We report on the first simultaneous Neutron Star Interior Composition Explore (NICER) and Nuclear Spectroscopic Telescope Array (NuSTAR) observations of the neutron star (NS) low-mass X-ray binary 4U ...1735−44, obtained in 2018 August. The source was at a luminosity of ∼1.8 (D/5.6 kpc)2 × 1037 erg s−1 in the 0.4-30 keV band. We account for the continuum emission with two different continuum descriptions that have been used to model the source previously. Despite the choice in continuum model, the combined passband reveals a broad Fe K line indicative of reflection in the spectrum. In order to account for the reflection spectrum we utilize a modified version of the reflection model relxill that is tailored for thermal emission from accreting NSs. Alternatively, we also use the reflection convolution model of rfxconv to model the reflected emission that would arise from a Comptonized thermal component for comparison. We determine that the innermost region of the accretion disk extends close to the innermost stable circular orbit (RISCO) at the 90% confidence level regardless of reflection model. Moreover, the current flux calibration of NICER is within 5% of the NuSTAR/FPMA(B).
We report on a Neutron star Interior Composition Explorer (NICER) observation of the Galactic X-ray binary and stellar-mass black hole candidate, MAXI J1535−571. The source was likely observed in an ..."intermediate" or "very high" state, with important contributions from both an accretion disk and hard X-ray corona. The 2.3-10 keV spectrum shows clear hallmarks of relativistic disk reflection. Fits with a suitable model strongly indicate a near-maximal spin parameter of and a disk that extends close to the innermost stable circular orbit, (1 statistical errors). In addition to the relativistic spectrum from the innermost disk, a relatively narrow Fe K emission line is also required. The resolution of NICER reveals that the narrow line may be asymmetric, indicating a specific range of emission radii. Fits with a relativistic line model suggest an inner radius of for the putative second reflection geometry; full reflection models suggest that radii a few times larger are possible. The origin of the narrow line is uncertain, but a warp likely provides the most physically plausible explanation. We discuss our results in terms of the potential for NICER to reveal new features of the inner and intermediate accretion disk around black holes.
We present results of recent Neutron Star Interior Composition Explorer (NICER) observations of the accreting millisecond X-ray pulsar (AMXP) IGR J17062−6143 that show that it resides in a circular, ...ultracompact binary with a 38-minute orbital period. NICER observed the source for 26 ks over a 5.3-day span in 2017 August, and again for 14 and 11 ks in 2017 October and November, respectively. A power spectral analysis of the August exposure confirms the previous detection of pulsations at 163.656 Hz in Rossi X-ray Timing Explorer (RXTE) data, and reveals phase modulation due to orbital motion of the neutron star. A coherent search for the orbital solution using the Z2 method finds a best-fitting circular orbit with a period of 2278.21 s (37.97 minutes), a projected semimajor axis of 0.00390 lt-s, and a barycentric pulsar frequency of 163.6561105 Hz. This is currently the shortest known orbital period for an AMXP. The mass function is 9.12 × 10−8 M , presently the smallest known for a stellar binary. The minimum donor mass ranges from 0.005 to 0.007 M for a neutron star mass from 1.2 to 2 M . Assuming mass transfer is driven by gravitational radiation, we find donor mass and binary inclination bounds of 0.0175-0.0155 M and 19° < i < 27 5, where the lower and upper bounds correspond to 1.4 and 2 M neutron stars, respectively. Folding the data accounting for the orbital modulation reveals a sinusoidal profile with fractional amplitude 2.04 0.11% (0.3-3.2 keV).
We report the discovery with the Neutron Star Interior Composition Explorer (NICER) of mHz X-ray brightness oscillations from the "clocked burster" GS 1826−238. NICER observed the source in the ...periods 2017 June 20-29, July 11-13, and September 9-15, for a total useful exposure of 34 ks. Two consecutive dwells obtained on 2017 September 9 revealed highly significant oscillations at a frequency of 8 mHz. The fractional, sinusoidal modulation amplitude increases from 0.7% at 1 keV to 2% at 6 keV. Similar oscillations were also detected at lower significance in three additional dwells. The oscillation frequency and amplitude are consistent with those of mHz QPOs reported in other accreting neutron star systems. A thermonuclear X-ray burst was also observed on 2017 June 22. The burst properties and X-ray colors are both consistent with GS 1826 being in a soft spectral state during these observations, findings that are confirmed by ongoing monitoring with MAXI and SWIFT-BAT. Assuming that the mHz oscillations are associated with blackbody emission from the neutron star surface, modeling of the phase-resolved spectra shows that the oscillation is consistent with being produced by modulation of the temperature component of this emission. In this interpretation, the blackbody normalization, proportional to the emitting surface area, is consistent with being constant through the oscillation cycle. We place the observations in the context of the current theory of marginally stable burning and briefly discuss the potential for constraining neutron star properties using mHz oscillations.
