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Публикации по объекту
Late-Time Radio Observations of 68 Type Ibc Supernovae: Strong Constraints on Off-Axis Gamma-Ray Bursts
We present late-time radio observations of 68 local Type Ibc supernovae,including six events with broad optical absorption lines(``hypernovae''). None of these objects exhibit radio emissionattributable to off-axis gamma-ray burst jets spreading into our line ofsight. Comparison with our afterglow models reveals the followingconclusions. (1) Less than ~10% of Type Ibc supernovae are associatedwith typical gamma-ray bursts initially directed away from our line ofsight; this places an empirical constraint on the GRB beaming factor of<~104, corresponding toan average jet opening angle, θj>~0.8d. (2) Thisholds in particular for the broad-lined supernovae (SNe 1997dq, 1997ef,1998ey, 2002ap, 2002bl, and 2003jd), which have been argued to host GRBjets. Our observations reveal no evidence for typical (or evensubenergetic) GRBs and rule out the scenario in which every broad-linedSN harbors a GRB at the 84% confidence level. Their large photosphericvelocities and asymmetric ejecta (inferred from spectropolarimetry andnebular spectroscopy) appear to be characteristic of the nonrelativisticSN explosion and do not necessarily imply the existence of associatedGRB jets.
| New Reference Galaxy Standards for H I Emission Observations
We have taken advantage of the improved baselines and higher sensitivityavailable with the upgraded Arecibo 305 m telescope to create a new H Ispectral line catalog of disk galaxies that can be used as a referencecatalog for anyone interested in 21 cm spectral line work. In all 108galaxies were observed, covering 24 hr of the sky at declinationsbetween 0° and 36° and velocities between 0 and 25,000 kms-1. The majority of the galaxies were observed at least twotimes on different nights to avoid problems with radio frequencyinterference, baseline fluctuations, etc. Comparing our measured valueswith all those available in the literature shows that although largeindividual variations may exist, the average difference between themeasurements is zero. In all we have considerable confidence in ourmeasurements, and the resulting catalog should be extremely useful as awell-defined reference catalog for anyone interested in 21 cm spectralline work.
| A search for Low Surface Brightness galaxies in the near-infrared. I. Selection of the sample
A sample of about 3800 Low Surface Brightness (LSB) galaxies wasselected using the all-sky near-infrared (J, H and Ks-band)2MASS survey. The selected objects have a mean central surfacebrightness within a 5'' radius around their centre fainter than 18 magarcsec-2 in the Ks band, making them the lowestsurface brightness galaxies detected by 2MASS. A description is given ofthe relevant properties of the 2MASS survey and the LSB galaxy selectionprocedure, as well as of basic photometric properties of the selectedobjects. The latter properties are compared to those of other samples ofgalaxies, of both LSBs and ``classical'' high surface brightness (HSB)objects, which were selected in the optical. The 2MASS LSBs have aBT_c-KT colour which is on average 0.9 mag bluerthan that of HSBs from the NGC. The 2MASS sample does not appear tocontain a significant population of red objects.All tables and Figs. 2a-c are only available in electronic form athttp://www.edpsciences.org
| The UZC-SSRS2 Group Catalog
We apply a friends-of-friends algorithm to the combined Updated ZwickyCatalog and Southern Sky Redshift Survey to construct a catalog of 1168groups of galaxies; 411 of these groups have five or more members withinthe redshift survey. The group catalog covers 4.69 sr, and all groupsexceed the number density contrast threshold, δρ/ρ=80. Wedemonstrate that the groups catalog is homogeneous across the twounderlying redshift surveys; the catalog of groups and their membersthus provides a basis for other statistical studies of the large-scaledistribution of groups and their physical properties. The medianphysical properties of the groups are similar to those for groupsderived from independent surveys, including the ESO Key Programme andthe Las Campanas Redshift Survey. We include tables of groups and theirmembers.
| Nebular Spectra of the Type Ic Supernovae 1997B and 1997X
New spectra of the Type Ic supernovae 1997B and 1997X at nebular phaseare shown. Although one of them, SN 1997X, was studied with some detailaround its maximum and its properties compared with other well-known SNeIb/c, both of these events were later followed within its nebular phase.Our aim is to explore the behavior of these supernovae when they reachedthe nebular phase. Comparisons with data of other SNe Ic at similarnebular phases, mainly by using spectra from the Canarias Database, arealso performed. The results derived from these comparisons reinforce thequite heterogeneous behavior found in SNe Ic nebular spectra. Inparticular, the widths of the [O I] and [Ca II] emissions found in SN1997B are wider than the average for Type Ic events, while the [O I]width of SN 1997X is narrower than the average and is nearly comparableto typical [O I] widths found in SNe Ib. Based on observations made withthe 2.5 m Isaac Newton Telescope and the 4.2 m William HerschelTelescope operated on La Palma by the Isaac Newton Group of Telescopesat Observatorio del Roque de los Muchachos of the Instituto deAstrofísica de Canarias.
