CFHT MegaCam Two Deep Fields Imaging Survey (2DFIS) II: 解码一个'旋转'团块的引力透镜轮廓 with 深度 CFHT 成像
CFHT MegaCam Two Deep Fields Imaging Survey (2DFIS) II: Decoding the Lensing Profile of a "Rotating" Cluster with Deep CFHT Imaging
Shanghai Normal University（上海师范大学）；Shanghai Astronomical Observatory, Chinese Academy of Sciences（中国科学院上海天文台）；China Three Gorges University（三峡大学）；Hefei Institute of Technology（合肥工业大学）；University of Science and Technology of China（中国科学技术大学）；Purple Mountain Observatory, Chinese Academy of Sciences（中国科学院紫金山天文台）；Université Paris-Saclay（巴黎萨克雷大学）；Université Paris Cité（巴黎西岱大学）
Yicheng Li, Liping Fu, Wentao Luo, Binyang Liu, Wei Du, Martin Kilbinger, Calum Murray, Christopher J. Miller, Ray Wang, David Turner, Lance Miller, Dezi Liu, M… 展开作者
Yicheng Li, Liping Fu, Wentao Luo, Binyang Liu, Wei Du, Martin Kilbinger, Calum Murray, Christopher J. Miller, Ray Wang, David Turner, Lance Miller, Dezi Liu, Mario Radovich, Jean-Paul Kneib, Huanyuan Shan, Kaiwen Mai, Zicheng Wang, Haoran Zhao
本研究通过深度 CFHT 成像分析 RXCJ0110.+=1358 星系团，揭示光学双峰性源于丝状体投影，解决光学与 X 射线观测间的矛盾。
摘要：
我们对星系团 RXCJ0110.0+1358（z=0.058）进行了多波段分析，这是一个旋转团块候选体，结合了深度 CFHT 成像、SDSS 光学测量、光谱红移和 XMM-Newton X 射线观测。我们发现光学和 X 射线视图之间存在显著差异：虽然光学数据揭示了明显的双峰星系分布以及显著的运动学子结构特征，但 X 射线发射则表现出一个单一、平滑延伸的组件，中心位于 BCG。我们的弱引力透镜分析解决了这一矛盾，发现质量主要集中在东南方（log M_200/M_太阳=14.04±0.40），而西北部子结构质量极小（约 10^13 M_太阳）。这种巨大的质量差异排除了旋转系统的动态可能性。我们证明，光学的双峰性源于一个丝状体的投影，导致光学分组算法将这些星系错误地分类为团块成员。这种污染产生了一个虚假的子结构，模仿旋转信号并导致亮度基的暗物质晕质量高估，解决了观察到的不一致。
英文摘要：
We present a multi-wavelength analysis of the galaxy cluster RXCJ0110.0+1358 ($z=0.058$), a rotating cluster candidate, combining deep CFHT imaging, SDSS photometry, spectroscopic redshifts, and XMM-Newton X-ray observations. We find a notable discrepancy between the optical and X-ray views: while optical data reveal a pronounced bimodal galaxy distribution with significant kinematic substructure signatures, the X-ray emission exhibits a single, smoothly extended component centered on the BCG. Our weak lensing analysis resolves this discrepancy by revealing that the mass is predominantly concentrated in the southeast ($\log M_{200}/M_\odot = 14.04_{-0.40}^{+0.24}$), while the northwestern substructure has a negligible mass ($\sim 10^{13} M_\odot$). This immense mass disparity rules out the dynamical possibility of a rotating system. We demonstrate that the apparent optical bimodality arises from the projection of a filament, which led optical group-finding algorithms to misclassify these galaxies as cluster members. This contamination creates a spurious substructure that mimics a rotation signal and leads to an overestimation of the luminosity-based halo mass, resolving the observed inconsistencies.
