138 research outputs found
Comprehensive X-ray and Multiwavelength Study of ULXs in NGC 1566
This paper presents a comprehensive X-ray and multi-wavelength study of
ultraluminous X-ray sources (ULXs) in NGC 1566 using archival Chandra,
Swift/XRT, James Webb Space Telescope, JWST, and Hubble Space Telescope, HST
observations. The main results are, first, from the hardness ratio diagram,
where spectral state transitions from hard to soft as seen in typical Galactic
high mass X-ray binaries for ULX-3 was observed. Second, a new transient ULX
candidate (ULX-4) was identified, reaching a peak luminosity of 10E40 erg/s.
Third, the optical and NIR (near-infrared) counterparts of the ULXs were
searched from the precise astrometric calculations. For ULX-1 and ULX-2,
evidence was found that the observed NIR emission is due to the circumbinary
disk/dust disrupted by X-rays. Fourth, the optical observations suggest that
the possible donor star of ULX-3 is a B-type supergiant. In the case of ULX-4,
the multi-wavelength properties are not clear since many sources are detected
within the astrometric error radius.Comment: Accepted for publication in MNRAS. Including correction
The First Glimpse of ULXs Through the Near-Infrared Images Captured by the James Webb Space Telescope
This work presents the first results of near-infrared (NIR) counterparts of
ultraluminous X-ray sources (ULXs) in the case of NGC 1672 by using James Webb
Space Telescope (JWST) observations. Through advanced astrometry, unique
counterparts were identified for four of the eight ULXs (ULX-1, ULX-4, ULX5,
and ULX-8) located in NGC 1672, while multiple counterparts were identified for
the remaining ULXs. The NIR observations show clues of warm dust or
circumbinary disk around ULX-5 and ULX-8. In the case of ULX-5, optical SED is
a well-fitted blackbody with 4300 K while NIR excess is well-fitted by a
blackbody with a temperature of 1600 K. The optical-NIR photometric results
show that the possible donor star of ULX-5 may be a K-M type RSG (red
supergiant) whose optical emission is affected by the presence of a
circumbinary disk or warm dust. Additionally, the counterpart of ULX-4 could be
an AGN (active galactic nuclei) or star cluster due to its high K-band
magnitude. Thanks to the good enough resolution of the JWST images, in past
studies, most of the point-like and/or bright NIR counterparts of ULXs in
distant galaxies observed appear to be likely blended sources, so most likely,
many of them do not have the red color that an RSG could have. The significant
improvement in sensitivity and resolution supplied by JWST will lead to a new
perspective on the ambiguous nature of ULXs donors and environments
necessitating a significant reassessment of earlier infrared studies of ULXs.Comment: After revision, ACCEPTED for publication in MNRA
Possible optical counterparts of ULXs in NGC 1672
In this study, we use archival data from HST, Chandra, XMM-Newton, and
Swift-XRT, to probe the nature of 9 (X1-X9) candidate ULXs in NGC 1672. Our
study focuses on using the precise source positions obtained via improved
astrometry based on {\it Chandra} and HST observations to search for and
identify optical counterparts for these ULXs.Unique optical counterparts are
identified for X2 an{d X6; two potential counterparts were determined for X1,
X5 and X7 within the respective error radii while no optical counterparts were
found for the remaining four sources. Based on spectral energy distributions
(SEDs), X-ray and optical temporal analyses, some evidences about the nature of
X1 and X2 were obtained.Comment: To appear in Astronomische Nachrichten / Astronomical Notes (AN).
arXiv admin note: substantial text overlap with arXiv:2207.0630
MSCEqF: A Multi State Constraint Equivariant Filter for Vision-aided Inertial Navigation
This letter re-visits the problem of visual-inertial navigation system (VINS)
and presents a novel filter design we dub the multi state constraint
equivariant filter (MSCEqF, in analogy to the well known MSCKF). We define a
symmetry group and corresponding group action that allow specifically the
design of an equivariant filter for the problem of visual-inertial odometry
(VIO) including IMU bias, and camera intrinsic and extrinsic calibration
states. In contrast to state-of-the-art invariant extended Kalman filter (IEKF)
approaches that simply tack IMU bias and other states onto the
group, our filter builds upon a symmetry that properly
includes all the states in the group structure. Thus, we achieve improved
behavior, particularly when linearization points largely deviate from the truth
(i.e., on transients upon state disturbances). Our approach is inherently
consistent even during convergence phases from significant errors without the
need for error uncertainty adaptation, observability constraint, or other
consistency enforcing techniques. This leads to greatly improved estimator
behavior for significant error and unexpected state changes during, e.g.,
long-duration missions. We evaluate our approach with a multitude of different
experiments using three different prominent real-world datasets.Comment: Accepted for publication in the IEEE Robotics and Automation Letters
(RA-L), 202
The Transient Ultra-luminous X-ray Source, ULX-4, in M51
We present the results of a temporal and spectral analysis of the transient
source ULX-4 in the galaxy M51. The data used were drawn from Chandra,
XMM-Newton and Swift-XRT archives, spanning the years 2000-2019. The X-ray flux
of the source is seen to vary by two orders of magnitudes within a month but a
short-term variability was not observed over the time intervals of 100-2000
second in the 0.3-10 keV energy band. We find some evidence for the existence
of bi-modality feature in the flux distribution of ULX-4. We identified two
optical sources as possible counterparts within an error radius of 0."18 at 95%
confidence level for ULX-4 based on the archival HST/ACS and HST/WFC3 data.
