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E. Liuzzo,
R. Falomo,
A. Treves,
C. Arcidiacono,
E. Torresi,
M. Uslenghi,
J. Farinato,
A. Moretti,
R. Ragazzoni,
E. Diolaiti,
M. Lombini,
R. Brast,
R. Donaldson,
J. Kolb,
E. Marchetti, S. Tordo
[show abstract]
[hide abstract]
ABSTRACT: PKS 2155-304 is one of the brightest BL Lac object in the sky and a very well
studied target from radio to TeV bands. We report on high-resolution (~ 0.12
arcsec) direct imaging of the field of PKS 2155-304 using adaptive optics
near-IR observations in J and Ks bands obtained with the ESO multi-conjugate
adaptive optic demonstrator (MAD) at the Very Large Telescope. These data are
complemented with archival VLA images at various frequencies to investigate the
properties of the close environment of the source. We characterized the faint
galaxies that form the poor group associated to the target. No radio emission
is present for these galaxies, while an old radio jet at ~ 20 kpc from the
nucleus of PKS 2155-304 and a jet-like structure of ~ 2 kpc (~ 1 arcsec) in the
eastern direction are revealed. No counterparts of these radio jets are found
in the NIR or in archival Chandra observations.
01/2013;
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R Arsenault,
P -Y Madec,
J Paufique,
P La Penna,
S Stroebele,
E Vernet,
J -F Pirard,
W Hackenberg,
H Kuntschner,
L Jochum, [......],
B Buzzoni,
J Quentin,
S Lewis,
P Jolley,
M Kraus,
T Pfrommer,
R Biasi,
D Gallieni,
C Bechet,
R Stuik
Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series; 07/2012
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E. Liuzzo,
R. Falomo,
A. Treves,
D. Donato,
M. Sambruna,
C. Arcidiacono,
G. Giovannini,
J. Farinato,
A. Moretti,
R. Ragazzoni,
E. Diolaiti,
M. Lombini,
R. Brast,
R. Donaldson,
J Kolb,
E. Marchetti, S. Tordo
[show abstract]
[hide abstract]
ABSTRACT: Relativistic jets are a common feature of radio loud active galactic nuclei. Multifrequency observations are a unique tool to constrain their physics. We report on a detailed study of the properties of the jet of the nearby BL Lac object PKS 2201+044, one of the rare cases where the jet is detected from radio to X-rays. We use new adaptive optics near-IR observations of the source, obtained with the ESO multi-conjugated adaptive optics demonstrator (MAD) at the Very Large Telescope. These observations acquired in Ground-Layer Adaptive Optics mode are combined with images previously achieved by HST, VLA and Chandra to perform a morphological and photometric study of the jet. We find a noticeable similarity in the morphology of the jet at radio, near-IR and optical wavelengths. We construct the spectral shape of the main knot of jet that appears dominated by synchrotron radiation. On the basis of the jet morphology and the weak lines spectrum we suggest that PKS 2201+044 belongs to the class of radio sources intermediate between FRIs and FRIIs. Comment: 11 pages, 8 figures, accepted for pubblication in A&A
12/2010;
-
R. Arsenault,
P.-Y. Madec,
J. Paufique,
S. Ströbele,
J.-F. Pirard,
É. Vernet,
W. Hackenberg,
N. Hubin,
L. Jochum,
H. Kuntschner, [......],
A. Silber,
P. Jolly,
A. Manescau,
P. Hammersley,
J. Reyes,
A. Jost,
M. Duchateau,
V. Heinz,
C. Bechet,
R. Stuik
The Messenger. 12/2010; 142:12-16.
