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1.
星系自转曲线测定对星系天文学研究有着重要的意义。现已发现,除旋涡星系外,其他类别的河外星系也有自转运动,但自转曲线的特征有所不同。自转曲线研究的内容颇为丰富,如是否存在普适自转曲线,星系团环境对成员星系运动特征的可能影响,星系物质转动速度的垂向梯度问题,以及星系中暗物质的分布等,对上述内容做了相关评述。 相似文献
2.
唐泽眉 《中国天文和天体物理学报》1984,(1)
观测指出,盘状星系有两个主要组成部分,中心椭球和外盘.在早型的以发光天体为主体的盘状星系中,根据光度分布规律可以得到面密度分布.本文根据中心具有核球的盘状星系面密度分布曲线和旋转曲线,用数值方法求解流体力学方程组和泊松方程,得出盘状星系中心区域的三维质量分布和弥散速度分布.结果表明,盘状星系的中心椭球为一高密度区,此区中的恒星或星团与椭圆星系的成员具有近似的动力学特征.这些结果与观测是一致的. 相似文献
3.
本文通过数值计算解出稳态星系模型，并与椭圆星系及旋涡星系核球的自转和弥散速度曲线相比较。由星系运动曲线传合出的星系半径与从光度曲线拟合出的潮汐半径不一致，后者总是前者的３倍左右，这是由于分布函数的截断方式不妥造成的。我们的结论是：该模型虽不能正确描述整个星系，但却能正确描述星系的较内部区域。我们分析了三个速度曲线资料的星系黑洞候选者：Ｍ１０４、Ｍ３１和银河系，发现它们由于有太快的自转，都不可能在达 相似文献
4.
Tully-Fisher关系和重子Tully-Fisher关系(简称TFR和BTFR)反映盘星系光度(重子物质质量)与气体旋转速度之间的关系。TFR和BTFR不仅是宇宙中重要测距工具,还是检验宇宙学模拟正确性的重要标尺。早期人们用各种波段的光度研究TFR,其中I与R波段弥散最小;后来的工作也采用星系恒星质量与旋转速度的关系。相比于TFR,BTFR具有弥散更小、适用范围更广的优点。星系旋转速度研究上,干涉阵望远镜相对于单天线的主要优势包括能得到更高的空间分辨率和速度场,再借助倾斜环模型能将中性氢运动特征参数化;而像FAST这样的大口径单天线望远镜,由于灵敏度高,在探测超弥散星系(UDG)等暗弱源候选体方面有优势。除综述研究进展以外,还初步研究了大质量星系BTFR受气体含量的影响。 相似文献
5.
6.
本文通过数值计算解出稳态星系模型，并与椭圆星系及旋涡星系核球的自转和弥散速度曲线相比较。由星系运动曲线拟合出的星系半径与从光度曲线拟合出的潮汐半径不一致，后者总是前者的３倍左右，这是由于分布函数的截断方式不妥造成的。我们的结论是：该模型虽不能正确描述整个星系，但却能正确描述星系的较内部区域，我们分析了三个有速度曲线资料的星系黑洞候选者：Ｍ１０４、Ｍ３１和银河系，发现它们由于有太快的自转，都不可能在达到稳态之后有满足形成黑洞所要求的≡ｃＪ／ＧＭ２＜１的区域存在，因此它们的中心如有黑洞，只能有更早的起源。 相似文献
7.
本文通过十三个星系的旋转曲线数据,对Ｍｏｆａｔ不对称引力理论中的两个宇宙普适常数ｒ０,Ｌ０进行了检验与讨论,发现在原来假定下,这两个常数的离散程度很大．如果摒弃所有星系质光比都为３的假定,重新确定ｒ０,Ｌ０的值并调整星系质光比的值,则可与观测数据符合得较好,且调整后的星系质光比的值沿着哈勃序列有减小的趋势．这符合许多人早就得到的结论,因而不对称引力理论在这个意义下是成功的． 相似文献
8.
