68 research outputs found
Assessment of GNC Impacts of Chemical Plume Impingement in the Case of Prisma Irides Experiment
This paper presents the preliminary analysis of an in-orbit demonstration opportunity to test plume impingement as a viable means to change the attitude state of a space debris based on the Prisma and Picard missions. This technique has been proposed as part of the COBRA concept studied by ESA in collaboration with GMV, Politecnico di Milano and Thales-Alenia Space, as an active debris removal concept relying on the exhaust plume of a monopropellant chemical propulsion system as a means to impart momentum and ultimately modify the orbit of a space debris object in a contactless manner. The feasibility of the experiment is presented as well as its critical areas, no showstoppers are identified
Consistent accretion-induced heating of the neutron-star crust in MXB 1659-29 during two different outbursts
Monitoring the cooling of neutron-star crusts heated during accretion
outbursts allows us to infer the physics of the dense matter present in the
crust. We examine the crust cooling evolution of the low-mass X-ray binary MXB
1659-29 up to ~505 days after the end of its 2015 outburst (hereafter outburst
II) and compare it with what we observed after its previous 1999 outburst
(hereafter outburst I) using data obtained from the Swift, XMM-Newton, and
Chandra observatories. The observed effective surface temperature of the
neutron star in MXB 1659-29 dropped from ~92 eV to ~56 eV from ~12 days to ~505
days after the end of outburst II. The most recently performed observation
after outburst II suggests that the crust is close to returning to thermal
equilibrium with the core. We model the crust heating and cooling for both its
outbursts collectively to understand the effect of parameters that may change
for every outburst (e.g., the average accretion rate, the length of outburst,
the envelope composition of the neutron star at the end of the outburst) and
those which can be assumed to remain the same during these two outbursts (e.g.,
the neutron star mass, its radius). Our modelling indicates that all parameters
were consistent between the two outbursts with no need for any significant
changes. In particular, the strength and the depth of the shallow heating
mechanism at work (in the crust) were inferred to be the same during both
outbursts, contrary to what has been found when modelling the cooling curves
after multiple outburst of another source, MAXI J0556-332. This difference in
source behaviour is not understood. We discuss our results in the context of
our current understanding of cooling of accretion-heated neutron-star crusts,
and in particular with respect to the unexplained shallow heating mechanism.Comment: Submitted to A&A. The supplementary video can be found at
https://www.youtube.com/watch?v=OpJ053zq9-
Magnetic and structural-properties of electrodeposited Co1-xPx amorphous ribbons
The specific magnetic moment, coercive force, anisotropy field, and saturation magnetostriction constant have been measured in Co(1-x)P(x) amorphous ribbons with 0.04 less-than-or-equal-to x less-than-or-equal-to 0.27. Differential scanning calorimetry, x-ray diffraction, and transmission electron microscopy analysis have been made in order to study the transition from the amorphous state to the crystalline one. Results suggest that transition takes place when x decreases from 0.19
VLA monitoring of LS V +44 17 reveals scatter in the X-ray – radio correlation of Be/X-ray binaries
Funding: JvdE acknowledges a Warwick Astrophysics prize post-doctoral fellowship made possible thanks to a generous philanthropic donation, and was supported by a Lee Hysan Junior Research Fellowship awarded by St. Hilda’s College, Oxford, during part of this work. ARE is supported by the European Space Agency (ESA) Research Fellowship. TDR acknowledges support as an INAF IAF fellow. GRS is supported by NSERC Discovery Grant RGPIN-2021-0400.LS V +44 17 is a persistent Be/X-ray binary (BeXRB) that displayed a bright, double-peaked period of X-ray activity in late 2022/early 2023. We present a radio monitoring campaign of this outburst using the Very Large Array. Radio emission was detected, but only during the second, X-ray brightest, peak, where the radio emission followed the rise and decay of the X-ray outburst. LS V +44 17 is therefore the third neutron star BeXRB with a radio counterpart. Similar to the other two systems (Swift J0243.6+6124 and 1A 0535+262), its X-ray and radio luminosity are correlated: we measure a power law slope β = 1.25+0.64-0.30 and a radio luminosity of LR = (1.6 ± 0.2) × 1026 erg s-1 at a 0.5 − 10 keV X-ray luminosity of 2 × 1036 erg s-1 (i.e. ∼ 1 per cent LEdd). This correlation index is slightly steeper than measured for the other two sources, while its radio luminosity is higher. We discuss the origin of the radio emission, specifically in the context of jet launching. The enhanced radio brightness compared to the other two BeXRBs is the first evidence of scatter in the giant BeXRB outburst X-ray – radio correlation, similar to the scatter observed in sub-classes of low-mass X-ray binaries. While a universal explanation for such scatter is not known, we explore several options: we conclude that the three sources do not follow proposed scalings between jet power and neutron star spin or magnetic field, and instead briefly explore the effects that ambient stellar wind density may have on BeXRB jet luminosity.Publisher PDFPeer reviewe
An X-ray Census of Fast Radio Burst Host Galaxies: Constraints on AGN and X-ray Counterparts
We present the first X-ray census of fast radio burst (FRB) host galaxies to
conduct the deepest search for AGN and X-ray counterparts to date. Our sample
includes seven well-localized FRBs with unambiguous host associations and
existing deep Chandra observations, including two events for which we present
new observations. We find evidence for AGN in two FRB host galaxies based on
the presence of X-ray emission coincident with their centers, including the
detection of a luminous ()
X-ray source at the nucleus of FRB20190608B's host, for which we infer an SMBH
mass of and an Eddington ratio , characteristic of geometrically thin disks in
Seyfert galaxies. We also report nebular emission line fluxes for 24 highly
secure FRB hosts (including 10 hosts for the first time), and assess their
placement on a BPT diagram, finding that FRB hosts trace the underlying galaxy
population. We further find that the hosts of repeating FRBs are not confined
to the star-forming locus, contrary to previous findings. Finally, we place
constraints on associated X-ray counterparts to FRBs in the context of
ultraluminous X-ray sources (ULXs), and find that existing X-ray limits for
FRBs rule out ULXs brighter than .
