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2401. M31 second ROSAT PSPC survey
ID:
ivo://CDS.VizieR/J/A+A/373/63
Title:
M31 second ROSAT PSPC survey
Short Name:
J/A+A/373/63
Date:
21 Oct 2021
Publisher:
CDS
Description:
This paper reports the results of the analysis of the second ROSAT PSPC survey of M 31 performed in summer 1992. We compare our results with those of the first survey, already published in Supper et al. (1997, Cat. <J/A+A/317/328>). Within the ~10.7deg^2^ field of view, 396 individual X-ray sources are detected in the second survey data, of which 164 are new detections. When combined with the first survey, this result in a total of 560 X-ray sources in the field of M 31. Their (0.1keV-2.0keV) fluxes range from 7x10^-15^erg/cm^2^/s to 7.6x10^-12^erg/cm^2^/s, and of these 560 sources, 55 are tentatively identified with foreground stars, 33 with globular clusters, 16 with supernova remnants, and 10 with radio sources and galaxies (including M 32). A comparison with the results of the Einstein M 31 survey reveals 491 newly detected sources, 11 long term variable sources, and 7 possible transient sources. Comparing the two ROSAT surveys, we come up with 34 long term variable sources and 8 transient candidates.
2402. M60 SLUGGS and Gemini/GMOS combined study
ID:
ivo://CDS.VizieR/J/MNRAS/450/1962
Title:
M60 SLUGGS and Gemini/GMOS combined study
Short Name:
J/MNRAS/450/1962
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present new wide-field photometry and spectroscopy of the globular clusters (GCs) around NGC 4649 (M60), the third brightest galaxy in the Virgo cluster. Imaging of NGC 4649 was assembled from a recently obtained Hubble Space Telescope/Advanced Camera for Surveys mosaic, and new Subaru/Suprime-Cam and archival Canada-France-Hawaii Telescope/MegaCam data. About 1200 sources were followed up spectroscopically using combined observations from three multi-object spectrographs: Keck/Deep Imaging Multi-Object Spectrograph, Gemini/Gemini Multi-Object Spectrograph and Multiple Mirror Telescope/Hectospec. We confirm 431 unique GCs belonging to NGC 4649, a factor of 3.5 larger than previous data sets and with a factor of 3 improvement in velocity precision. We confirm significant GC colour bimodality and find that the red GCs are more centrally concentrated, while the blue GCs are more spatially extended. We infer negative GC colour gradients in the innermost 20kpc and flat gradients out to large radii. Rotation is detected along the galaxy major axis for all tracers: blue GCs, red GCs, galaxy stars and planetary nebulae. We compare the observed properties of NGC 4649 with galaxy formation models. We find that formation via a major merger between two gas-poor galaxies, followed by satellite accretion, can consistently reproduce the observations of NGC 4649 at different radii. We find no strong evidence to support an interaction between NGC 4649 and the neighbouring spiral galaxy NGC 4647. We identify interesting GC kinematic features in our data, such as counter-rotating subgroups and bumpy kinematic profiles, which encode more clues about the formation history of NGC 4649.
2403. M33 SNR candidates properties
ID:
ivo://CDS.VizieR/J/ApJ/793/134
Title:
M33 SNR candidates properties
Short Name:
J/ApJ/793/134
Date:
21 Oct 2021
Publisher:
CDS
Description:
Narrowband images covering strong emission lines are efficient for surveying supernova remnants (SNRs) in nearby galaxies. Using the narrowband images provided by the Local Group Galaxy Survey, we searched for SNRs in M33. Culling the objects with enhanced [S II]/H{alpha} and round morphology in the continuum-subtracted H{alpha} and [S II] images, we produced a list of 199 sources. Among them, 79 are previously unknown. Their progenitor and morphology types were classified. A majority of the sample (170 objects) are likely remnants of core-collapse supernovae (SNe), and 29 are remnants of Type Ia SNe. The cumulative size distribution of these objects is found to be similar to that of the M31 remnants derived in a similar way. We obtain a power-law slope, {alpha}=2.38+/-0.05. Thus, a majority of the sources are considered to be in the Sedov-Taylor phase, consistent with previous findings. The histogram of the emission-line ratio ([S II]/H{alpha}) of the remnants has two concentrations at [S II]/H{alpha} ~0.55 and ~0.8, as in M31. Interestingly, L_X_(and L_20 cm_) of the compact center-bright objects are correlated with their optical luminosity. The remnants with X-ray emission have brighter optical surface brightnesses and smaller diameters than those without X-ray emission.
