and the estimated molecular mass inflow rate, ~0.1M_{Sun}_/yr, is significantly higher than the SMBH accretion rate (dM/dt=4.8x10^-5^M_{Sun}_/yr).
2477. NGC1808 ALMA datacubes
- ID:
- ivo://CDS.VizieR/J/A+A/656/A60
- Title:
- NGC1808 ALMA datacubes
- Short Name:
- J/A+A/656/A60
- Date:
- 21 Mar 2022 07:01:58
- Publisher:
- CDS
- Description:
- We report on Atacama Large Millimeter Array (ALMA) observations of CO(3-2) emission in the Seyfert2/starburst galaxy NGC 1808, at a spatial resolution of 4pc. Our aim is to investigate the morphology and dynamics of the gas inside the central 0.5kpc and to probe the nuclear feeding and feedback phenomena. We discovered a nuclear spiral of radius 1"=45pc. Within it, we found a decoupled circumnuclear disk or molecular torus of a radius of 0.13"=6pc. The HCN(4-3) and HCO^+^(4-3) and CS(7-6) dense gas line tracers were simultaneously mapped and detected in the nuclear spiral and they present the same misalignment in the molecular torus. At the nucleus, the HCN/HCO^+^ and HCN/CS ratios indicate the presence of an active galactic nucleus (AGN). The molecular gas shows regular rotation, within a radius of 400pc, except for the misaligned disk inside the nuclear spiral arms. The computations of the torques exerted on the gas by the barred stellar potential reveal that the gas within a radius of 100pc is feeding the nucleus on a timescale of five rotations or on an average timescale of ~60Myr. Some non-circular motions are observed towards the center, corresponding to the nuclear spiral arms. We cannot rule out that small extra kinematic perturbations could be interpreted as a weak outflow attributed to AGN feedback. The molecular outflow detected at >=250pc in the NE direction is likely due to supernovae feedback and it is connected to the kpc-scale superwind.
- ID:
- ivo://CDS.VizieR/J/A+A/582/A91
- Title:
- NGC 4418 ALMA mm-wave spectral scan
- Short Name:
- J/A+A/582/A91
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Extragalactic observations allow the study of molecular chemistry and excitation under physical conditions which may differ greatly from what found in the Milky Way. The compact, obscured nuclei (CON) of luminous infrared galaxies (LIRG) combine large molecular columns with intense infrared (IR), ultra-violet (UV) and X- radiation and represent ideal laboratories to study the chemistry of the interstellar medium (ISM) under extreme conditions. To obtain for the first time a multi-band spectral scan of a LIRG, in order to derive the molecular abundances and excitation, to be compared to other Galactic and extragalactic environments. We obtained an ALMA Cycle 0 spectral scan of the dusty LIRG NGC 4418, spanning a total of 70.7GHz in bands 3, 6, and 7. We use a combined local thermal equilibrium (LTE) and non-LTE (NLTE) fit of the spectrum in order to identify the molecular species and derive column densities and excitation temperatures. We derive molecular abundances and compare them with other Galactic and extragalactic sources by means of a principal component analysis.
- ID:
- ivo://CDS.VizieR/J/A+AS/119/499
- Title:
- NGC 628 and companions photometric distances
- Short Name:
- J/A+AS/119/499
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Based on photometry of the brightest blue stars we derived distance moduli for NGC 628 and its dwarf irregular companions: DDO 13, UGC 1171, UGC 1104, and K 10. The mean modulus of the group is estimated to be 29.46 mag with a formal (internal) error of 0.11. The total mass to luminosity ratio of 40M_{sun}_/L_{sun}_ seems sufficient for NGC 628 to keep its companions in bound orbits.
- ID:
- ivo://CDS.VizieR/J/A+A/622/A8
- Title:
- NGC 3184, 4736, 5055 and 5194 LOFAR & WSRT maps
- Short Name:
- J/A+A/622/A8
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Radio continuum (RC) emission in galaxies allows us to measure star formation rates (SFRs) unaffected by extinction due to dust, of which the low-frequency part is uncontaminated from thermal (free-free) emission. We calibrate the conversion from the spatially resolved 140MHz RC emission to the SFR surface density (SFR) at 1kpc scale. Radio spectral indices give us, by means of spectral ageing, a handle on the transport of cosmic rays using the electrons as a proxy for GeV nuclei. We used recent observations of three galaxies (NGC 3184, 4736, and 5055) from the LOFAR Two-metre Sky Survey (LoTSS), and archival LOw Frequency ARay (LOFAR) data of NGC 5194. Maps were created with the facet calibration technique and converted to radio {Sigma}SFR maps using the Condon relation. We compared these maps with hybrid {Sigma}SFR maps from a combination of GALEX far-ultraviolet and Spitzer 24um data using plots tracing the relation at the highest angular resolution allowed by our data at 1.2x1.2-kpc^2^ resolution.
