Methanol Masers as Precursors of Gamma-Ray Sources

Methanol masers are known to be associated with regions of massive star formation. By studying the distribution of these masers with respect to unidentified EGRET sources, one may be able to identify regions of enhanced star formation leading to either supernova remnants and/or pulsars. In this study, we test for positional coincidences between class II methanol masers and EGRET sources and determine the statistical significance of these coincidences.     

A Rate-Independent Test for Solar Flare Sympathy

Solar flare sympathy is the triggering of a flare in one active region by a flare in another. Statistical tests for flare sympathy have returned varying results. However, existing tests have relied on flaring rates in active regions being constant in time, or else have attempted to model the rate variation, which is a difficult task. A simple test is described which is independent of flaring rates. The test generalizes the approach of L. Fritzová-Švestkova, R.C. Chase, and Z. Švestka [Solar Phys. 48, 275, 1976], and examines the distribution of flare coincidences in pairs of active regions as a function of coincidence interval τ. The test is applied to available soft X-ray and Hα flare event listings. The soft X-ray events exhibit a deficit of flare coincidences for τ≤;20 min, which is most likely due to an event-selection effect whereby the increased soft X-ray emission due to one flare prevents a second flare being identified. The Hα events show an excess of flare coincidences for τ≤; 10 min, suggesting flare sympathy. The number of Hα event pairs occurring within 10 min of one another is higher than that expected on the basis of random coincidence by a fraction 0.12± 0.02. Nearby active regions (spatial separation <50˚) show a greater excess of coincidences for τ≤; 10 min than do active regions which are far apart (spatial separation ≥50˚). However, the active regions which are far apart still show some evidence for an excess of coincidences at very short coincidence intervals (τ≤; 2 min), which appears to exclude the possibility of a coronal disturbance propagating from one region to another.     

Variations of the coupling constants of fundamental interactions in Dirac's cosmology

It is pointed out that several interesting coincidences and relationships connecting the parameters of cosmology and elementary particle physics suggest that the coupling constants of the weak, strong and electromagnetic interactions do not change with time in Dirac's cosmology. This would be consistent with the stringent limits imposed on their variation by recent data on isotopic abundances.     

On the relation of the large numbers problem to the nature of mass

The large numbers problem is usually stated in terms of coincidences between dimensionaless numbers of order 10⁴⁰, constructed from quantities arising in local physics on the one hand and cosmology on the other hand. The problem is usually thought of in terms of explaining these coincidences. In the Introduction it is shown that the coincidences are all derivative from the same source; namely, a multiplying constant of order 10^–38 which appears in the mass-gravitational physical action formula, when the latter is expressed in its most economical form as a single term. Thus the problem can be seen to arise from the smallness of this mass-gravity coupling rather than from coincidences which have no particular significance in themselves.A hint towards explaining the origin of this very small number arises already in the classical theory, but a proper understanding appears only in a quantum formulation. Such a formulation leads to a removal of 10^–38 from the action and to its replacement byg ², the strong coupling constant. In the outcome it turns out that the nucleon mass can be calculated to within about 15% of the experimentally-determined value of 938 MeV, a result which strongly supports the proposition that physics, even in its apparently most fundamental form, cannot be separated from cosmology. Cosmology is not simply an application of physics, as it is commonly supposed to be. Much of the great complexity of modern physics is probably due to attempting to formulate the basic laws in the absence of cosmology.     

A laboratory study of magnesium-tetrabenz-porphyrin; Lack of agreement with diffuse interstellar bands

We have measured the visible and infrared spectra and thermal behavior of the moleculebis-pyridal-magnesium-tetrabenz-porphyrin, the molecule proposed as the carrier of the diffuse interstellar bands. Of the six band coincidences reported by F. M. Johnson, only one, 4430 Å, occurs in our experiments. This coincidence requires a special environment, not likely in interstellar space. The infrared spectrum does not support Johnson's vibrational scheme. Our spectroscopic and thermal measurements contradict the hypothesis that this molecule causes the diffuse bands.     

