16 research outputs found
Progenitor constraint using line ratios of the CNO elements in supernova remnants
Unveiling the nature of progenitors is crucial for understanding the origin
and the mechanism of core-collapse and thermonuclear supernovae (SNe). While
several methods have been developed to derive stellar properties so far, many
questions remain poorly understood. In this paper we demonstrate an
observational approach to constrain progenitors of supernova remnants (SNRs)
using abundances of carbon (C), nitrogen (N), and oxygen (O) in shock-heated
circumstellar material (CSM). Our calculations with stellar evolution codes
indicate that a total amount of these CNO elements will provide a more
sensitive determination of the progenitor masses than the conventional method
based on ejecta abundances. If the CNO lines (particularly those of C and N)
are detected and measured their abundance ratios accurately, they can provide
relatively robust constraint on the progenitor mass (and in some cases the
rotation velocity) of SNRs. Since our method requires a better energy
resolution and larger effective area in the soft X-ray band (~keV), XRISM
launched on September 7, 2023 and next-generation microcalorimeter missions
such as Athena, Lynx, LEM, and HUBS will bring a new insight into link between
the progenitors and their remnants.Comment: 17 pages, 8 figures. Proceedings of the Conference "Multifrequency
Behaviour of High Energy Cosmic Sources XIV" (MULTIF2023). Accepted for
publication on Po
Global deceleration and inward movements of X-ray knots and rims of RCW 103
Kinematics of shocks, ejecta knots, and the compact remnant of a supernova
remnant gives an insight into the nature of the progenitor and surrounding
environment. We report on a proper motion measurement of X-ray knots and rims
of the magnetar-hosting supernova remnant RCW 103. Chandra data obtained in
three epochs, 1999, 2010, and 2016 are used. We find a global deceleration of
12 knots and rims both in northern and southern regions within the last yrs, even though its age is thought to be larger than 2 kyr. Some of them
even changed their moving directions from outward ( km s) to
inward ( km s). Our findings can be explained with a
collision with a high-density medium both in the northern and southern edges of
the remnant, although the remnant may still be expanding in the wind-blown
cavity. The proper motion of the associated magnetar 1E1613485055 is
possibly detected with a velocity of km s.Comment: 8 pages, 4 figures, accepted for publication in Ap
Progenitor constraint with circumstellar material for the magnetar-hosting supernova remnant RCW 103
Stellar winds blown out from massive stars () contain
precious information on the progenitor itself, and in this context, the most
important elements are carbon (C), nitrogen (N), and oxygen (O), which are
produced by the CNO cycle in the H-burning layer. Although their X-ray
fluorescence lines are expected to be detected in swept-up shock-heated
circumstellar materials (CSMs) in supernova remnants (SNRs), particularly those
of C and N have been difficult to detect so far. Here, we present a
high-resolution spectroscopy of a young magnetar-hosting SNR RCW~103 with the
Reflection Grating Spectrometer (RGS) onboard XMM-Newton and report on the
detection of \ion{N}{7} Ly (0.50~keV) line for the first time. By
comparing the obtained abundance ratio of N to O (N/O) with
various stellar evolution models, we show that the progenitor of RCW~103 is
likely to have a low-mass (10--12~) and medium-rotation velocities
(). The results also rule out the possibility of
dynamo effects in massive () stars as a formation mechanism
of the associated magnetar 1E~1613485055. Our method is useful for
estimating various progenitor parameters for future missions with
microcalorimeters such as XRISM and Athena.Comment: Accepted for publication in ApJ. 11 pages, 8 figure
Image hierarchy in gaussian scale space
