196 research outputs found
BUDH IES V:The baryonic Tully-Fisher relation at z = 0.2 based on direct H I detections
We present H I-based B- and R-band Tully-Fisher relations (TFRs) and the Baryonic TFR (BTFR) at z = 0.2 using direct H I detections from the Blind Ultra-Deep H I Environmental Survey (BUDH IES). Deep photometry from the Isaac Newton Telescope was used for 36 out of 166 H I sources, matching the quality criteria required for a robust TFR analysis. Two velocity definitions at 20 and 50 per cent of the peak flux were measured from the global H I profiles and adopted as proxies for the circular velocities. We compare our results with an identically constructed z= 0 TFR from the Ursa Major association (UMa) of galaxies. To ensure an unbiased comparison of the TFR, all the samples were treated identically regarding sample selection and applied corrections. We provide catalogues and an atlas showcasing the properties of the galaxies. Our analysis is focused on the zero points of the TFR and BTFR with their slopes fixed to the z = 0 relation. Our main results are: (1) The BUDH IES galaxies show more asymmetric H I profiles with shallower wings compared to the UMa galaxies, which is likely due to the environment in which they reside, (2) The luminosity-based z= 0.2 TFRs are brighter and bluer than the z = 0 TFRs, even when cluster galaxies are excluded from the BUDH IES sample, (3) The BTFR shows no evolution in its zero point over the past 2.5 billion yr and does not significantly change on the inclusion of cluster galaxies, and (4) proper sample selection and consistent corrections are crucial for an unbiased analysis of the evolution of the TFR
Galaxy pre-processing in substructures around z0.4 galaxy clusters
We present a detailed analysis of galaxy colours in two galaxy clusters at
\mbox{z 0.4}, \mbox{MACS J0416.1-2403} and \mbox{MACS J1206.2-0847},
drawn from the CLASH-VLT survey, to investigate the role of pre-processing in
the quenching of star formation. We estimate the fractions of red and blue
galaxies within the main cluster and the detected substructures and study the
trends of the colour fractions as a function of the projected distance from the
cluster and substructure centres. Our results show that the colours of cluster
and substructure members have consistent spatial distributions. In particular,
the colour fractions of galaxies inside substructures follow the same spatial
trends observed in the main clusters. Additionally, we find that at large
cluster-centric distances \mbox{()} the fraction of blue
galaxies in both the main clusters and in the substructures is always lower
than the average fraction of UVJ-selected star-forming galaxies in the field as
measured in the COSMOS/UltraVista data set. We finally estimate environmental
quenching efficiencies in the clusters and in the substructures and find that
at large distances from the cluster centres, the quenching efficiency of
substructures becomes comparable to the quenching efficiency of clusters. Our
results suggest that pre-processing plays a significant role in the formation
and evolution of passive galaxies in clusters at low redshifts.Comment: Accepted for publication in MNRAS. 28 pages, 14 figures, 20 table
The dynamical state of Abell 2399: a bullet-like cluster
While there are many ways to identify substructures in galaxy clusters using
different wavelengths, each technique has its own caveat. In this paper, we
conduct a detailed substructure search and dynamical state characterisation of
Abell 2399, a galaxy cluster in the local Universe (), by
performing a multi-wavelength analysis and testing the results through
hydro-dynamical simulations. In particular, we apply a Gaussian Mixture Model
to the spectroscopic data from SDSS, WINGS, and Omega WINGS Surveys to identify
substructures. We further use public \textit{XMM-Newton} data to investigate
the intracluster medium (ICM) thermal properties, creating temperature,
metallicity, entropy, and pressure maps. Finally, we run hydro-dynamical
simulations to constrain the merger stage of this system. The ICM is very
asymmetrical and has regions of temperature and pressure enhancement that
evidence a recent merging process. The optical substructure analysis retrieves
the two main X-ray concentrations. The temperature, entropy, and pressure are
smaller in the secondary clump than in the main clump. On the other hand, its
metallicity is considerably higher. This result can be explained by the
scenario found by the hydro-dynamical simulations where the secondary clump
passed very near to the centre of the main cluster possibly causing the
galaxies of that region to release more metals through the increase of
ram-pressure stripping.16Comment: 16 pages, 11 figures. Accepted in MNRA
The Geometry of Mass Outflows and Fueling Flows in the Seyfert 2 Galaxy Mrk 3
We present a study of the resolved emission-line regions and an inner
dust/gas disk in the Seyfert 2 galaxy Mrk 3, based on Hubble Space Telescope
observations. We show that the extended narrow-line region (ENLR), spanning ~4
kpc, is defined by the intersection of the ionizing bicone of radiation from
the AGN and the inner disk, which is not coplanar with the large-scale stellar
disk. This intersection leads to different position and opening angles of the
ENLR compared to the narrow-line region (NLR). A number of emission-line arcs
in the ENLR appear to be continuations of dust lanes in the disk, supporting
this geometry. The NLR, which consists of outflowing emission-line knots
spanning the central ~650 pc, is in the shape of a backwards S. This shape may
arise from rotation of the gas, or it may trace the original fueling flow close
to the nucleus that was ionized after the AGN turned on.Comment: 22 page, 7 figures, accepted for publication in the Astronomical
Journa
BUDHIES IV:Deep 21-cm neutral Hydrogen, optical, and UV imaging data of Abell 963 and Abell 2192 at z â 0.2
In this paper, we present data from the Blind Ultra-Deep H I Environmental Survey (BUDHIES), which is a blind 21-cm H I spectral line imaging survey undertaken with the Westerbork Synthesis Radio Telescope. Two volumes were surveyed, each with a single pointing and covering a redshift range of 0.164 < z < 0.224. Within these two volumes, this survey targeted the clusters Abell 963 and Abell 2192, which are dynamically different and offer unique environments to study the process of galaxy evolution within clusters. With an integration time of 117 Ă 12 h on Abell 963 and 72 Ă 12 h on Abell 2192, a total of 166 galaxies were detected and imaged in H I. While the clusters themselves occupy only 4 per cent of the 73 400 Mpc3 surveyed by BUDHIES, most of the volume consists of large-scale structures in which the clusters are embedded, including foreground and background overdensities and voids. We present the data processing and source detection techniques and counterpart identification based on a wide-field optical imaging survey using the Isaac Newton Telescope and deep ultraviolet (UV) Galaxy Evolution Explorer (GALEX) imaging. Finally, we present H I and optical catalogues of the detected sources as well as atlases of their global H I properties, which include integrated column density maps, position-velocity diagrams, global H I profiles, and optical and UV images of the H I sources
Ram pressure feeding super-massive black holes
When supermassive black holes at the center of galaxies accrete matter
(usually gas), they give rise to highly energetic phenomena named Active
Galactic Nuclei (AGN). A number of physical processes have been proposed to
account for the funneling of gas towards the galaxy centers to feed the AGN.
