Query Results from the ADS Database
Retrieved 51 abstracts, starting with number 1. Total number selected: 134150.
TY - Journal
T1 - Quantitative analysis of spirality in elliptical galaxies
A1 - Dojcsak, Levente
A1 - Shamir, Lior
JO - New Astronomy
VL - 28
Y1 - 2014/4/1
SP - 1
EP - 8
UR - http://adsabs.harvard.edu/abs/2014NewA...28....1D
N2 - We use an automated galaxy morphology analysis method to quantitatively
measure the spirality of galaxies classified manually as elliptical. The
data set used for the analysis consists of 60,518 galaxy images with
redshift obtained by the Sloan Digital Sky Survey (SDSS) and classified
manually by Galaxy Zoo, as well as the RC3 and NA10 catalogues. We
measure the spirality of the galaxies by using the Ganalyzer method,
which transforms the galaxy image to its radial intensity plot to detect
galaxy spirality that is in many cases difficult to notice by manual
observation of the raw galaxy image. Experimental results using manually
classified elliptical and S0 galaxies with redshift <0.3 suggest that
galaxies classified manually as elliptical and S0 exhibit a nonzero
signal for the spirality. These results suggest that the human eye
observing the raw galaxy image might not always be the most effective
way of detecting spirality and curves in the arms of galaxies.
DO - 10.1016/j.newast.2013.09.006
C1 - eprint: arXiv:1310.0387
SN - 1384-1076
ER -
TY - Journal
T1 - Green Bank Telescope Observations of Low Column Density H I around NGC 2997 and NGC 6946
A1 - Pisano, D. J.
JO - The Astronomical Journal
VL - 147
Y1 - 2014/3/1
SP - 48
KW - galaxies: evolution/ galaxies: formation/ galaxies: individual: NGC 6946 NGC 2997/ galaxies: interactions/ intergalactic medium
UR - http://adsabs.harvard.edu/abs/2014AJ....147...48P
N2 - Observations of ongoing H I accretion in nearby galaxies have only
identified about 10% of the fuel necessary to sustain star formation in
these galaxies. Most of these observations have been conducted using
interferometers and may have missed lower column density, diffuse, H I
gas that may trace the missing 90% of gas. Such gas may represent the
so-called cold flows predicted by current theories of galaxy formation
to have never been heated above the virial temperature of the dark
matter halo. As a first attempt to identify such cold flows around
nearby galaxies and complete the census of H I down to N H I
~ 1018 cm--2, I used the Robert C. Byrd
Green Bank Telescope (GBT) to map the circumgalactic (r lsim 100-200
kpc) H I environment around NGC 2997 and NGC 6946. The resulting GBT
observations cover a 4 deg2 area around each galaxy with a
5sigma detection limit of N H I ~ 1018
cm--2 over a 20 km s--1 line width. This
project complements absorption line studies, which are well-suited to
the regime of lower N H I . Around NGC 2997, the GBT H I data
reveal an extended H I disk and all of its surrounding gas-rich
satellite galaxies, but no filamentary features. Furthermore, the H I
mass as measured with the GBT is only 7% higher than past
interferometric measurements. After correcting for resolution
differences, the H I extent of the galaxy is 23% larger at the N H
I = 1.2 × 1018 cm--2 level as
measured by the GBT. On the other hand, the H I observations of NGC 6946
reveal a filamentary feature apparently connecting NGC 6946 with its
nearest companions. This H I filament has N H I ~ 5 ×
1018 cm--2 and an FWHM of 55 ± 5 km
s--1 and was invisible in past interferometer
observations. The properties of this filament are broadly consistent
with being a cold flow or debris from a past tidal interaction between
NGC 6946 and its satellites.
DO - 10.1088/0004-6256/147/3/48
C1 - eprint: arXiv:1312.3953
SN - 0004-6256
ER -
TY - Journal
T1 - Velocity distributions in galaxy clusters -- How to combine different normality tests
A1 - Sampaio, F. S.
A1 - Ribeiro, A. L. B.
JO - New Astronomy
VL - 27
Y1 - 2014/2/1
SP - 41
EP - 55
UR - http://adsabs.harvard.edu/abs/2014NewA...27...41S
N2 - We study 416 galaxy systems with more than 7 members selected from the
2MASS catalog. We applied five well known normality tests to the
velocity distributions of these systems to distinguish Gaussian and
non-Gaussian clusters. Using controlled samples, we estimated type I and
II errors for each test. We verified that individual tests minimize the
chances of classifying a Gaussian system as non-Gaussian, while the
Fisher's meta-analysis method, a procedure to combine p-values from
several statistical tests, minimizes the chances of classifying a
non-Gaussian system as Gaussian. Taking the positive elements of each
method and also including a modality analysis of the velocity
distribution, we defined objective criteria to split up the sample into
Gaussian and non-Gaussian clusters. Our analysis indicates that
50--58% of groups have Gaussian distribution, a lower fraction than
that we found using individual normality tests, 71--87%. We also
found that some properties of galaxy clusters are significantly
different between Gaussian and non-Gaussian systems. For instance,
non-Gaussian clusters have larger radii and contain more galaxies than
Gaussian clusters. Finally, we discussed the importance of choosing the
adequate methodology to classify galaxy systems from their velocity
distributions and also the dependence of the results on the criteria
used to identify clusters in galaxy surveys.
DO - 10.1016/j.newast.2013.08.008
SN - 1384-1076
ER -
TY - Journal
T1 - On the origin of galactic cosmic rays
A1 - Istomin, Ya. N.
JO - New Astronomy
VL - 27
Y1 - 2014/2/1
SP - 13
EP - 18
UR - http://adsabs.harvard.edu/abs/2014NewA...27...13I
N2 - It is shown that the relativistic jet, emitted from the center of the
Galaxy during its activity, possessed power and energy spectrum of
accelerated protons sufficient to explain the current cosmic rays
distribution in the Galaxy. Proton acceleration takes place on the light
cylinder surface formed by the rotation of a massive black hole caring
into rotation the radial magnetic field and the magnetosphere. Observed
in gamma, X-ray and radio bands bubbles above and below the galactic
plane can be remnants of this bipolar get. The size of the bubble
defines the time of the jet's start, ~=2.4·107
years ago. The jet worked more than 107 years, but less than
2.4·107 years.
DO - 10.1016/j.newast.2013.08.001
SN - 1384-1076
ER -
TY - Journal
T1 - Bar slowdown and the distribution of dark matter in barred galaxies
A1 - Athanassoula, E.