《天文学进展》2018,(4)
星系棒的图案速度(或转动角速度)是棒旋星系的一个最重要的动力学参量。棒的图案速度?_(bar)的测量并不容易。目前直接测量?_(bar)的唯一方法是Tremaine和Weinberg (TW)在1984年提出来的。他们假设星系中示踪源的表面亮度满足连续性方程,即可利用示踪源的测光学和运动学参量推导出?_(bar)。详细介绍了TW方法,整理了文献中?_(bar)的测量结果,并讨论了测量过程中的误差来源。目前学术界利用老年恒星、中性氢气体H I、分子氢气体H_2,以及离化氢气体Hα作为示踪源,测量了大约50个星系的图案速度,并结合?_(bar)和星系自转曲线得到共转半径RCR。通过比较RCR和棒长a_(bar)发现,大部分星系棒都是快速旋转的(1≦RCR/a_(bar)≦1.4)。极少部分星系棒慢速旋转,并且这些棒似乎都位于由暗物质主导的星系中。同时也有研究声称发现了一些超快旋转的棒,但目前理论上无法解释它们,也无法确定它们的?_(bar)是否可靠,或是否由于违反了TW方法的某些条件而导致测量结果不准确。由于已有的测量样本太小,并偏向于早型星系,人们暂未发现图案速度与星系类型及星系棒性质之间的关系,但人们认为,星系棒的图案速度有可能与星系中暗物质的分布有关。积分视场光谱仪(integral field unit, IFU)巡天数据在测量?_(bar)上有着独特的优势。随着IFU数据的普及,未来将有更多的TW测量结果来检验这些结论。 相似文献
9.
Chandrasekhar等和Sunder等讨论了具有局部各向同性速度分布的旋转椭球星系的短期（远小于哈勃时间）演化,本文运用Laskar的频率分析方法研究这种星系的长期（大于哈勃时间）演化．得到的新结论主要有：（1）这种星系存在唯一的平衡态（球对称平衡态）,它是临界线性稳定的;（2）其半轴一般在平衡态的半径邻近作拟周期或近拟周期（这种近似在远大于哈勃时间后仍可行）振动,从而是长期稳定的;（3）存在一个半轴趋于零,另一个半轴趋于有限值的情形,且一般趋于零的是对称轴的轴长（从而星系趋于扁平）,这意味着某些盘星系可能来源于具旋转棉球构形的星系前物质． 相似文献
10.
本文讨论在考虑恒星速度椭球分布情形下旋涡星系的性质。由分析可知:旋涡星系的运动是恒星“气流”的紧卷旋涡式轴对称基本运动与密度波扰动的迭加,也即既有物质运动也有波的传播。当旋涡星系的旋臂为曳式时,它是旋闭的,并且恒星速度的椭球分布能导致星系密度波模式的不稳定。这种不稳定性提供了激发并维持星系密度波的一种机制,得以使且系旋臂长期维持。 相似文献
11.
In this paper, it is pointed out that if the spiral galaxy revolves about some common centre as a whole, the rotation curve will be changed by the kinematic effects. The common centre could be the centre of supercluster or the centre of dark matter and luminous matter.The kinematic effects on rotation curve are calculated. The additional velocity caused by revolving about the common centre is obtained. In case the direction of revolution is opposite (or consistent) to the direction of rotation, then in the outer region of nucleus, a flat rotation curve could be changed to a constant negative (or postive) gradient. The 44 rotation curves of Sb and Sc galaxies are expressed by means of linear least-squares fit, from which the period of revolving and the ratio of tidal force to self-gravitating force are calculated for every galaxy in extreme cases. The periods for most galaxies are in the reasonable region about 109 years. The tidal force is always less than gravitating force, so the system could be maintained in such a revolving cases. At last, rotation curves in all directions of disk are suggested to pick out the kinematic effects from pure rotation.Work supported by the National Science Foundation of China, under Grant No. 1860610. 相似文献
12.
