In hierarchical models of galaxy formation, stellar tidal streams are expected around most, if not all, galaxies. Although these features may provide useful diagnostics of the $Λ$CDM model, their observational properties remain poorly constrained because they are challenging to detect and interpret and have been studied in detail for only a sparse sampling of galaxy population. More quantitative, systematic approaches are required. We advocate statistical analysis of the counts and properties of such features in archival wide-field imaging surveys for a direct comparison against results from numerical simulations. Thus, in this paper we aim to study systematically the frequency of occurrence and other observational properties of tidal features around nearby galaxies. The sample we construct will act as a foundational dataset for statistical comparison with cosmological models of galaxy formation. Our approach is based on a visual classification of diffuse features around a volume-limited sample of nearby galaxies, using a post-processing of Sloan Digital Sky Survey imaging optimized for the detection of stellar structure with low surface brightness. At a limiting surface brightness of $28\ \mathrm{mag~arcsec^{-2}}$, 14% of the galaxies in our sample exhibit evidence of diffuse features likely to have arisen from minor merging events. Our technique recovers all previously known streams in our sample and yields a number of new candidates. Consistent with previous studies, coherent arc-like features and shells are the most common type of tidal structures found in this study. We conclude that although some detections are ambiguous and could be corroborated or refuted with deeper imaging, our technique provides a reliable foundation for the statistical analysis of diffuse circumgalactic features in wide-area imaging surveys, and for the identification of targets for follow-up studies.
Candidate members of the Pal 5, GD-1, Cetus Polar, and Orphan tidal stellar halo streams from Sdss DR9, Lamost DR3 and APOGEE catalogues
我们提出了候选成员的105，GD-1，鲸鱼座极地，和孤儿潮汐恒星流发现在LAMOST DR 3，SDSS DR 9和APOGEE目录。在LAMOST DR 3中，我们分别找到了GD-1、Cetus Polar和Orphan的20、4和24个高置信度候选者。我们还列出了SDSS DR 9光谱目录59，118，10个高置信度的候选潮汐流鲸鱼座极地，孤儿和115，分别。此外，我们发现7个高置信度的候选人的2005年潮流的APOGEE数据。与SDSS相比，LAMOST DR 3的新候选者更亮，因此可以探索更多的色星等图，包括巨星分支。SDSS数据的分析表明，有3个金属丰度峰值的孤儿流，也显示出一些空间分离。LAMOST数据证实了这条溪流中的多种金属含量。由高分辨率的APOGEE仪器给出的1995年潮汐流的金属丰度为[Fe/H] $\sim -1.2$，高于先前由SDSS光谱给出的值。许多以前未识别的流成员首次与现有成员一起在这里列表，使未来的研究人员能够进一步限制这些物体在银河系暗物质势内移动时的轨道。
In this Letter, we report further evidence to support a tidal disruption event (TDE) in the known changing-look AGN SDSS J0159, through the unique variabilities of asymmetric broad H$α$: broader but redder in 2010 than in 2000. Accepted the broad H$α$ emission regions tightly related to accreting debris in a central TDE, the well-known relativistic accretion disk origination can be applied to well explain the asymmetric broad H$α$ variabilities in SDSS J0159. Moreover, the model determined broad H$α$ emission regions have the sizes not follow the empirical R-L relation valid in normal broad li…