JO - Monthly Notices of the Royal Astronomical Society
VL - 438
Y1 - 2014/2/1
SP - L81
EP - L85
KW - galaxies: evolution/ galaxies: haloes/ galaxies: kinematics and dynamics/ galaxies: structure
UR - http://adsabs.harvard.edu/abs/2014MNRAS.438L..81A
N2 - `Conspiracy' between the dark and the baryonic matter prohibits an
unambiguous decomposition of disc galaxy rotation curves into the
corresponding components. Several methods have been proposed to counter
this difficulty, but their results are widely discrepant. In this paper,
I revisit one of these methods, which relies on the relation between the
halo density and the decrease of the bar pattern speed. The latter is
routinely characterized by the ratio R of the corotation radius
RCR to the bar length Lb, R = R_CR/L_b. I use a
set of N-body+SPH simulations, including subgrid physics, whose initial
conditions cover a range of gas fractions and halo shapes. The models,
by construction, have roughly the same azimuthally averaged circular
velocity curve and halo density and they are all submaximal, i.e.
according to previous works, they are expected to have all roughly the
same R value, well outside the fast bar range (1.2 ± 0.2).
Contrary to these expectations, however, these simulations end up having
widely different R values, either within the fast bar range or well
outside it. This shows that the R value cannot constrain the halo
density, nor determine whether galactic discs are maximal or submaximal.
I argue that this is true even for early-type discs (S0s and Sas).
DO - 10.1093/mnrasl/slt163
C1 - eprint: arXiv:1312.1690
SN - 0035-8711
ER -
TY - Journal
T1 - Detection of H I absorption in the dwarf galaxy Haro 11
A1 - MacHattie, Jeremy A.
A1 - Irwin, Judith A.
A1 - Madden, Suzanne C.
A1 - Cormier, Diane
A1 - Rémy-Ruyer, Aurélie
JO - Monthly Notices of the Royal Astronomical Society
VL - 438
Y1 - 2014/2/1
SP - L66
EP - L70
KW - galaxies: individual: ESO 350-IG038/ galaxies: individual: Haro 11/ galaxies: ISM/ radio lines: ISM
UR - http://adsabs.harvard.edu/abs/2014MNRAS.438L..66M
N2 - We present the results of an analysis of archival 21 cm (H I) data of
the blue compact dwarf galaxy Haro 11 (ESO 350-IG038). Observations were
obtained at the Very Large Array, and the presence of a compact
absorption feature near the optical centre of the galaxy has been
detected. The central location of the absorption feature coincides with
the centre of the continuum background of the galaxy, as well as with
the location of knot B. The absorption feature yields an H I mass in the
range of 3-10 × 108 M⊙, corresponding to
spin temperatures from 91 K to 200 K, respectively. The absence of H I
seen in emission places an upper limit of 1.7 × 109
M⊙ on the mass. To our knowledge this is the first
example of a dwarf galaxy that shows H I absorption from its own
background continuum. The continuum emission from the galaxy is also
used to determine star formation rates, namely 6.85 ± 0.05
M⊙ yr-1 (for a stellar mass range of 5
M⊙ < M < 100 M⊙), or 32.8 ±
0.2 M⊙ yr-1 (for an extended range of 0.1
M⊙ < M < 100 M⊙).
DO - 10.1093/mnrasl/slt160
SN - 0035-8711
ER -
TY - Journal
T1 - MOND and IMF variations in early-type galaxies from ATLAS3D
A1 - Tortora, C.
A1 - Romanowsky, A. J.
A1 - Cardone, V. F.
A1 - Napolitano, N. R.
A1 - Jetzer, Ph.
JO - Monthly Notices of the Royal Astronomical Society
VL - 438
Y1 - 2014/2/1
SP - L46
EP - L50
KW - galaxies: elliptical and lenticular/ cD/ galaxies: evolution/ galaxies: general
UR - http://adsabs.harvard.edu/abs/2014MNRAS.438L..46T
N2 - Modified Newtonian Dynamics (MOND) represents a phenomenological
alternative to dark matter (DM) for the missing mass problem in galaxies
and clusters of galaxies. We analyse the central regions of a local
sample of ˜220 early-type galaxies from the ATLAS3D
survey, to see if the data can be reproduced without recourse to DM. We
estimate dynamical masses in the MOND context through Jeans analysis and
compare to ATLAS3D stellar masses from stellar population
synthesis. We find that the observed stellar mass-velocity dispersion
relation is steeper than expected assuming MOND with a fixed stellar
initial mass function (IMF) and a standard value for the acceleration
parameter a0. Turning from the space of observables to model
space (a) fixing the IMF, a universal value for a0 cannot be
fitted, while, (b) fixing a0 and leaving the IMF free to
vary, we find that it is `lighter' (Chabrier like) for low-dispersion
galaxies and `heavier' (Salpeter like) for high dispersions. This
MOND-based trend matches inferences from Newtonian dynamics with DM and
from the detailed analysis of spectral absorption lines, adding to the
converging lines of evidence for a systematically varying IMF.
DO - 10.1093/mnrasl/slt155
C1 - eprint: arXiv:1310.7606
SN - 0035-8711
ER -
TY - Journal
T1 - Clustering of extremely red objects in Elais-N1 from the UKIDSS DXS with optical photometry from Pan-STARRS 1 and Subaru
A1 - Kim, Jae-Woo
A1 - Edge, Alastair C.
A1 - Wake, David A.
A1 - Gonzalez-Perez, Violeta
A1 - Baugh, Carlton M.
A1 - Lacey, Cedric G.
A1 - Yamada, Toru
A1 - Sato, Yasunori
A1 - Burgett, William S.
A1 - Chambers, Kenneth C.
A1 - Price, Paul A.
A1 - Foucaud, Sebastien
A1 - Draper, Peter
A1 - Kaiser, Nick
JO - Monthly Notices of the Royal Astronomical Society
VL - 438
Y1 - 2014/2/1
SP - 825
EP - 840
KW - surveys/ galaxies: evolution/ galaxies: photometry/ cosmology: observations/ infrared: galaxies
UR - http://adsabs.harvard.edu/abs/2014MNRAS.438..825K
N2 - We measure the angular clustering of 33 415 extremely red objects (EROs)
in the Elais-N1 field covering 5.33 deg2, which cover the
redshift range z = 0.8 to 2. This sample was made by merging the UKIDSS
Deep eXtragalactic Survey (DXS) with the optical Subaru and Pan-STARRS
PS1 data sets. We confirm the existence of a clear break in the angular
correlation function at Ëœ0.02° corresponding to 1
h-1 Mpc at z ˜ 1. We find that redder or brighter EROs
are more clustered than bluer or fainter ones. Halo occupation
distribution (HOD) model fits imply that the average mass of dark matter
haloes which host EROs is over 1013 h-1
M⊙ and that EROs have a bias ranging from 2.7 to 3.5.