Many attempts have been made to explain the flat rotation curve of spiral galaxies regardless of distance from the center, in disagreement with the Newtonian prediction that this speed should diminish as the inverse square of distance. One explanation for this discrepancy is that the galaxy is embedded in dark matter, which interacts with baryonic matter only gravitationally. Many studies have focused on finding the distribution of this dark matter that fits well with observed data, but it is by definition undetectable by current technology, and must therefore remain hypothetical. Instead of dark matter, we propose a novel force, named mirinae force, generated by the mass of relatively-moving particles, and demonstrate that this force explains the rotation curve and evolution of a galaxy in which some of the inner mass of the supermassive black hole at the galactic center is assumed to be revolving at a relativistic speed. The calculation yielded important results that support the existence of mirinae force and validate the proposed model: First, the mirinae force explains why most of the matter is in the galactic disk and in circular motion which is similar to that of particles in a cyclotron. Second, the mirinae force explains well both the flat rotation curve and the varied slope of the rotation curve observed in spiral galaxies. Third, at the flat velocity of 220 km/s, the inner mass of the Milky Way calculated by using the proposed model is 6.0×1011 M ⊙, which is very close to 5.5×1011 M ⊙ (r<50 kpc, including Leo I) estimated by using the latest kinematic information. 相似文献
13.
We present kinematic observations of NGC 3923, one of the best-known examples of an elliptical galaxy with shells. Although NGC 3923 has no rotation on its major axis, it has minor axis rotation with an amplitude of some 20 km s−1 out to 25 arcsec radius. This is possibily the result of a kinematically decoupled core, but we present arguments against this hypothesis, and if the core were formed by a merger, this must have been a different merger from that which gave rise to the shells. The minor axis rotation suggests that NGC 3923 is prolate or triaxial, at least in the inner region. A prolate geometry for the whole galaxy would favour the merger model over the interaction model for the shell formation mechanism. There is other evidence, however, that the shape of the underlying galaxy changes with radius, in which case it is possible that the minor axis rotation could be confined to the galaxy core. The kinematics could reflect a triaxial mass distribution, in which the long and short axes are aligned with the photometric major and minor axes, and the axial ratios change such that the galaxy is near-prolate in the inner regions and near-oblate at larger radii. Measuring the rotation curve to about double this radius along the minor axis, as well as offset from the nucleus along the major axis at the radius of the innermost shells, would enable the true extent of the minor axis rotation to be determined. 相似文献
14.
为了避开旧物质臂理论中旋臂的缠绕困难，本文提出了旋涡星系的循环假设，并在文中提供了旋涡星系的双臂、气体层反卷、银河系中旋臂物质径向向内的速度分量和棒旋星系中棒物质沿着棒向内的流动等观测证据，进而还尝试利用此循环假设去解释旋臂物质的平自转曲线和棒旋星系的棒结构等的成因。 相似文献
15.
Edvige Corbelli Paolo Salucci 《Monthly notices of the Royal Astronomical Society》2000,311(2):441-447
We present the 21-cm rotation curve of the nearby galaxy M33 out to a galactocentric distance of 16 kpc (13 disc scalelengths). The rotation curve keeps rising out to the last measured point and implies a dark halo mass ≳5×1010 M⊙ . The stellar and gaseous discs provide virtually equal contributions to the galaxy gravitational potential at large galactocentric radii, but no obvious correlation is found between the radial distribution of dark matter and the distribution of stars or gas.
Results of the best fit to the mass distribution in M33 picture a dark halo which controls the gravitational potential from 3 kpc outward, with a matter density which decreases radially as R−1.3 . The density profile is consistent with the theoretical predictions for structure formation in hierarchical clustering cold dark matter (CDM) models, and favours lower mass concentrations than those expected in the standard cosmogony. 相似文献
Results of the best fit to the mass distribution in M33 picture a dark halo which controls the gravitational potential from 3 kpc outward, with a matter density which decreases radially as R
16.
