The XXL Survey Farahi, Arya; Guglielmo, Valentina; Evrard, August E. ...
Astronomy & astrophysics,
12/2018, Volume:
620
Journal Article
Peer reviewed
Open access
Context. An X-ray survey with the XMM-Newton telescope, XMM-XXL, has identified hundreds of galaxy groups and clusters in two 25 deg2 fields. Combining spectroscopic and X-ray observations in one ...field, we determine how the kinetic energy of galaxies scales with hot gas temperature and also, by imposing prior constraints on the relative energies of galaxies and dark matter, infer a power-law scaling of total mass with temperature. Aims. Our goals are: i) to determine parameters of the scaling between galaxy velocity dispersion and X-ray temperature, T300 kpc, for the halos hosting XXL-selected clusters, and; ii) to infer the log-mean scaling of total halo mass with temperature, ⟨lnM200 | T300 kpc, z⟩. Methods. We applied an ensemble velocity likelihood to a sample of >1500 spectroscopic redshifts within 132 spectroscopically confirmed clusters with redshifts z < 0.6 to model, ⟨lnσgal | T300 kpc, z⟩, where σgal is the velocity dispersion of XXL cluster member galaxies and T300 kpc is a 300 kpc aperture temperature. To infer total halo mass we used a precise virial relation for massive halos calibrated by N-body simulations along with a single degree of freedom summarising galaxy velocity bias with respect to dark matter. Results. For the XXL-N cluster sample, we find σgal ∝ T300 kpc0.63±0.05 $\sigma_{\textrm{gal}} \propto {{T_{\textrm{300~kpc}}}^{0.63\pm0.05}$ σgal∝T300 kpc0.63±0.05, a slope significantly steeper than the self-similar expectation of 0.5. Assuming scale-independent galaxy velocity bias, we infer a mean logarithmic mass at a given X-ray temperature and redshift, 〈ln(E(z)M200/1014 M⊙)|T300 kpc, z〉 = πT + αT ln (T300 kpc/Tp) + βT ln (E(z)/E(zp)) $\langle \ln (E(z) M_{200}/10^{14} {{\, M_{\odot}}})|{{T_{\textrm{300~kpc}}},z\rangle=\pi_{T}+\alpha_{T}\ln\left({{T_{\textrm{300~kpc}}}/T_{\textrm{p}}\right)+\beta_{T}\ln\left(E(z)/E(z_{\textrm{p}})\right)$ 〈ln(E(z)M200/1014 M⊙)|T300 kpc,z〉=πT+αTln(T300 kpc/Tp)+βTln(E(z)/E(zp)) using pivot values kTp = 2.2 keV and zp = 0.25, with normalization πT = 0.45 ± 0.24 and slope αT = 1.89 ± 0.15. We obtain only weak constraints on redshift evolution, βT = −1.29 ± 1.14. Conclusions. The ratio of specific energies in hot gas and galaxies is scale dependent. Ensemble spectroscopic analysis is a viable method to infer mean scaling relations, particularly for the numerous low mass systems with small numbers of spectroscopic members per system. Galaxy velocity bias is the dominant systematic uncertainty in dynamical mass estimates.
We present new radial velocities from AAOmega on the Anglo-Australian Telescope for 307 galaxies (bJ
< 19.5) in the region of the rich cluster Abell 1386. Consistent with other studies of galaxy ...clusters that constitute subunits of superstructures, we find that the velocity distribution of A1386 is very broad (21 000-42 000 km s−1, or z= 0.08-0.14) and complex. The mean redshift of the cluster that Abell designated as number 1386 is found to be ∼ 0.104. However, we find that it consists of various superpositions of line-of-sight components. We investigate the reality of each component by testing for substructure and searching for giant elliptical galaxies in each and show that A1386 is made up of at least four significant clusters or groups along the line of sight whose global parameters we detail. Peculiar velocities of brightest galaxies for each of the groups are computed and found to be different from previous works, largely due to the complexity of the sky area and the depth of analysis performed in the present work. We also analyse A1386 in the context of its parent superclusters: Leo A and especially the Sloan Great Wall. Although the new clusters may be moving towards mass concentrations in the Sloan Great Wall or beyond, many are most likely not yet physically bound to it.
The XXL Survey Farahi, Arya; Guglielmo, Valentina; Evrard, August E. ...
Astronomy and astrophysics (Berlin),
12/2018, Volume:
620
Journal Article
Peer reviewed
Open access
Context.
An X-ray survey with the
XMM-Newton
telescope, XMM-XXL, has identified hundreds of galaxy groups and clusters in two 25 deg
2
fields. Combining spectroscopic and X-ray observations in one ...field, we determine how the kinetic energy of galaxies scales with hot gas temperature and also, by imposing prior constraints on the relative energies of galaxies and dark matter, infer a power-law scaling of total mass with temperature.
Aims.
Our goals are: i) to determine parameters of the scaling between galaxy velocity dispersion and X-ray temperature,
T
300 kpc
, for the halos hosting XXL-selected clusters, and; ii) to infer the log-mean scaling of total halo mass with temperature, ⟨ln
M
200
|
T
300 kpc
,
z
⟩.