We investigate the topological structure of an image and the hierarchical relationship between local and global structures provided by spatial gradients at different levels of scale in the Gaussian scale space. The gradient field curves link stationary points of an image, including a local minimum at infinity, and construct the topological structure of the image. The evolution of the topological structure with respect to scale is analyzed using pseudograph representation. The hierarchical relationships among the structures at different scales are expressed as trajectories of the stationary points in the scale space, which we call the stationary curves. Each top point of the local extremum curve generically has a specific gradient field curve, which we call the antidirectional figure-flow curve. The antidirectional figure-flow curve connects the top-point and another local extremum to which the toppoint is subordinate. A point at infinity can also be connected to the top points of local minimum curves. These hierarchical relationships among the stationary points are expressed as a tree. This tree expresses a hierarchical structure of dominant parts. We clarify the graphical grammar for the construction of this tree in the Gaussian scale space. Furthermore, we show a combinatorial structure of singular points in the Gaussian scale space using conformal mapping from Euclidean space to the spherical surface. We define segment edges as a zero-crossing set in the Gaussian scale space using the singular points. An image in the Gaussian scale space is the convolution of the image and the Gaussian kernel. The Gaussian kernel of an appropriate variance is a typical presmoothing operator for segmentation. The variance is heuristically selected using statistics of images such as the noise distribution in images. The variance of the kernel is determined using the singular-point configuration in the Gaussian scale space, since singular points in the Gaussian scale space allow the extraction of the dominant parts of an image. This scale-selection strategy derives the hierarchical structure of the segments. Unsupervised segmentation methods, however, have difficulty in distinguishing valid segments associated with the objects from invalid random segments due to noise. By showing that the number of invalid segments monotonically decreases with increasing scale, we characterize the valid and invalid segments in the Gaussian scale space. This property allows us to identify the valid segments from coarse to fine and does us to prevent undersegmentation and oversegmentation. Finally, we develop principal component analysis (PCA) of a point cloud on the basis of the scale-space representation of its probability density function. We explain the geometric features of a point cloud in the Gaussian scale space and observe reduced dimensionality with respect to the loss of information. Furthermore, we introduce a hierarchical clustering of the point cloud and analyze the statistical significance of the clusters and their subspaces. Moreover, we present a mathematical framework of the scale-based PCA, which derives a statistically reasonable criterion for choosing the number of components to retain or reduce the dimensionality of a point cloud. Finally, we also develop a segmentation algorithm using configurations of singular points in the Gaussian scale space
Destratification in the Progenitor Interior of the Mg-rich Supernova Remnant N49B
Simulations of pre-supernova evolution suggest that some intense shell
burning can be so active that, in extreme cases, it can merge with the outer
shell, changing the initial conditions for the supernova explosion. However,
such violent activity in the interior of stars has been difficult to confirm
from observations of stars. Here we propose that the elemental composition of
O-rich ejecta in supernova remnants can be a tool to test for this kind of
intense shell burning activity in the final stages of progenitor evolution. As
an example, we discuss the origin of "Mg-rich" ejecta in the supernova remnant
N49B. A high Mg/Ne mass ratio suggests that the Ne- or O-burning
shell has broken into or merged with the outer shell before the collapse. Such
Mg-rich (or Ne-poor) ejecta has been identified in some other supernova
remnants, supporting the idea that some destratification process, such as a
shell merger, does indeed occur in the interiors of some massive stars,
although they may not be the majority. Our results suggest that X-ray
observations of O-rich ejecta in core-collapse supernova remnants will be a
unique tool to probe the shell burning activity during the final stage of a
massive star's interior.Comment: Submitted to ApJ and received positive peer review. This is the
version in the first submission. 11 pages, 7 figures, 2 table
Periostin as a novel biomarker for postoperative recurrence of chronic rhinosinitis with nasal polyps