ROSAT选射电源的性质：Ⅰ.样本

ＲＯＳＡＴ卫星的全天巡天观测到了一大批射电星系和各种活动星核,为我们研究这些活动性剧烈的河外天体的辐射机制、多波段辐射相关性以及各类星系核之间的演化联系提供了重要数据。通过将ＲＯＳＡＴ全天巡天观测与ＰＭＮ射电（５ＧＨｚ）巡天观测进行交叉证认,我们得到了６４２颗天射电源。对这些对应体随后进行的光学证认构建了一个星系和活动星系核的大样本。其中３１１个对应体（占５２％）被过去的光学观测证实为河外天体（包     

A systematic cross-search for radio/infrared counterparts of XMM-<Emphasis Type="Italic">Newton</Emphasis> sources

We present a catalog of cross-correlated radio, infrared and X-ray sources using a very restrictive selection criteria with an IDL-based code developed by us. The significance of the observed coincidences was evaluated through Monte Carlo simulations of synthetic sources following a well-tested protocol. We found 3320 coincident radio/X-ray sources with a high statistical significance characterized by the sum of error-weighted coordinate differences. For 997 of them, 2MASS counterparts were found. The percentage of chance coincidences is less than 1%. X-ray hardness ratios of well-known populations of objects were used to provide a crude representation of their X-ray spectrum and to make a preliminary diagnosis of the possible nature of unidentified X-ray sources. The results support the fact that the X-ray sky is largely dominated by Active Galactic Nuclei at high galactic latitudes (|b|≥10°). At low galactic latitudes (|b|≤10°) most of unidentified X-ray sources (∼94%) lie at |b|≤2°. This result suggests that most of the unidentified sources found toward the Milky Way plane are galactic objects. Well-known and unidentified sources were classified in different tables with their corresponding radio/infrared and X-ray properties. These tables are intended as a useful tool for researchers interested in particular identifications.     

The quasar PKS 0237-233: Chance coincidences and the alleged co redshift systems

It is shown that the number of redshifted CO absorption-line systems which are found in the spectrum of the quasar PKS 0237-233, using the rules of Varshalovich and Levshakov (1981), differ insignificantly from that that would be expected from chance coincidences. Consequently, the CO systems proposed by Varshalovich and Levshakov have no physical reality.     

Optical identification of QSOs with flat radio spectrum

Preliminary results of a program to identify optically a sample of flat spectrum radio sources are described. The identifications are based only on positional coincidences, and have yielded at least one object with a very high redshift.Paper presented at the IAU Third Asian-Pacific Regional Meeting, held in Kyoto, Japan, between 30 September–6 October, 1984.     

Chance coincidences and the so-called redshift systems in the absorption spectrum of PKS 0237-23

It is shown that the number of redshift systems based on Civ doublets, proposed by Borosonet al. (1978) in the absorption spectrum of the quasar PKS 0237-23, is insignificantly different from that that would be expected from chance coincidences. Consequently, these systems and theirz-values appear to be devoid of any physical significance.     

Common lines in the rest-frame absorption-line spectra of QSOs?

Libbyet al. (1984) have studied the absorption-line data for 13 QSOs in the rest-frames of the QSOs. It is shown that the number of groups in which 5 lines or more lie within a wavelength interval of 1.0 Å found by these authors is insignificantly different from that that would be expected from chance coincidences. Consequently, there is no evidence that the rest-frame wavelengths at which these groups occur have any special significance.     

A search for astrophysical burst signals at the Sudbury Neutrino Observatory

The Sudbury Neutrino Observatory (SNO) has confirmed the standard solar model and neutrino oscillations through the observation of neutrinos from the solar core. In this paper we present a search for neutrinos associated with sources other than the solar core, such as gamma-ray bursts and solar flares. We present a new method for looking for temporal coincidences between neutrino events and astrophysical bursts of widely varying intensity. No correlations were found between neutrinos detected in SNO and such astrophysical sources.     

The flare-related depression of the noise storm on May 5, 1978

Though a number of flares is capable to trigger the emission of a noise storm, in some other rare cases flares may also lead to a depression of the radio flux of a pre-existing noise storm. Details of this phenomenon are demonstrated at the flare of May 5, 1978 which can be regarded as an instructive example. Using extensive observations during the solar cycle No. 20 a number of further noise storm depressions could be detected whereas chance coincidences with flares could be ruled out by a statistical treatment. Possible mechanisms related to the noise storm depression effect are briefly discussed.     

An evolutionary feature of the magnetic field related to flares in active regions

Wavelength coincidences are noted between laboratory and solar spectral line lists for the twenty-electron ions CaI, TiIII, CrV, MnVI, FeVII, and NiIX, which imply likely identifications for a large number of unidentified lines in the solar lists. These identifications should be useful, e.g., for improving chromospheric/coronal abundance estimates of the less abundant elements titanium, chromium, and manganese.     

The Cygnus X region XXI. Radio emission at 1420 MHz from Cyg OB2 stars and two probable cometary HII regions

We have searched our previously published radio surveys of the Cygnus X region for faint radio point sources that may be associated with luminous stars of the Cyg OB2 association. Five positional coincidences have been found between stars and 1420 MHz radio sources. A particularly interesting example is the Wolf-Rayet star VCLS 146, which has shown a rapid change in 1420 MHz flux density. In addition, sensitive upper limits have been derived for the emission from 14 early-type stars, which help establish the time history of their non-thermal radio emission. Two radio features have been detected which have the properties of cometary HII regions, except that they are several arcminutes in size. Their detection provides evidence of recent star formation in Cyg OB2.     