We present Neutron Star Interior Composition Explorer (NICER) observations of the neutron star (NS) low-mass X-ray binary Serpens X-1 during the early mission phase in 2017. With the high spectral ...sensitivity and low-energy X-ray passband of NICER, we are able to detect the Fe L line complex in addition to the signature broad, asymmetric Fe K line. We confirm the presence of these lines by comparing the NICER data to archival observations with XMM-Newton/Reflection Grating Spectrometer (RGS) and NuSTAR. Both features originate close to the innermost stable circular orbit (ISCO). When modeling the lines with the relativistic line model relline, we find that the Fe L blend requires an inner disk radius of RISCO and Fe K is at RISCO (errors quoted at 90%). This corresponds to a position of km and km for a canonical NS mass ( ) and dimensionless spin value of a = 0. Additionally, we employ a new version of the relxill model tailored for NSs and determine that these features arise from a dense disk and supersolar Fe abundance.
Cancer-associated mesothelial cells (CAMCs) in the tumor microenvironment are thought to promote growth and immune evasion. We find that, in mouse and human ovarian tumors, cancer cells express ...anti-Müllerian hormone (AMH) while CAMCs express its receptor AMHR2, suggesting a paracrine axis. Factors secreted by cancer cells induce AMHR2 expression during their reprogramming into CAMCs in mouse and human in vitro models. Overexpression of AMHR2 in the Met5a mesothelial cell line is sufficient to induce expression of immunosuppressive cytokines and growth factors that stimulate ovarian cancer cell growth in an AMH-dependent way. Finally, syngeneic cancer cells implanted in transgenic mice with Amhr2−/− CAMCs grow significantly slower than in wild-type hosts. The cytokine profile of Amhr2−/− tumor-bearing mice is altered and their tumors express less immune checkpoint markers programmed-cell-death 1 (PD1) and cytotoxic T lymphocyte-associated protein 4 (CTLA4). Taken together, these data suggest that the AMH/AMHR2 axis plays a critical role in regulating the pro-tumoral function of CAMCs in ovarian cancer.
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•Cancer-cell-secreted factors reprogram normal omental mesothelial cells to induce AMHR2•AMH secreted by cancer cells modulates cancer-associated mesothelial cell cytokines•The paracrine AMH/AMHR2 axis regulates the pro-tumoral and immune functions of CAMCs•Deletion of Amhr2 in mesothelium reduces ovarian tumor growth and immune exhaustion
Cancer cells reprogram normal omental mesothelium into cancer-associated mesothelial cells (CAMCs) by inducing expression of AMHR2. In turn, cancer cells secrete AMH to regulate expression of immunosuppressive cytokines and growth factors by CAMCs. Ovarian tumors implanted in transgenic mice deficient in AMHR2 have a slower growth and reduced immune exhaustion.
We report the discovery by the Nuclear Spectroscopic Telescope Array (NuSTAR) and the Neutron Star Interior Composition Explorer (NICER) of the accreting millisecond X-ray pulsar IGR J17591–2342. ...Coherent X-ray pulsations around 527.4 Hz (1.9 ms) with a clear Doppler modulation were detected. This implies an orbital period of ∼8.8 h and a projected semi-major axis of ∼1.23 lt-s. With the binary mass function, we estimate a minimum companion mass of 0.42 M⊙, obtained assuming a neutron star mass of 1.4 M⊙ and an inclination angle lower than 60°, as suggested by the absence of eclipses or dips in the light curve of the source. The broad-band energy spectrum, obtained by combining NuSTAR, swift and INTEGRAL observations, is dominated by Comptonisation of soft thermal seed photons with a temperature of ∼0.7 keV by electrons heated to 21 keV. We also detect black-body-like thermal direct emission that is compatible with an emission region of a few kilometers and a temperature compatible with the seed source of Comptonisation. A weak Gaussian line centred on the iron Kα complex can be interpreted as a signature of disc reflection. A similar spectrum characterises the NICER spectra, which was measured when the outburst faded.