We previously reported that chronic rhinosinusitis with nasal polyps (CRSwNP) was subdivided into four chronic rhinosinusitis (CRS) subtypes using the JESREC scoring system. We sought to identify the gene expression profile and biomarkers related with CRSwNP by RNA-sequence. RNA-sequencing was performed to identify differentially expressed genes between nasal polyps (NPs) and inferior turbinate mucosa from 6 patients with CRSwNP, and subsequently, quantitative real-time PCR was performed to verify the results. ELISA was performed to identify possible biomarkers for postoperative recurrence. In the RNA-sequencing results, periostin (POSTN) expression was the highest in NP. We focused on POSTN and investigated the protein level of POSTN by immunohistochemistry and ELISA. POSTN was diffusely expressed in moderate and severe eosinophilic CRS using immunohistochemistry, and its staining pattern was associated with the severity of the phenotype of the CRSwNP (P < 0.05). There was a significant difference between the POSTN high/low groups for postoperative recurrence when the cutoff point was set at 115.5 ng/ml (P = 0.0072). Our data suggests that the protein expression level of POSTN was associated with the severity of CRSwNP, and serum POSTN can be a novel biomarker for postoperative recurrence of CRSwNP
Prognostic nutritional index of early post-pembrolizumab therapy predicts long-term survival in patients with advanced urothelial carcinoma
Pembrolizumab has been widely used to treat advanced urothelial carcinoma that has progressed after first-line platinum-based chemotherapy. Because its clinical benefits are limited, biomarkers that can predict a good response to pembrolizumab are required. The prognostic nutritional index (PNI), calculated using the serum albumin level and peripheral lymphocyte count, has been evaluated as a predictive biomarker in cancer immunotherapy. The present study investigated the application of PNI as a predictive biomarker for pembrolizumab response in patients with advanced urothelial cancer. A retrospective study was conducted on 34 patients treated with pembrolizumab at Shiga University of Medical Science Hospital between January 2018 and July 2022. The posttreatment PNI (post-PNI) was calculated within 2 months of starting pembrolizumab. The present study investigated the association between post-PNI and objective response, overall survival (OS) and progression-free survival (PFS). The patient cohort was stratified into two categories, high and low post-PNI groups, with a cutoff value of post-PNI at 40. The higher post-PNI group demonstrated a better disease control rate than the lower post-PNI group (complete response + partial response + stable disease, 75 vs. 21%, P=0.004). Regarding median OS, the higher post-PNI group exhibited a significantly longer survival time than the lower post-PNI group (23.1 vs. 2.9 months, P<0.001). Similarly, the higher post-PNI group exhibited a significantly longer PFS than the lower post-PNI group (10.2 vs.1.9 months, P<0.001). Multivariate analysis showed that a higher post-PNI value was an independent predictor for OS (hazard ratio, 0.04; 95% confidence interval, 0.01-0.14; P<0.001) and PFS (hazard ratio, 0.12; 95% confidence interval, 0.04-0.35; P<0.001). The present study indicated that the post-PNI was a predictor of favorable clinical outcomes in patients treated with pembrolizumab for advanced urothelial carcinoma
Progenitor Constraint with Circumstellar Material for the Magnetar-hosting Supernova Remnant RCW 103
Stellar winds blown out from massive stars (≳10 M⊙) contain precious information on the progenitor itself, and in this context the most important elements are carbon (C), nitrogen (N), and oxygen (O), which are produced by the CNO cycle in the H-burning layer. Although their X-ray fluorescence lines are expected to be detected in swept-up shock-heated circumstellar materials in supernova remnants, those of C and N have been particularly difficult to detect so far. Here, we present high-resolution spectroscopy of the young magnetar-hosting supernova remnant RCW 103 with the Reflection Grating Spectrometer on board XMM-Newton and report on the detection of the N vii Lyα (0.50 keV) line for the first time. By comparing the obtained abundance ratio of N to O (N/O = 3.8 ± 0.1) with various stellar evolution models, we show that the progenitor of RCW 103 is likely to have a low mass (10–12 M⊙) and medium rotation velocity (≲100 km s⁻¹). The results also rule out the possibility of dynamo effects in massive (≥35 M⊙) stars as a mechanism for forming the associated magnetar 1E 161348−5055. Our method is useful for estimating various progenitor parameters for future missions with microcalorimeters such as XRISM and Athena