检索结果-南通市图书馆

Kinematic Decoupled Core Paradigm: Counterrotation or Just Warping

International Journal of Astronomy and Astrophysics 2016年第2期6卷 198-205页

作者： Rubén J. Díaz horacio dottori ICATE CONICET San Juan Argentina Gemini Observatory La Serena Chile Instituto de Física UFRGS Porto Alegre Brazil

Several mechanisms have been proposed in recent years to explain kinematic decoupled cores (KDCs) in early type galaxies as well as the large differences in angular momentum between KDCs and host galaxy. Most of the proposed scenarios involve large fractions of merging events, high speed interactions with dwarf spheroidal galaxies, cusp effect of the dark matter density profiles, etc. We here argue that counterrotation as well as fast and slow rotation of disks or spheroids at the center of galaxies can also be explained by a misalignment of the central spheroid equatorial plane with regard to that defined by the observed external stellar rotation. Contrary to what happens at the outer region of disk galaxies, once instability has led to the inner warped core, the perturbed orbits can maintain a common orientation due to the rigid body like rotation at the central region of the galaxy. The spatial configuration that furnishes the smallest angular momentum difference between the KDC and the host galaxy is completely defined by observed parameters in the plane of the sky, namely, the inclination of the inner and outer disks and the angle between the two lines of nodes. As an example we modeled the paradigmatic and extreme case of the 2D radial velocity field of NGC 4382 nucleus. Tilt angles of the KDC not larger than 30 degrees also allow explaining fast and low rotators of the called “Sauron paradigm” in a unified scenario. The maximum for the three parameters, namely, velocity of the inner rotator, difference of position angle and difference with the outer rotation velocity of the whole Sauron sample, are consistently correlated in agreement with the proposed scenario. These quantities do not correlate with the galaxies magnitude, mass (since large and dwarf spheroidals show apparent counterrotation as well) or environment, also suggesting that an internal phenomenon like the central spheroid warping, that we are here proposing, may be at work.

关键词： Galaxies Disks Counterrotation Inner Warps Kinematics

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Modeling the Black Hole Recoil from the Nucleus of M83

引用

Journal of Modern Physics 2013年第7期4卷 55-63页

作者： Guilherme G. Ferrari horacio dottori Rubén J. Díaz ICATE-CONICET San Juan Argentina Instituto de Física Universidade Federal do Rio Grande do Sul Porto Alegre Brazil

GEMINI + GMOS and Chandra emission-line spectroscopy reveal that the Fanaroff-Riley II radio-source J133658.3-295105 is a local object behind the barred-spiral galaxy M83 that is projected onto the galaxy’s disk at about 60' from the galaxy’s optical nucleus. J133658.3-295105 and its radiolobes are aligned with the optical nucleus of M83 and two other radio-sources neither of which are supernova remnants or HII regions. The optical nucleus of M83 is off-centered by 2.7' (≈60 pc) with regard to the kinematic center. Its mass is within the range (1 -4) × 106 and the velocity dispersion at its center points to a non-resolved mass concentration of ≤106 . In this paper we study the circumstances in which the radio source would have been ejected from the central region of M83. We analyze different types of collisions of binary and triple systems of super-massive black holes (SMBHs) by numerical simulations using a Post-Newtonian approximation of order 7/2 (~1/c7). We developed an N-body code specially built to numerically integrate the Post-Newtonian equations of motion with a symplectic method. Numerical experiments show that the code is robust enough to handle virtually any mass ratio between particles and to follow the interaction up to a SMBH separation of three Schwarzschild radii. We show that within the current Post-Newtonian approximation, a scenario in which one of the three SMBHs suffers a slingshot-like kick is best suited to explain the ejection of J133658.3-295105, which simultaneously produces the recoil of the remaining BH pair, which drags together a subset of stars from the original cluster forming a structure that mimics the off-center optical nucleus of M83. The simulation parameters are tuned to reproduce the velocities and positions of J133658.3-295105 as well as the optical nucleus and the putative SMBH at its center.

关键词： Galaxies Nuclei Dynamics Black Holes Interaction Kick-Off

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Nuclear Activity in Circumnuclear Ring Galaxies

引用

International Journal of Astronomy and Astrophysics 2016年第3期6卷 219-235页

作者： María P. Agüero Rubén J. Díaz horacio dottori Observatorio Astronómico de Córdoba UNCand CONICET Córdoba Argentina ICATE CONICET San Juan Argentina Gemini Observatory La Serena Chile Instituto de Física UFRGS Porto Alegre Brazil

We have analyzed the frequency and properties of the nuclear activity in a sample of galaxies with circumnuclear rings and spirals (CNRs), compiled from published data. From the properties of this sample a typical circumnuclear ring can be characterized as having a median radius of 0.7 kpc (mean 0.8 kpc, rms 0.4 kpc), located at a spiral Sa/Sb galaxy (75% of the hosts), with a bar (44% weak, 37% strong bars). The sample includes 73 emission line rings, 12 dust rings and 9 stellar rings. The sample was compared with a carefully matched control sample of galaxies with very similar global properties but without detected circumnuclear rings. We discuss the relevance of the results in regard to the AGN feeding processes and present the following results: 1) bright companion galaxies seem not to be important for the appearance of CNRs, which appear to be more related to intrinsic properties of the host galaxies or to minor merger processes;2) the proportion of weak bars in galaxies with a CNR is higher than expected;3) the incidence of Seyfert (Sy) activity coeval with CNRs is significantly larger than the rate expected from the morphological distribution of the host galaxies;4) the rate of Sy 2 to Sy 1 type galaxies with CNRs is about three times larger than the expected ratio for galaxies without CNRs and is opposite to that predicted by the geometric paradigm of the classical unified model for AGNs, although it does support the hypothesis that Sy 2 activity is linked to circumnuclear star formation. The possible selection effects of the sample are discussed, and we conclude that the detected trends are strong enough to justify high quality observations of as large as possible set of galaxies with circumnuclear rings and their matched control samples.

关键词： Galaxies Spiral Nuclei Structure Dynamics Active

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：