CFHT MegaCam Two Deep Fields Imaging Survey (2DFIS) I: Overview
Purple Mountain Observatory, Chinese Academy of Sciences（中国科学院紫金山天文台）；Hefei Institute of Technology（合肥工业大学）；University of Science and Technology of China（中国科学技术大学）；CEA Paris-Saclay（巴黎萨克雷原子能委员会）；Kavli Institute for Particle Astrophysics and Cosmology（卡弗里粒子天体物理与宇宙学研究所）；Brown University（布朗大学）；Shanghai Normal University（上海师范大学）；Tsung-Dao Lee Institute and State Key Laboratory of Dark Matter Physics, Shanghai Jiao Tong University（上海交通大学）
In this paper we analyze Sloan g,r,i archival imaging data of M33 taken by Hartman et al. (2006) using Megacam at the Canada-France-Hawaii Telescope. To determine the distance to the M33 galaxy, we performed several analytical steps to identify its Cepheid population. We used the Lomb-Scargle algorithm to find periodicity and visually identified 1989 periodic variable stars. Since Cepheids occupy a specific region of the color-magnitude diagram, to differentiate Cepheids from other variables we used the expected position of the Cepheid instability strip to down-select Cepheids in M33 from othe…
The $AKARI$ infrared (IR) space telescope conducted two surveys (Deep and Wide) in the North Ecliptic Pole (NEP) field to find more than 100,000 IR sources using its Infrared Camera (IRC). IRC's 9 filters, which cover wavebands from 2 to 24 $μ$m continuously, make $AKARI$ unique in comparison with other IR observatories such as $Spitzer$ or $WISE$. However, studies of the $AKARI$ NEP-Wide field sources had been limited due to the lack of follow-up observations in the ultraviolet (UV) and optical. In this work, we present the Canada-France-Hawaii Telescope (CFHT) MegaPrime/MegaCam $u$-band sour…
The Andromeda (M31) galaxy subtends nearly 100 sq. deg. on the sky, with severe contamination from the Milky Way halo stars whose surface density displays a steep gradient across the entire M31 field-of-view. Planetary Nebulae (PNe) are a population of stars firmly associated with M31, that are excellent tracers of light, chemistry and motion in galaxies. We present a 16 sq. deg. survey of the disk and inner halo of M31 with MegaCam@CFHT to identify PNe, characterize their luminosity-specific PN number and luminosity function (PNLF). PNe were identified based on their bright OIII 5007 $\unicod…
A Megacam Survey of Outer Halo Satellites. IV. Two foreground populations possibly associated with the Monoceros substructure in the direction of NGC2419 and Koposov2
The Subaru Hyper Suprime-Cam (HSC) Strategic Survey is the latest-generation multi-band optical imaging survey for galaxy evolution and structure formation. The "Ultra-Deep" component of the HSC survey provides $grizy$ broad-band images over $\sim3.4$ deg$^2$ to detection limits of $\sim26$-28 AB, along with narrow-band images, in the COSMOS and the SXDS fields. These images provide an unprecedented combination of depths and area coverage, for the studies galaxies up to $z\sim7$. However, the lack of coverage at $<4000$ Ang implies incomplete sampling of the rest-frame UV at $z\lesssim 3$, whi…
The CFHT Large Area U-band Deep Survey (CLAUDS) uses data taken with the MegaCam mosaic imager on CFHT to produce images of 18.60 deg2 with median seeing of FWHM=0.92 arcsec and to a median depth of U = 27.1 AB (5 sigma in 2 arcsec apertures), with selected areas that total 1.36 deg2 reaching a median depth of U=27.7 AB. These are the deepest U-band images assembled to date over this large an area. These data are located in four fields also imaged to comparably faint levels in grizy and several narrowband filters as part of the Hyper Suprime-Cam (HSC) Subaru Strategic Program (HSC-SSP). These …
We present structural parameters from a wide-field homogeneous imaging survey of Milky Way satellites carried out with the MegaCam imagers on the 3.6m Canada-France-Hawaii Telescope (CFHT) and 6.5m Magellan-Clay telescope. Our survey targets an unbiased sample of "outer halo" satellites (i.e., substructures having Galactocentric distances greater than 25 kpc) and includes classical dSph galaxies, ultra-faint dwarfs, and remote globular clusters. We combine deep, panoramic $gr$ imaging for 44 satellites and archival $gr$ imaging for 14 additional objects (primarily obtained with the DECam instr…
Strong lensing is one of the most spectacular views in the universe. Many cosmological applications have been proposed, but the number of such lensing systems is still limited. In this work, we applied an improved version of a previously developed spectroscopic lensing search method to the SDSS-III BOSS and proposed a list of highly possible candidates. Follow-up CFHT Megacam imaging observations were performed for five systems, and two out of five are probably strong lensing systems with at least one image close to the central galaxy, although no counter images are detected.
