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1.
Results are presented from a detailed spectrophotometric study of a unique system of physically coupled galaxies whose spectra
contain identical emission lines. This system consists of four galaxies, three of which have a double or multiple structure
in their central portions and are, by definition, galaxies with two or multiple nuclei. Two of these objects are the galaxies
with an ultraviolet excess (UVE), Mark 261 and Mark 262, while one is a galaxy made up of two identical starlike nuclei that
are referred to as the “twin objects.” In the DSS2 charts, the latter show up as two adjacent stars without any surroundings.
However, there are two condensations between these starlike nuclei. The fourth object has a triplet structure. It is shown
here that all these objects have the same emission (line) spectra and red shifts. All the physical characteristics that can
be determined from the spectra are determined: red shifts, relative intensities of emission lines, their equivalent widths,
distances to the galaxies, etc. It is concluded that the members of this system have a common origin, more or less consistent
with Ambartsumyan's idea of the fragmentation of an isolated, high density body.
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Translated from Astrofizika, Vol. 48, No. 4, pp. 503–514 (November 2005). 相似文献
2.
Results of spectral observations of 45 objects from the BIG sample (corresponding to 35 IRAS sources) obtained on the 2.6-m
telescope at the BAO are reported. Emission lines are observed for 42 galaxies, 1 object is an absorption galaxy, and 2 turned
out to be stars. The red shifts are determined, the radial velocities, distances, sizes, and absolute stellar magnitudes are
calculated, the parameters of the spectral lines are determined, the objects are classified according to their activity type,
and the IR and far IR luminosities are calculated. Of the 42 emission galaxies, 1 was type Sy2, 2 were LINERs, 1 was an AGN
(Sy2 or LINER), 4 were composite, 25 were HII (including 6 with nuclear star-formation activity), and 9 were Em of undetermined
type (3 of which may be AGN). Calculations show that 23 of the objects are LIG. A physical coupling is discovered for 9 multiple
systems. Spectra of some of the galaxies are shown.
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Translated from Astrofizika, Vol. 49, No. 1, pp. 23–40 (February 2006). 相似文献
3.
A. M. Mickaelian 《Astrophysics》2004,47(3):361-377
Results of spectral observations of 66 objects from the BIG (Byurakan IRAS Galaxies) sample made with the 1.93 m telescope at the Observatoire de Haute Provence (OHP, France) are presented. Emission lines are observed from 64 of the galaxies. The red shifts are determined, the radial velocities, distances, and absolute stellar magnitudes are calculated, the spectrum line parameters are determined, diagnostic diagrams are constructed, the objects are classified according to activity type, and their IR and far-IR luminosities are calculated. Of the 66 objects (corresponding to 61 IRAS sources), 6 are Sy2, 2 are LINERs, 8 are AGN (Sy2 or LINER), 10 are composite, 34 are HII, and 4 are Em of undetermined type. It is calculated that IRAS 07479+7832= BIG d141a is a ultraluminous IR galaxy (ULIG), and 21 are LIG. Spectra of several of the galaxies being studied are presented. 相似文献
4.
利用66个OH megamaser的光度和它们的宿主星系的红外光度之间的相关关系,得到log L(OH)=1.71log L(IR)-17.67,即L(OH)α[L(IR)]1。71.这个结果介于Baan所得到的L(OH)α[L(IR)]2和Kandalian所得到的L(OH)α[L(IR)]1.38的结果之间.由于统计时所取的样本数最多,因此结果更能反映实际情况.进一步,可把这66个OH megamaser分为两类;第一类为L(OH)<102L(?)的小光度OH megamaser,小光度OH megamaser包含了14个OH megamaser;第二类为L(OH)≥102L的大光度OH megamaser,大光度OH megamaser包含了52个OHmegamaser.研究结果表明,小光度OH megamaser的光度和它们的宿主星系的红外光度之间相关关系为L(OH)α[L(IR)]1.43,与Kandalia所得到的结果相接近.大光度OH megamaser的光度和它们的宿主星系的红外光度之间的相关关系为L(OH)α[L(IR)]2,与Baan所得到的结果相一致. 相似文献
5.