Blackbody fits of the spectral energy distributions (SEDs) indicate the
spectral type to be B-type stars. One of these counterparts exhibits a
low-amplitude optical periodicity of 264 days in the F606W filter; if we assume
this apparent periodicity is associated with the orbital motion of the donor,
then it is more likely that the donor is a red supergiant satisfying the long
periodicity and accretion via Roche-lobe overflow. Consequently, the SED would
then have to be interpreted as a superposition of emissions from a cold donor
and a hot flow component, most likely from an accretion disk. If, on the other
hand, the periodicity is super orbital in nature i.e., due to possible
interactions of the compact object with a circumstellar disk, the donor could
then be a Be/X star hosting a neutron star.Comment: Accepted for publication in MNRAS. 16 pages, 12 figures, 6 table
Examination of silver-graphite lithographically printed resistive strain sensors
This paper reports the design and manufacture of three differing types of resistive strain sensitive structures fabricated using the Conductive Lithographic Film (CLF) printing process. The structures, utilising two inks prepared with silver and graphite particulates as the conductive phase, have been analysed to determine electrical and mechanical properties with respect to strain, temperature and humidity when deposited on four alternative substrate materials (GlossArt, PolyArt, Teslin and Melinex)
The hemolytic propertiesof clinical isolates of Morganella morganii
Morganella morganii is a gram-negative bacterium from the Enterobacteriaceae family which causes a wide range of clinical infections sometimes with fatal consequences. It is known that more than 50% of isolates of M. morganii from clinical specimens have hemolytic activity that increase their virulence. Pore-forming toxins (PFT) represent the most common group of cytotoxic proteins which contribute the delivering of the bacterial proteins into host cells, loss of nutrients and ions by eukaryotic cells, as well as the exit of bacteria from phagosome into cytosol. In this study we investigated the hemolytic activity of two M. morganii strains. It has been shown that hemolytic activity for strain of M. morganii 4 is 3 times higher than for strain of M. morganii 1. The maximum hemolytic activity is observed in LB medium but synthesis of hemolysins is higher in synthetic urine. Finally, the PCR-analysis of 5 hypothetical hemolysin genes has shown that strain M. morganii 1 does not contain homologous of α-hemolysin from E. coli that may explain the observed differences in hemolytic activity of the investigated strains
Dietary Supplementation of Moringa Oleifera Leaves and Their Nanoparticles to Rabbit Does Altered the Neonates Performance, Behavioural and Physiological Response to Stress
This study was conducted to investigate the effects of supplementing rabbits does with nano-zinc (NZn), nano-moringa (NMo), or moringa extract (MoE) on their growing rabbits (GR; fed on a moringa diet) behaviour, performance, and weaning stress alleviation. Twenty four does were equally divided into 4 groups; NZn-treated dams, NMo-treated dams, moringa extract MoE-treated dams, and non-treated dams (control; NTD) throughout gestation, lactation, and until the weaning of neonates. Immediately after weaning at about 35 days of age, 48 GR [12 from each treated dam group] were subdivided into 8 equal groups (each 12 GR/gp divided into 2 sub-groups: n = 6 per each); one sub group fed on a basal diet (BD) and the other fed on a 5% Moringa olifera-containing ration (MD) for 4 weeks. Feed intake (FI), body weight, and behavioural changes in the GR were recorded. Blood samples were collected at the termination of the experiment to assess oxidative stress (MDA, GSH), growth indicators (T3, T4), and liver and kidney functions. As a result, MD supplementation significantly (P < 0.01) increased FI compared to BD in the GR from control and NZn-treated dams. In addition, MD supplementation resulted in increased feeding and drinking behaviours frequency and duration, while self-grooming was reduced in both NTD and NZn-treated dams in relation to BD supplemented groups. Moreover, MD significantly decreased oxidative stress in GR from NTD. Also, MD induced a significant (P < 0.01) increase in T3 level and enhanced the liver and kidney functions in GR from all treated dams compared to control. Furthermore, MD supplementation increased the economic efficiency of GR. In conclusion, MD supplementation to GRs or treatment of their dams with the mentioned treatments decreased weaning stress, improved rabbit behaviour, and improved economic efficiency, but no significant improvement in the GRs' performance was observed. However, treatments of dams and their GR with MD resulted in GR inability to cope with weaning stress and induced renal and hepatic damage. Thus, it is recommended to supplement GR with MD after weaning or prenatal treatment of their dams with herbal extract or nano-herbal particles, but a combination of both treatments is not recommended
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