We present Canada-France-Hawaii Telescope (CFHT) MegaCam observations of a galaxy-quasar strong gravitational lens system, SDSS J1640+1932. This system, located at z=0.195 (foreground elliptical galaxy) and z=0.778 (background quasar), was first visually identified by us in the Sloan Digital Sky Survey (SDSS) database. Our CFHT imaging with an angular resolution of 0.7$^{\prime \prime}$ clearly resolves 4 lensed images and a nearly complete Einstein ring. Modeling the system with a singular isothermal ellipsoid (SIE) total mass distribution, we find an Einstein radius of ${2.49^{\prime \prime}…
We present an optical study of the strong lensing galaxy cluster MS 0440.5$+$0204 at $z=0.19593$, based on CFHT/MegaCam g', r'-photometry and GMOS/Gemini and CFHT/MOS/SIS spectroscopy in a broader area compared to previous works. We have determined new spectroscopic redshifts for the most prominent gravitational arcs surrounding the central galaxy in the cluster. The new redshifts and the information provided by the photometric catalog yield us to perform a detailed weak and strong lensing mass reconstruction of the cluster. The large number of member galaxies and the area covered by our obser…
We introduce the Solitary Local Dwarfs Survey (Solo), a wide field photometric study targeting every isolated dwarf galaxy within 3 Mpc of the Milky Way. Solo is based on (u)gi multi-band imaging from CFHT/MegaCam for northern targets, and Magellan/Megacam for southern targets. All galaxies fainter than Mv = -18 situated beyond the nominal virial radius of the Milky Way and M31 (>300 kpc) are included in this volume-limited sample, for a total of 42 targets. In addition to reviewing the survey goals and strategy, we present results for the Sagittarius Dwarf Irregular Galaxy (Sag DIG), one of t…
While our current cosmological model places galaxy clusters at the nodes of a filament network (the cosmic web), we still struggle to detect these filaments at high redshifts. We perform a weak lensing study for a sample of 16 massive, medium-high redshift (0.4<z<0.9) galaxy clusters from the DAFT/FADA survey, that are imaged in at least three optical bands with Subaru/Suprime-Cam or CFHT/MegaCam. We estimate the cluster masses using an NFW fit to the shear profile measured in a KSB-like method, adding our contribution to the calibration of the observable-mass relation required for cluster abu…
Stephan's Quintet, a compact group of galaxies, is often used as a laboratory to study a number of phenomena, including physical processes in the interstellar medium, star formation, galaxy evolution, and the formation of fossil groups. As such, it has been subject to intensive multi-wavelength observation campaigns. Yet, models lack constrains to pin down the role of each galaxy in the assembly of the group. We revisit here this system with multi-band deep optical images obtained with MegaCam on the Canada-France-Hawaii Telescope (CFHT), focusing on the detection of low surface brightness (LS…
Deep imaging of the diffuse light emitted by the stellar fine structures and outer halos around galaxies is now often used to probe their past mass assembly. Because the extended halos survive longer than the relatively fragile tidal features, they trace more ancient mergers. We use images reaching surface brightness limits as low as 28.5-29 mag.arcsec-2 (g-band) to obtain light and color profiles up to 5-10 effective radii of a sample of nearby early-type galaxies. They were acquired with MegaCam as part of the CFHT MATLAS large programme. These profiles may be compared to those produced by s…