Compared to EROs at z ˜ 1.1, at z ˜ 1.5 EROs have a higher
bias and fewer are expected to be satellite galaxies. Furthermore, EROs
reside in similar dark matter haloes to those that host
1011.0 M⊙ < M* <
1011.5 M⊙ galaxies. We compare our new
measurement and HOD fits with the predictions of the GALFORM
semi-analytical galaxy formation model. Overall, the clustering
predicted by GALFORM gives an encouraging match to our results. However,
compared to our deductions from the measurements, GALFORM puts EROs into
lower mass haloes and predicts that a larger fraction of EROs are
satellite galaxies. This suggests that the treatment of gas cooling may
need to be revised in the model. Our analysis illustrates the potential
of clustering analyses to provide observational constraints on
theoretical models of galaxy formation.
DO - 10.1093/mnras/stt2245
C1 - eprint: arXiv:1311.4624
SN - 0035-8711
ER -
TY - Journal
T1 - zCOSMOS 20k: satellite galaxies are the main drivers of environmental effects in the galaxy population at least to z ˜ 0.7
A1 - Kovac, K.
A1 - Lilly, S. J.
A1 - Knobel, C.
A1 - Bschorr, T. J.
A1 - Peng, Y.
A1 - Carollo, C. M.
A1 - Contini, T.
A1 - Kneib, J.-P.
A1 - Le Févre, O.
A1 - Mainieri, V.
A1 - Renzini, A.
A1 - Scodeggio, M.
A1 - Zamorani, G.
A1 - Bardelli, S.
A1 - Bolzonella, M.
A1 - Bongiorno, A.
A1 - Caputi, K.
A1 - Cucciati, O.
A1 - de la Torre, S.
A1 - de Ravel, L.
A1 - Franzetti, P.
A1 - Garilli, B.
A1 - Iovino, A.
A1 - Kampczyk, P.
A1 - Lamareille, F.
A1 - Le Borgne, J.-F.
A1 - Le Brun, V.
A1 - Maier, C.
A1 - Mignoli, M.
A1 - Oesch, P.
A1 - Pello, R.
A1 - Montero, E. Perez
A1 - Presotto, V.
A1 - Silverman, J.
A1 - Tanaka, M.
A1 - Tasca, L.
A1 - Tresse, L.
A1 - Vergani, D.
A1 - Zucca, E.
A1 - Aussel, H.
A1 - Koekemoer, A. M.
A1 - Le Floc'h, E.
A1 - Moresco, M.
A1 - Pozzetti, L.
JO - Monthly Notices of the Royal Astronomical Society
VL - 438
Y1 - 2014/2/1
SP - 717
EP - 738
KW - galaxies: evolution/ galaxies: groups: general/ galaxies: star formation/ galaxies: statistics/ cosmology: observations
UR - http://adsabs.harvard.edu/abs/2014MNRAS.438..717K
N2 - We explore the role of environment in the evolution of galaxies over 0.1
< z < 0.7 using the final zCOSMOS-bright data set. Using the red
fraction of galaxies as a proxy for the quenched population, we find
that the fraction of red galaxies increases with the environmental
overdensity delta and with the stellar mass M*, consistent
with previous works. As at lower redshift, the red fraction appears to
be separable in mass and environment, suggesting the action of two
processes: mass ɛm(M*) and environmental
ɛrho(delta) quenching. The parameters describing
these appear to be essentially the same at z ˜ 0.7 as locally. We
explore the relation between red fraction, mass and environment also for
the central and satellite galaxies separately, paying close attention to
the effects of impurities in the central-satellite classification and
using carefully constructed samples well matched in stellar mass. There
is little evidence for a dependence of the red fraction of centrals on
overdensity. Satellites are consistently redder at all overdensities,
and the satellite quenching efficiency, ɛsat(delta,
M*), increases with overdensity at 0.1 < z < 0.4. This
is less marked at higher redshift, but both are nevertheless consistent
with the equivalent local measurements. At a given stellar mass, the
fraction of galaxies that are satellites, fsat(delta,
M*), also increases with overdensity. The obtained
ɛrho(delta)/fsat(delta,
M*) agrees well with ɛsat(delta,
M*), demonstrating that the environmental quenching in the
overall population is consistent with being entirely produced by a
satellite quenching process at least up to z = 0.7. However, despite the
unprecedented size of our high-redshift samples, the associated
statistical uncertainties are still significant and our statements
should be understood as approximations to physical reality, rather than
physically exact formulae.
DO - 10.1093/mnras/stt2241
C1 - eprint: arXiv:1307.4402
SN - 0035-8711
ER -
TY - Journal
T1 - What obscures low-X-ray-scattering active galactic nuclei
A1 - Hönig, S. F.
A1 - Gandhi, P.
A1 - Asmus, D.
A1 - Mushotzky, R. F.
A1 - Antonucci, R.
A1 - Ueda, Y.
A1 - Ichikawa, K.
JO - Monthly Notices of the Royal Astronomical Society
VL - 438
Y1 - 2014/2/1
SP - 647
EP - 656
KW - galaxies: active/ galaxies: individual: ESO103/ G35/ galaxies: nuclei/ galaxies: Seyfert/ infrared: galaxies/ X-rays: galaxies
UR - http://adsabs.harvard.edu/abs/2014MNRAS.438..647H
N2 - X-ray surveys have revealed a new class of active galactic nuclei (AGN)
with a very low observed fraction of scattered soft X-rays,
fscat <0.5 per cent. Based on X-ray modelling, these
`X-ray new-type', or low observed X-ray-scattering (hereafter,
`low-scattering') sources have been interpreted as deeply buried AGN
with a high covering factor of gas. In this paper, we address the
questions whether the host galaxies of low-scattering AGN may contribute
to the observed X-ray properties, and whether we can find any direct
evidence for high covering factors from the infrared (IR) emission. We
find that X-ray low-scattering AGN are preferentially hosted by highly
inclined galaxies or merger systems as compared to other Seyfert
galaxies, increasing the likelihood that the line of sight towards the
AGN intersects with high columns of host-galactic gas and dust.