Leveraging the CHIME/FRB catalog and existing ULX catalogs, we search for
spatially coincident ULX-FRB pairs. We identify two ULX in the galaxy NGC 2633
that are spatially coincident with the repeating FRB20180908B and for which the
DM-inferred redshift is comparable to the distance of the galaxy, assuming a
contribution of .Comment: 15 pages, 5 figures; submitted to Ap
Discovery of the Optical Afterglow and Host Galaxy of Short GRB 181123B at z = 1.754: Implications for Delay Time Distributions
We present the discovery of the optical afterglow and host galaxy of the Swift short-duration gamma-ray burst (SGRB) GRB 181123B. Observations with Gemini-North starting ≈9.1 hr after the burst reveal a faint optical afterglow with i ≈ 25.1 mag at an angular offset of 0.”59 ± 0.”16 from its host galaxy. Using grizYJHK observations, we measure a photometric redshift of the host galaxy of z = 1.77^(+0.30)_(−0.17). From a combination of Gemini and Keck spectroscopy of the host galaxy spanning 4500–18000 Å, we detect a single emission line at 13390 Å, inferred as Hβ at z = 1.754 ± 0.001 and corroborating the photometric redshift. The host galaxy properties of GRB 181123B are typical of those of other SGRB hosts, with an inferred stellar mass of ≈9.1 × 10⁹ M⊙, a mass-weighted age of ≈0.9 Gyr, and an optical luminosity of ≈0.9L*. At z = 1.754, GRB 181123B is the most distant secure SGRB with an optical afterglow detection and one of only three at z > 1.5. Motivated by a growing number of high-z SGRBs, we explore the effects of a missing z > 1.5 SGRB population among the current Swift sample on delay time distribution (DTD) models. We find that lognormal models with mean delay times of ≈4–6 Gyr are consistent with the observed distribution but can be ruled out to 95% confidence, with an additional ≈one to five Swift SGRBs recovered at z > 1.5. In contrast, power-law models with ∝t⁻¹ are consistent with the redshift distribution and can accommodate up to ≈30 SGRBs at these redshifts. Under this model, we predict that ≈1/3 of the current Swift population of SGRBs is at z > 1. The future discovery or recovery of existing high-z SGRBs will provide significant discriminating power on their DTDs and thus their formation channels
Short GRB Host Galaxies. II. A Legacy Sample of Redshifts, Stellar Population Properties, and Implications for their Neutron Star Merger Origins
We present the stellar population properties of 69 short gamma-ray burst
(GRB) host galaxies, representing the largest uniformly-modeled sample to-date.
Using the Prospector stellar population inference code, we jointly fit
photometry and/or spectroscopy of each host galaxy. We find a population median
redshift of ( confidence), including 10 new or
revised photometric redshifts at . We further find a median
mass-weighted age of Gyr, stellar mass of
, star formation rate of
SFR=yr, stellar metallicity of
, and dust attenuation of
~mag (68\% confidence). Overall, the majority of
short GRB hosts are star-forming (), with small fractions that are
either transitioning () or quiescent (); however, we
observe a much larger fraction () of quiescent and transitioning
hosts at , commensurate with galaxy evolution. We find that
short GRB hosts populate the star-forming main sequence of normal field
galaxies, but do not include as many high-mass galaxies, implying that their
binary neutron star (BNS) merger progenitors are dependent on a combination of
host star formation and stellar mass. The distribution of ages and redshifts
implies a broad delay-time distribution, with a fast-merging channel at
and a decreased BNS formation efficiency at lower redshifts. If short GRB hosts
are representative of BNS merger hosts within the horizon of current
gravitational wave detectors, these results can inform future searches for
electromagnetic counterparts. All of the data and modeling products are
available on the BRIGHT website.Comment: 32 pages, 15 figures, 3 tables, accepted to Ap
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