-
A Deep,
R Arsenault,
W Boland,
B Delabre,
N Hubin,
P La Penna,
P -Y Madec,
F Molster,
R Stuik, S Tordo,
E Wiegers
Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series; 08/2010
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R. Falomo,
E. Pian,
A. Treves,
G. Giovannini,
T. Venturi,
A. Moretti,
C. Arcidiacono,
J. Farinato,
R. Ragazzoni,
E. Diolaiti,
M. Lombini,
F. Tavecchio,
R. Brast,
E. Marchetti, S. Tordo
[show abstract]
[hide abstract]
ABSTRACT: BL Lac objects are low--power active nuclei exhibiting a variety of peculiar properties that are caused by the presence of a relativistic jet and orientation effects. We present here adaptive optics near-IR images at high spatial resolution of the nearby BL Lac object PKS 0521-365, which is known to display a prominent jet both at radio and optical frequencies. The observations were obtained in Ks--band using the ESO multi-conjugated adaptive optics demonstrator at the Very Large Telescope. This allowed us to obtain images with 0.1 arcsec effective resolution. We performed a detailed analysis of the jet and its related features from the near-IR images, and combined them with images previously obtained with HST in the R band and by a re-analysis of VLA radio maps. We find a remarkable similarity in the structure of the jet at radio, near-IR, and optical wavelengths. The broad--band emission of the jet knots is dominated by synchrotron radiation, while the nucleus also exhibits a significant inverse Compton component. We discovered the near-IR counterpart of the radio hotspot and found that the near-IR flux is consistent with being a synchrotron emission from radio to X-ray. The bright red object (red-tip), detached but well aligned with the jet, is well resolved in the near-IR and has a linear light profile. Since it has no radio counterpart, we propose that it is a background galaxy not associated with the jet. The new adaptive optics near-IR images and previous observations at other frequencies allow us to study the complex environment around the remarkable BL Lac object PKS 0521-365. These data exemplify the capabilities of multi conjugate adaptive optics observations of extragalactic extended sources. Comment: accepted for publication in Astronomy and Astrophysics 9 pages. A & A 2009, in press
06/2009;
-
A. Moretti,
G. Piotto,
C. Arcidiacono,
A. P. Milone,
R. Ragazzoni,
R. Falomo,
J. Farinato,
L. R. Bedin,
J Anderson,
A. Sarajedini,
A. Baruffolo,
E. Diolaiti,
M. Lombini,
R. Brast,
R. Donaldson,
J Kolb,
E. Marchetti, S. Tordo
[show abstract]
[hide abstract]
ABSTRACT: Deep photometry of crowded fields, such as Galactic Globular Clusters, is severely limited by the actual resolution of ground-based telescopes. On the other hand, the Hubble Space Telescope does not provide the near-infrared (NIR) filters needed to allow large color baselines. In this work we aim at demonstrating how ground based observations can reach the required resolution when using Multi-Conjugated Adaptive Optic (MCAO) devices in the NIR, such as the experimental infrared camera (MAD) available on the VLT. This is particularly important since these corrections are planned to be available on all ground--based telescopes in the near future. We do this by combining the infrared photometry obtained by MAD/VLT with ACS/HST optical photometry of our scientific target, the bulge globular cluster NGC 6388, in which we imaged two fields. In particular, we constructed color-magnitude diagrams with an extremely wide color baseline in order to investigate the presence of multiple stellar populations in this cluster. From the analysis of the external field, observed with better seeing conditions, we derived the deepest optical-NIR CMD of NGC 6388 to date. The high-precision photometry reveals that two distinct sub-giant branches are clearly present in this cluster. We also use the CMD from the central region to estimate the distance ((m-M)=15.33) and the reddening (E(B-V)=0.38) for this cluster. We estimate the age to be ~11.5+/- 1.5 Gyr. The large relative-age error reflects the bimodal distribution of the SGB stars. This study clearly demonstrates how MCAO correction in the NIR bands implemented on ground based telescopes can complement the high-resolution optical data from HST. Comment: 9 pages, 10 figures. Accepted for publication on A. & A
10/2008;
-
M. Gullieuszik,
L. Greggio,
E. V. Held,
A. Moretti,
C. Arcidiacono,
P. Bagnara,
A. Baruffolo,
E. Diolaiti,
R. Falomo,
J. Farinato,
M. Lombini,
R. Ragazzoni,
R. Brast,
R. Donaldson,
J Kolb,
E. Marchetti, S. Tordo
[show abstract]
[hide abstract]
ABSTRACT: We present a study aimed at deriving constraints on star formation at intermediate ages from the evolved stellar populations in the dwarf irregular galaxy UKS2323-326. These observations were also intended to demonstrate the scientific capabilities of the multi-conjugated adaptive optics demonstrator (MAD) implemented at the ESO Very Large Telescope as a test-bench of adaptive optics (AO) techniques. We perform accurate, deep photometry of the field using J and Ks band AO images of the central region of the galaxy. The near-infrared (IR) colour-magnitude diagrams clearly show the sequences of asymptotic giant branch (AGB) stars, red supergiants, and red giant branch (RGB) stars down to ~1 mag below the RGB tip. Optical-near-IR diagrams, obtained by combining our data with Hubble Space Telescope observations, provide the best separation of stars in the various evolutionary stages. The counts of AGB stars brighter than the RGB tip allow us to estimate the star formation at intermediate ages. Assuming a Salpeter initial mass function, we find that the star formation episode at intermediate ages produced ~6x10^5 M_sun of stars in the observed region. Comment: 4 pages, 4 figures, Accepted for publication in A&A Letters
03/2008;
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H. U. Käufl,
P. Amico,
P. Ballester,
E. Bendek,
P. Biereichel,
P. Bristow,
M. Casali,
B. Delabre,
R. Dorn,
S. Eschbaumer, [......],
A. Seifahrt,
R. Siebenmorgen,
A. Silber,
A. Smette,
B. Sokar,
J. Stegmeier,
L. Tacconi-Garman, S. Tordo,
S. Uttenthaler,
U. Weilenmann
[show abstract]
[hide abstract]
ABSTRACT: CRIRES is a cryogenic, pre-dispersed, infrared echelle spectrograph
designed to provide a nominal resolving power λ/Δλ
of 105 between 1000 and 5000 nm for a nominal slit width of 0.2'. The
CRIRES installation at the Nasmyth focus A of the 8-m VLT UT1 (Antu)
marks the completion of the original instrumentation plan for the VLT. A
curvature sensing adaptive optics system feed is used to minimise slit
losses and to provide 0.2' spatial resolution along the slit. A mosaic
of four Aladdin InSb-arrays packaged on custom-fabricated ceramic boards
has been developed. It provides for an effective 4096 × 512 pixel
focal plane array to maximise the free spectral range covered in each
exposure. Insertion of gas cells is possible in order to measure radial
velocities with high precision. Measurement of circular and linear
polarisation in Zeeman sensitive lines for magnetic Doppler imaging is
foreseen but not yet fully implemented. A cryogenic Wollaston prism on a
kinematic mount is already incorporated. The retarder devices are
located close to the Unit Telescope focal plane. Here we briefly recall
the major design features of CRIRES and describe the commissioning of
the instrument including a report of extensive laboratory testing and a
preview of astronomical results. Thanks to the strong efforts of the
CRIRES commissioning team and all other ESO staff involved, it was
possible to include the instrument in the general ESO call for proposals
for Period 79.
