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ACCEPTCAT - Archive of Chandra Cluster Entropy Profile Tables (ACCEPT) Catalog

HEASARC
Archive

Overview

This table, the Archive of Chandra Cluster Entropy Profile Tables (ACCEPT) Catalog, contains the radial entropy profiles of the intracluster medium (ICM) for a collection of 239 clusters taken from the Chandra X-ray Observatory's Data Archive. Entropy is of great interest because it controls ICM global properties and records the thermal history of a cluster. The authors find that most ICM entropy profiles are well fitted by a model which is a power law at large radii and approaches a constant value at small radii: K(r) = K0 + K100 (r/100 kpc)alpha, where K0 quantifies the typical excess of core entropy above the best-fitting power law found at larger radii. The authors also show that the K0 distributions of both the full archival sample and the primary Highest X-Ray Flux Galaxy Cluster Sample of Reiprich (2001, Ph.D. thesis) are bimodal with a distinct gap between K0 ~ 30 - 50 keV cm2 and population peaks at K0 ~ 15 keV cm2 and K0 ~ 150 keV cm2. The effects of point-spread function smearing and angular resolution on best-fit K0 values are investigated using mock Chandra observations and degraded entropy profiles, respectively. The authors find that neither of these effects is sufficient to explain the entropy-profile flattening they measure at small radii. The influence of profile curvature and the number of radial bins on the best-fit K0 is also considered, and they find no indication that K0 is significantly impacted by either.

All data and results associated with this work are publicly available via the project web site http://www.pa.msu.edu/astro/MC2/accept/.

The sample is collected from observations taken with the Chandra X-ray Observatory and which were publicly available in the CDA (Chandra Data Archive) as of 2008 August.


Catalog Bibcode

2009ApJS..182...12C

References

Intracluster medium entropy profiles for a Chandra archival sample of
galaxy clusters.
    Cavagnolo K.W., Donahue M., Voit G.M., Sun M.
   <Astrophys. J. Suppl. Ser., 182, 12-32 (2009)>
   =2009ApJS..182...12C

Provenance

This table was created by the HEASARC in January 2012 based on CDS Catalog J/ApJS/182/12 files table1.dat and table5.dat.

HEASARC Implementation

The HEASARC has combined and reformatted the data given in Tables 1 and 5 of the reference paper into a single table and such that there is exactly one row per cluster, making 240 altogether (one more than the authors state in their abstract). For each cluster, fits using two different model radial distributions for the entropy profiles were used, and also two different methods for interpolating the temperature profile across the higher resolution radial grid of the deprojected electron density profile in the central bin. Thus, for each cluster there are results from 4 separate fits reported herein, with the relevant parameters from these fits given the suffixes 1, 2, 3 and 4, accordingly.

Parameters

Name
The name of the cluster of galaxies

ObsID_1
The Chandra observation identifier (ObsID) for the dataset used in the analysis of the particular cluster. Some clusters have been observed multiple times by Chandra, notice, in which case this is the first such observation

RA
The Right Ascension of the cluster center in the selected equinox. This was given in J2000.0 equatorial coordinates to a precision of 0.001 seconds of time in the original table.

Dec
The Declination of the cluster center in the selected equinox. This was given in J2000.0 equatorial coordinates to a precision of 0.01 arcseconds in the original table.

LII
The Galactic Longitude of the cluster center.

BII
The Galactic Latitude of the cluster center.

Exposure_Obsid_1
The exposure time for the (first if multiple observations were made) Chandra observation, in seconds (converted by the HEASARC from the kilosecond units given in the reference paper).

Center_CCD_Obsid_1
The ACIS CCD on which the cluster center is located in the first Chandra observation.

Redshift
The redshift of the cluster of galaxies.

kT
The average cluster ICM temperature, in keV.

Notes
Codes for assigned note(s) for the specified clusters of galaxies, as follows:

      a = Clusters analyzed using the best-fit beta-model for the surface
          brightness profiles (discussed in Sect. 3.2 of the reference paper);
      b = Clusters with complex surface brightness of which only the central
          regions were used in fitting K(r);
      c = Clusters only used during analysis of the HIFLUGCS sub-sample
          (discussed in Sect. 5.4 of the reference paper);
      d = Clusters with central AGN removed during analysis
          (discussed in Sect. 3.5 of the reference paper);
      e = Clusters with central compact source removed during analysis
          (discussed in Sect. 3.5 of the reference paper);
      f = Clusters with central bin ignored during fitting
          (discussed in Sect. 3.5 of the reference paper).
  

ObsID_2
The Chandra observation identifier (ObsID) for the second dataset used in the analysis of the particular cluster

Exposure_Obsid_2
The exposure time for the second Chandra observation, in seconds (converted by the HEASARC from the kilosecond units given in the reference paper).

Center_CCD_Obsid_2
The ACIS CCD on which the cluster center is located in the second Chandra observation.

ObsID_3
The Chandra observation identifier (ObsID) for the third dataset used in the analysis of the particular cluster

Exposure_Obsid_3
The exposure time for the third Chandra observation, in seconds (converted by the HEASARC from the kilosecond units given in the reference paper).