The velocity field in the galaxy Mark 8 is studied by means of observations with the 2.6-m telescope at the Byurakan Astrophysical
Observatory using the VAGR spectrograph. In the optical range, the central portion of this galaxy consists of five bright
condensations which are superassociations (SA). These studies were made in a wavelength range that encompasses images of the
galaxy in the Hα and [NII] λλ6548 and 6583Å emission lines. The radial velocity field was obtained. The velocities of all
the superassociations were measured and a rotation curve constructed for the galaxy. The relative intensities of the emission
lines have been determined. Images are constructed in the Hα and [NII] lines and in the red continuum. It is concluded that
the superassociations were formed together and are, as a whole, young. The shape of the rotation curve shows that Mark 8 is
an isolated galaxy with a composite multicomponent nucleus.
Translated from Astrofizika, Vol. 51, No. 4, pp. 543–553 (November 2008). 相似文献
17.
《New Astronomy Reviews》2002,46(12):791-799
The nature of the dark matter that binds galaxies remains an open question. It is usually assumed to consist in a gas of massive particles with evanescent interactions; however, such particles—which have never been observed directly—should have a clumpy distribution on scales ≤10−2 kpc, which may be in contradiction with observations. We focus here on an exotic dark matter candidate: a light non-interacting (or only self-interacting) complex scalar field. We investigate the distribution of the field in gravitational interaction with matter, assuming no singularities (like black holes) at the galaxy center. This simplistic model accounts quite well for the rotation curve of low-luminosity spirals. A chi-squared analysis points towards a preferred mass m∼0.4 to 1.6×10−23 eV in absence of self-interaction. A rough calculation shows that allowing for a quartic self-coupling may shift the upper bound to around 1 eV. We conclude that a scalar field is a promising candidate for galactic dark matter. Our comparison should be extended to other rotation curves in order to derive better constraints on the scalar potential. We finally give a hint of the issues that appear when one tries to implement this scenario on cosmological time scales. 相似文献
18.
A.M. Fridman O.V. Khoruzhii V.V. Lyakhovich V.S. Avedisova O.K. Sil'chenko A.V. Zasov A.S. Rastorguev V.L. Afanas'iev S.N. Dodonov J. Boulesteix 《Astrophysics and Space Science》1997,252(1-2):115-131
General ideas, as well as experimental and theoretical efforts concerning the prediction and discovery of new structures in the disks of spiral galaxies – giant anticyclones - are reviewed. A crucial point is the development of a new method to restore the full vector velocity field of the galactic gas from the line-of-sight velocity field. This method can be used to get self-consistent solutions for the following problems: 1) determination of non-circular velocities associated with spiral-vortex structure; 2) determination of fundamental parameters of this structure: pattern speed, corotation radius, location of giant anticyclones; 3) refinement of galactic rotation curves taking into account regular non-circular motion in the spiral density wave, which makes it possible to build more accurate models of the mass distribution in the galaxy; 4) refinement of parameters of the rotating gaseous disk: inclination angle, center of rotation and position angle of the major dynamical axis, systematic velocity. The method is demonstrated using the restoration of the velocity field of the galaxy NGC 157 as an example. Results for this and some other spiral galaxies suggest that giant anticyclones are a universal property of galaxies with grand design structure. 相似文献
19.
E. Pignatelli E. M. Corsini J. C. Vega Beltrán C. Scarlata A. Pizzella J. G. Funes S. J. W. W. Zeilinger J. E. Beckman F. Bertola 《Monthly notices of the Royal Astronomical Society》2001,323(1):188-210
We present V -band surface photometry and major-axis kinematics of stars and ionized gas of three early-type spiral galaxies, namely NGC 772, 3898 and 7782. For each galaxy we present a self-consistent Jeans model for the stellar kinematics, adopting the light distribution of bulge and disc derived by means of a two-dimensional parametric photometric decomposition. This allows us to investigate the presence of non-circular gas motions, and derive the mass distribution of luminous and dark matter in these objects.