| Supernovae in isolated galaxies, in pairs and in groups of galaxies
In order to investigate the influence of environment on supernova (SN)production, we have performed a statistical investigation of the SNediscovered in isolated galaxies, in pairs and in groups of galaxies. 22SNe in 18 isolated galaxies, 48 SNe in 40 galaxy members of 37 pairs and211 SNe in 170 galaxy members of 116 groups have been selected andstudied. We found that the radial distributions of core-collapse SNe ingalaxies located in different environments are similar, and consistentwith those reported by Bartunov, Makarova & Tsvetkov. SNe discoveredin pairs do not favour a particular direction with respect to thecompanion galaxy. Also, the azimuthal distributions inside the hostmembers of galaxy groups are consistent with being isotropics. The factthat SNe are more frequent in the brighter components of the pairs andgroups is expected from the dependence of the SN rates on the galaxyluminosity. There is an indication that the SN rate is higher in galaxypairs compared with that in groups. This can be related to the enhancedstar formation rate in strongly interacting systems. It is concludedthat, with the possible exception of strongly interacting systems, theparent galaxy environment has no direct influence on SN production.
| Optical Spectroscopy of Type IB/C Supernovae
We present 84 spectra of Type Ib/c and Type IIb supernovae (SNe),describing the individual SNe in detail. The relative depths of thehelium absorption lines in the spectra of the SNe Ib appear to provide ameasurement of the temporal evolution of the SN, with He I λ5876and He I λ7065 growing in strength relative to He I λ6678over time. Light curves for three of the SNe Ib provide a sequence forcorrelating the helium line strengths. We find that some SNe Ic showevidence for weak helium absorption, but most do not. Aside from thepresence or absence of the helium lines, there are other spectroscopicdifferences between SNe Ib and SNe Ic. On average, the O I λ7774line is stronger in SNe Ic than in SNe Ib. In addition, the SNe Ic havedistinctly broader emission lines at late times, indicating aconsistently larger explosion energy and/or lower envelope mass for SNeIc than for SNe Ib. While SNe Ib appear to be basically homogeneous, theSNe Ic are quite heterogeneous in their spectroscopic characteristics.Three SNe Ic that may have been associated with gamma-ray bursts arealso discussed; two of these have clearly peculiar spectra, while thethird seems fairly typical.
| Nearby Optical Galaxies: Selection of the Sample and Identification of Groups
In this paper we describe the Nearby Optical Galaxy (NOG) sample, whichis a complete, distance-limited (cz<=6000 km s-1) andmagnitude-limited (B<=14) sample of ~7000 optical galaxies. Thesample covers 2/3 (8.27 sr) of the sky (|b|>20deg) andappears to have a good completeness in redshift (97%). We select thesample on the basis of homogenized corrected total blue magnitudes inorder to minimize systematic effects in galaxy sampling. We identify thegroups in this sample by means of both the hierarchical and thepercolation ``friends-of-friends'' methods. The resulting catalogs ofloose groups appear to be similar and are among the largest catalogs ofgroups currently available. Most of the NOG galaxies (~60%) are found tobe members of galaxy pairs (~580 pairs for a total of ~15% of objects)or groups with at least three members (~500 groups for a total of ~45%of objects). About 40% of galaxies are left ungrouped (field galaxies).We illustrate the main features of the NOG galaxy distribution. Comparedto previous optical and IRAS galaxy samples, the NOG provides a densersampling of the galaxy distribution in the nearby universe. Given itslarge sky coverage, the identification of groups, and its high-densitysampling, the NOG is suited to the analysis of the galaxy density fieldof the nearby universe, especially on small scales.
| Arcsecond Positions of UGC Galaxies
We present accurate B1950 and J2000 positions for all confirmed galaxiesin the Uppsala General Catalog (UGC). The positions were measuredvisually from Digitized Sky Survey images with rms uncertaintiesσ<=[(1.2")2+(θ/100)2]1/2,where θ is the major-axis diameter. We compared each galaxymeasured with the original UGC description to ensure high reliability.The full position list is available in the electronic version only.
| Galaxies with a UV excess in which supernovae have been observed.
Not Available
| Influence of a partial incompleteness of the sample on the determination of the Hubble constant.
This paper presents a study of the Malmquist bias effect in thedetermination of the Hubble constant from the method of "sosies"(look-alike) galaxies. It is shown that a bias appears when a partialincompleteness exists in the sample. A new method, based on the use ofthe completeness curve, is proposed to correct for such a bias. Afterthis correction, the Hubble constant drops of about 20% just because ofthe existence of the partial incompleteness. From the present resultsand on the acceptance of the distance modulus of primary calibrators,the value of the Hubble constant would be: H_0_=~60km/s/Mpc with aninternal statistical error of about 2km/s/Mpc.
| The statistics analysis of recent supernovae.