Moreover, while a detailed analysis of the IR emission of low-scattering
AGN ESO 103-G35 remains inconclusive, we do not find any indication of
systematically higher dust covering factors in a sample of
low-scattering AGN based on their IR emission. For ESO 103-G35, we
constrained the temperature, mass and location of the IR emitting dust
which is consistent with expectations for the dusty torus. However, a
deep silicate absorption feature probably from much cooler dust suggests
an additional screen absorber on larger scales within the host galaxy.
Taking these findings together, we propose that the low fscat
observed in low-scattering AGN is not necessarily the result of
circumnuclear dust but could originate from interference of
host-galactic gas with a column density of the order of 1022
cm-2 with the line of sight. We discuss implications of this
hypothesis for X-ray models, high-ionization emission lines and observed
star formation activity in these objects.
DO - 10.1093/mnras/stt2234
C1 - eprint: arXiv:1311.4880
SN - 0035-8711
ER -
TY - Journal
T1 - Radiation pressure confinement - II. Application to the broad-line region in active galactic nuclei
A1 - Baskin, Alexei
A1 - Laor, Ari
A1 - Stern, Jonathan
JO - Monthly Notices of the Royal Astronomical Society
VL - 438
Y1 - 2014/2/1
SP - 604
EP - 619
KW - galaxies: active/ quasars: emission lines/ quasars: general
UR - http://adsabs.harvard.edu/abs/2014MNRAS.438..604B
N2 - Active galactic nuclei (AGN) are characterized by similar broad emission
lines properties at all luminosities (1039 - 1047
erg s-1). What produces this similarity over a vast range of
108 in luminosity? Photoionization is inevitably associated
with momentum transfer to the photoionized gas. Yet, most of the
photoionized gas in the broad-line region (BLR) follows Keplerian
orbits, which suggests that the BLR originates from gas with a large
enough column for gravity to dominate. The photoionized surface layer of
the gas must develop a pressure gradient due to the incident radiation
force. We present solutions for the structure of such a hydrostatic
photoionized gas layer in the BLR. The gas is stratified, with a
low-density highly ionized surface layer, a density rise inwards and a
uniform-density cooler inner region, where the gas pressure reaches the
incident radiation pressure. This radiation pressure confinement (RPC)
of the photoionized layer leads to a universal ionization parameter U
˜ 0.1 in the inner photoionized layer, independent of luminosity
and distance. Thus, RPC appears to explain the universality of the BLR
properties in AGN. We present predictions for the BLR emission per unit
covering factor, as a function of distance from the ionizing source, for
a range of ionizing continuum slopes and gas metallicity. The predicted
mean strength of most lines (excluding H beta), and their different
average-emission radii, are consistent with available observations.
DO - 10.1093/mnras/stt2230
C1 - eprint: arXiv:1309.7953
SN - 0035-8711
ER -
TY - Journal
T1 - Optically selected BLR-less active galactic nuclei from the SDSS Stripe82 Database - I. The sample
A1 - Zhang, Xue-Guang
JO - Monthly Notices of the Royal Astronomical Society
VL - 438
Y1 - 2014/2/1
SP - 557
EP - 572
KW - galaxies: active/ galaxies: nuclei/ quasars: emission lines/ galaxies: Seyfert
UR - http://adsabs.harvard.edu/abs/2014MNRAS.438..557Z
N2 - This is the first paper in a dedicated series to study the properties of
the optically-selected broad-line-region-less (BLR-less) active galactic
nuclei (AGNs; with no-hidden central broad emission line regions). We
carried out a systematic search for the BLR-less AGNs through the Sloan
Digital Sky Survey Legacy Survey (SDSS Stripe82 Database). Based on the
spectral decomposition results for all the 136 676 spectroscopic objects
(galaxies and quasars) with redshift less than 0.35 covered by the SDSS
Stripe82 region, our spectroscopic sample for the BLR-less AGNs includes
22 693 pure narrow line objects without broad emission lines but with
apparent AGN continuum emission RAGN > 0.3 and apparent
stellar lights Rssp > 0.3. Then, using the properties of
the photometry magnitude RMS (RMS) and Pearson's coefficients (R1,
2) between two different SDSS band light curves: RMS_k>3×
RMS_{M_k} and R1, 2 > ˜0.8, the final 281 pure
narrow line objects with true photometry variabilities are our selected
reliable candidates for the BLR-less AGNs. The selected candidates with
higher confidence levels not only have the expected spectral features of
the BLR-less AGNs, but also show significant true photometry
variabilities. The reported sample enlarges at least four times the
current sample of the BLR-less AGNs, and will provide more reliable
information to explain the lack of the BLRs of AGNs in our following
studies.
DO - 10.1093/mnras/stt2226
C1 - eprint: arXiv:1311.4399
SN - 0035-8711
ER -
TY - Journal
T1 - Colours of isolated galaxies selected from the Two-Micron All-Sky Survey
A1 - Melnyk, O.
A1 - Mitronova, S.
A1 - Karachentseva, V.
JO - Monthly Notices of the Royal Astronomical Society
VL - 438
Y1 - 2014/2/1
SP - 548
EP - 556
KW - galaxies: evolution/ galaxies: fundamental parameters/ galaxies: general
UR - http://adsabs.harvard.edu/abs/2014MNRAS.438..548M
N2 - The properties of isolated galaxies are driven mainly by intrinsic
evolution and not by the external influence of their environments.
Therefore, the sample of isolated galaxies can be considered as a
reference sample to study different environmental effects. We have made
detailed comparisons between the near-infrared (Two-Micron All-Sky
Survey, 2MASS) and optical (Sloan Digital Sky Survey, SDSS) colours of
the 2MASS Isolated Galaxies (2MIG) sample selected from the 2MASS
Extended Source Catalogue and with other objects from the wide range of
denser environments (field, groups/clusters, triplets and pairs). We
have found that early-type galaxies show similar (J - H)rest
and (g - r)rest colours in practically all types of
environments, except for the massive early-type galaxies located in
compact pairs with high velocity difference (dV ˜ 180 km
s-1), which are significantly redder and brighter than
isolated galaxies. We assume that these pairs are located in the centres
of more populated groups and clusters. In general, galaxies in groups
and pairs of spiral and late morphological types have redder
near-infrared colours (J - H)rest than 2MIG isolated
galaxies. The (g - r)rest colours of galaxies in groups and
pairs with high velocity difference are also significantly redder than
the corresponding colours of 2MIG isolated galaxies. In contrast, the
members of most compact pairs (dV ˜ 50 km s-1, R
˜ 30 kpc) show the same (g - r)rest colour and even
tend to be bluer than 2MIG isolated galaxies. In summary, our results
show that the colours of galaxies depend very much on external factors.