Methods.
We applied an ensemble velocity likelihood to a sample of >1500 spectroscopic redshifts within 132 spectroscopically confirmed clusters with redshifts
z
< 0.6 to model, ⟨ln
σ
gal
|
T
300 kpc
,
z
⟩, where
σ
gal
is the velocity dispersion of XXL cluster member galaxies and
T
300 kpc
is a 300 kpc aperture temperature. To infer total halo mass we used a precise virial relation for massive halos calibrated by
N
-body simulations along with a single degree of freedom summarising galaxy velocity bias with respect to dark matter.
Results.
For the XXL-N cluster sample, we find σ
gal
∝ T
300 kpc
0.63±0.05
, a slope significantly steeper than the self-similar expectation of 0.5. Assuming scale-independent galaxy velocity bias, we infer a mean logarithmic mass at a given X-ray temperature and redshift,
〈ln(
E
(
z
)
M
200
/10
14
M
⊙
)|T
300
kpc,
z
〉 = π
T
+ α
T
ln (
T
300
kpc/
T
p
) +
β
T
ln (
E
(
z
)/
E
(
z
p
)) using pivot values
kT
p
= 2.2 keV and
z
p
= 0.25, with normalization
π
T
= 0.45 ± 0.24 and slope
α
T
= 1.89 ± 0.15. We obtain only weak constraints on redshift evolution,
β
T
= −1.29 ± 1.14.
Conclusions.
The ratio of specific energies in hot gas and galaxies is scale dependent. Ensemble spectroscopic analysis is a viable method to infer mean scaling relations, particularly for the numerous low mass systems with small numbers of spectroscopic members per system. Galaxy velocity bias is the dominant systematic uncertainty in dynamical mass estimates.
This study presents the results from several case studies on the application of passive seismic Horizontal to Vertical Spectral Ratio (HVSR) surveying methods for Heavy Mineral Sand (HMS) deposit ...subsurface layer detection for exploration and mining. The results from these case studies demonstrate the usefulness of this rapid and low cost survey method to complement HMS deposit mapping and its ability to provide additional stratigraphic information in gaps between drillholes.
HMS deposits typically occur in geological settings that are ideal for the application of the passive seismic HVSR method, because HMS deposits are typically shallow and may demonstrate acoustic impedance contrasts relative to surrounding sedimentary deposits or underlying acoustic bedrock. Trial HVSR survey results vary between different styles of heavy mineral sand deposits, from providing a direct estimate of the depth to the top of known HMS mineralisation based on a positive HVSR response from more dense and higher velocity HMS lenses, to detecting parallel silt and clay horizons, sometimes producing an inverted HVSR response, to be used as a bounding marker horizons for HMS deposits, and in many cases detecting the acoustic hard rock basement forming the base to the unconsolidated, young sedimentary deposits and basin fill containing HMS layers.
In each case study, the use of a lightweight, self-contained and simple to use seismometer has allowed HMS explorers to carry out surveys quickly and cost effectively, in some remote areas with difficult access, mostly using company field staff following a short training session. The techniques and approaches to process and model HVSR data for shallow stratigraphic mapping during these trial surveys have contributed to advancing the passive seismic HVSR surveying method to become more commonly used for large production surveys.
The ANU WiFeS SuperNovA Programme (AWSNAP)
Publications of the Astronomical Society of Australia/Publications Astronomical Society of Australia,
01/2016
Journal Article
We have modified the minimum curvature gridding method to cope with various flight line gaps, by employing a line spacing compression technique. The line spacing compression method was applied to ...magnetic data from a survey in northern Canada and was able to smoothly interpolate across the unevenly spaced lines without creating false anomalies. We have also derived a new, longer minimum curvature operator to handle flight lines of various lengths. The longer operator was applied to South Australia Salinity Project data and it removed the artificial boundaries at changes in flight line spacing and smoothly interpolated anomalies even over wider flight line gaps.
This paper presents the first major data release and survey description for the ANU WiFeS SuperNovA Program (AWSNAP). AWSNAP is an ongoing supernova spectroscopy campaign utilising the Wide Field ...Spectrograph (WiFeS) on the Australian National University (ANU) 2.3m telescope. The first and primary data release of this program (AWSNAP-DR1) releases 357 spectra of 175 unique objects collected over 82 equivalent full nights of observing from July 2012 to August 2015. These spectra have been made publicly available via the WISeREP supernova spectroscopy repository. We analyse the AWSNAP sample of Type Ia supernova spectra, including measurements of narrow sodium absorption features afforded by the high spectral resolution of the WiFeS instrument. In some cases we were able to use the integral-field nature of the WiFeS instrument to measure the rotation velocity of the SN host galaxy near the SN location in order to obtain precision sodium absorption velocities. We also present an extensive time series of SN 2012dn, including a near-nebular spectrum which both confirms its "super-Chandrasekhar" status and enables measurement of the sub-solar host metallicity at the SN site.
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