Results from a spectrophotometric study of 21 galaxies with UV excess are presented. The half widths (FWHM) and equivalent widths of observed spectrum lines of these galaxies, as well as the relative intensities of the emission lines observed in the spectrum of the galaxy Kaz243, are determined. It is conjectured that the latter galaxy has the properties of an Sy2 type galaxy. The electron densities and masses of the gaseous components are found for 15 galaxies, along with the masses of 8 galaxies for which the ratio M/L has been calculated. It is shown that the spectral structures of these galaxies do not depend on whether they are members of physical systems or are isolated. 相似文献
6.
G. Hasinger J.-U. Fischer A. D. Schwope T. Boller J. Trümper W. Voges 《Astronomische Nachrichten》1997,318(6):329-334
We have selected a complete, flux-limited sample of bright point-like sources with absorbed X-ray spectra from the ROSAT All-Sky survey, the ROSAT Hard Survey (RHS). The sample is drawn from the high-galactic latitude sky, |bII| > ±30°, and avoids the general direction of the Magellanic Clouds and the Virgo Cluster. It comprises a total of 182 objects of which 118 were previosly catalogued objects and 64 were new AGN candidates. Through optical follow-up studies at La Silla, Calar Alto and the 6m Zelentchuk telescope we could identify 56 of the new objects, thus achieving a spectrscopic completeness of 96% of the sample. The selection strategy turned out to be extremely useful. Out of the new identifications, 84% are indeed active galaxies or emission line galaxies. While 14 objects are new BL Lac candidates 33 of the new AGN are Seyfert galaxies with a redshift distribution in the range 0.021–0.63, peaking at around 0.06, i.e. relatively local. Surprisingly, about 40% of the X-ray selected Seyfert galaxies seem to reside in interacting systems. With smaller selection uncertainties this fraction exceeds the number of paired galaxies in optically selected samples and therefore gives strong support to the idea that AGN activity is triggered by interaction. 相似文献
7.
Matthew Middleton Chris Done Nick Schurch 《Monthly notices of the Royal Astronomical Society》2008,383(4):1501-1505
The Unified Model of active galactic nuclei (AGN) predicts that the sole difference between type 1 and 2 Seyfert galaxies nuclei is the viewing angle with respect to an obscuring structure around the nucleus. High-energy photons above 20 keV are not affected by this absorption if the column is Compton thin, so their 30–100 keV spectra should be the same. However, the observed spectra at high energies appear to show a systematic difference, with type 1 Seyfert galaxies having Γ∼ 2.1 whereas type 2 Seyfert galaxies are harder with Γ∼ 1.9. We estimate the mass and the accretion rate of Seyferts detected in these high-energy samples, and show that they span a wide range in L / L Edd . Both black hole binary systems and AGN show a correlation between spectral softness and Eddington fraction, so these samples are probably heterogeneous, spanning a range of intrinsic spectral indices which are hidden in individual objects by poor signal-to-noise ratio. However, the mean Eddington fraction for the type 1 Seyfert galaxies is higher than for the type 2 Seyfert galaxies, so the samples are consistent with this being the origin of the softer spectra seen in type 1 Seyfert galaxies. We stress that high-energy spectra alone are not necessarily a clean test of Unification schemes, but that the intrinsic nuclear properties should also change with L / L Edd . 相似文献
8.
