The dusty heart of nearby active galaxies. I. High-spatial resolution mid-IR spectro-photometry of Seyfert galaxies

We present 8-13 micron imaging and spectroscopy of 9 type 1 and 10 type 2 AGN obtained with the VLT/VISIR instrument at spatial resolution <100 pc. The emission from the host galaxy sources is resolved out in most cases. The silicate absorption features are moderately deep and emission features are shallow. We compare the mid-IR luminosities to AGN luminosity tracers and found that the mid-IR radiation is emitted quite isotropically. In two cases, IC5063 and MCG-3-34-64, we find evidence for extended dust emission in the narrow-line region. We confirm the correlation between observed silicate feature strength and Hydrogen column density recently found in Spitzer data. In a further step, our 3D clumpy torus model has been used to interpret the data. We show that the strength of the silicate feature and the mid-IR spectral index can be used to get reasonable constraints on the dust distribution in the torus. The mid-IR spectral index, alpha, is almost exclusively determined by the radial dust distribution power-law index, a, and the silicate feature depth is mostly depending on the average number of clouds, N0, along an equatorial line-of-sight and the torus inclination. A comparison of model predictions to our type 1 and type 2 AGN reveals typical average parameters a=-1.0+/-0.5 and N0=5-8, which means that the radial dust distribution is rather shallow. As a proof-of-concept of this method, we compared the model parameters derived from alpha and the silicate feature to more detailed studies of IR SEDs and interferometry and found that the constraints on a and N0 are consistent. Finally, we might have found evidence that the radial structure of the torus changes from low to high AGN luminosities towards steeper dust distributions, and we discuss implications for the IR size-luminosity relation. (abridged)Comment: 22 pages, 13 figues, 6 tables; Accepted for publication in A&A; Note that this is the second submitted paper from the series, but we changed paper order. This one will be referred to as paper I, the previously submitted arXiv:0909.4539 will become paper I

Spatial, Temporal and Spectral Properties of X-ray Emission from the Magnetar SGR~0501+4516

SGR~0501+4516 was discovered with the Swift satellite on 2008 August 22, after it emitted a series of very energetic bursts. Since then, the source was extensively monitored with Swift, the Rossi X-ray Timing Explorer (RXTE) and observed with Chandra and XMM-Newton, providing a wealth of information about its outburst behavior and burst induced changes of its persistent X-ray emission. Here we report the most accurate location of SGR~0501+4516 (with an accuracy of 0.11'') derived with Chandra. Using the combined RXTE, Swift/X-ray Telescope, Chandra and XMM-Newton observations we construct a phase connected timing solution with the longest time baseline (~240 days) to date for the source. We find that the pulse profile of the source is energy dependent and exhibits remarkable variations associated with the SGR~0501+4516 bursting activity. We also find significant spectral evolution (hardening) of the source persistent emission associated with bursts. Finally, we discuss the consequences of the SGR~0501+4516 proximity to the supernova remnant, SNR G160.9+2.6 (HB9).Comment: Accepted for publication in the Ap

MAXI J1659-152: the shortest orbital period black-hole binary

Following the detection of a bright new X-ray source, MAXI J1659-152, a series of observations was triggered with almost all currently flying high-energy missions. We report here on XMM-Newton, INTEGRAL and RXTE observations during the early phase of the X-ray outburst of this transient black-hole candidate. We confirm the dipping nature in the X-ray light curves. We find that the dips recur on a period of 2.4139+/-0.0005 hrs, and interpret this as the orbital period of the system. It is thus the shortest period black-hole X-ray binary known to date. Using the various observables, we derive the properties of the source. The inclination of the accretion disk with respect to the line of sight is estimated to be 60-75 degrees. The companion star to the black hole is possibly a M5 dwarf star, with a mass and radius of about 0.15 M_sun and 0.23 R_sun, respectively. The system is rather compact (orbital separation is about 1.35 R_sun) and is located at a distance of roughly 7 kpc. In quiescence, MAXI J1659-152 is expected to be optically faint, about 28 mag in the V-band.Comment: 5 pages, 4 figures, to be published in the proceedings of the 4th International MAXI Workshop `The First Year of MAXI: Monitoring variable X-ray sources', 2010 Nov 30 - Dec 2, Tokyo, Japa