Not Available
| An image database. II. Catalogue between δ=-30deg and δ=70deg.
A preliminary list of 68.040 galaxies was built from extraction of35.841 digitized images of the Palomar Sky Survey (Paper I). For eachgalaxy, the basic parameters are obtained: coordinates, diameter, axisratio, total magnitude, position angle. On this preliminary list, weapply severe selection rules to get a catalog of 28.000 galaxies, wellidentified and well documented. For each parameter, a comparison is madewith standard measurements. The accuracy of the raw photometricparameters is quite good despite of the simplicity of the method.Without any local correction, the standard error on the total magnitudeis about 0.5 magnitude up to a total magnitude of B_T_=17. Significantsecondary effects are detected concerning the magnitudes: distance toplate center effect and air-mass effect.
| The CfA Redshift Survey: Data for the NGP +36 Zone
We have assembled redshifts for a complete sample of 719 galaxies withm_zw_ <= 15.5 in the declination range 32.5^deg^ <= δ <=38.5^deg^ and right ascension range 8^h^ <= α <= 17^h^. Wehave determined morphological types for all galaxies in the magnitudelimited sample by direct inspection of the POSS-O plates. 576 of theredshifts are measurements from Mount Hopkins, and 405 are newredshifts. We also include new redshifts for 77 fainter galaxies in thesame strip.
| Distribution of supernovae relative to spiral arms and H II regions
We have studied the association of supernovae in spiral galaxies withsites of recent stars formation -- sprial arms and H II regions. It isshown that supernovae (SNe) of Types Ia, Ib, and II exhibitconcentration to spiral arms and their distributions over the distanceto the nearest spiral arm do not differ significantly. This result isconfirmed by a Kolmogorov-Smirnov test comparison with the distancedistributions, expected if SNe are distributed randomly inside the modelgalaxy. SNe of types Ib and II show a strong concentration towards H IIregions, while distribution of SNe Ia can be explained by chancesuperposition. All studied distributions of SNe Ib and II show strikingsimilarity, which suggests that their progenitors are massive stars withsimilar ages and initial masses. The association of SNe Ia with spiralarms suggests that their progenitors in spiral galaxies are likely to beintermediate mass stars.
| Searching for supernovae--Visually and otherwise
The main features of visual searching for supernovae in other galaxiesby amateur astronomers are described, and an outline is given of theresults which have been achieved so far by this method. A shortcomparison is made between visual searching and photographic searching.A more extensive comparison is then made between visual searching forsupernovae in Australia, and the work of the Berkeley AutomaticSupernova Search at Leuschner Observatory, since 1986. Among theconclusions is the claim that a competent visual observer could producesimilar results to those produced by the Berkeley group if a telescopeof similar aperture was used for a similar amount of observing time, andfrom a good observing site. Indeed, visual searching might possiblyproduce more results, and such a search would only cost a small fractionof what was spent on this automatic search. It would be a worthwhileproject to conduct a visual search with a suitably desinged 76-cmtelescope, or a one metre telescope, over a period of a few years, tosee if this conclusion could be supported in practice.
| A catalog of recent supernovae
A listing is given of all supernovae discovered between 1 Jan 1989 and 1Apr 1993. The data show no evidence for a significant dependence of thediscovery probability of supernovae on parent galaxy inclination to theline of sight. If no inclination corrections need to be applied then thesupernova rates in spirals are only about half as large as previouslybelieved. The mean linear separation of supernovae of Type II (SNe II)from the center of their parent galaxy increases with increasingdistance (Shaw effect). The Shaw effect appears less evident, or absent,for (more luminous) supernovae of Type Ia. The data are consistent with,but do not prove, the hypothesis that (presumably reddended) SNe II aremore likely to be discovered in the red than in the blue. Due tointensive surveillance, most bright SNe Ia tend to be found beforemaximum, whereas the majority of faint SNe Ia are discovered aftermaximum light.
| Spectral evolution of the He-Poor supernovae 1990U in NGC 7479 and 1991A in IC 2973
We present the spectral evolution, from about one to six months afteroptical maximum, of two type Ic supernovae, 1990U in NGC 7479 and 1991Ain IC 2973 (UGC 6872). We analyze and compare the SN 1990U and SN 1991Aspectral sequences. We looked for differences, at similar phases,between the more characteristic spectral features and their evolution.From this analysis, we have found that the overall spectral evolution ofthese two supernovae followed the same trend. The onset of their nebularphases must have occurred not later than three months after opticalmaximum. However, we have found some differences between these objectsas derived from their spectra. We suggest that SN 1991A was a moreoxygen rich and helium poor supernova than SN 1990U.