The ultracool-field dwarf luminosity-function and space density from the Canada-France Brown Dwarf Survey
上下文由于最近和正在进行的大规模调查，在过去十年中发现了数百颗褐矮星。加拿大-法国棕矮星巡天（英语：Canada-France Brown Dwarf Survey）是一项利用加拿大-法国-夏威夷望远镜（英语：Canada-France-Hawaii Telescope）上的MegaCam照相机进行的宽视场冷棕矮星巡天。目标。我们的目标是找到超冷的棕矮星，并从一个大的和均匀的L和T矮星样本约束场棕矮星光度函数和质量函数。方法.我们在CFHT/MegaCam i'和z'图像中确定候选者，并在几个望远镜上用指向近红外（NIR）成像跟踪它们。在我们的调查进行到一半时，我们发现了~50个T矮星和~170个L或超冷M矮星，这些矮星是从1400个候选者中抽取的，具有典型的超冷矮星i' - z'颜色，在780平方度内发现。结果我们目前已经完成了对所有候选者的大部分调查的近红外跟踪，从中L矮星到最新的T矮星，已知具有超冷矮星的颜色。这使我们能够利用一个完整的和定义良好的102个超冷矮星的样本来研究场矮星的光度函数和空间密度。结论.我们发现L5到T0晚期矮星的密度为2.0 pm0.8 x 10-3个pc-3，T0.5到T5.5矮星的密度为1.4 pm0.3 x 10-3个pc-3，T6到T8矮星的密度为5.3 pm3.1 x 10-3个pc-3。我们发现，这些结果更符合一个平坦的亚恒星质量函数。在T…
Within a cluster, gravitational effects can lead to the removal of stars from their parent galaxies. Gas hydrodynamical effects can additionally strip gas and dust from galaxies. The properties of the ICL can therefore help constrain the physical processes at work in clusters by serving as a fossil record of the interaction history. The present study is designed to characterise this ICL in a ~10^14 M_odot and z~0.53 cluster of galaxies from imaging and spectroscopic points of view. By applying a wavelet-based method to CFHT Megacam and WIRCAM images, we detect significant quantities of diffuse…
We present the results of an extensive search for dwarf satellite galaxies around 10 primary host galaxies in the Local Volume (D$<$12 Mpc) using archival CFHT/MegaCam imaging data. The hosts span a wide range in properties, with stellar masses ranging from that of the LMC to ${\sim}3$ times that of the Milky Way (MW). The surveyed hosts are: NGC 1023, NGC 1156, NGC 2903, NGC 4258, NGC 4565, NGC 4631, NGC 5023, M51, M64, and M104. We detect satellite candidates using a consistent semi-automated detection algorithm that is optimized for the detection of low surface brightness objects. Depending…
We have observed the giant elliptical galaxy M87 during the Virgo Environmental Survey Tracing Galaxy Evolution (VESTIGE), a blind narrow-band Halpha+[NII] imaging survey of the Virgo cluster carried out with MegaCam at the Canada French Hawaii Telescope (CFHT). The deep narrow-band image confirmed the presence of a filament of ionised gas extending up to ~ 3 kpc in the north-western direction and ~ 8 kpc to the south-east, with a couple of plumes of ionised gas, the weakest of which, at ~ 18 kpc from the nucleus, was previously unknown. The analysis of deep optical images taken from the NGVS …
During pilot observations of the Virgo Environmental Survey Tracing Galaxy Evolution (VESTIGE), a blind narrow-band Halpha+[NII] imaging survey of the Virgo cluster carried out with MegaCam at the CFHT, we have observed the spiral galaxy NGC 4254 (M99). Deep Halpha+[NII] narrow-band and GALEX UV images revealed the presence of 60 compact (70-500 pc radius) star forming regions up to ~ 20 kpc outside the optical disc of the galaxy. These regions are located along a tail of HI gas stripped from the disc of the galaxy after a rapid gravitational encounter with another Virgo cluster member that si…
Spectroscopy of brown dwarf candidates in IC 348 and the determination of its substellar IMF down to planetary masses
上下文棕矮星代表了我们银河系中相当大的一部分恒星成分，并占据了恒星和行星质量制度之间的过渡。但是，对于这些组织的形成过程，没有达成一致意见。目标。我们对年轻的邻近星系团IC 348进行了一次大规模的调查，以揭示其低质量的褐矮星人口，并研究亚恒星区域的星系团性质。方法.使用加拿大-法国-夏威夷望远镜（CFHT）的MegaCam和WIRCam拍摄的深光学和近红外图像用于选择光度候选成员。对大部分候选人进行了光谱跟踪，以评估他们的年轻程度和成员资格。结果我们通过光谱确认了IC 348星系团的16个新成员，其中包括13颗褐矮星，这对该星系团的亚恒星普查做出了重大贡献，而以前只知道30颗褐矮星。新成员中有五个具有L0光谱类型，这是迄今为止在该集群中发现的最新类型的对象。在300万年前，演化模型估计这些褐矮星的质量约为木星的13倍。结合新成员和以前的星团普查，我们构建了IMF完整的13个木星质量。结论. IC 348的IMF很好地拟合了对数正态函数，与其他年轻星团相比，我们没有看到质量函数变化到行星质量的证据。