Hubble Space Telescope Wide Field Planetary Camera 2 observations of hyperluminous infrared galaxies
D. Farrah A. Verma S. Oliver M. Rowan-Robinson R. McMahon 《Monthly notices of the Royal Astronomical Society》2002,329(3):605-619
We present Hubble Space Telescope Wide Field Planetary Camera 2 I -band imaging for a sample of nine hyperluminous infrared galaxies (HLIRGs) spanning a redshift range . Three of the sample have morphologies showing evidence for interactions and six are quasi-stellar objects (QSOs). Host galaxies in the QSOs are detected reliably out to . The detected QSO host galaxies have an elliptical morphology with scalelengths spanning and absolute k -corrected magnitudes spanning There is no clear correlation between the infrared (IR) power source and the optical morphology. None of the sources in the sample, including F15307+3252, shows any evidence for gravitational lensing. We infer that the IR luminosities are thus real. Based on these results, and previous studies of HLIRGs, we conclude that this class of object is broadly consistent with being a simple extrapolation of the ULIRG population to higher luminosities; ULIRGs being mainly violently interacting systems powered by starbursts and/or active galactic nuclei. Only a small number of sources, the infrared luminosities of which exceed 1013 L⊙ , are intrinsically less luminous objects that have been boosted by gravitational lensing. 相似文献
9.
Recent spectroscopic observations of galaxies in the Fornax-Cluster reveal nearly unresolved ‘star-like’ objects with red-shifts
appropriate to the Fornax-Cluster. These objects have intrinsic sizes of ≈ 100 pc and absolute B-band magnitudes in the range
- 14 < MB < -11.5 mag and lower limits for the central surface brightness μB ≥ 23 mag/arcsec2 (Phillipps et al., 2001, Hilker et al., 1999), and so appear to constitute a new population of ultra-compact dwarf galaxies
(UCDs). Such compact dwarfs were predicted to form from the amalgamation of stellar super-clusters (= clusters of star clusters;
not to confuse with super stellar clusters (SSC)) by P. Kroupa (1998), which are rich aggregates of young massive star clusters
(YMCs) that can form in collisions between gas-rich galaxies. Here we present the evolution of super-clusters in a tidal field.
The YMCs merge on a few super-cluster crossing times. Super-clusters that are initially as concentrated and massive as Knot
S in the interacting Antennae galaxies (Whitmore et al., 1999) evolve to merger objects that are long-lived and show properties
comparable to the newly discovered UCDs.
This revised version was published online in September 2006 with corrections to the Cover Date. 相似文献
10.
We report on the results of cross-correlation of a sample of 903 Utraluminous IRAS galaxies (ULIRGs) with the ROSAT-All Sky Survey Bright Source Catalogue and the ROSAT archived pointing observations. The sample of ULIRGs has been compiled from the recently released PSCz redshift survey. In total,35 ULIRGs are securely detected by the ROSAT All-Sky Survey and pointing observations, five of which are blazars. The statistical properties of these sources in the soft X-ray band are determined and compared with their properties on other wavebands. We find that the ratio of the soft X-ray to the far-infrared flux spans about five orders of magnitude and reaches values of about unity. This ratio is a good indicator of the main energy source of ULIRGs. Those with soft X-ray to far-infrared flux exceeding 0.01 are probably powered by accretion onto central supermassive black holes while those with ratios smaller than 0.001 are probably powered by starbursts or other heating processes, or are Compton thick sources. Some ULIRGs have energy contributions from both. This ratio is low for most ULIRGs and hyperluminous infrared galaxies, which explains their low detection rate by ROSAT and ASCA.We also find that some ULIRGs have a similar soft X-ray luminosity vs. temperature relation to that for groups of galaxies and elliptical galaxies,suggesting a common origin of these systems. Our study also reveals a tight correlation between the hardness ratio and the soft X-ray luminosity for Seyfert 1s/QSOs. 相似文献
11.
R. A. Kandalyan 《Astrophysics》2005,48(1):99-110
Radio observations with the VLA-A radio telescope of 30 OH megamaser galaxies at a frequency of 1.49 GHz are discussed. Radio emission was detected from all 30 of these galaxies. Radio emission was detected from 5 of the 30 objects for the first time. Important results were obtained for 12 galaxies that had previously been little studied in the radio continuum. Additional data at 1.49 GHz were obtained for the remaining 13 objects. The core component of the continuum radio emission predominates in the OH megamaser galaxies.Translated from Astrofizika, Vol. 48, No. 1, pp. 125–138 (February 2005). 相似文献
12.
