scholarly journals The K-Band Hubble Diagram for X-Ray Selected Brightest Cluster Galaxies

1998 ◽  
Vol 179 ◽  
pp. 339-341
Author(s):  
R.G. Mann ◽  
C.A. Collins
Keyword(s):  
Star Formation ◽  
List Type ◽  
Type Number ◽  
Hubble Diagram ◽  
Technical Problems ◽  
X Ray ◽  
Cluster Galaxies ◽  
Brightest Cluster Galaxies ◽  
The Absolute ◽  
Small Dispersion

The Hubble (magnitude-redshift) diagram for brightest cluster galaxies (BCGs) is a classic cosmological tool, widely studied because of the remarkably small dispersion (∼ 0.3 mag) in the absolute optical magnitudes of low redshift BCGs (Postman and Lauer 1995). Extending the BCG Hubble diagram to higher redshifts would greatly enhance its role as a cosmological probe, but this has been frustrated by several technical problems: – the conventional means of cluster selection in the optical become increasingly compromised by projection effects at z > 0.1– at higher redshifts the interpretation of optical magnitudes becomes increasingly complicated by the effects of possible star formation.

scholarly journals Spectroscopic Evidences for Star Formation in Cooling Flow Galaxies

1996 ◽  
Vol 171 ◽  
pp. 349-349
Author(s):  
N. Cardiel ◽  
J. Gorgas ◽  
A. Aragon-Salamanca
Keyword(s):  
Star Formation ◽  
Galaxy Clusters ◽  
X Ray ◽  
Cluster Galaxies ◽  
Cooling Flows ◽  
Cooling Flow ◽  
Brightest Cluster Galaxies

X-ray observations have led to the conclusion that many galaxy clusters are hosting cooling flows. The brightest cluster galaxies could have accreted masses of the order of 1011–1012M⊙, but is still uncertain what the final fate of the accreted gas may be.

scholarly journals Stellar formation in Brightest Cluster Galaxies

2009 ◽  
Vol 5 (S262) ◽  
pp. 450-451
Author(s):  
Tatiana Zapata Pichinao ◽  
Gastão B. Lima Neto
Keyword(s):  
Star Formation ◽  
Stellar Population ◽  
External Source ◽  
Star Formation History ◽  
Dynamic State ◽  
X Ray ◽  
Cluster Galaxies ◽  
Brightest Cluster Galaxies ◽  
First Results ◽  
Low Metallicity

AbstractWe study the interplay between stellar population of the Brightest Cluster Galaxies (BCG) and cluster global properties. We use X-ray properties from Chandra, ROSAT and ASCA observations and BCGs spectra from SDSS-DR6. Using STARLIGHT we determined the star formation history of the BCGs and look for relations with the intra-cluster gas properties. Our first results show no correlation between the recent star formation with x-ray temperature and dynamic state. An important star formation is happening in cool-core Cluster. This new stellar population has low metallicity, pointing to an external source of cold gas to form stars.

scholarly journals Why are some brightest cluster galaxies forming stars?

2007 ◽  
Vol 3 (S245) ◽  
pp. 185-188
Author(s):  
Christopher P. O'Dea ◽  
Alice Quillen ◽  
Nicholas Zufelt ◽  
Jaehong Park ◽  
Alastair Edge ◽  
...  
Keyword(s):  
Star Formation ◽  
Formation Rate ◽  
Line Emission ◽  
Optical Emission ◽  
Infrared Emission ◽  
X Ray ◽  
Cluster Galaxies ◽  
Brightest Cluster Galaxies ◽  
First Results ◽  
Optical Line

AbstractWe present first results from an imaging survey with the Spitzer Space Telescope of 62 brightest cluster galaxies with optical line emission located in the cores of X-ray luminous clusters selected from the ROSAT All-Sky Survey. We find that 1/3 of these sources have signs of excess infrared emission; 22 objects of 62 are detected at 70 μm and 19 have 8 to 5.8 μm flux ratios above 0.98. The strength of the excess emission correlates with the luminosity of the optical emission lines. Excluding the four systems dominated by an AGN, the excess mid-infrared emission in the remaining brightest cluster galaxies is likely powered by star formation. We find a correlation between mass deposition rate from a cooling flow model for the X-ray emission and the star formation rate estimated from the infrared luminosity. The star formation rates are 1/10 to 1/100 of the mass deposition rates expected in the absence of heating suggesting that the re-heating of the ICM is generally very effective in reducing the amount of mass cooling from the hot phase.