DO - 10.1093/mnras/stt2225
SN - 0035-8711
ER -
TY - Journal
T1 - A wide search for obscured active galactic nuclei using XMM-Newton and WISE
A1 - Rovilos, E.
A1 - Georgantopoulos, I.
A1 - Akylas, A.
A1 - Aird, J.
A1 - Alexander, D. M.
A1 - Comastri, A.
A1 - Del Moro, A.
A1 - Gandhi, P.
A1 - Georgakakis, A.
A1 - Harrison, C. M.
A1 - Mullaney, J. R.
JO - Monthly Notices of the Royal Astronomical Society
VL - 438
Y1 - 2014/2/1
SP - 494
EP - 512
KW - galaxies: active/ infrared: galaxies/ X-rays: galaxies
UR - http://adsabs.harvard.edu/abs/2014MNRAS.438..494R
N2 - Heavily obscured and Compton-thick active galactic nuclei (AGNs) are
missing even in the deepest X-ray surveys, and indirect methods are
required to detect them. Here we use a combination of the XMM-Newton
serendipitous X-ray survey with the optical Sloan Digital Sky Survey
(SDSS), and the infrared WISE all-sky survey in order to check the
efficiency of the low X-ray-to-infrared luminosity selection method in
finding heavily obscured AGNs. We select the sources which are detected
in the hard X-ray band (2-8 keV), and also have a redshift determination
(photometric or spectroscopic) in the SDSS catalogue. We match this
sample with the WISE catalogue, and fit the spectral energy
distributions of the 2844 sources which have three, or more, photometric
data points in the infrared. We then select the heavily obscured AGN
candidates by comparing their 12 mum luminosity to the observed 2-10
keV X-ray luminosity and the intrinsic relation between the X-ray and
the mid-infrared luminosities. With this approach, we find 20 candidate
heavily obscured AGNs and we then examine their X-ray and optical
spectra. Of the 20 initial candidates, we find nine (64 per cent; out of
the 14, for which X-ray spectra could be fitted) based on the X-ray
spectra, and seven (78 per cent; out of the nine detected
spectroscopically in the SDSS) based on the [O III] line fluxes.
Combining all criteria, we determine the final number of heavily
obscured AGNs to be 12-19, and the number of Compton-thick AGNs to be
2-5, showing that the method is reliable in finding obscured AGNs, but
not Compton thick. However, those numbers are smaller than what would be
expected from X-ray background population synthesis models, which
demonstrates how the optical-infrared selection and the scatter of the
Lx-LMIR relation limit the efficiency of the
method. Finally, we test popular obscured AGN selection methods based on
mid-infrared colours, and find that the probability of an AGN to be
selected by its mid-infrared colours increases with the X-ray
luminosity. The (observed) X-ray luminosities of heavily obscured AGNs
are relatively low (L_{2-10 keV}<10^{44} erg s^{-1}), even though
most of them are located in the `quasi stellar object (QSO) locus'.
However, a selection scheme based on a relatively low X-ray luminosity
and mid-infrared colours characteristic of QSOs would not select
˜25 per cent of the heavily obscured AGNs of our sample.
DO - 10.1093/mnras/stt2228
C1 - eprint: arXiv:1311.3700
SN - 0035-8711
ER -
TY - Journal
T1 - Distribution function for the system of galaxies for any ratio of gravitational potential to kinetic energies
A1 - Ahmad, Farooq
A1 - Malik, Manzoor A.
A1 - Mir, Hameeda
JO - Monthly Notices of the Royal Astronomical Society
VL - 438
Y1 - 2014/2/1
SP - 438
EP - 443
KW - gravitation/ methods: analytical/ galaxies: clusters: general/ cosmology: theory/ large-scale structure of Universe
UR - http://adsabs.harvard.edu/abs/2014MNRAS.438..438A
N2 - We evaluate a distribution function for the system of galaxies
clustering gravitationally in an expanding universe on the basis of
statistical mechanics. We extend our previous work to incorporate the
effect of any ratio of gravitational potential to kinetic energies. We
determine the cosmological many-body partition function inclusive of
higher order terms and calculate all thermodynamic quantities and the
distribution function from it. We find that our new results are
consistent with the previous ones, particularly in the large bar{N}
(average number of galaxies) limit. We also investigate the effect on
clustering parameter b and find our new results in very good agreement
with the previous ones in the small b limit. We find that for large b,
the departure from the original distribution function is greater. We
also observe that the effect of softening on the distribution function
is consistent with our previous work.
DO - 10.1093/mnras/stt2214
SN - 0035-8711
ER -
TY - Journal
T1 - The circumnuclear environment of NGC 613: a nuclear starburst caught in the act?
A1 - Falcón-Barroso, J.
A1 - Ramos Almeida, C.
A1 - Böker, T.
A1 - Schinnerer, E.
A1 - Knapen, J. H.
A1 - Lançon, A.
A1 - Ryder, S.
JO - Monthly Notices of the Royal Astronomical Society
VL - 438
Y1 - 2014/2/1
SP - 329
EP - 340
KW - galaxies: active/ galaxies: individual: NGC 613/ galaxies: ISM/ galaxies: nuclei
UR - http://adsabs.harvard.edu/abs/2014MNRAS.438..329F
N2 - We present near-infrared (H- and K-band) integral-field observations of
the inner ˜700 pc of the active spiral galaxy NGC 613, obtained
with SINFONI on the Very Large Telescope. We use emission-line ratios to
determine the dominant excitation mechanisms in different regions within
our field of view, in particular, the active nucleus and the
star-forming circumnuclear ring. Diagnostic diagrams involving [Fe II]
and H2 fluxes indicate that the gas is not only photoionized
by the active galactic nucleus (AGN) in the nucleus of NGC 613, but also
shock heated. On the other hand, the emission-line ratios measured in
the `hotspots' along the ring are fully consistent with them being young
star-forming regions. We find no sign of radial gas transport from the
ring into the core region dominated by the AGN. The ring morphology
appears disturbed by a radial outflow of material from the AGN, which is
confirmed by the existence of a weak jet in archival radio maps.
