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RASSCALS - ROSAT All-Sky Survey CALS Galaxy Groups Catalog |
HEASARC Archive |
The data in this table replace the preliminary analysis of the X-ray data which was presented in Mahdavi et al., 1999, ApJ, 518, 69 (CDS Cat. <J/ApJ/518/69>.
The RASSCALS: an X-ray and optical study of 260 galaxy groups. Mahdavi A., Bohringer H., Geller M.J., Ramella M. <Astrophys. J. 534, 114 (2000)> =2000ApJ...534..114M
Name
The RASSCALS object designation. The authors assigned each system
a 7-character name, beginning with 'NRG', 'SRG', or 'SS2', followed by 'b'
or 's' (specifying the angular size of the system as 'big', with cz < 8500
km/s, or 'small', with cz > 8500 km/s, respectively), followed by a 3-digit
number.
RA
The Right Ascension of the galaxy group in the selected equinox.
For the 59 groups with a listed X-ray luminosity, the position reported is
the X-ray centroid, while for the others it is the mean position of the
galaxies in the group. This was given in J2000.0 equatorial coordinates
to a precision of 0.1 seconds of time in the original table.
Dec
The Declination of the galaxy group in the selected equinox.
For the 59 groups with a listed X-ray luminosity, the position reported is
the X-ray centroid, while for the others it is the mean position of the
galaxies in the group. This was given in J2000.0 equatorial coordinates
to a precision of 1 arcsecond in the original table.
LII
The Galactic Longitude of the galaxy group.
BII
The Galactic Latitude of the galaxy group.
N_Group
The number of known group members.
N_17
The number of group members brighter than an absolute magnitude
M_z = -17, corresponding to an apparent Zwicky magnitude m_z = 15.5 for
a group at cz = 3200 km/s. To calculate n_17, the authors assumed that
the galaxies in groups have the same luminosity function as the CfA
Redshift Survey (Marzke, Huchra and Geller 1994, ApJ, 428, 43), reconvolved
with the magnitude errors. The resulting distribution is well-represented
by a Schechter (1976, ApJ, 203, 297) function with a characteristic
absolute magnitude M(*) = -19.1 and a faint-end slope alpha = -1.
The median value of n_17 is 44.
Radial_Velocity
The recession velocity of the galaxy group, in km/s.
Radial_Velocity_Error
The RMS uncertainty in the recession velocity of the
galaxy group, in km/s.
Log_Sigma_P
The log10 of the projected velocity dispersion of the
galaxy group, in km/s.
Log_Sigma_P_Error
The RMS uncertainty in log10 of the projected velocity
dispersion, in km/s.
Log_Lx_P5_Limit
The limit flag for the X-ray luminosity in the 0.1 - 2.4
keV band within an aperture of 0.5 h(100)^-1 Mpc.
Log_Lx_P5
The log10 of the X-ray luminosity of the galaxy group in the
0.1 - 2.4 keV band within an aperture of 0.5 h(100)^-1 Mpc, in h(100)^-2 erg/s.
Log_Lx_P5_Error
The RMS uncertainty in the log10 of the X-ray luminosity
of the galaxy group in the 0.1 - 2.4 keV band within an aperture of
0.5 h(100)^-1 Mpc, in h(100)^-2 erg/s.
Log_Lx_P5_Flag
This parameter is a flag which is set to 'd' to indicate
two X-ray luminous Abell clusters (NRGs372 and NRGs392) which the optical
group finding algorithm has confused with the field. The authors counted
these as detections, but did not calculate their other X-ray properties.
Alt_Names
Other identifications for the galaxy group, by no means complete:
A: Abell (CDS Cat. <VII/4>) cluster AWM: Albert et al. (1977ApJ...211..309A) Groups HCG: Hickson Compact Groups (Hickson, 1982, CDS Cat. <VII/213>) MGBR: Studied in greater detail in Mahdavi et al. 1999 MKW: Morgan, Kayser, & White (1975ApJ...199..545M) Groups PPS: Loose Groups in the Perseus-Pisces Survey (Trasarti-Battistoni, 1998, CDS Cat. <J/A+AS/130/341>) ZM: Zabludoff & Mulchaey (1998, CDS Cat. <J/ApJ/496/39>) Poor Groups
Log_Lx_P25
The log10 of the X-ray luminosity of the galaxy group in the 0.1
- 2.4 keV band within an aperture of 0.25 h(100)^-1 Mpc, in h(100)^-2 erg/s.
Log_Lx_P25_Error
The RMS uncertainty in the log10 of the X-ray luminosity
of the galaxy group in the 0.1 - 2.4 keV band within an aperture of
0.25 h(100)^-1 Mpc, in h(100)^-2 erg/s.
Log_Lx_R_Xi
The log10 of the X-ray luminosity of the galaxy group in the 0.1
- 2.4 keV band within the NOCORE radius, R(xi), in h(100)^-2 erg/s.
Log_Lx_R_Xi_Error
The RMS uncertainty in the log10 of the X-ray luminosity
of the galaxy group in the 0.1 - 2.4 keV band within the NOCORE radius,
R(xi), in h(100)^-2 erg/s.
R_Xi
The NOCORE radius, R(xi), of the X-ray-detected galaxy group, in Mpc.
R(xi) provides a characteristic scale for the X-ray emission, and, hence, for
for the gravitational potential of the galaxy group. The procedure for
estimating this quantity is discussed in Section 2.4 of the reference paper.
R_Xi_Error
The RMS uncertainty in the NOCORE radius, R(xi), in Mpc.
Log_Time_Cross
The log10 of the system's crossing time, in units
of the Hubble time (H_0^-1), defined as R(xi)*H_0/sigma(p).
Log_Time_Cross_Error
The RMS uncertainty in log10 of the crossing time,
in units of the Hubble time (H_0^-1).
F_Spiral
The fraction of group members that are spiral galaxies.