Fluorescence effects in quantitative microprobe analysis

1990 ◽  
Vol 48 (2) ◽  
pp. 188-189
Author(s):  
S.J.B. Reed
Keyword(s):  
Microprobe Analysis ◽  
Depth Distribution ◽  
Exciting Radiation ◽  
Primary Radiation ◽  
List Type ◽  
Type Number ◽  
Computing Power ◽  
X Ray ◽  
Fluorescent Radiation

Characteristic fluorescenceThe theory of characteristic fluorescence corrections was first developed by Castaing. The same approach, with an improved expression for the relative primary x-ray intensities of the exciting and excited elements, was used by Reed, who also introduced some simplifications, which may be summarized as follows (with reference to K-K fluorescence, i.e. K radiation of element ‘B’ exciting K radiation of ‘A’):1.The exciting radiation is assumed to be monochromatic, consisting of the Kα line only (neglecting the Kβ line).2.Various parameters are lumped together in a single tabulated function J(A), which is assumed to be independent of B.3.For calculating the absorption of the emerging fluorescent radiation, the depth distribution of the primary radiation B is represented by a simple exponential.These approximations may no longer be justifiable given the much greater computing power now available. For example, the contribution of the Kβ line can easily be calculated separately.

Interactive multiple area spectrum integration (MASI)

1994 ◽  
Vol 52 ◽  
pp. 942-943
Author(s):  
John A. Hunt ◽  
Richard D. Leapman ◽  
David B. Williams
Keyword(s):  
Image Processing ◽  
Low Dose ◽  
Routine Analysis ◽  
Reference Image ◽  
Area Spectrum ◽  
List Type ◽  
Type Number ◽  
Image Processor ◽  
X Ray ◽  
Scanning Path

Interactive MASI involves controlling the raster of a STEM or SEM probe to areas predefined byan integration mask which is formed by image processing, drawing or selecting regions manually. EELS, x-ray, or other spectra are then acquired while the probe is scanning over the areas defined by the integration mask. The technique has several advantages: (1) Low-dose spectra can be acquired by averaging the dose over a great many similar features. (2) MASI can eliminate the risks of spatial under- or over-sampling of multiple, complicated, and irregularly shaped objects. (3) MASI is an extremely rapid and convenient way to record spectra for routine analysis. The technique is performed as follows:Acquire reference imageOptionally blank beam for beam-sensitive specimensUse image processor to select integration mask from reference imageCalculate scanning path for probeUnblank probe (if blanked)Correct for specimen drift since reference image acquisition

scholarly journals Brightest cluster galaxies: the centre can(not?) hold

2020 ◽  
Vol 500 (1) ◽  
pp. 310-318
Author(s):  
Roberto De Propris ◽  
Michael J West ◽  
Felipe Andrade-Santos ◽  
Cinthia Ragone-Figueroa ◽  
Elena Rasia ◽  
...  
Keyword(s):  
Dark Matter ◽  
Local Environment ◽  
Major Axis ◽  
Theoretical Models ◽  
Dark Matter Halo ◽  
Gas Distribution ◽  
X Ray ◽  
Cluster Galaxies ◽  
Peculiar Velocities ◽  
Brightest Cluster Galaxies

ABSTRACT We explore the persistence of the alignment of brightest cluster galaxies (BCGs) with their local environment. We find that a significant fraction of BCGs do not coincide with the centroid of the X-ray gas distribution and/or show peculiar velocities (they are not at rest with respect to the cluster mean). Despite this, we find that BCGs are generally aligned with the cluster mass distribution even when they have significant offsets from the X-ray centre and significant peculiar velocities. The large offsets are not consistent with simple theoretical models. To account for these observations BCGs must undergo mergers preferentially along their major axis, the main infall direction. Such BCGs may be oscillating within the cluster potential after having been displaced by mergers or collisions, or the dark matter halo itself may not yet be relaxed.

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