Center_CCD_Obsid_3
The ACIS CCD on which the cluster center is located in the third Chandra observation.

ObsID_4
The Chandra observation identifier (ObsID) for the fourth dataset used in the analysis of the particular cluster

Exposure_Obsid_4
The exposure time for the fourth Chandra observation, in seconds (converted by the HEASARC from the kilosecond units given in the reference paper).

Center_CCD_Obsid_4
The ACIS CCD on which the cluster center is located in the fourth Chandra observation.

ObsID_5
The Chandra observation identifier (ObsID) for the fifth dataset used in the analysis of the particular cluster

Exposure_Obsid_5
The exposure time for the fifth Chandra observation, in seconds (converted by the HEASARC from the kilosecond units given in the reference paper).

Center_CCD_Obsid_5
The ACIS CCD on which the cluster center is located in the fifth Chandra observation.

ObsID_6
The Chandra observation identifier (ObsID) for the sixth dataset used in the analysis of the particular cluster

Exposure_Obsid_6
The exposure time for the sixth Chandra observation, in seconds (converted by the HEASARC from the kilosecond units given in the reference paper).

Center_CCD_Obsid_6
The ACIS CCD on which the cluster center is located in the sixth Chandra observation.

ObsID_7
The Chandra observation identifier (ObsID) for the seventh dataset used in the analysis of the particular cluster

Exposure_Obsid_7
The exposure time for the seventh Chandra observation, in seconds (converted by the HEASARC from the kilosecond units given in the reference paper).

Center_CCD_Obsid_7
The ACIS CCD on which the cluster center is located in the seventh Chandra observation.

Fit_Method_1
The method of TX interpolation performed for the inner region of the cluster for the first fit, where a single temperature bin encompasses several density profile bins: 'flat' meaning Delta-Tcenter = 0, i.e., the temperature across the central density bins is assumed to be isothermal, or 'extr' meaning that the temperature is free to decline across the central density bins, assuming a linear gradient consistent with the slope of the temperature profile at radii larger than the central TX bin, i.e., a linear extrapolation is used.

Num_Radial_Bins
The number of radial bins included in the fit.

Max_Fit_Radius
The maximum radius for the fit, in Mpc.

BF_Core_Entropy_1
The best-fit core entropy, K0, in keV cm2, for the first fit, using the model distribution specified by equation (4) in the reference paper (if non-zero), or, if the model distribution is that specified by equation (5) of the reference paper, the value of 0.0.

BF_Core_Entropy_1_Error
The uncertainty in the corresponding parameter, in the same units as that parameter. If blank, this parameter was either not included in the fit or set to a fixed value.

Num_Sigma_K0_Gt_0_1
The number of sigma that the best-fit value for the core entropy K0 differs from zero, for the first fit. This is left blank in fits where model distribution is that specified by equation (5) of the reference paper, since in them the value of 0.0 for K0 is adopted a priori.

BF_100k_Entropy_1
The best-fit entropy, K100, at 100 kpc radius, in keV cm2, for the first fit, using the model distribution specified by equation (4) in the reference paper if K0 is non-zero, or by that specified by equation (5) of the reference paper if the value of K0 is 0.0.

BF_100k_Entropy_1_Error
The uncertainty in the corresponding parameter, in the same units as that parameter.

Alpha_1
The best-fit power-law index alpha of the radial entropy profile, for the first fit.

Alpha_1_Error
The uncertainty in the corresponding parameter, in the same units as that parameter.

DoF_1
The number of degrees of freedom (dof) for the first fit.

Chi_Squared_1
The chi-squared statistic of the best-fit model for the first fit.

P_Value_1
The p-value probability for the first fit, given the Chi-Squared and degrees of freedom, i.e., the probability of obtaining a test statistic at least as extreme as the one that was actually obtained

Fit_Method_2
The method of TX interpolation performed for the inner region of the cluster for the second fit, where a single temperature bin encompasses several density profile bins: 'flat' meaning Delta-Tcenter = 0, i.e., the temperature across the central density bins is assumed to be isothermal, or 'extr' meaning that the temperature is free to decline across the central density bins, assuming a linear gradient consistent with the slope of the temperature profile at radii larger than the central TX bin, i.e., a linear extrapolation is used.

BF_Core_Entropy_2
The best-fit core entropy, K0, in keV cm2, for the second fit, using the model distribution specified by equation (4) in the reference paper (if non-zero), or, if the model distribution is that specified by equation (5) of the reference paper, the value of 0.0.

BF_Core_Entropy_2_Error
The uncertainty in the corresponding parameter, in the same units as that parameter. If blank, this parameter was either not included in the fit or set to a fixed value.

Num_Sigma_K0_Gt_0_2
The number of sigma that the best-fit value for the core entropy K0 differs from zero, for the second fit. This is left blank in fits where model distribution is that specified by equation (5) of the reference paper, since in them the value of 0.0 for K0 is adopted a priori.