| A revised catalog of CfA1 galaxy groups in the Virgo/Great Attractor flow field
A new identification of groups and clusters in the CfA1 Catalog ofHuchra et al. is presented, using a percolation algorithm to identifydensity enhancements. It is shown that in the resulting catalog,contamination by interlopers is significantly reduced. The Schechterluminosity function is redetermined, including the Malmquist bias.
| General study of group membership. II - Determination of nearby groups
We present a whole sky catalog of nearby groups of galaxies taken fromthe Lyon-Meudon Extragalactic Database. From the 78,000 objects in thedatabase, we extracted a sample of 6392 galaxies, complete up to thelimiting apparent magnitude B0 = 14.0. Moreover, in order to considersolely the galaxies of the local universe, all the selected galaxieshave a known recession velocity smaller than 5500 km/s. Two methods wereused in group construction: a Huchra-Geller (1982) derived percolationmethod and a Tully (1980) derived hierarchical method. Each method gaveus one catalog. These were then compared and synthesized to obtain asingle catalog containing the most reliable groups. There are 485 groupsof a least three members in the final catalog.
| High rate for Type IC supernovae
Using an automated telescope, 20 SNe in carefully documentedobservations of nearby galaxies were detected. The SN rates for latespiral (Sbc, Sc, Scd, and Sd) galaxies, normalized to a blue luminosityof 10 exp 10 are 0.4, 1.6, and 1.1 h squared per 100 years for Types Ia,Ic, and II SNe. The rate for Type Ic SNe is significantly higher thanfound in previous surveys. The rates are not corrected for detectioninefficiencies and do not take into account the indications that the IcSNe are fainter on the average than the previous estimates; thereforethe true rates are probably higher. The rates are not strongly dependenton the galaxy inclination, in contradiction to previous compilations. Ifthe Milky Way is a late spiral, then the rate of the Galactic SNe isgreater than 1 per 30 +/-7 yr, assuming h = 0.75. This high rate hasencouraging consequences for future neutrino and gravitational waveobservatories.
| High signal-to-noise ratio observations of H I in 243 galaxies
The 21 cm spectral-line system of the Arecibo Observatory was used tomeasure neutral hydrogen emission from 243 faint galaxies. Most lie nearthe plane of the Local Supercluster. All observations reach anunsmoothed signal-to-noise ratio of at least 7.0; the average for theset is 23. The resulting data are used to estimate H I masses, systemicvelocities, and accurate profile widths at 20 percent, 25 percent, 50percent, and 80 percent of peak intensity levels. The widths are used tocalibrate directly the bias introduced by popular data-smoothingoperation. The data include observations of 65 objects with previouslyunknown redshifts.
| KISO survey for ultraviolet-excess galaxies. III
Presented here are the third list and identification charts of theultraviolet-excess galaxies which have been detected on the multicolorplates taken with the Kiso Schmidt telescope for 10 survey fields. Inthe sky area of some 300 square degrees 712 objects are catalogued downto the photographic magnitude of about 17.5.
| A search for environmental effects on the optical properties of galaxies in groups
Environmental density-related modifications of basic optical properties(luminosities, sizes, axial ratios, and colors) of galaxies belonging toGeller and Huchra's (1983) groups have been investigated. Remarkably, itis found that the broad maxima of the distributions of luminosities anddiameters of spirals and the whole corresponding distributions oflenticulars tend to move to lower values as one goes to groups of highcompactness, whereas the luminosity-diameter relationship of spiralstends to become flatter. No color and axial ratio differences betweengalaxies of high- and low-compactness groups have been detected.
| The Coma/A 1367 filament of galaxies
In the Coma/A 1367 supercluster the surface distribution of galaxiesfrom Zwicky and UGC catalogs outlines a filamentary structure in whichthe Coma cluster itself is embedded. In its densest part the filamentextends for approximately 3.5 h in right ascension and shows an averagedensity contrast of about 2.7 with respect to the nearby regions. Theposition angle of Coma is well oriented along the filament and pointssignificantly toward another cluster of the filament which also shows anelongated shape in the same direction. A sample of new 21-cm redshiftsis used together with the redshifts data available in the literature tostudy the structure of the filament: the majority of the galaxies on itfalls in the velocity range of Coma indicating that the filament is acoherent structure in the three-dimensional space and represents animportant element of the supercluster. The possibility that thefilamentary structure continues at a lower density contrast to bridgethe Lynx-Ursa Major and the Hercules supercluster is discussed.
| A survey of galaxy redshifts. IV - The data
The complete list of the best available radial velocities for the 2401galaxies in the merged Zwicky-Nilson catalog brighter than 14.5mz and with b (II) above +40 deg or below -30 deg ispresented. Almost 60 percent of the redshifts are from the CfA surveyand are accurate to typically 35 km/s.
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