The Virgo Environmental Survey Tracing Ionised Gas Emission (VESTIGE) is a blind narrow-band Halpha+[NII] imaging survey of the Virgo cluster carried out with MegaCam at the Canada-French-Hawaii telescope (CFHT). We use a new set of data extracted from VESTIGE to study the impact of the hostile cluster environment on the star formation process down to the scale of HII regions (~ 50 pc). HII regions are identified and their parameters measured using the HIIphot code on a sample of 114 late-type galaxies spanning a wide range in morphological type (Sa-Sd, Im, BCD), stellar mass (10^6.5 <= M_star…
M104 (NGC 4594, the Sombrero galaxy) is a mysterious massive early-type galaxy that shows a dominant bulge and a prominent disk. However, the presence of a halo in M104 has been elusive, and it is not yet known how M104 has acquired such a peculiar structure. Using wide ($\sim2$ deg$^2$) and deep $ugi$ images of M104 obtained with the CFHT/MegaCam, we detect a large number of globular clusters (GCs) found out to $R\approx35'$ ($\sim100$ kpc). The color distribution of these GCs shows two subpopulations: a blue (metal-poor) system and a red (metal-rich) system. The total number of GCs is estima…
Diffuse Galactic light has been observed in the optical since the 1930s. We propose that, when observed in the optical with deep imaging surveys, it can be used as a tracer of the turbulent cascade in the diffuse interstellar medium (ISM), down to scales of about 1 arcsec. Here we present a power spectrum analysis of the dust column density of a diffuse cirrus at high Galactic latitude (l ~ 198 deg, b ~ 32 deg) as derived from the combination of a MegaCam g-band image, obtained as part of the MATLAS large programme at the CFHT, with Planck radiance and Wise 12 micron data. The combination of t…
Galaxy clusters provide an excellent probe in various research fields in astrophysics and cosmology. However, the number of galaxy clusters detected so far in the $AKARI$ North Ecliptic Pole (NEP) field is limited. In this work, we provide galaxy cluster candidates in the $AKARI$ NEP field with the minimum requisites based only on coordinates and photometric redshift (photo-$z$) of galaxies. We used galaxies detected in 5 optical bands ($g$, $r$, $i$, $z$, and $Y$) by the Subaru Hyper Suprime-Cam (HSC), assisted with $u$-band from Canada-France-Hawaii Telescope (CFHT) MegaPrime/MegaCam, and IR…
Recent observations have highlighted a significant population of faint but large (r_eff>1.5 kpc) galaxies in the Coma cluster. The origin of these Ultra Diffuse Galaxies (UDGs) remains puzzling, as the interpretation of the observational results has been hindered by the subjective selection of UDGs, and the limited study of only the Coma (and some examples in the Virgo-) cluster. We extend the study of UDGs using 8 clusters in the redshift range 0.044<z<0.063 with deep g- and r-band imaging data taken with MegaCam at the CFHT. We describe an automatic selection pipeline for quantitative identi…
We present a detailed study of the faint Milky Way satellite Draco II (Dra II) from deep CFHT/MegaCam broadband $g$ and $i$ photometry and narrow-band metallicity-sensitive CaHK observations, along with follow-up Keck II/DEIMOS multi-object spectroscopy. Forward modeling of the deep photometry allows us to refine the structural and photometric properties of Dra II: the distribution of stars in colour-magnitude space implies Dra II is old (13.5 $ \pm 0.5 $ Gyr), very metal poor, very faint ($ L_V = 180 ^{+124}_{-72} L_\odot $), and at a distance $d = 21.5 \pm 0.4$ kpc. The narrow-band, metallic…