Effects of ultrafine particles on the allergic inflammation in the lung of asthmatics : results of a double-blinded randomized cross-over clinical pilot study

Background: Epidemiological and experimental studies suggest that exposure to ultrafine particles (UFP) might aggravate the allergic inflammation of the lung in asthmatics. Methods: We exposed 12 allergic asthmatics in two subgroups in a double-blinded randomized cross-over design, first to freshly generated ultrafine carbon particles (64 μg/m3; 6.1 ± 0.4 × 105 particles/cm3 for 2 h) and then to filtered air or vice versa with a 28-day recovery period in-between. Eighteen hours after each exposure, grass pollen was instilled into a lung lobe via bronchoscopy. Another 24 hours later, inflammatory cells were collected by means of bronchoalveolar lavage (BAL). (Trial registration: NCT00527462) Results: For the entire study group, inhalation of UFP by itself had no significant effect on the allergen induced inflammatory response measured with total cell count as compared to exposure with filtered air (p = 0.188). However, the subgroup of subjects, which inhaled UFP during the first exposure, exhibited a significant increase in total BAL cells (p = 0.021), eosinophils (p = 0.031) and monocytes (p = 0.013) after filtered air exposure and subsequent allergen challenge 28 days later. Additionally, the potential of BAL cells to generate oxidant radicals was significantly elevated at that time point. The subgroup that was exposed first to filtered air and 28 days later to UFP did not reveal differences between sessions. Conclusions: Our data demonstrate that pre-allergen exposure to UFP had no acute effect on the allergic inflammation. However, the subgroup analysis lead to the speculation that inhaled UFP particles might have a long-term effect on the inflammatory course in asthmatic patients. This should be reconfirmed in further studies with an appropriate study design and sufficient number of subjects

Spreading depolarization and angiographic spasm are separate mediators of delayed infarcts

In DISCHARGE-1, a recent Phase III diagnostic trial in aneurysmal subarachnoid haemorrhage patients, spreading depolarization variables were found to be an independent real-time biomarker of delayed cerebral ischaemia. We here investigated based on prospectively collected data from DISCHARGE-1 whether delayed infarcts in the anterior, middle, or posterior cerebral artery territories correlate with (i) extravascular blood volumes; (ii) predefined spreading depolarization variables, or proximal vasospasm assessed by either (iii) digital subtraction angiography or (iv) transcranial Doppler-sonography; and whether spreading depolarizations and/or vasospasm are mediators between extravascular blood and delayed infarcts. Relationships between variable groups were analysed using Spearman correlations in 136 patients. Thereafter, principal component analyses were performed for each variable group. Obtained components were included in path models with a priori defined structure. In the first path model, we only included spreading depolarization variables, as our primary interest was to investigate spreading depolarizations. Standardised path coefficients were 0.22 for the path from extravascular bloodcomponent to depolarizationcomponent (P = 0.010); and 0.44 for the path from depolarizationcomponent to the first principal component of delayed infarct volume (P < 0.001); but only 0.07 for the direct path from bloodcomponent to delayed infarctcomponent (P = 0.36). Thus, the role of spreading depolarizations as a mediator between blood and delayed infarcts was confirmed. In the principal component analysis of extravascular blood volume, intraventricular haemorrhage was not represented in the first component. Therefore, based on the correlation analyses, we also constructed another path model with bloodcomponent without intraventricular haemorrhage as first and intraventricular haemorrhage as second extrinsic variable. We found two paths, one from (subarachnoid) bloodcomponent to delayed infarctcomponent with depolarizationcomponent as mediator (path coefficients from bloodcomponent to depolarizationcomponent = 0.23, P = 0.03; path coefficients from depolarizationcomponent to delayed infarctcomponent = 0.29, P = 0.002), and one from intraventricular haemorrhage to delayed infarctcomponent with angiographic vasospasmcomponent as mediator variable (path coefficients from intraventricular haemorrhage to vasospasmcomponent = 0.24, P = 0.03; path coefficients from vasospasmcomponent to delayed infarctcomponent = 0.35, P < 0.001). Human autopsy studies shaped the hypothesis that blood clots on the cortex surface suffice to cause delayed infarcts beneath the clots. Experimentally, clot-released factors induce cortical spreading depolarizations that trigger (i) neuronal cytotoxic oedema and (ii) spreading ischaemia. The statistical mediator role of spreading depolarization variables between subarachnoid blood volume and delayed infarct volume supports this pathogenetic concept. We did not find that angiographic vasospasm triggers spreading depolarizations, but angiographic vasospasm contributed to delayed infarct volume. This could possibly result from enhancement of spreading depolarization-induced spreading ischaemia by reduced upstream blood supply.Peer Reviewe