By mining the data from $Gaia$ EDR3, SDSS/SEGUE DR16 and LAMOST DR8, 11 member stars of the NGC 5466 tidal stream are detected and 7 of them are newly identified. To reject contaminators, a variety of cuts are applied in sky position, color-magnitude diagram, metallicity, proper motion and radial velocity. We compare our data to a mock stream generated by modeling the cluster's disruption under a smooth Galactic potential plus the Large Magellanic Cloud (LMC). The concordant trends in phase-space between the model and observations imply that the stream might have been perturbed by LMC. The two…
We report here our finding of two new blueberry galaxies using optical IFU spectroscopic data from the MaNGA survey. Both the blueberries are found to be compact ($\leq$ $1 - 2$ kpc) starburst systems located at the outskirts of Low Surface Brightness (LSB) galaxies. Our blueberries have the lowest stellar masses $\sim$ 10$^{5}$ M$_{\odot}$ amongst the locally known blueberry galaxies. We find a significantly large mean metallicity difference ($\sim$ 0.5 dex) between the blueberry sources and their associated LSBs. Moreover, the radial metallicity gradients in our blueberries are also differen…
Box/Peanut and Bar structures in edge-on and face-on SDSS nearby galaxies I. Catalogue
我们调查盒/花生和酒吧结构的图像数据的边缘和面对的附近星系的SDSS（斯隆数字巡天），目前的目录包含表面亮度参数和形态分类。从SDSS DR 7中选取了约1700个边朝星系和2600个面朝星系在g、r和i波段的数据。每个星系的图像拟合的2维表面亮度的Sérsic球和指数盘的模型。在去除一些不规则的数据后，使用残差（观察减去模型）图像，可以很容易地通过眼睛区分Box/Peanut，bar和其他结构。在去除了一些不规则的数据后，我们在1329个边对样本中发现了292个Box/Peanut结构，在1890个面对样本中发现了630个Bar结构。然后，盒子/花生星系的比例约为22%，相对于边缘样本，棒星系的比例约为33%（如果去掉629个椭圆星系，则约为50%）。此外，Box/Peanut和棒的强度被评价为“强”、“标准”和“弱”。我们发现，随着$B/T$（膨胀与总通量比）的增加，强度略有增加，并且无论强度和$B/T$如何，Box/Peanut的分数通常约为棒的分数的一半。我们的研究结果支持的想法，盒子/花生是酒吧看到的边缘。
Post-starburst galaxies are crucial to disentangling the effect of star formation and quenching on galaxy demographics. They comprise, however, a heterogeneous population of objects, described in numerous ways. To obtain a well-defined and uncontaminated sample, we take advantage of spatially resolved spectroscopy to construct an unambiguous sample of E + A galaxies - post-starburst systems with no observed ongoing star formation. Using data from the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) Survey, in the fourth generation of the Sloan Digital Sky Survey (SDSS-IV), we have i…
We present a comparative study of active galactic nuclei (AGN) between galaxy pairs and isolated galaxies with the final data release of the MaNGA integral field spectroscopic survey. We build a sample of 391 kinematic galaxy pairs within the footprint of the survey and select AGN using the survey's spectra. We use the comoving volume densities of the AGN samples to quantify the effects that tidal interactions have on the triggering of nuclear accretion. Our hypothesis is that the pair sample contains AGN that are triggered by not only stochastic accretion but also tidally induced accretion an…
Tidal streams in newly discovered M32 analogues: evidence for the stripping scenario
我们提出了两个新发现的紧凑的椭圆（cE）星系，表现出明确的证据潮汐蒸汽，并发现在搜索的SDSS DR 7 cE候选人。的结构参数的CE使用GALFIT，给出有效半径，Re，388和263秒差距，和B波段平均表面亮度内Re的19.4和19.2的幅度每弧秒平方。我们重新分析了SDSS光谱，表明它们拥有年轻到中等年龄的恒星星族。这两个cE提供了直接的证据，一个“吸烟枪”，潮汐剥离的过程，被认为是M32型星系的起源。这两个星系都是在一个小的星系群中，有很大的螺旋部分，这表明我们可能会在动态年轻的环境中看到这样的cE星系的形成。更紧凑的星系是在一个与本星系群类似的小星系群中发现的，因此为理解M32提供了一个额外的模型。
The Peculiar Globular Cluster Palomar 1 and Persistence in the SDSS-APOGEE Database