Comparison of unidentified absorption lines of quasar spectra with unidentified lines of stellar spectra

Conclusions Thus, we have considered the possibility of comparing unidentified lines of quasar spectra with unidentified lines of stellar spectra. Since the majority of absorption lines in the spectrum of Oph have wavelength shorter than 1000 Å, a comparison could be made in practice only with the absorption lines of Pup. Significant excesses in the number of coincidences over the mean level were not found, but in the case of the quasar 2351–154 the number of such coincidences within the reliable system is somewhat higher than for the other spectra. It is interesting that all the lines in the spectrum of this quasar that we distinguished belong to the unidentified lines.Of course, such comparison of the absorption lines of quasar spectra and the lines of stellar spectra can be regarded only as a weak attempt to win back in the L forest at least some lines for the absorption systems. However, for more distant absorption systems that could possibly be detected this method could play a more important part.Institute of Cosmic Research, USSR Academy of Sciences. Translated from Astrofizika, Vol. 38, No. 1, pp. 27–33, January–February, 1989.     

Soft gamma-ray bursts from the superluminal source GRS 1915+105?

The power required to eject relativistic plasma clouds in the hard X-ray transient GRS 1915+105 is at least 100 times the luminosity of the soft-ray bursts (SGRs) that were observed by BATSE from the same region of the sky in the year 1992. We show that there are spatial, time, and spectral coincidences between GRS 1915+105 and the SGRs observed by BATSE which suggest that they are one and the same source. However, the position of the SGRs is rather uncertain and until better positions are obtained, the question on the association of GRS 1915+105 with the SGRs must remain open.     

Testing isotropy of cosmic microwave background radiation

We introduce new symmetry-based methods to test for isotropy in cosmic microwave background (CMB) radiation. Each angular multipole is factored into unique products of power eigenvectors, related multipoles and singular values that provide two new rotationally invariant measures mode by mode. The power entropy and directional entropy are new tests of randomness that are independent of the usual CMB power. Simulated Galactic plane contamination is readily identified. The ILC– WMAP data maps show seven axes well aligned with one another and the direction Virgo. Parameter free statistics find 12 independent cases of extraordinary axial alignment, low power entropy, or both having 5 per cent probability or lower in an isotropic distribution. Isotropy of the ILC maps is ruled out to confidence levels of better than 99.9 per cent, whether or not coincidences with other puzzles coming from the Virgo axis are included. Our work shows that anisotropy is not confined to the low l region, but extends over a much larger l range.     

Longitudinal and temporal variations of sunspot regions and coronal holes during Cycle 21

The relationship between sunspot activity in heliographic longitude and coronal holes is investigated for the period corresponding to Cycle 21 (Carrington rotations 1623–1779). The major result is that, based on He i 10830 Å data, a strong inverse association is found between the longitudinal positions of sunspot groups and the size and number of coronal holes (especially, the equatorial extensions of polar holes). Frequencies of coincidences in longitude were determined for both types of activity and the evolution of coronal holes over Cycle 21 is depicted in the form of a butterfly diagram displaying their latitudinal and longitudinal extents. A tabular listing identifies average longitude and persistence of sunspot active longitudes.     

Modulation of the Solar Magnetic Cycle

The modulation model of the solar magnetic cycle for the time interval from 1650 to 1996 A.D. describes an harmonic oscillator with a basic (22.13 ± 0.05)-yr period, which is subjected to amplitude and phase variations that can be represented by a sum of trigonometric series. The simulated sunspot data explain 97.9% of cycle peak height variance and the residual standard deviation is 8.6 mean annual sunspots. A peak height of 139 for cycle 23 occurring in 2001 is predicted, whereas cycle 24 would have a maximum around 132 in 2014. Simulation of the sunspot numbers from 1000 until 2400 A.D. shows that the model recreates recurring minima (Maunder and Spörer Minimum). The prediction also expects a high level of amplitude modulation in the interval 1950–2010 with a rapid decrease afterwards. A greatly reduced cycle activity is reproduced by the simulation from about 2065 to 2100 A.D. No direct explanation of the long-term periodicities of the model can be advanced. The high-frequency contribution of the phase modulation, which accounts for the skewness of the solar cycle, shows coincidences with the orbital periods of Jupiter and Saturn, but no physical basis for the matching periodicities can be conceived.