The first GRB survey of the IBIS/PICsIT archive

The multi-purpose INTEGRAL mission is continuously contributing to Gamma Ray Burst (GRB) science, thanks to the performances of its two main instruments, IBIS and SPI, operating in the hard X-ray/soft gamma-ray domain. We investigate the possibilities offered to the study of GRBs by PICsIT, the high-energy detector of the IBIS instrument. We searched for transient episodes in the PICsIT light curves archive from May 2006 to August 2009, using stringent criteria optimized for the detection of long events. In the time interval under examination PICsIT provides an energy coverage from 208 to 2600 keV, resolved in eight energy channels, combined with a fine time resolution of 16 ms. PICsIT successfully observes GRBs in the 260-2600 keV energy range with an incoming direction spread over half the sky for the brightest events. We compiled a list of 39 bursts, most of which are confirmed GRBs or simultaneous to triggers from other satellites/instruments. We produced light curves with a time sampling down to 0.25 s in three energy intervals for all events. Because an adequate response matrix is not yet available for the PICsIT burst sample, we obtained a calibration coefficient in three selected energy bands by comparing instrumental counts with physical fluences inferred from observations with different satellites. The good time resolution provided by the PICsIT data allows a spectral variability study of our sample through the hardness ratio.Comment: 20 pages, 48 figures. Accepted for publication in A&

Tissue specific mutagenic and carcinogenic responses in NER defective mouse models.

Several mouse models with defects in genes encoding components of the nucleotide excision repair (NER) pathway have been developed. In NER two different sub-pathways are known, i.e. transcription-coupled repair (TC-NER) and global-genome repair (GG-NER). A defect in one particular NER protein can lead to a (partial) defect in GG-NER, TC-NER or both. GG-NER defects in mice predispose to cancer, both spontaneous as well as UV-induced. As such these models (Xpa, Xpc and Xpe) recapitulate the human xeroderma pigmentosum (XP) syndrome. Defects in TC-NER in humans are associated with Cockayne syndrome (CS), a disease not linked to tumor development. Mice with TC-NER defects (Csa and Csb) are - except for the skin - not susceptible to develop (carcinogen-induced) tumors. Some NER factors, i.e. XPB, XPD, XPF, XPG and ERCC1 have functions outside NER, like transcription initiation and inter-strand crosslink repair. Deficiencies in these processes in mice lead to very severe phenotypes, like trichothiodystrophy (TTD) or a combination of XP and CS. In most cases these animals have a (very) short life span, display segmental progeria, but do not develop tumors. Here we will overview the available NER-related mouse models and will discuss their phenotypes in terms of (chemical-induced) tissue-specific tumor development, mutagenesis and premature aging features

Morphologic characterization of osteosarcoma growth on the chick chorioallantoic membrane