However, this jet does not seem to have any significant effect on the
morphology of the large (Ëœ8 × 107
M⊙) reservoir of molecular gas that has accumulated
inside the central ˜100 pc. Such a concentration of molecular gas
around an AGN is unusual, and supports a scenario in which star
formation is recurrent and episodic in spiral galaxies. In this context,
NGC 613 appears to be in final stages of the gas accumulation phase and
is likely to undergo a nuclear starburst in the near future.
DO - 10.1093/mnras/stt2189
C1 - eprint: arXiv:1311.2041
SN - 0035-8711
ER -
TY - Journal
T1 - The dependence of the galaxy mass-metallicity relation on environment and the implied metallicity of the IGM
A1 - Peng, Ying-jie
A1 - Maiolino, Roberto
JO - Monthly Notices of the Royal Astronomical Society
VL - 438
Y1 - 2014/2/1
SP - 262
EP - 270
KW - galaxies: abundances/ galaxies: evolution/ galaxies: formation/ galaxies: fundamental parameters
UR - http://adsabs.harvard.edu/abs/2014MNRAS.438..262P
N2 - We explore the dependence of the galaxy mass-metallicity relation on
environment in SDSS, in terms of both over-density and central/satellite
dichotomy. We find that at a given stellar mass, there is a strong
dependence of metallicity on over-density for star-forming satellites
(i.e. all galaxies members of groups/clusters which are not centrals).
High metallicity satellites reside, on average, in regions four times
denser than the low metallicity ones. Instead, for star-forming centrals
no correlation is found. Star-forming satellites at different stellar
masses form a tight sequence in the average over-density - metallicity
plane, which covers the entire observed range of metallicities and
stellar masses. This remarkable result appears to imply that there
exists a universal evolutionary path for all star-forming satellites,
regardless of their stellar masses. The strong correlation between
over-density and metallicity for star-forming satellites indicates that
the gas inflow of satellite galaxies is progressively metal-enriched in
denser regions. We interpret our results by employing the gas regulator
model and find that the metallicity of the enriched inflow of
star-forming satellite galaxies, Z0, sat, strongly increases
with increasing over-density. The derived Z0, sat-
overdensity relation is largely independent of stellar mass and can be
well described by a simple power law. If the metallicity of the inflow
of star-forming satellites can represent the metallicity of the IGM,
then the implied metallicity of the IGM rises from ˜0.01
Z⊙ in the void-like environment to ˜0.3
Z⊙ in the cluster-like environment, in broad agreement
with observations. We show that the observed metallicity difference
between star-forming centrals and star-forming satellites becoming
smaller towards high stellar masses can be simply explained by the
mass-independent enriched inflow, without the need to involve any
mass-dependent environmental effect on metallicity. Since satellite
galaxies account for at least half of the galaxy population, our
findings prompt for a revision of many galaxy evolutionary models, which
generally assume pristine gas inflows.
DO - 10.1093/mnras/stt2175
C1 - eprint: arXiv:1311.1816
SN - 0035-8711
ER -
TY - Journal
T1 - On the role of AGN feedback on the thermal and chemodynamical properties of the hot intracluster medium
A1 - Planelles, S.
A1 - Borgani, S.
A1 - Fabjan, D.
A1 - Killedar, M.
A1 - Murante, G.
A1 - Granato, G. L.
A1 - Ragone-Figueroa, C.
A1 - Dolag, K.
JO - Monthly Notices of the Royal Astronomical Society
VL - 438
Y1 - 2014/2/1
SP - 195
EP - 216
KW - methods: numerical/ galaxies: clusters: general/ cosmology: miscellaneous/ X-rays: galaxies
UR - http://adsabs.harvard.edu/abs/2014MNRAS.438..195P
N2 - We present an analysis of the properties of the intracluster medium
(ICM) in an extended set of cosmological hydrodynamical simulations of
galaxy clusters and groups performed with the TREEPM+SPH GADGET-3 code.
Besides a set of non-radiative simulations, we carried out two sets of
simulations including radiative cooling, star formation, metal
enrichment and feedback from supernovae (SNe), one of which also
accounts for the effect of feedback from active galactic nuclei (AGN)
resulting from gas accretion on to supermassive black holes. These
simulations are analysed with the aim of studying the relative role
played by SN and AGN feedback on the general properties of the diffuse
hot baryons in galaxy clusters and groups: scaling relations,
temperature, entropy and pressure radial profiles, and ICM chemical
enrichment. We find that simulations including AGN feedback produce
scaling relations between X-ray observable quantities that are in good
agreement with observations at all mass scales. Observed pressure
profiles are also shown to be quite well reproduced in our radiative
simulations, especially when AGN feedback is included. However, our
simulations are not able to account for the observed diversity between
cool-core and non-cool-core clusters, as revealed by X-ray observations:
unlike for observations, we find that temperature and entropy profiles
of relaxed and unrelaxed clusters are quite similar and resemble more
the observed behaviour of non-cool-core clusters. As for the pattern of
metal enrichment, we find that an enhanced level of iron abundance is
produced by AGN feedback with respect to the case of purely SN feedback.
As a result, while simulations including AGN produce values of iron
abundance in groups in agreement with observations, they over-enrich the
ICM in massive clusters. The efficiency of AGN feedback in displacing
enriched gas from haloes into the intergalactic medium at high redshift
also creates a widespread enrichment in the outskirts of clusters and
produces profiles of iron abundance whose slope is in better agreement
with observations. By analysing the pattern of the relative abundances
of silicon and iron and the fraction of metals in the stellar phase, our
results clearly show that different sources of energy feedback leave
different imprints in the enrichment pattern of the hot ICM and stars.
Our results confirm that including AGN feedback goes in the right
direction of reconciling simulation predictions and observations for
several observational ICM properties. Still a number of important
discrepancies highlight that the model still needs to be improved to
produce the correct interplay between cooling and feedback in central
cluster regions.
DO - 10.1093/mnras/stt2141
C1 - eprint: arXiv:1311.0818
SN - 0035-8711
ER -
TY - Journal
T1 - Galaxy And Mass Assembly (GAMA): the large-scale structure of galaxies and comparison to mock universes
A1 - Alpaslan, Mehmet
A1 - Robotham, Aaron S. G.
A1 - Driver, Simon
A1 - Norberg, Peder
A1 - Baldry, Ivan
A1 - Bauer, Amanda E.
A1 - Bland-Hawthorn, Joss
A1 - Brown, Michael
A1 - Cluver, Michelle
A1 - Colless, Matthew
A1 - Foster, Caroline
A1 - Hopkins, Andrew
A1 - Van Kampen, Eelco
A1 - Kelvin, Lee
A1 - Lara-Lopez, Maritza A.