SDSS-III APOGEE DR 12是一个独特的资源，用于搜索星团潮汐半径以外的恒星。我们已经检查了APOGEE DR 12数据库中年轻星团Palomar 1的新候选者，Palomar 1是一个具有先前报道的潮汐尾的系统（Niederste-Ostholt et al. 2010）。APOGEE ASPCAP数据库包含了两颗已知的恒星I和II的光谱和恒星参数，但这些数据与Sakari等人（2011）根据光谱确定的恒星参数不一致。我们发现这两颗恒星的APOGEE分析受到已知持久性问题的强烈影响（Mauriski et al. 2015; Nidever et al. 2015）。通过重新检查个人的访问，并删除蓝色（有时绿色）APOGEE探测器光谱的持久性影响，然后我们发现在重新分析的组合光谱非常一致。这些方法被应用到另外五颗星的APOGEE领域与类似的径向速度和金属丰度的那些的RISK 1。只有一个新的候选者，星F，可能是位于潮汐尾的成员，基于它的日心径向速度，金属丰度和化学。其他四个候选者并没有很好地与潮汐尾对齐，与贝桑松模型（Robin et al. 2003）的比较表明，它们更有可能是非成员，即星系晕的一部分。如果可以从APOGEE光谱数据库中消除持久性问题，则可以重新检查该APOGEE字段以寻找其他新的候选者。
Spin alignments of spiral galaxies within the large-scale structure from SDSS DR7
利用Sloan数字巡天数据发布7（SDSS DR 7）和星系动物园2（GZ 2）中的一组旋涡星系，研究了旋涡星系的自旋轴与周围大尺度结构的排列，其特征是利用一定质量阈值以上的星系群数据重建的大尺度潮汐场.我们发现，只有自旋轴有微弱的倾向，是对齐（或垂直于）本地潮汐张量的中（或短）轴。信号是最强的\cluster环境中的所有三个特征值的本地潮汐张量是积极的。与N体模拟中得到的晕自旋与局域潮汐场的一致性相比，上述观测结果与晕内区自旋的一致性最好，表明盘物质追踪了内区暗物质晕的角动量.
Reduction of bar fraction in paired galaxies in the SDSS
Hebei Normal University（河北师范大学）；Shijiazhuang Key Laboratory of Astronomy and Space Science / Guoshoujing Institute of Astronomy, Hebei Normal University（石家庄天文与空间科学重点实验室/郭守敬天文台，河北师范大学）；Hebei Key Laboratory of Photophysics Research and Application（河北省光物理研究与应用重点实验室）；Shanghai Astronomical Observatory, Chinese Academy of Sciences（中国科学院上海天文台）；Shanghai Key Lab for Astrophysics（上海市天体物理重点实验室）；Department of Astronomy, School of Physics and Astronomy, Shanghai Jiao Tong University（上海交通大学物理与天文学院天文学系）；State Key Laboratory of Dark Matter Physics, Tsung-Dao Lee Institute & School of Physics and Astronomy, Shanghai Jiao Tong University（上海交通大学物理与天文学院及李政道研究所暗物质物理全国重点实验室）
The distribution of stellar metallicities within and across galaxies is an excellent relic of the chemical evolution across cosmic time. We present a detailed analysis of spatially resolved stellar populations based on $>2.6$ million spatial bins from 7439 nearby galaxies in the SDSS-IV MaNGA survey. To account for accurate inclination corrections, we derive an equation for morphology dependent determination of galaxy inclinations. Our study goes beyond the well-known global mass-metallicity relation and radial metallicity gradients by providing a statistically sound exploration of local relat…
Using the largest sample of galaxies observed with an optical integral field unit (IFU, the SDSS-IV MaNGA survey, $\sim$10000 targets), we derive the radial distribution of the physical properties obtained from the stellar continuum and the ionized-gas emission lines. Given the large sample, we are able to explore the impact of the total stellar mass and morphology by averaging those radial distributions for different bins of both global properties. We use a piece-wise analysis to characterize the slopes of the gradients from those properties at different galactocentric distances. In general w…
Mid-Infrared Outbursts in Nearby Galaxies: Nuclear Obscuration and Connections to Hidden Tidal Disruption Events and Changing-Look Active Galactic Nuclei
Identifying Tidal Disruption Events via Prior Photometric Selection of Their Preferred Hosts
