An official website of the United States government
Abstract We present a detailed analysis of nearly two decades of optical/UV and X-ray data to study the multi-wavelength pre-explosion properties and post-explosion X-ray properties of nearby SN2023ixf located in M101. We find no evidence of precursor activity in the optical to UV down to a luminosity of$$\lesssim$$$$1.0\times10^{5}\, \textrm{L}_{\odot}$$, while X-ray observations covering nearly 18 yr prior to explosion show no evidence of luminous precursor X-ray emission down to an absorbed 0.3–10.0 keV X-ray luminosity of$$\sim$$$$6\times10^{36}$$erg s$$^{-1}$$. ExtensiveSwiftobservations taken post-explosion did not detect soft X-ray emission from SN2023ixf within the first$$\sim$$3.3 days after first light, which suggests a mass-loss rate for the progenitor of$$\lesssim$$$$5\times10^{-4}\,\textrm{M}_{\odot}$$yr$$^{-1}$$or a radius of$$\lesssim$$$$4\times10^{15}$$cm for the circumstellar material. Our analysis also suggests that if the progenitor underwent a mass-loss episode, this had to occur$$>$$0.5–1.5 yr prior to explosion, consistent with previous estimates.Swiftdetected soft X-rays from SN2023ixf$$\sim$$$$4.25$$days after first light, and it rose to a peak luminosity of$$\sim10^{39}$$erg s$$^{-1}$$after 10 days and has maintained this luminosity for nearly 50 days post first light. This peak luminosity is lower than expected, given the evidence that SN2023ixf is interacting with dense material. However, this might be a natural consequence of an asymmetric circumstellar medium. X-ray spectra derived from merging allSwiftobservations over the first 50 days are best described by a two-component bremsstrahlung model consisting of a heavily absorbed and hotter component similar to that found usingNuSTAR, and a less-absorbed, cooler component. We suggest that this soft component arises from cooling of the forward shock similar to that found in Type IIn SN2010jl.
more »
« less
The radio re-brightening of the Type IIb SN 2001ig
Abstract We study the late-time evolution of the compact Type IIb SN 2001ig in the spiral galaxy NGC 7424, with new and unpublished archival data from the Australia Telescope Compact Array and the Australian Square Kilometre Array Pathfinder. More than two decades after the SN explosion, its radio luminosity is showing a substantial re-brightening: it is now two orders of magnitude brighter than expected from the standard model of a shock expanding into a uniform circumstellar wind (i.e. with a density scaling as$$R^{-2}$$). This suggests that the SN ejecta have reached a denser shell, perhaps compressed by the fast wind of the Wolf–Rayet progenitor or expelled centuries before the final stellar collapse. We model the system parameters (circumstellar density profile, shock velocity, and mass loss rate), finding that the denser layer was encountered when the shock reached a distance of$$\approx 0.1$$pc; the mass-loss rate of the progenitor immediately before the explosion was$$\dot{M}/v_{w} \sim 10^{-7} {\rm M}_\odot {\mathrm {~yr}}^{-1} {\mathrm {km}}^{-1} {\mathrm {s}}$$. We compare SN 2001ig with other SNe that have shown late-time re-brightenings, and highlight the opposite behaviour of some extended Type IIb SNe which show instead a late-time flux cut-off.
more »
« less
- Award ID(s):
- 2224255
- PAR ID:
- 10613945
- Publisher / Repository:
- PASP
- Date Published:
- Journal Name:
- Publications of the Astronomical Society of Australia
- Volume:
- 42
- ISSN:
- 1323-3580
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Abstract We considerG, a linear algebraic group defined over$$\Bbbk $$, an algebraically closed field (ACF). By considering$$\Bbbk $$as an embedded residue field of an algebraically closed valued fieldK, we can associate to it a compactG-space$$S^\mu _G(\Bbbk )$$consisting of$$\mu $$-types onG. We show that for each$$p_\mu \in S^\mu _G(\Bbbk )$$,$$\mathrm {Stab}^\mu (p)=\mathrm {Stab}\left (p_\mu \right )$$is a solvable infinite algebraic group when$$p_\mu $$is centered at infinity and residually algebraic. Moreover, we give a description of the dimension of$$\mathrm {Stab}\left (p_\mu \right )$$in terms of the dimension ofp.more » « less
-
