اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدThe Black Hole Mass of Abell 1836-BCG and Abell 3565-BCG
198
0
0.0
(
0
)
تأليف
E. Dalla Bonta
اسأل ChatGPT حول البحث
ﻻ يوجد ملخص باللغة العربية
Two brightest cluster galaxies (BCGs), namely Abell 1836-BCG and Abell 3565-BCG, were observed with the Advanced Camera for Surveys (ACS) and the Space Telescope Imaging Spectrograph (STIS) on board the Hubble Space Telescope. By modeling the available photometric and kinematic data, it resulted that the mass of Abell 1836-BCG and Abell 3565-BCG are M_bh=4.8(+0.8,-0.7)x10^9 M_sun and M_bh=1.3(+0.3,-0.4)x10^9 M_sun at 1 sigma confidence level, respectively.
قيم البحث
اقرأ أيضاً
We analyze the stellar growth of Brightest Cluster Galaxies (BCGs) produced by cosmological zoom-in hydrodynamical simulations of the formation of massive galaxy clusters. The evolution of the stellar mass content is studied considering different ape
rtures, and tracking backwards either the main progenitor of the $z=0$ BCG or that of the cluster hosting the BCG at $z=0$. Both methods lead to similar results up to $z simeq 1.5$. The simulated BCGs masses at $z=0$ are in agreement with recent observations. In the redshift interval from $z=1$ to $z=0$ we find growth factors 1.3, 1.6 and 3.6 for stellar masses within 30kpc, 50kpc and 10% of $R_{500}$ respectively. The first two factors, and in general the mass evolution in this redshift range, are in agreement with most recent observations. The last larger factor is similar to the growth factor obtained by a semi-analytical model (SAM). Half of the star particles that end up in the inner 50 kpc was typically formed by redshift $sim$ 3.7, while the assembly of half of the BCGs stellar mass occurs on average at lower redshifts $sim 1.5$. This assembly redshift correlates with the mass attained by the cluster at high $z gtrsim 1.3$, due to the broader range of the progenitor clusters at high-$z$. The assembly redshift of BCGs decreases with increasing apertures. Our results are compatible with the {it inside-out} scenario. Simulated BCGs could lack intense enough star formation (SF) at high redshift, while possibly exhibit an excess of residual SF at low redshift.
We present the first application of lens magnification to measure the absolute mass of a galaxy cluster; Abell 1689. The absolute mass of a galaxy cluster can be measured by the gravitational lens magnification of a background galaxy population by th
e cluster potential. The lensing signal is complicated by the variation in number counts due to galaxy clustering and shot-noise, and by additional uncertainties in relating magnification to mass in the strong lensing regime. Clustering and shot-noise can be dealt with using maximum likelihood methods. Local approximations can then be used to estimate the mass from magnification. Alternatively if the lens is axially symmetric we show that the amplification equation can be solved nonlocally for the surface mass density and the tangential shear. In this paper we present the first maps of the total mass distribution in Abell 1689, measured from the deficit of lensed red galaxies behind the cluster. Although noisier, these reproduce the main features of mass maps made using the shear distortion of background galaxies but have the correct normalisation, finally breaking the ``sheet-mass degeneracy that has plagued lensing methods based on shear. We derive the cluster mass profile in the inner 4 (0.48 Mpc/h). These show a profile with a near isothermal surface mass density kappa = (0.5+/-0.1)(theta/1)^{-1} out to a radius of 2.4 (0.28Mpc/h), followed by a sudden drop into noise. We find that the projected mass interior to 0.24 h^{-1}$Mpc is M(<0.24 Mpc/h)=(0.50+/- 0.09) times 10^{15} Msol/h. We compare our results with masses estimated from X-ray temperatures and line-of-sight velocity dispersions, as well as weak shear and lensing arclets and find all are in fair agreement for Abell 1698.