I. S. Glass 《Astrophysics and Space Science》1995,230(1-2):215-223
The term Active Galactic Nuclei includes QSOs (Quasi-Stellar Objects), Seyfert galaxies, BL Lac objects and nuclei showing unusual amounts of star formation. South African work has centred on the photometric properties of these objects, both in the optical(UBVRI) and the infrared(JHKL). Photometry has been used to investigate the nature of the relevant emission mechanisms by studying both the colours of the nuclear components and their variations. In particular, it has been demonstrated convincingly that circumnuclear dust shells are present in several Seyfert 1 galaxies at temperatures of around 1500 K.It has also been shown that the variable component in many Seyfert 1 galaxies retains a constant spectral shape independent of its actual flux at a given time. Further, there is evidence that this shape is largely the same in all Seyfert 1 galaxies. Other studies have concentrated on surveys of morphological, spectroscopic and photometric characteristics of certain classes of galaxies such as those found by the IRAS satellite and those listed in the Arp-Madore catalogue of interacting galaxies. 相似文献
13.
The sample of Byurakan–IRAS galaxies (BIG) has been created based on optical identifications of IRAS Point Source Catalog (PSC) at high galactic latitudes. As a result, 1178 galaxies have been identified. 172 of them have been observed spectroscopically with Byurakan Astrophysical Observatory (BAO, Armenia) 2.6 m, Special Astrophysical Observatory (SAO, Russia) 6m and Observatoire de Haute Provence (OHP, France) 1.93 m telescopes. Later on, spectra were obtained for more 83 BIG objects in Sloan Digital Sky Survey (SDSS). We have extracted and studied these spectra, classified them and measured spectral features. Diagnostic diagrams have been built to distinguish starbursts (SB), LINERs and Seyfert galaxies. Cross-correlations weremade for these objects with multiwavelength (MW) catalogues and their physical properties were studied. Among these 83 objects, 55 HII, 8 Seyfert galaxies, 2 LINERs, 4 other AGN, 6 composite spectrum objects, and 8 other emission-line galaxies have been revealed. Three of these objects are Ultra-Luminous InfraRed Galaxies (ULIRG). 相似文献
14.
《New Astronomy Reviews》2000,44(7-9):551-553
Broad infrared spectra (7–200 μm) of four NLS1 galaxies, obtained with the imaging photo-polarimeter (ISOPHOT) on board the Infrared Space Observatory (ISO), are presented. The infrared luminosities and temperatures, opacities and sizes of the emitting dust components are derived. A comparison between the observed infrared spectra and the optical emission line fluxes of a sample of 16 NLS1 galaxies suggests that these objects suffer different degrees of dust absorption according to the inclination of the line of sight with respect to the dust distribution. 相似文献
15.
Based on spectropolarimetric observations Seyfert 2 (Sy2) galaxies are generally divided into two populations. Some Sy2s show polarized broad emission lines (PBLs) which is an evidence for the hypothesis of the Unified model while others do not. In order to determine the properties of these two apparently different populations we compiled a sample of 66 Sy2 objects with and without detected PBLs. We used a (J − H) − (H − Ks) diagram based on 2MASS J, H, Ks magnitudes in 14 arcsec aperture, the F[OIII] emission line flux and the infrared emission flux FKs using the Ks filter. From the (J − H) − (H − Ks) diagram we determined that one third of the Sy2 objects with PBLs have a power-law infrared component which could be a result of both a non-thermal AGN component scattered by free electrons (or dust) and emission from hot dust near its sublimation temperature. The rest of the objects (with PBLs) are significantly dominated by a dust thermal re-emission. The Sy2s without PBLs show infrared emission dominated by a host galaxy stellar component and also by thermal dust re-emission. The Sy2s with PBLs tend to have a few times larger L[OIII] luminosities than those without. Following the median values of F[OIII]/FKs, it seems that this ratio is sensitive enough to separate our sample of Sy2 galaxies into two types - with and without PBLs. There are no Sy2s with PBLs having Eddington ratio below 10−3 which confirms the results of Nicastro et al. (2003). 相似文献
16.