Abstract Given a permutation statistic$$\operatorname {\mathrm {st}}$$, define its inverse statistic$$\operatorname {\mathrm {ist}}$$by. We give a general approach, based on the theory of symmetric functions, for finding the joint distribution of$$\operatorname {\mathrm {st}}_{1}$$and$$\operatorname {\mathrm {ist}}_{2}$$whenever$$\operatorname {\mathrm {st}}_{1}$$and$$\operatorname {\mathrm {st}}_{2}$$are descent statistics: permutation statistics that depend only on the descent composition. We apply this method to a number of descent statistics, including the descent number, the peak number, the left peak number, the number of up-down runs and the major index. Perhaps surprisingly, in many cases the polynomial giving the joint distribution of$$\operatorname {\mathrm {st}}_{1}$$and$$\operatorname {\mathrm {ist}}_{2}$$can be expressed as a simple sum involving products of the polynomials giving the (individual) distributions of$$\operatorname {\mathrm {st}}_{1}$$and$$\operatorname {\mathrm {st}}_{2}$$. Our work leads to a rederivation of Stanley’s generating function for doubly alternating permutations, as well as several conjectures concerning real-rootedness and$$\gamma $$-positivity.more » « less
-
Abstract Let$$(W,S)$$be a Coxeter system, and write$$S=\{s_i:i\in I\}$$, whereIis a finite index set. Fix a nonempty convex subset$$\mathscr {L}$$ofW. IfWis of typeA, then$$\mathscr {L}$$is the set of linear extensions of a poset, and there are importantBender–Knuth involutions$$\mathrm {BK}_i\colon \mathscr {L}\to \mathscr {L}$$indexed by elements ofI. For arbitraryWand for each$$i\in I$$, we introduce an operator$$\tau _i\colon W\to W$$(depending on$$\mathscr {L}$$) that we call anoninvertible Bender–Knuth toggle; this operator restricts to an involution on$$\mathscr {L}$$that coincides with$$\mathrm {BK}_i$$in typeA. Given a Coxeter element$$c=s_{i_n}\cdots s_{i_1}$$, we consider the operator$$\mathrm {Pro}_c=\tau _{i_n}\cdots \tau _{i_1}$$. We sayWisfuturisticif for every nonempty finite convex set$$\mathscr {L}$$, every Coxeter elementcand every$$u\in W$$, there exists an integer$$K\geq 0$$such that$$\mathrm {Pro}_c^K(u)\in \mathscr {L}$$. We prove that finite Coxeter groups, right-angled Coxeter groups, rank-3 Coxeter groups, affine Coxeter groups of types$$\widetilde A$$and$$\widetilde C$$, and Coxeter groups whose Coxeter graphs are complete are all futuristic. WhenWis finite, we actually prove that if$$s_{i_N}\cdots s_{i_1}$$is a reduced expression for the long element ofW, then$$\tau _{i_N}\cdots \tau _{i_1}(W)=\mathscr {L}$$; this allows us to determine the smallest integer$$\mathrm {M}(c)$$such that$$\mathrm {Pro}_c^{{\mathrm {M}}(c)}(W)=\mathscr {L}$$for all$$\mathscr {L}$$. We also exhibit infinitely many non-futuristic Coxeter groups, including all irreducible affine Coxeter groups that are not of type$$\widetilde A$$,$$\widetilde C$$, or$$\widetilde G_2$$.more » « less
-
Abstract Let$$\mathrm {R}$$be a real closed field. Given a closed and bounded semialgebraic set$$A \subset \mathrm {R}^n$$and semialgebraic continuous functions$$f,g:A \rightarrow \mathrm {R}$$such that$$f^{-1}(0) \subset g^{-1}(0)$$, there exist an integer$$N> 0$$and$$c \in \mathrm {R}$$such that the inequality (Łojasiewicz inequality)$$|g(x)|^N \le c \cdot |f(x)|$$holds for all$$x \in A$$. In this paper, we consider the case whenAis defined by a quantifier-free formula with atoms of the form$$P = 0, P>0, P \in \mathcal {P}$$for some finite subset of polynomials$$\mathcal {P} \subset \mathrm {R}[X_1,\ldots ,X_n]_{\leq d}$$, and the graphs of$$f,g$$are also defined by quantifier-free formulas with atoms of the form$$Q = 0, Q>0, Q \in \mathcal {Q}$$, for some finite set$$\mathcal {Q} \subset \mathrm {R}[X_1,\ldots ,X_n,Y]_{\leq d}$$. We prove that the Łojasiewicz exponent in this case is bounded by$$(8 d)^{2(n+7)}$$. Our bound depends ondandnbut is independent of the combinatorial parameters, namely the cardinalities of$$\mathcal {P}$$and$$\mathcal {Q}$$. The previous best-known upper bound in this generality appeared inP. Solernó, Effective Łojasiewicz Inequalities in Semi-Algebraic Geometry, Applicable Algebra in Engineering, Communication and Computing (1991)and depended on the sum of degrees of the polynomials defining$$A,f,g$$and thus implicitly on the cardinalities of$$\mathcal {P}$$and$$\mathcal {Q}$$. As a consequence, we improve the current best error bounds for polynomial systems under some conditions. Finally, we prove a version of Łojasiewicz inequality in polynomially bounded o-minimal structures. We prove the existence of a common upper bound on the Łojasiewicz exponent for certain combinatorially defined infinite (but not necessarily definable) families of pairs of functions. This improves a prior result of Chris Miller (C. Miller, Expansions of the real field with power functions, Ann. Pure Appl. Logic (1994)).more » « less
- Free Publicly Accessible Full Text
-
Accepted Manuscript
- Journal Article:
- https://doi.org/10.1017/pasa.2025.38