A1 - Liske, Jochen
A1 - Lopez-Sanchez, Angel R.
A1 - Loveday, Jon
A1 - McNaught-Roberts, Tamsyn
A1 - Merson, Alexander
A1 - Pimbblet, Kevin
JO - Monthly Notices of the Royal Astronomical Society
VL - 438
Y1 - 2014/2/1
SP - 177
EP - 194
KW - methods: observational/ surveys/ large-scale structure of Universe
UR - http://adsabs.harvard.edu/abs/2014MNRAS.438..177A
N2 - From a volume-limited sample of 45 542 galaxies and 6000 groups with z
<= 0.213, we use an adapted minimal spanning tree algorithm to
identify and classify large-scale structures within the Galaxy And Mass
Assembly (GAMA) survey. Using galaxy groups, we identify 643 filaments
across the three equatorial GAMA fields that span up to 200
h-1 Mpc in length, each with an average of eight groups
within them. By analysing galaxies not belonging to groups, we identify
a secondary population of smaller coherent structures composed entirely
of galaxies, dubbed `tendrils' that appear to link filaments together,
or penetrate into voids, generally measuring around 10 h-1
Mpc in length and containing on average six galaxies. Finally, we are
also able to identify a population of isolated void galaxies. By running
this algorithm on GAMA mock galaxy catalogues, we compare the
characteristics of large-scale structure between observed and mock data,
finding that mock filaments reproduce observed ones extremely well. This
provides a probe of higher order distribution statistics not captured by
the popularly used two-point correlation function.
DO - 10.1093/mnras/stt2136
C1 - eprint: arXiv:1311.1211
SN - 0035-8711
ER -
TY - Journal
T1 - On the physics of radio haloes in galaxy clusters: scaling relations and luminosity functions
A1 - Zandanel, Fabio
A1 - Pfrommer, Christoph
A1 - Prada, Francisco
JO - Monthly Notices of the Royal Astronomical Society
VL - 438
Y1 - 2014/2/1
SP - 124
EP - 144
KW - catalogues/ galaxies: clusters: general/ galaxies: clusters: intracluster medium/ gamma-rays: galaxies: clusters/ radio continuum: galaxies
UR - http://adsabs.harvard.edu/abs/2014MNRAS.438..124Z
N2 - The underlying physics of giant and mini radio haloes in galaxy clusters
is still an open question. We find that mini haloes (such as in Perseus
and Ophiuchus) can be explained by radio-emitting electrons that are
generated in hadronic cosmic ray (CR) interactions with protons of the
intracluster medium. By contrast, the hadronic model either fails to
explain the extended emission of giant radio haloes (as in Coma at low
frequencies) or would require a flat CR profile, which can be realized
through outward streaming and diffusion of CRs (in Coma and A2163 at 1.4
GHz). We suggest that a second leptonic component could be responsible
for the missing flux in the outer parts of giant haloes within a new
hybrid scenario and we describe its possible observational consequences.
To study the hadronic emission component of the radio-halo population
statistically, we use a cosmological mock galaxy cluster catalogue built
from the MultiDark simulation. Because of the properties of CR streaming
and the different scalings of the X-ray luminosity (LX) and
the Sunyaev-Zel'dovich flux (Y) with gas density, our model can
simultaneously reproduce the observed bimodality of radio-loud and
radio-quiet clusters at the same LX as well as the unimodal
distribution of radio-halo luminosity versus Y; thereby suggesting a
physical solution to this apparent contradiction. We predict radio-halo
emission down to the mass scale of galaxy groups, which highlights the
unique prospects for low-frequency radio surveys (such as the Low
Frequency Array Tier 1 survey) to increase the number of detected radio
haloes by at least an order of magnitude.
DO - 10.1093/mnras/stt2250
C1 - eprint: arXiv:1311.4795
SN - 0035-8711
ER -
TY - Journal
T1 - A phenomenological model for the intracluster medium that matches X-ray and Sunyaev-Zel'dovich observations
A1 - Zandanel, Fabio
A1 - Pfrommer, Christoph
A1 - Prada, Francisco
JO - Monthly Notices of the Royal Astronomical Society
VL - 438
Y1 - 2014/2/1
SP - 116
EP - 123
KW - catalogues/ galaxies: clusters: intracluster medium/ X-rays: galaxies: clusters
UR - http://adsabs.harvard.edu/abs/2014MNRAS.438..116Z
N2 - Cosmological hydrodynamical simulations of galaxy clusters are still
challenged to produce a model for the intracluster medium that matches
all aspects of current X-ray and Sunyaev-Zel'dovich observations. To
facilitate such comparisons with future simulations and to enable
realistic cluster population studies for modelling e.g. non-thermal
emission processes, we construct a phenomenological model for the
intracluster medium that is based on a representative sample of observed
X-ray clusters. We create a mock galaxy cluster catalogue based on the
large collisionless N-body simulation MultiDark, by assigning our gas
density model to each dark matter cluster halo. Our clusters are
classified as cool core and non-cool core according to a dynamical
disturbance parameter. We demonstrate that our gas model matches the
various observed Sunyaev-Zel'dovich and X-ray scaling relations as well
as the X-ray luminosity function, thus enabling to build a reliable mock
catalogue for present surveys and forecasts for future experiments. In a
companion paper, we apply our catalogues to calculate non-thermal radio
and gamma-ray emission of galaxy clusters. We make our cosmologically
complete multifrequency mock catalogues for the (non-)thermal cluster
emission at different redshifts publicly and freely available online
through the MultiDark data base.
DO - 10.1093/mnras/stt2196
C1 - eprint: arXiv:1311.4793
SN - 0035-8711
ER -
TY - Journal
T1 - Star formation rates of star-forming galaxies from the WISE All-Sky Survey
A1 - Wen, Xiao-Qing
A1 - Wu, Hong
A1 - Zhu, Yi-Nan
A1 - Lam, Man I.
A1 - Wu, Chao-Jian
A1 - Wicker, James
A1 - Long, R. J.
