We present the star-formation history of the low surface brightness (LSB) galaxy UGC 628 as part of the MUSCEL program (MUltiwavelength observations of the Structure, Chemistry, and Evolution of LSB galaxies). The star-formation histories of LSB galaxies represent a significant gap in our knowledge of galaxy assembly, with implications for dark matter / baryon feedback, IGM gas accretion, and the physics of star formation in low metallicity environments. Our program uses ground-based IFU spectra in tandem with space-based UV and IR imaging to determine the star-formation histories of LSB galaxies in a spatially resolved fashion. In this work we present the fitted history of our first target to demonstrate our techniques and methodology. Our technique splits the history of this galaxy into 15 semi-logarithmically spaced timesteps. Within each timestep the star-formation rate of each spaxel is assumed constant. We then determine the set of 15 star-formation rates that best recreate the spectra and photometry measured in each spaxel. Our main findings with respect to UGC 628 are: a) the visible properties of UGC 628 have varied over time, appearing as a high surface brightness spiral earlier than 8 Gyr ago and a starburst galaxy during a recent episode of star formation several tens of Myr ago, b) the central bar/core region was established early, around 8-10 Gyr ago, but has been largely inactive since, and c) star formation in the past 3 Gyr is best characterised as patchy and sporadic.
A Malin 1 'cousin' with counter-rotation: internal dynamics and stellar content of the giant low surface brightness galaxy UGC 1922
巨大的低表面亮度（gLSB）星系的形成方案与光盘大到100千秒差距仍然不清楚。这些恒星系统非常罕见，很难观察到，因此对每一个额外物体的详细了解有助于了解它们的性质。在这里，我们提出了一个详细的观测研究的gLSB UGC 1922使用深光学成像和光谱观测结合档案紫外数据。我们推导了恒星和电离气体运动学的空间分辨性质以及恒星星族和星际介质的特性。我们揭示了存在一个运动学解耦的中央组件，它相对于UGC 1922的主盘反向旋转。电离气体的径向金属丰度梯度与中等大小的LSB星系一致。与此同时，银河系的一个缓慢旋转和动态热的中心区域拥有大量古老的富含金属的恒星，这创造了一个巨大的椭圆星系的外观，形成了一个巨大的恒星形成盘。我们再现了大部分的观察到的功能UGC 1922在N体/流体动力学模拟的巨大的Sa和Sd星系的平面合并。我们还讨论了这种不寻常的系统的替代形成方案。
The dominant physical processes responsible for the formation and longevity of giant gaseous and stellar discs in galaxies remain controversial. Although they are rare (less than 10 confirmed as of now), giant low-surface brightness (gLSB) discy galaxies provide interesting insights given their extreme nature. We describe observations of UGC 1378 including deep spectroscopy with the Russian 6m telescope and multi-band imaging with Binospec at the MMT. Galaxy UGC 1378 has both high surface brightness and an extended low surface brightness discs. Our stellar velocity dispersion data for the high…
Giant low surface brightness galaxies (gLSB) with radii of discs as large as 130 kpc challenge galaxy formation scenarios and it is still not well understood how they form and evolve through the cosmic time. Here we present analysis of deep long-slit spectroscopic observations of six gLSBs that we obtained with the Russian 6-m telescope: UGC 1922, Malin 2, UGC 6614, UGC1382, NGC 7589 and UGC 1378. We derived spatially resolved properties of stellar and ionized gas kinematics and characteristics of stellar populations and interstellar medium. The stars in the central regions are old and metal r…
Searching in HI for Massive Low Surface Brightness Galaxies: II. Completing the UGC Sample
Green Bank Observatory（绿岸天文台）；LUX, Observatoire de Paris, Université PSL, Sorbonne Université, CNRS（卢米埃尔宇宙学联合实验室，巴黎天文台，巴黎文理研究大学，索邦大学，法国国家科学研究中心）；University of Massachusetts（马萨诸塞大学）
We theoretically study the vertical structure of the edge-on low surface brightness (LSB) galaxy UGC 7321. This is one of the few well-observed LSBs. We modeled it as a gravitationally coupled disk system of stars and atomic hydrogen gas in the potential of the dark matter halo and treated the realistic case where the rotation velocity varies with radius. We used a dense and compact halo as implied by the observed rotation curve in this model. We calculated the thickness of stellar and HI disks in terms of the half-width at half-maximum of the vertical density distribution in a region of R=0 t…
The low surface brightness (LSB) spiral UGC 8839 is nearly devoid of star formation aside from a large HII region complex located in the extreme outer disc. In order to understand the origin and nature of this complex, we compare new Hα and archival broad-band images of UGC 8839 to similar data for four other spiral galaxies. We conclude that the extreme off-axis star formation in UGC 8839 is likely due to a hyper-stable disc that is dark matter dominated at all radii, with the Toomre parameter reaching a minimum only in the extreme outer disc. Using analysis strategies designed to be particul…
On the nature of the peculiar superthin galaxy UGC 12281
UGC 12281被归类为具有纯盘和低表面亮度星系（LSBG），因此是所谓的超薄星系的明显成员。同时，它代表了一种非常不典型的LSBG类型，因为它有大量的恒星形成和平面外电离气体的证据。这使得它成为一个完美的工具，以调查触发恒星形成的LSB星系，位于一个所谓的孤立地区。通过深测光和长缝光谱分析H $α$晕，并验证了我们在处理的SDSS图像上发现的潜在矮伴星的存在。
Low surface brightness (LSBs) superthins constitute classic examples of very late-type galaxies, with their disc dynamics strongly regulated by their dark matter halos. In this work we consider a gravitational origin of dark matter in the brane world scenario, where the higher dimensional Weyl stress term projected onto the 3-brane acts as the source of dark matter. In the context of the braneworld model, this dark matter is referred to as the \emph{`dark mass'}.This model has been successful in reproducing the rotation curves of several low surface brightness and high surface brightness galax…