BF_100k_Entropy_2
The best-fit entropy, K100, at 100 kpc radius, in keV cm2, for the second fit, using the model distribution specified by equation (4) in the reference paper if K0 is non-zero, or by that specified by equation (5) of the reference paper if the value of K0 is 0.0.

BF_100k_Entropy_2_Error
The uncertainty in the corresponding parameter, in the same units as that parameter.

Alpha_2
The best-fit power-law index alpha of the radial entropy profile, for the second fit.

Alpha_2_Error
The uncertainty in the corresponding parameter, in the same units as that parameter.

DoF_2
The number of degrees of freedom (dof) for the second fit.

Chi_Squared_2
The chi-squared statistic of the best-fit model for the second fit.

P_Value_2
The p-value probability for the second fit, given the Chi-Squared and degrees of freedom, i.e., the probability of obtaining a test statistic at least as extreme as the one that was actually obtained

Fit_Method_3
The method of TX interpolation performed for the inner region of the cluster for the third fit, where a single temperature bin encompasses several density profile bins: 'flat' meaning Delta-Tcenter = 0, i.e., the temperature across the central density bins is assumed to be isothermal, or 'extr' meaning that the temperature is free to decline across the central density bins, assuming a linear gradient consistent with the slope of the temperature profile at radii larger than the central TX bin, i.e., a linear extrapolation is used.

BF_Core_Entropy_3
The best-fit core entropy, K0, in keV cm2, for the third fit, using the model distribution specified by equation (4) in the reference paper (if non-zero), or, if the model distribution is that specified by equation (5) of the reference paper, the value of 0.0.

BF_Core_Entropy_3_Error
The uncertainty in the corresponding parameter, in the same units as that parameter. If blank, this parameter was either not included in the fit or set to a fixed value.

Num_Sigma_K0_Gt_0_3
The number of sigma that the best-fit value for the core entropy K0 differs from zero, for the third fit. This is left blank in fits where model distribution is that specified by equation (5) of the reference paper, since in them the value of 0.0 for K0 is adopted a priori.

BF_100k_Entropy_3
The best-fit entropy, K100, at 100 kpc radius, in keV cm2, for the third fit, using the model distribution specified by equation (4) in the reference paper if K0 is non-zero, or by that specified by equation (5) of the reference paper if the value of K0 is 0.0.

BF_100k_Entropy_3_Error
The uncertainty in the corresponding parameter, in the same units as that parameter.

Alpha_3
The best-fit power-law index alpha of the radial entropy profile, for the third fit.

Alpha_3_Error
The uncertainty in the corresponding parameter, in the same units as that parameter.

DoF_3
The number of degrees of freedom (dof) for the third fit.

Chi_Squared_3
The chi-squared statistic of the best-fit model for the third fit.

P_Value_3
The p-value probability for the third fit, given the Chi-Squared and degrees of freedom, i.e., the probability of obtaining a test statistic at least as extreme as the one that was actually obtained

Fit_Method_4
The method of TX interpolation performed for the inner region of the cluster for the fourth fit, where a single temperature bin encompasses several density profile bins: 'flat' meaning Delta-Tcenter = 0, i.e., the temperature across the central density bins is assumed to be isothermal, or 'extr' meaning that the temperature is free to decline across the central density bins, assuming a linear gradient consistent with the slope of the temperature profile at radii larger than the central TX bin, i.e., a linear extrapolation is used.

BF_Core_Entropy_4
The best-fit core entropy, K0, in keV cm2, for the fourth fit, using the model distribution specified by equation (4) in the reference paper (if non-zero), or, if the model distribution is that specified by equation (5) of the reference paper, the value of 0.0.

BF_Core_Entropy_4_Error
The uncertainty in the corresponding parameter, in the same units as that parameter. If blank, this parameter was either not included in the fit or set to a fixed value.

Num_Sigma_K0_Gt_0_4
The number of sigma that the best-fit value for the core entropy K0 differs from zero, for the fourth fit. This is left blank in fits where model distribution is that specified by equation (5) of the reference paper, since in them the value of 0.0 for K0 is adopted a priori.

BF_100k_Entropy_4
The best-fit entropy, K100, at 100 kpc radius, in keV cm2, for the fourth fit, using the model distribution specified by equation (4) in the reference paper if K0 is non-zero, or by that specified by equation (5) of the reference paper if the value of K0 is 0.0.

BF_100k_Entropy_4_Error
The uncertainty in the corresponding parameter, in the same units as that parameter.

Alpha_4
The best-fit power-law index alpha of the radial entropy profile, for the fourth fit.

Alpha_4_Error
The uncertainty in the corresponding parameter, in the same units as that parameter.

DoF_4
The number of degrees of freedom (dof) for the fourth fit.

Chi_Squared_4
The chi-squared statistic of the best-fit model for the fourth fit.

P_Value_4
The p-value probability for the fourth fit, given the Chi-Squared and degrees of freedom, i.e., the probability of obtaining a test statistic at least as extreme as the one that was actually obtained.


Contact Person

Questions regarding the ACCEPTCAT database table can be addressed to the HEASARC User Hotline.

Page Author: Browse Software Development Team
Last Modified: 4-Jan-2012