2404. M82 spectral maps
ID:
ivo://CDS.VizieR/J/A+A/578/A49
Title:
M82 spectral maps
Short Name:
J/A+A/578/A49
Date:
21 Oct 2021
Publisher:
CDS
Description:
M82 is one of the nearest and brightest starburst galaxies. It has been extensively studied in the past decade and by now is considered the prototypical extragalactic photon-dominated region (PDR) and a reference for studying star formation feedback. Our aim is to characterize the molecular chemistry in M82 at spatial scales of giant molecular clouds (GMCs), ~100pc, to investigate the feedback effects of the star formation activity.
2405. M81 star cluster candidates
ID:
ivo://CDS.VizieR/J/AJ/139/1413
Title:
M81 star cluster candidates
Short Name:
J/AJ/139/1413
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a catalog of extended objects in the vicinity of M81 based on a set of 24 Hubble Space Telescope Advanced Camera for Surveys Wide Field Camera F814W (I-band) images. We have found 233 good globular cluster (GC) candidates; 92 candidate HII regions, OB associations, or diffuse open clusters; 489 probable background galaxies; and 1719 unclassified objects. We have color data from ground-based g- and r-band MMT Megacam images for 79 galaxies, 125 GC candidates, 7 HII regions, and 184 unclassified objects. The color-color diagram of GC candidates shows that most fall into the range 0.25<g-r<1.25 and 0.5<r-I<1.25, similar to the color range of Milky Way GCs. Unclassified objects are often blue, suggesting that many of them are likely to be HII regions and open clusters, although a few galaxies and GCs may be among them.
2406. M 31 Stokes images
ID:
ivo://CDS.VizieR/J/A+A/633/A5
Title:
M 31 Stokes images
Short Name:
J/A+A/633/A5
Date:
21 Oct 2021
Publisher:
CDS
Description:
Magnetic fields play an important role in the dynamics and evolution of galaxies; however, the amplification and ordering of the initial seed fields are not fully understood. The nearby spiral galaxy M 31 is an ideal laboratory for extensive studies of magnetic fields. Our aim was to measure the intrinsic structure of the magnetic fields in M 31 and compare them with dynamo models of field amplification. The intensity of polarized synchrotron emission and its orientation are used to measure the orientations of the magnetic field components in the plane of the sky. The Faraday rotation measure gives information about the field components along the line of sight. With the Effelsberg 100-m telescope three deep radio continuum surveys of the Andromeda galaxy, M 31, were performed at 2.645, 4.85, and 8.35 GHz (wavelengths of 11.3, 6.2, and 3.6 cm). The {lambda} 3.6 cm survey is the first radio survey of M 31 at such small wavelengths. Maps of the Faraday rotation measures (RMs) are calculated from the distributions of the polarization angle. At all wavelengths the total and polarized emission is concentrated in a ring-like structure of about 7-13 kpc in radius from the centre. Propagation of cosmic rays away from the star-forming regions is evident. The ring of synchrotron emission is wider than the ring of the thermal radio emission, and the radial scale length of synchrotron emission is larger than that of thermal emission. The polarized intensity from the ring in the plane of the sky varies double-periodically with azimuthal angle, indicating that the ordered magnetic field is oriented almost along the ring, with a pitch angle of -14{deg}+/-2{deg} at {lambda}6.2 cm. The RM varies systematically along the ring. The analysis shows a large-scale sinusoidal variation with azimuthal angle, signature of an axisymmetric spiral (ASS) regular magnetic field, plus a superimposed double-periodic variation of a bisymmetric spiral (BSS) regular field with about six times smaller amplitude. The RM amplitude of (118+/-3) rad/m^2^ between {lambda}6.2 cm and {lambda}3.6 cm is about 50% larger than between {lambda}11.3 cm and {lambda}6.2 cm, indicating that Faraday depolarization at {lambda}11.3 cm is stronger (i.e. with a larger Faraday thickness) than at {lambda}6.2 cm and {lambda}3.6 cm. The phase of the sinusoidal RM variation of -7{deg}+/-1{deg} is interpreted as the average spiral pitch angle of the regular field. The average pitch angle of the ordered field, as derived from the intrinsic orientation of the polarized emission (corrected for Faraday rotation), is significantly smaller: -26{deg}+/-3{deg}. The dominating ASS plus the weaker BSS field of M 31 is the most compelling case so far of a field generated by the action of a mean-field dynamo. The difference in pitch angle of the regular and the ordered fields indicates that the ordered field contains a significant fraction of an anisotropic turbulent field that has a different pattern than the regular (ASS + BSS) magnetic field.