There are also several physical processes that can strip gas from a galaxy, and
one of them is ram pressure stripping in galaxy clusters due to the hot and
dense gas filling the space between galaxies. We report the discovery of a
strong connection between severe ram pressure stripping and the presence of AGN
activity. Searching in galaxy clusters at low redshift, we have selected the
most extreme examples of jellyfish galaxies, which are galaxies with long
tentacles of material extending for dozens of kpc beyond the galaxy disk. Using
the MUSE spectrograph on the ESO Very Large Telescope, we find that 6 out of
the 7 galaxies of this sample host a central AGN, and two of them also have
galactic-scale AGN ionization cones. The high incidence of AGN among the most
striking jellyfishes may be due to ram pressure causing gas to flow towards the
center and triggering the AGN activity, or to an enhancement of the stripping
caused by AGN energy injection, or both. Our analysis of the galaxy position
and velocity relative to the cluster strongly supports the first hypothesis,
and puts forward ram pressure as another, yet unforeseen, possible mechanism
for feeding the central supermassive black hole with gas.Comment: published in Nature, Vol.548, Number 7667, pag.30
Unconventional Gravitational Excitation of a Schwarzschild Black Hole
Besides the well-known quasinormal modes, the gravitational spectrum of a
Schwarzschild black hole also has a continuum part on the negative imaginary
frequency axis. The latter is studied numerically for quadrupole waves. The
results show unexpected striking behavior near the algebraically special
frequency . This reveals a pair of unconventional damped modes very
near , confirmed analytically.Comment: REVTeX4, 4pp, 6 EPS figure files. N.B.: "Alec" is my first, and
"Maassen van den Brink" my family name. v2: better pole placement in Fig. 1.
v3: fixed Refs. [9,20]. v4: added context on "area quantum" research; trimmed
one Fig.; textual clarification
Tales of Tails: Gas Stripping Phenomena in Galaxies with MUSE
The MUSE spectrograph is observing a sample of over 100 galaxies at z = 0.04-0.07 in order to investigate how environmental effects can cause galaxies to lose their gas. These galaxies have a wide range of galaxy stellar masses and environments, from clusters and groups to isolated galaxies, and have been selected because they show unilateral debris or tails suggestive of gas stripping. MUSEâs large field of view, sensitivity, and spatial and spectral resolution allow us to study the physics of the stars and ionised gas in each galaxy in great detail, including the outskirts and extraplanar tails or debris out to 50-100 kpc away from each galaxy: a distance of more than ten times the galaxyâs effective radius. We present the ongoing programme, GAs Stripping Phenomena in galaxies (GASP), and report on the first set of results
GASP - XVII. H I imaging of the jellyfish galaxy JO206:Gas stripping and enhanced star formation
We present VLA HI observations of JO206, a prototypical ram-pressure stripped
galaxy in the GASP sample. This massive galaxy (M 8.5
10 M) is located at a redshift of 0.0513, near the
centre of the low-mass galaxy cluster, IIZw108 ( km/s). JO206
is characterised by a long tail (90 kpc) of ionised gas stripped away by
ram-pressure. We find a similarly long HI tail in the same direction as the
ionised gas tail and measure a total HI mass of
M. This is about half the expected HI mass given the stellar mass and
surface density of JO206. A total of M (60%) of
the detected HI is in the gas stripped tail. An analysis of the star formation
rate shows that the galaxy is forming more stars compared to galaxies with the
same stellar and HI mass. On average we find a HI gas depletion time of
0.5 Gyr which is about four times shorter than that of "normal" spiral
galaxies. We performed a spatially resolved analysis of the relation between
star formation rate density and gas density in the disc and tail of the galaxy
at the resolution of our HI data. The star formation efficiency of the disc is
about 10 times higher than that of the tail at fixed HI surface densities. Both
the inner and outer parts of JO206 show an enhanced star formation compared to
regions of similar HI surface density in field galaxies. The enhanced star
formation is due to ram-pressure stripping during the galaxy's first infall
into the cluster.Comment: 13 pages, 12 figures, Accepted for publication in MNRA
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