NGC 772 and 7782 have apparently normal kinematics with the ionized gas tracing the gravitational equilibrium circular speed. This is not true in the innermost region (| r |≲8 arcsec) of NGC 3898, where the ionized gas is rotating more slowly than the circular velocity predicted by dynamical modelling. This phenomenon is common in the bulge-dominated galaxies for which dynamical modelling enables us to make the direct comparison between the gas velocity and the circular speed, and it poses questions about the reliability of galaxy mass distributions derived by the direct decomposition of the observed ionized-gas rotation curve into the contributions of luminous and dark matter. 相似文献
NGC 772 and 7782 have apparently normal kinematics with the ionized gas tracing the gravitational equilibrium circular speed. This is not true in the innermost region (| r |≲8 arcsec) of NGC 3898, where the ionized gas is rotating more slowly than the circular velocity predicted by dynamical modelling. This phenomenon is common in the bulge-dominated galaxies for which dynamical modelling enables us to make the direct comparison between the gas velocity and the circular speed, and it poses questions about the reliability of galaxy mass distributions derived by the direct decomposition of the observed ionized-gas rotation curve into the contributions of luminous and dark matter. 相似文献
20.
Per Olof Lindblad 《Astronomy and Astrophysics Review》1999,9(3-4):221-271
Summary. The aim of the present review is to give a global picture of the supergiant barred galaxy NGC 1365. This galaxy with its
strong bar and prominent spiral structure displays a variety of nuclear activity and ongoing star formation.
The kinematics of the galaxy has been mapped in detail by optical long slit and Fabry–Perot observations as well as radio
observations of Hi and CO interstellar lines. From these observations a combined velocity field has been derived, describing the circulation
of interstellar gas in the symmetry plane of the galaxy. With a gravitational potential based on near infrared photometry
of the bar and the shape of the apparent rotation curve, computer simulations of the dynamics of the interstellar gas have
been made with the aim to reproduce both the morphology of the interstellar matter as well as the observed velocity field.
The simulations demonstrate the role of the bar and the importance of resonances between the bar rotation and the rotation
of the galaxy for the formation of the spiral structure. Polarization of radio radiation reveals magnetic fields concentrated
to the dust lanes along and across the bar, where they are aligned with the flow pattern of the gas, and along the spiral
arms. The kinematics of the outer region of the galaxy with a fairly unique decline of the rotation curve leads to the conclusion
that NGC 1365 lacks a very massive dark matter halo, which may permit the formation of a very strong bar.
The galaxy contains an active nucleus with both broad and narrow components of the permitted spectral emission lines. The
nucleus is surrounded by a molecular torus, numerous star forming regions and continuum radio sources. The star forming regions
are, as seen with the Hubble Space Telescope (HST), resolved into a large number of super star clusters suggested to be young
globular clusters. A very compact radio source, seen at high spatial resolution with the Very Large Array (VLA), has been
claimed to coincide with one of the super star clusters. This compact source has a radio brightness of the order of 100 times
that of the bright galactic supernova remnant Cas A and is suggested to be a so called ‘radio supernova’. Two other such compact
radio sources, positioned in the prominent dark dust lane penetrating the nuclear region, are identified as strong infrared
sources by observations with the Very Large Telescope (VLT). The cause of this infrared radiation may be dust heated by the
objects that drive the radio sources.
The X-ray radiation from the nucleus is interpreted to consist of hard continuum radiation from the active nucleus itself,
Fe-K line emission from a rotating disk, and thermal emission from the surrounding star burst activity. A secondary, highly
variable source has been discovered close to the nuclear region. It seems to be one of the most luminous and most highly variable
off-nuclear X-ray sources known.
The higher excitation optical emission lines in the nuclear region, primarily from [Oiii], reveal a velocity field quite different from that described by the galactic rotation. The deviating [Oiii] morphology and velocity field in the nuclear region is interpreted in terms of a high excitation outflow double-cone with
its apex at the nucleus and symmetry axis perpendicular to the symmetry plane of the galaxy. One of the circumnuclear radio
sources seems to be a one-sided jet emerging from the nucleus aligned with the cone axis. According to the model, the outward
flow within the cone is accelerated and the flow velocity highest at the cone axis.
Received 15 January 1999 相似文献