We present multi-color high-resolution imaging of the host galaxy of the dwarf Seyfert UGC 06728. As the lowest-mass black hole to be described with both a direct mass constraint and a spin constraint, UGC 06728 is an important source for comparison with black hole evolutionary models, yet little is known about the host galaxy. Using Hubble Space Telescope imaging in the optical and near-infrared, we find that UGC 06728 is a barred lenticular (SB0) galaxy with prominent ansae at the ends of the bar. We cleanly separated the AGN from the resolved galaxy with two-dimensional image decompositions…
The cosmological numerical simulations tell us that accretion of external metal-poor gas drives star-formation (SF) in galaxy disks. One the best pieces of observational evidence supporting this prediction is the existence of low metallicity star-forming regions in relatively high metallicity host galaxies. The SF is thought to be fed by metal-poor gas recently accreted. Since the gas accretion is stochastic, there should be galaxies with all the properties of a host but without the low metallicity starburst. These galaxies have not been identified yet. The exception may be UGC 2162, a nearby …
The Smallest Scale of Hierarchy (SSH) survey is an ongoing strategic large program at the Large Binocular Telescope, aimed at the detection of faint stellar streams and satellites around 45 late-type dwarf galaxies located in the Local Universe within $\simeq$10 Mpc. SSH exploits the wide-field, deep photometry provided by the Large Binocular Cameras in the two wide filters $g$ and $r$. This paper describes the survey, its goals, and the observational and data reduction strategies. We present preliminary scientific results for five representative cases (UGC 12613, NGC 2366, UGC 685, NGC 5477 a…
Giant low surface brightness galaxies (gLSBGs) with dynamically cold stellar discs reaching the radius of 130 kpc challenge currently considered galaxy formation mechanisms. We analyse new deep long-slit optical spectroscopic observations, archival optical images and published HI and optical spectroscopic data for a sample of seven gLSBGs, for which we performed mass modelling and estimated the parameters of dark matter haloes assuming the Burkert dark matter density profile. Our sample is not homogeneous by morphology, parameters of stellar populations and total mass, however, six of seven ga…
MUSE Study of Two Giant Low-surface-brightness Galaxies with Compact Satellites
Sternberg Astronomical Institute, Moscow M.V. Lomonosov State University（莫斯科罗蒙诺索夫国立大学斯特恩伯格天文研究所）；Astronomisches Rechen-Institut, Zentrum für Astronomie der Universität Heidelberg（海德堡大学天文学计算中心）；Université Côte d’Azur, Observatoire de la Côte d’Azur, CNRS, Laboratoire Lagrange（蔚蓝海岸大学、蔚蓝海岸天文台、法国国家科学研究中心拉格朗日实验室）；Center for Astrophysics — Harvard and Smithsonian（哈佛-史密森尼天体物理中心）；Faculty of Physics and Earth System Sciences, Leipzig University（莱比锡大学物理与地球系统科学学院）；Faculty of Physics, Moscow M.V. Lomonosov State University（莫斯科罗蒙诺索夫国立大学物理学院）
Thin and thick disks are found in most spiral galaxies, yet their formation scenarios remain uncertain. Whether thick disks form through slow or fast, internal or environmental, processes is unclear. The physical origin of outer truncations in thin and thick disks, observed as a drop in optical and near-infrared (NIR) surface brightness profiles, is also a much debated topic. These truncations have been linked to star formation (SF) thresholds in Milky-Way type galaxies, but no such connection has been made for their low-mass counterparts or in thick disks. Our photometric analysis of the edge…
We use surface brightness fluctuation (SBF) measurements to constrain the distance to low surface brightness (LSB) dwarfs in the vicinity of M101. Recent work has discovered many LSB candidate satellite companions of M101. However, without accurate distances, it is problematic to identify these dwarfs as physical satellites of M101. We use CFHT Legacy Survey (CFHTLS) data to measure the SBF signal for 43 candidate dwarfs. The data is deep enough that we constrain 29 of these to be unassociated background galaxies by their lack of SBF. We measure high S/N SBF signals for two of the candidate dw…
Euclid: Early Release Observations of ram-pressure stripping in the Perseus cluster. Detection of parsec scale star formation with in the low surface brightness stripped tails of UGC 2665 and MCG +07-07-070
The Taffy system (UGC 12914/15) consists of two massive spiral galaxies which had a head-on collision about 20 Myr ago. New sensitive, high-resolution CO(1-0) observations of the Taffy system with the IRAM PdBI are presented. About 25% of the total interferometric CO luminosity stems from the bridge region. Assuming a Galactic N(H2)/ICO conversion factor for the galactic disks and a third of this value for the bridge gas, about 10% of the molecular gas mass is located in the bridge region. The giant HII region close to UGC 12915 is located at the northern edge of the high-surface brightness gi…
The low surface brightness galaxies are gas-rich and yet have a low star formation rate, this is a well-known puzzle. The spiral features in these galaxies are weak and difficult to trace, although this aspect has not been studied much. These galaxies are known to be dominated by the dark matter halo from the innermost regions. Here we do a stability analysis for the galactic disc of UGC 7321, a low surface brightness, superthin galaxy, for which the various observational input parameters are available. We show that the disc is stable against local, linear axisymmetric and non-axisymmetric per…