We obtained using MegaCam at the CFHT a deep narrow band Halpha+[NII] wide field image of NGC 4569, the brightest late-type galaxy in the Virgo cluster. The image reveals the presence of long tails of diffuse ionised gas without any associated stellar component extending from the disc of the galaxy up to ~ 80 kpc (projected distance) with a typical surface brightness of a few 10^-18 erg s-1 cm-2 arcsec-2. These features provide direct evidence that NGC 4569 is undergoing a ram presure stripping event. The image also shows a prominent 8 kpc spur of ionised gas associated to the nucleus that spe…
We present the combination of the Canada-France-Hawaii Telescope (CHFT) Large Area $U$-bands Deep Survey (CLAUDS) and the Hyper-Suprime-Cam (HSC) Subaru Strategic Program (HSC-SSP) data over their four deep fields. We provide photometric catalogs for $u$, $u^*$ (CFHT--MegaCam), $g$, $r$, $i$, $z$, and $y$ (Subaru--HSC) bands over $\sim 20~{\rm deg}^2$, complemented in two fields by data from the Visible and Infrared Survey Telescope for Astronomy (VISTA) Deep Extragalactic Observations (VIDEO) survey and the UltraVISTA survey, thus extending the wavelength coverage toward near-infrared with VI…
The Virgo Environmental Survey Tracing Ionised Gas Emission (VESTIGE) is a blind narrow-band H$α$+[NII] imaging survey carried out with MegaCam at the CFHT. During pilot observations we have observed NGC 4330, an intermediate mass, edge-on star forming spiral currently falling into the core of the Virgo cluster. New deep observations revealed a low surface brightness 10 kpc tail exhibiting a peculiar filamentary structure. The filaments are remarkably parallel one another and clearly indicate the direction of motion of the galaxy in the Virgo potential. Motivated by the detection of these feat…
Using the VESTIGE survey, a deep narrow-band H$α$ imaging survey of the Virgo cluster carried on at the CFHT with MegaCam, we discovered a long diffuse tail of ionised gas in the edge-on late-type galaxy NGC 4330. This peculiar feature witnesses an ongoing ram pressure stripping (RPS) event able to remove the gas in the outer disc region. Tuned hydrodynamic simulations suggest that the RPS event is occurring almost face-on, making NGC 4330 the ideal candidate to study the effects of the perturbation in the direction perpendicular to the disc plane. We present here two new independent sets of F…
We have observed the late-type peculiar galaxy NGC 4424 during VESTIGE, a blind narrow-band Halpha[NII] imaging survey of the Virgo cluster carried out with MegaCam at the CFHT. The presence of a 110 kpc long HI tail in the S direction indicates that this galaxy is undergoing a ram pressure stripping event. The deep narrow-band image revealed the presence of a low surface brightness ionised gas tail ~10 kpc long extending from the centre of the galaxy to the NW direction, in the direction opposite to the HI tail. Chandra and XMM X-rays data do not show any compact source in the nucleus nor the…
We present the Pristine survey, a new narrow-band photometric survey focused on the metallicity-sensitive Ca H & K lines and conducted in the northern hemisphere with the wide-field imager MegaCam on the Canada-France-Hawaii Telescope (CFHT). This paper reviews our overall survey strategy and discusses the data processing and metallicity calibration. Additionally we review the application of these data to the main aims of the survey, which are to gather a large sample of the most metal-poor stars in the Galaxy, to further characterise the faintest Milky Way satellites, and to map the (metal-po…