Holm 15A, the brightest cluster galaxy (BCG) of the galaxy cluster Abell 85, has an ultra-diffuse central region, 2 mag fainter than the faintest depleted core of any early-type galaxy (ETG) that has been dynamically modelled in detail. We use orbit-
based, axisymmetric Schwarzschild models to analyse the stellar kinematics of Holm 15A from new high-resolution, wide-field spectral observations obtained with MUSE at the VLT. We find a supermassive black hole (SMBH) with a mass of (4.0 +- 0.80) x 10^10 solar masses at the center of Holm 15A. This is the most massive black hole with a direct dynamical detection in the local universe. We find that the distribution of stellar orbits is increasingly biased towards tangential motions inside the core. However, the tangential bias is less than in other cored elliptical galaxies. We compare Holm 15A with N-body simulations of mergers between galaxies with black holes and find that the observed amount of tangential anisotropy and the shape of the light profile are consistent with a formation scenario where Holm 15A is the remnant of a merger between two ETGs with pre-existing depleted cores. We find that black hole masses in cored galaxies, including Holm 15A, scale inversely with the central stellar surface brightness and mass density, respectively. These correlation are independent of a specific parameterization of the light profile.
We report the first X-ray detection of a proto-supermassive binary black hole at the centre of Abell 400. Using the Chandra ACIS, we are able to clearly resolve the two active galactic nuclei in 3C 75, the well known double radio source at the centre
of Abell 400. Through analysis of the new Chandra observation of Abell 400 along with 4.5 GHz and 330 MHz VLA radio data, we will show new evidence that the Active Galactic Nuclei in 3C 75 are a bound system. Methods. Using the high quality X-ray data, we map the temperature, pressure, density, and entropy of the inner regions as well as the cluster profile properties out to ~18. We compare features in the X-ray and radio images to determine the interaction between the intra-cluster medium and extended radio emission. The Chandra image shows an elongation of the cluster gas along the northeast-southwest axis; aligned with the initial bending of 3C 75s jets. Additionally, the temperature profile shows no cooling core, consistent with a merging system. There is an apparent shock to the south of the core consistent with a Mach number of M~1.4 or speed of v~1200 km s^-1. Both Active Galactic Nuclei, at least in projection, are located in the low entropy, high density core just north of the shock region. We find that the projected path of the jets does not follow the intra-cluster medium surface brightness gradient as expected if their path were due to buoyancy. We also find that both central AGN are extended and include a thermal component. Based on this analysis, we conclude that the Active Galactic Nuclei in 3C 75 are a bound system from a previous merger. They are contained in a low entropy core moving through the intra-cluster medium at 1200 km s^-1. The bending of the jets is due to the local intra-cluster medium wind.
We present Giant Metrewave Radio Telescope (GMRT) HI 21-cm line data for the smallest known eXtremely Metal Deficient (XMD) blue compact galaxy (BCG) HS0822+3542. From HST imaging it has been suggested that HS0822+3542 actually consists of two still
smaller (~ 100pc sized) ultra-compact dwarfs that are in the process of merging. The brighter of these two putative ultra compact dwarfs has an ocular appearance, similar to that seen in galaxies that have suffered a penetrating encounter with a smaller companion. From our HI imaging we find that the gas distribution and kinematics in this object are similar to that of other low mass galaxies, albeit with some evidence for tidal disturbance. On the other hand, the HI emission has an angular size ~25 times larger than that of the putative ultra-compact dwarfs. The optical emission is also offset from the centre of the HI emission. HS0822+3542 is located in the Lynx-Cancer void, but has a nearby companion LSB dwarf galaxy SAO0822+3545. In light of all this we also consider a scenario where the optical emission from HS0822+3542 comes not from two merging ultra-compact dwarfs but from multiple star forming regions in a tidally disturbed galaxy. In this model, the ocular appearance of the brighter star forming region could be the result of triggered star formation.
سجل دخول لتتمكن من نشر تعليقات
التعليقات
جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