P. Augusto J. I. Gonzalez-Serrano A. C. Edge N. A. B. Gizani P. N. Wilkinson I. Perez-Fournon 《New Astronomy Reviews》1999,43(8-10)
We are conducting a multi-wavelength (radio, optical, and X-ray) observational campaign to classify, morphologically and physically, a sample of 55 flat-spectrum radio sources dominated by structure on kpc-scales. This sample contains 22 compact-/medium-sized symmetric object candidates, a class of objects thought to be in the early stages of the evolution of radio galaxies. The vast majority of the remaining objects have core-plus-one-sided-jet structures, half of which show sharply bent jets, probably due to strong interactions with the interstellar medium of the host galaxies. Once the observational campaign is completed, we will constrain evolutionary theories of radio galaxies at their intermediate stages and possibly understand the physics of the hypothesised narrow-line region in active galactic nuclei, given our advantageous statistical position. 相似文献
17.
E. L. Karapetyan 《Astrophysics》2006,49(3):299-305
Spectral observations of 19 galaxies with UV-excesses from Kazarian’s list are reported. The spectra were obtained with the
2.6-m telescope at the Byurakan Observatory using the SCORPIO spectral camera. A grism was used to obtain spectra in the wavelength
interval λλ7420-3920 Å. 43 spectra in which emission lines are mainly observed were obtained from the 19 galaxies, except
for the spectra of Kaz 21, Kaz 178, Kaz 183, and Kaz 184. The spectra of Kaz 17, Kaz 151, Kaz 153, and Kaz 357 have type Sy2
galactic features. In the spectra of the galaxies Kaz 17, Kaz 151, and Kaz 153, absorption lines are observed along with high
excitation emission lines such as HeI λ5876 Å and HeII λ4686 Å. No lines were observed within the interval λλ7420-3920 Å in
the spectra of the galaxies Kaz 183 and Kaz 184.
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Translated from Astrofizika, Vol. 49, No. 3, pp. 351–358 (August 2006). 相似文献
18.
利用SDSS光谱,研究了IRAS卫星亮红外源星表中的盘状星系中的恒星形成性质,并着重探讨了棒对星系核区恒星形成活动的影响.利用星族合成的方法得到了每个样本星系核区的恒星组成性质、恒星形成活动的强度等信息,并比较了星系整体和核区恒星形成性质的差异.得到的结论:除去相互作用,样本中的棒星系显示出比非棒旋星系更强的核区恒星形成活动和更多的年轻星族成分. 相似文献
19.
Eline Tolstoy 《Astrophysics and Space Science》2003,284(2):579-588
The smallest dwarf galaxies are the most straight forward objects in which to study star formation processes on a galactic
scale. They are typically single cell star forming entities, and as small potentials in orbit around a much larger one they
are unlikely to accrete much (if any) extraneous matter during their lifetime (either intergalactic gas, or galaxies) because
they will typically lose the competition with the much larger galaxy. We can utilise observations of stars of a range of ages
to measure star formation and enrichment histories back to the earliest epochs. The most ancient objects we have ever observed
in the Universe are stars found in and around our Galaxy. Their proximity allows us to extract from their properties detailed
information about the time in the early Universe into which they were born. A currently fashionable conjecture is that the
earliest star formation in the Universe occurred in the smallest dwarf galaxy sized objects. Here I will review some recent
observational highlights in the study of dwarf galaxies in the Local Group and the implications for understanding galaxy formation
and evolution.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
20.