2407. M31 supersoft and quasi-soft X-ray sources
ID:
ivo://CDS.VizieR/J/ApJ/610/247
Title:
M31 supersoft and quasi-soft X-ray sources
Short Name:
J/ApJ/610/247
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report on very soft X-ray sources (VSSs) in M31. In a survey that was most sensitive to soft sources in four 8'x8' regions covered by Chandra's ACIS-S S3 CCD, we find 33 VSSs that appear to belong to M31. Fifteen VSSs have spectral characteristics mirroring the supersoft X-ray sources studied in the Magellanic Clouds and Milky Way (kT_eff_<=100eV); we therefore call these "classical" supersoft sources, or simply supersoft sources (SSSs). Eighteen VSSs may have either small (<10%) hard components or slightly higher effective temperatures (but still less than 350eV). We refer to these VSSs as quasi-soft sources (QSSs).
2408. MSX galaxy observations
ID:
ivo://CDS.VizieR/J/AJ/124/2990
Title:
MSX galaxy observations
Short Name:
J/AJ/124/2990
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have imaged eight nearby spiral galaxies with the SPIRIT III infrared telescope on the Midcourse Space Experiment (MSX) satellite in the mid-infrared at 18" resolution at 8.3, 12.1, 14.7, and 21.3{mu}m. Each of the eight shows interesting structure not previously detected with older, lower resolution infrared data sets, such as a resolved nucleus or spiral structure. The MSX data are compared with existing data sets at ultraviolet, optical, and infrared wavelengths, including recent observations from the Infrared Space Observatory. The infrared structures in M83 and NGC 5055 show a striking similarity to the ultraviolet emission but are less similar to the optical emission. Several point sources with no identified counterparts at other wavelengths are found near M31, NGC 4945, M83, and M101. Over 200 previously known objects are also detected at 8{mu}m.
2409. 2MTF. HI observations of 303 southern galaxies
ID:
ivo://CDS.VizieR/J/MNRAS/432/1178
Title:
2MTF. HI observations of 303 southern galaxies
Short Name:
J/MNRAS/432/1178
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present new 21-cm neutral hydrogen (HI) observations of spiral galaxies for the 2MASS Tully-Fisher (2MTF) survey. Using the 64-m Parkes radio telescope multibeam system we obtain 152 high signal to noise ratio HI spectra from which we extract 148 high-accuracy (<5% error) velocity widths and derive reliable rotation velocities. The observed sample consists of 303 southern ({delta}<-40{deg}) galaxies selected from the 2MASS Redshift Survey with Ks<11.25mag, cz<10000km/s and axis ratio b/a<0.5. The HI observations reported in this paper will be combined with new HI spectra from the Green Bank and Arecibo telescopes, together producing the most uniform Tully-Fisher survey ever constructed (in terms of sky coverage). In particular, due to its near-infrared selection, 2MTF will be significantly more complete at low Galactic latitude (|b|<15{deg}) and will provide a more reliable map of peculiar velocities in the local Universe.
2410. M51 total intensity image at 333MHz
ID:
ivo://CDS.VizieR/J/A+A/592/A123
Title:
M51 total intensity image at 333MHz
Short Name:
J/A+A/592/A123
Date:
21 Oct 2021
Publisher:
CDS
Description:
Cosmic ray electrons (CREs) are a crucial part of the ISM and are observed via synchrotron emission. While much modelling has been carried out on the CRE distribution and propagation of the Milky Way, little has been done on normal external star-forming galaxies. Recent spectral data from a new generation of radio telescopes enable us to find more robust estimations of the CRE propagation To model the synchrotron spectral index of M51 using the diffusion energy-loss equation and to compare the model results with the observed spectral index determined from recent low-frequency observations with LOFAR. We solve the time-dependent diffusion energy-loss equation for CREs in M51. This is the first time that this model for CRE propagation has been solved for a realistic distribution of CRE sources, which we derive from the observed star formation rate, in an external galaxy. The radial variation of the synchrotron spectral index and scale-length produced by the model are compared to recent LOFAR and older VLA observational data and also to new observations of M51 at 325MHz obtained with the GMRT. We find that propagation of CREs by diffusion alone is sufficient to reproduce the observed spectral index distribution in M51. An isotropic diffusion coefficient with a value of 6.6+/-0.2Dunits is found to fit best and is similar to what is seen in the Milky Way. We estimate an escape time of 11Myr from the central galaxy to 88Myr in the extended disk. It is found that an energy dependence of the diffusion coefficient is not important for CRE energies in the range 0.01GeV-3GeV. We are able to reproduce the dependence of the observed synchrotron scale-lengths on frequency, with l{propto}{nu}^-1/4^ in the outer disk and l{propto}{nu}^-1/8^ in the inner disk.

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