<p>Abstract</p> <p>Background</p> <p>The chick chorio-allantoic membrane (CAM) assay is a commonly used method for studying angiogenic or anti-angiogenic activities <it>in vivo</it>. The ease of access allows direct monitoring of tumour growth by biomicroscopy and the possibility to screen many samples in an inexpensive way. The CAM model provides a powerful tool to study effects of molecules, which interfere with physiological angiogenesis, or experimental tumours derived from cancer cell lines. We therefore screened eight osteosarcoma cell lines for their ability to form vascularized tumours on the CAM.</p> <p>Findings</p> <p>We implanted 3-5 million cells of human osteosarcoma lines (HOS, MG63, MNNG-HOS, OST, SAOS, SJSA1, U2OS, ZK58) on the CAM at day 10 of embryonic development. Tumour growth was monitored by <it>in vivo </it>biomicroscopy at different time points and tumours were fixed in paraformaldehyde seven days after cell grafting. The tissue was observed, photographed and selected cases were further analyzed using standard histology.</p> <p>From the eight cell lines the MNNG-HOS, U2OS and SAOS were able to form solid tumours when grafted on the CAM. The MNNG-HOS tumours showed the most reliable and consistent growth and were able to penetrate the chorionic epithelium, grow in the CAM stroma and induce a strong angiogenic response.</p> <p>Conclusions</p> <p>Our results show that the CAM assay is a useful tool for studying osteosarcoma growth. The model provides an excellent alternative to current rodent models and could serve as a preclinical screening assay for anticancer molecules. It might increase the speed and efficacy of the development of new drugs for the treatment of osteosarcoma.</p

Search for Gravitational Wave Bursts from Six Magnetars

Soft gamma repeaters (SGRs) and anomalous X-ray pulsars (AXPs) are thought to be magnetars: neutron stars powered by extreme magnetic fields. These rare objects are characterized by repeated and sometimes spectacular gamma-ray bursts. The burst mechanism might involve crustal fractures and excitation of non-radial modes which would emit gravitational waves (GWs). We present the results of a search for GW bursts from six galactic magnetars that is sensitive to neutron star f-modes, thought to be the most efficient GW emitting oscillatory modes in compact stars. One of them, SGR 0501+4516, is likely similar to 1 kpc from Earth, an order of magnitude closer than magnetars targeted in previous GW searches. A second, AXP 1E 1547.0-5408, gave a burst with an estimated isotropic energy >10(44) erg which is comparable to the giant flares. We find no evidence of GWs associated with a sample of 1279 electromagnetic triggers from six magnetars occurring between 2006 November and 2009 June, in GW data from the LIGO, Virgo, and GEO600 detectors. Our lowest model-dependent GW emission energy upper limits for band-and time-limited white noise bursts in the detector sensitive band, and for f-mode ringdowns (at 1090 Hz), are 3.0 x 10(44)d(1)(2) erg and 1.4 x 10(47)d(1)(2) erg, respectively, where d(1) = d(0501)/1 kpc and d(0501) is the distance to SGR 0501+4516. These limits on GW emission from f-modes are an order of magnitude lower than any previous, and approach the range of electromagnetic energies seen in SGR giant flares for the first time.United States National Science FoundationScience and Technology Facilities Council of the United KingdomMax-Planck-SocietyState of Niedersachsen/GermanyItalian Istituto Nazionale di Fisica NucleareFrench Centre National de la Recherche ScientifiqueAustralian Research CouncilCouncil of Scientific and Industrial Research of IndiaIstituto Nazionale di Fisica Nucleare of ItalySpanish Ministerio de Educacion y CienciaConselleria d'Economia Hisenda i Innovacio of the Govern de les Illes BalearsFoundation for Fundamental Research on Matter supported by the Netherlands Organisation for Scientific ResearchPolish Ministry of Science and Higher EducationFoundation for Polish ScienceRoyal SocietyScottish Funding CouncilScottish Universities Physics AllianceNational Aeronautics and Space Administration NNH07ZDA001-GLASTCarnegie TrustLeverhulme TrustDavid and Lucile Packard FoundationResearch CorporationAlfred P. Sloan FoundationRussian Space AgencyRFBR 09-02-00166aIPN JPL Y503559 (Odyssey), NASA NNG06GH00G, NASA NNX07AM42G, NASA NNX08AC89G (INTEGRAL), NASA NNG06GI896, NASA NNX07AJ65G, NASA NNX08AN23G (Swift), NASA NNX07AR71G (MESSENGER), NASA NNX06AI36G, NASA NNX08AB84G, NASA NNX08AZ85G (Suzaku), NASA NNX09AU03G (Fermi)Astronom