The Messenger. 11/2006; 126:32-36.
-
J. Paufique,
P. Biereichel,
B. Delabre,
R. Donaldson,
R Esteves,
E. Fedrigo,
P. Gigan,
D. Gojak,
N. Hubin,
M Kasper,
U. Kaeufl,
JL. Lizon,
E. Marchetti,
S. Oberti,
JF. Pirard,
E. Pozna,
J Santos,
S. Stroebele, S. Tordo
[show abstract]
[hide abstract]
ABSTRACT: The adaptive optics MACAO has been implemented in 6 focii of the VLT observatory, in three different flavors. We present in this paper the results obtained during the commissioning of the last of these units, MACAO-CRIRES. CRIRES is a high-resolution spectrograph, which efficiency will be improved by a factor two at least for point-sources observations with a NGS brighter than R=15. During the commissioning, Strehl exceeding 60% have been observed with fair seeing conditions, and a general description of the performance of this curvature adaptive optics system is done. Comment: SPIE conference 2006, Advances in adaptive optics, 12 pages, 11 figures
08/2006;
-
R. Falomo,
E. Pian,
A. Treves,
G. Giovannini,
T. Venturi,
A. Moretti,
C. Arcidiacono,
J. Farinato,
R. Ragazzoni,
E. Diolaiti,
M. Lombini,
F. Tavecchio,
R. Brast,
R. Donaldson,
J Kolb,
E. Marchetti, S. Tordo
[show abstract]
[hide abstract]
ABSTRACT: Context. BL Lac objects are low-power active nuclei exhibiting a variety of peculiar properties caused by the presence of a relativistic jet and orientation effects. Aims. We present adaptive optics near-IR images at high spatial resolution of the nearby BL Lac object PKS 0521-365, which is known to display a prominent jet both at radio and optical frequencies.Methods. The observations were obtained in $K$s-band using the ESO multi-conjugated adaptive optics demonstrator at the Very Large Telescope. This allowed us to obtain images with 0.1 arcsec effective resolution. We performed a detailed analysis of the jet and its related features from the near-IR images, and combined them with images previously obtained with HST in the $R$ band and by a re-analysis of VLA radio maps. Results. We find a remarkable similarity in the structure of the jet at radio, near-IR, and optical wavelengths. The broad–band emission of the jet knots is dominated by synchrotron radiation, while the nucleus also exhibits a significant inverse Compton component. We discovered the near-IR counterpart of the radio hotspot and found that the near-IR flux is consistent with being a synchrotron emission from radio to X-ray wavelengths. The bright red object (red-tip), detached but well aligned with the jet, is well resolved in the near-IR and has a linear light profile. Since it has no radio counterpart, we propose that it is a background galaxy not associated with the jet. Conclusions. The new adaptive optics near-IR images and previous observations at other frequencies allow us to study the complex environment around the remarkable BL Lac object PKS 0521-365. These data exemplify the capabilities of multi conjugate adaptive optics observations of extragalactic extended sources.
http://dx.doi.org/10.1051/0004-6361/200912077.
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R. Arsenault,
J. Alonso,
H. Bonnet,
J. Brynnel,
B. Delabre,
R. Donaldson,
C. Dupuy,
E. Fedrigo,
J. Spyromilio,
T. Erm, [......],
S. Rossi, S. Tordo,
S. Stroebele,
J.-L. Lizon,
P. Gigan,
F. Pouplard,
F. Delplancke,
A. Silber,
M. Quattri,
R. Reiss
[show abstract]
[hide abstract]
ABSTRACT: The AO department of ESO has completed the design of an adaptive AO system for the VLT Interferometer. Ordering of components, manufacturing and integration took place in 2001 and 2002. The system is built in four copies, one for each VLT. It is installed at the Coudé room and the Coudé train is used as a "science path". Only one of the mirrors (M8, pupil conjugated) is replaced by the corrective optics. The 60 elements system should allow a Strehl ratio of ~0.6 on bright sources. Commissioning activities started in April 2003 and the delivery of the 4th system is planned for late 2004. At the time of this writing the first commissioning of the first MACAO has been completed and results are encouraging. The integration and test phase of the 2nd system is in full swing.
The Messenger, v.112, 7-12 (2003).