在星暴后的星系或其他具有强烈巴耳末吸收的静止星系中检测到的核瞬变很可能是潮汐破裂事件（TDE）。在大型综合巡天望远镜（LSST）的计划调查足迹内识别这些星系-在检测到瞬变之前-将使TDE分类立即和后续更有效。不幸的是，大多数这类星系的光谱都是不可用的，简单的光度选择是无效的;切割“绿谷”紫外/光学/红外颜色产生的样品是高度污染和不完整的。在这里，我们提出了一个新的策略，只使用光度光学/UV/IR数据从大型调查。将机器学习随机森林分类器应用于GALEX和WISE测光的~ 400 k SDSS星系样本，包括13，592个静态Balmer强星系，我们获得了53-61%的纯度和8-21%的完整性，给出了红移范围。对于1299个恒星暴增后星系的子集，我们实现了63-73%的纯度和5-12%的完整性。考虑到这些结果，可能的TDE和超新星发生率的范围，以及36-75%的TDE发生在静止的Balmer强宿主中，我们估计在光度选择的宿主星系中观察到的瞬变中有13-99%将是TDE，并且我们将发现LSST每年119-248个TDE。使用我们的技术，我们提出了一个新的目录67,484候选星系预计有一个高的TDE率，从SDSS，泛星，DES和WISE测光调查。这个样本比目前SDSS的类似星系样本大3.5倍，从而为瞬态科学和星系演化研究提供了一条新的前进道路。
We derive the metallicity (traced by the O/H abundance) of the Narrow Line Region ( NLR) of 108 Seyfert galaxies as well as radial metallicity gradients along their galaxy disks and of these of a matched control sample of no active galaxies. In view of that, observational data from the SDSS-IV MaNGA survey and strong emission-line calibrations taken from the literature were considered. The metallicity obtained for the NLRs %each Active Galactic Nucleus (AGN) was compared to the value derived from the extrapolation of the radial oxygen abundance gradient, obtained from \ion{H}{ii} region estima…
We propose that fourteen co-moving groups of stars uncovered by Kounkel & Covey (2019) may be related to known nearby moving groups and bridge those and nearby open clusters with similar ages and space velocities. This indicates that known nearby moving groups may be spatially much more extended than previously though, and some of them might be parts of tidal tails around the cores of known open clusters, reminiscent of those recently found around the Hyades and a handful of other nearby clusters. For example, we find that both the nearby Carina and Columba associations may be linked to Theia …
We present the first data release of the MaNGA-ARO Survey of CO Targets (MASCOT), an ESO Public Spectroscopic Survey conducted at the Arizona Radio Observatory (ARO). We measure the CO(1-0) line emission in a sample of 187 nearby galaxies selected from the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey that has obtained integral field unit (IFU) spectroscopy for a sample of ~ 10,000 galaxies at low redshift. The main goal of MASCOT is to probe the molecular gas content of star-forming galaxies with stellar masses > 10^9.5 M_solar and with associated MaNGA IFU observations a…
SDSS-IV MaNGA: The Roles of AGNs and Dynamical Processes in Star Formation Quenching in Nearby Disk Galaxies
我们研究如何在低红移盘星系的恒星形成（SF）淬火积分场光谱。我们选取了131个恒星质量大于$\rm 3\times10^{10}M_\odot$，且具有来自MaNGA DR 13的空间分辨光谱的正面螺旋星系。我们将样本分为四个组的基础上的偏移量的全球特定的恒星形成率（SFR）的恒星形成的主要序列和堆叠的径向配置文件的恒星质量和SFR。通过比较静止盘星系和恒星形成盘星系的堆积轮廓，我们发现，全球SFR的减少是由于在所有半径的SF的抑制，但从中心到外部区域的内部-外部模式的下降更显着。由于全球特定的SFR减少，中央恒星质量，部分盘星系托管恒星酒吧，和活动星系核（AGN，包括LINER和Seyferts）都增加，表明动力学过程和AGN反馈可能是贡献者的内向外淬火的SF在本地宇宙。然而，如果我们只包括Seyferts，或活动星系核与${\rm EW(Hα)>3Å}$，活动星系核的分数增加的趋势与全球sSFR减少消失。因此，如果活动星系核的反馈是有助于淬火，我们怀疑它在低光度活动星系核模式，如更被动的盘星系的大凸起质量的增加所示。
We present a detailed visual morphological classification for the 4614 MaNGA galaxies in SDSS Data Release 15, using image mosaics generated from a combination of r-band (SDSS and deeper DESI Legacy Surveys) images and their digital post-processing. We distinguish 13 Hubble types and identify the presence of bars and bright tidal debris. After correcting the MaNGA sample for volume completeness, we calculate the morphological fractions, the bi-variate distribution of type and stellar mass M*-where we recognise a morphological transition "valley" around S0a-Sa types- and the variations of the g…