A1 - Zhao, Yong-Heng
JO - Monthly Notices of the Royal Astronomical Society
VL - 438
Y1 - 2014/2/1
SP - 97
EP - 115
KW - dust/ extinction/ H II regions/ galaxies: evolution/ galaxies: ISM/ galaxies: star formation/ infrared: galaxies
UR - http://adsabs.harvard.edu/abs/2014MNRAS.438...97W
N2 - We explore correlations between extinction-corrected Halpha, Hbeta
and {[O II]_{double}} luminosities versus 12- and 22-mum band
luminosities, based on matching samples from the Sloan Digital Sky
Survey (SDSS) and the Wide-field Infrared Survey Explorer (WISE). All
the coefficients show strong correlations between Balmer lines and
mid-infrared (MIR) luminosities, while the extinction-corrected {[O
II]_{double}} shows a weaker correlation with MIR luminosities. The
extinction-corrected emission-line (EL) luminosities are more tightly
correlated with linear combinations of EL(obs) and MIR luminosities than
with pure MIR luminosities. Linear combinations include both direct and
dust-obscured star formation activity in galaxies and offer an improved
star formation rate (SFR) indicator for star-forming galaxies. The
factor that causes
log10LMIR/log10LHalpha to
vary is the metallicity. We find that
log10(LHalpha(obs) + alpha ×
LMIR) and {log _{10}(L[O II]_double(obs)+alpha ×
L_MIR)}, rather than pure MIR luminosities or {[O II]_{double}} alone,
are good proxies for extinction-corrected
log10LHalpha, with a residual that is
independent of metallicity. The morphologies have weak correlations with
log10LMIR/log10LEL ratios.
E(B - V) can be estimated by
log10[LMIR/LHalpha(obs)].
DO - 10.1093/mnras/stt2112
SN - 0035-8711
ER -
TY - Journal
T1 - Closing the loop: a self-consistent model of optical, X-ray and Sunyaev-Zel'dovich scaling relations for clusters of Galaxies
A1 - Rozo, E.
A1 - Bartlett, J. G.
A1 - Evrard, A. E.
A1 - Rykoff, E. S.
JO - Monthly Notices of the Royal Astronomical Society
VL - 438
Y1 - 2014/2/1
SP - 78
EP - 96
KW - galaxies: clusters: general
UR - http://adsabs.harvard.edu/abs/2014MNRAS.438...78R
N2 - We demonstrate that optical data from Sloan Digital Sky Survey, X-ray
data from ROSAT and Chandra, and Sunyaev-Zel'dovich (SZ) data from
Planck can be modelled in a fully self-consistent manner. After
accounting for systematic errors and allowing for property covariance,
we find that scaling relations derived from optical and X-ray selected
cluster samples are consistent with one another. Moreover, these cluster
scaling relations satisfy several non-trivial spatial abundance
constraints and closure relations. Given the good agreement between
optical and X-ray samples, we combine the two and derive a joint set of
LX-M and YSZ-M relations. Our best-fitting
YSZ-M relation is in good agreement with the observed
amplitude of the thermal SZ power spectrum for a Wilkinson Microwave
Anisotropy Probe 7 cosmology, and is consistent with the masses for the
two CLASH galaxy clusters published thus far. We predict the halo masses
of the remaining z <= 0.4 CLASH clusters, and use our scaling
relations to compare our results with a variety of X-ray and weak
lensing cluster masses from the literature.
DO - 10.1093/mnras/stt2161
C1 - eprint: arXiv:1204.6305
SN - 0035-8711
ER -
TY - Journal
T1 - A comparative study of local galaxy clusters - II. X-ray and SZ scaling relations
A1 - Rozo, E.
A1 - Evrard, A. E.
A1 - Rykoff, E. S.
A1 - Bartlett, J. G.
JO - Monthly Notices of the Royal Astronomical Society
VL - 438
Y1 - 2014/2/1
SP - 62
EP - 77
KW - galaxies: clusters: general
UR - http://adsabs.harvard.edu/abs/2014MNRAS.438...62R
N2 - We compare cluster scaling relations published for three different
samples selected via X-ray and Sunyaev-Zel'dovich (SZ) signatures. We
find tensions driven mainly by two factors: (i) systematic differences
in the X-ray cluster observables used to derive the scaling relations
and (ii) uncertainty in the modelling of how the gas mass of galaxy
clusters scales with total mass. All scaling relations are in agreement
after accounting for these two effects. We describe a multivariate
scaling model that enables a fully self-consistent treatment of multiple
observational catalogues in the presence of property covariance and
apply this formalism when interpreting published results. The
corrections due to scatter and observable covariance can be significant.
For instance, our predicted YSZ-LX scaling
relation differs from that derived using the naive `plug in' method by
≈25 per cent. Finally, we test the mass normalization for each of the
X-ray data sets we consider by applying a space density consistency
test: we compare the observed ROSAT-ESO Flux-Limited X-ray (REFLEX)
luminosity function to expectations from published LX-M
relations convolved with the mass function for a Wilkinson Microwave
Anisotropy Probe 7 flat Lambda cold dark matter model.
DO - 10.1093/mnras/stt2160
C1 - eprint: arXiv:1204.6292
SN - 0035-8711
ER -
TY - Journal
T1 - A comparative study of local galaxy clusters - I. Derived X-ray observables
A1 - Rozo, E.
A1 - Rykoff, E. S.
A1 - Bartlett, J. G.
A1 - Evrard, A.
JO - Monthly Notices of the Royal Astronomical Society
VL - 438
Y1 - 2014/2/1
SP - 49
EP - 61
KW - galaxies: clusters: general
UR - http://adsabs.harvard.edu/abs/2014MNRAS.438...49R
N2 - We examine systematic differences in the derived X-ray properties of
galaxy clusters as reported by three different groups: Vikhlinin et al.,
Mantz et al. and Plank Collaboration. The sample overlap between any two
pairs of works ranges between 16 to 28 galaxy clusters. We find
systematic differences in most reported X-ray properties, including the
total cluster mass, M500. The most extreme case is an average
45 ± 5 per cent difference in cluster mass between the Plank
Collaboration and Mantz et al., for clusters at z > 0.13 (averaged
over 16 clusters). These differences also induce differences in cluster
observables defined within an R500 aperture. After accounting
for aperture differences, we find very good agreement in gas mass
estimates between the different groups. However, the soft-band X-ray
luminosity, LX, core-excised spectroscopic temperature,
TX, and gas thermal energy, YX =
MgasTX display mean differences at the 5-15 per
cent level. We also find that the low (z <= 0.13) and high (z >=
0.13) redshift galaxy cluster samples in Plank Collaboration appear to
be systematically different: the YSZ/YX ratio for
each of these two sub-samples is ln (YSZ/YX) =
-0.06 ± 0.04 and ln (YSZ/YX) = 0.08
± 0.04, respectively.
DO - 10.1093/mnras/stt2091
C1 - eprint: arXiv:1204.6301
SN - 0035-8711
ER -