We report on X-ray and radio observations of the ultra-compact X-ray binary 4U 1543−624 taken in August 2017 during an enhanced accretion episode. We obtained Neutron Star Interior Composition ...Explorer (NICER) monitoring of the source over a ∼10 day period during which target-of-opportunity observations were also conducted with Swift, INTErnational Gamma-Ray Astrophysics Laboratory (INTEGRAL), and the Australia Telescope Compact Array. Emission lines were measured in the NICER X-ray spectrum at ∼0.64 keV and ∼6.4 keV that correspond to O and Fe, respectively. By modeling these line components, we are able to track changes in the accretion disk throughout this period. The innermost accretion flow appears to move inwards from hundreds of gravitational radii (Rg = GM/c2) at the beginning of the outburst to <8.7 Rg at peak intensity. We do not detect the source in radio, but are able to place a 3 upper limit on the flux density at 27 Jy beam−1. Comparing the radio and X-ray luminosities, we find that the source lies significantly away from the range typical of black holes in the - plane, suggesting a neutron star primary. This adds to the evidence that neutron stars (NSs) do not follow a single track in the - plane, limiting its use in distinguishing between different classes of NSs based on radio and X-ray observations alone.
We report the discovery with the Neutron Star Interior Composition Explorer (NICER) of narrow emission and absorption lines during photospheric radius expansion (PRE) X-ray bursts from the ...ultracompact binary 4U 1820−30. NICER observed 4U 1820−30 in 2017 August during a low-flux, hard spectral state, accumulating about 60 ks of exposure. Five thermonuclear X-ray bursts were detected, of which four showed clear signs of PRE. We extracted spectra during the PRE phases and fit each to a model that includes a Comptonized component to describe the accretion-driven emission, and a blackbody for the burst thermal radiation. The temperature and spherical emitting radius of the fitted blackbody are used to assess the strength of PRE in each burst. The two strongest PRE bursts (burst pair 1) had blackbody temperatures of 0.6 keV and emitting radii of 100 km (at a distance of 8.4 kpc). The other two bursts (burst pair 2) had higher temperatures ( 0.67 keV) and smaller radii ( 75 km). All of the PRE bursts show evidence of narrow line emission near 1 keV. By coadding the PRE phase spectra of burst pairs 1 and, separately, 2, we find, in both coadded spectra, significant, narrow, spectral features near 1.0 (emission), 1.7, and 3.0 keV (both in absorption). Remarkably, all the fitted line centroids in the coadded spectrum of burst pair 1 appear systematically blueshifted by a factor of 1.046 0.006 compared to the centroids of pair 2, strongly indicative of a gravitational shift, a wind-induced blueshift, or more likely some combination of both effects. The observed shifts are consistent with this scenario in that the stronger PRE bursts in pair 1 reach larger photospheric radii, and thus have weaker gravitational redshifts, and they generate faster outflows, yielding higher blueshifts. We discuss possible elemental identifications for the observed features in the context of recent burst-driven wind models.
Purpose
To determine the added value of mammography in women with focal breast complaints and the utility of initial targeted ultrasound in this setting.
Methods
Women with symptomatic breast disease ...who were evaluated by breast imaging (mammography/digital breast tomosynthesis and ultrasound) between January 2016 and December 2016 in the Radboud University Medical Centre were included. We retrospectively collected the following data: date of birth, indication of imaging, visibility on mammography/ultrasound, whether biopsy was taken, additional findings, BI-RADS-classification, pathology and follow-up results.
Results
A total of 494 women were included (mean age 46.5, range 30 to 93). In 49 women (9.9%), symptomatic breast cancer was diagnosed, all visible during targeted ultrasound. The negative predictive value of targeted ultrasound was very high (99.8%). Additional findings on mammography were significantly more often malignant when the symptomatic lesion was also malignant (3.8% vs 70%,
P
< 0.05). In only one patient with symptoms caused by a benign finding, an incidental malignancy was detected on mammography outside the area of complaint (detection rate 2.2/1000 examinations).
Conclusions
The contribution of mammography for cancer detection in women with focal breast complaints is very low when targeted ultrasound is performed. Additional findings are most common in patients with symptomatic breast cancer. Our results suggest that initial targeted ultrasound is a more appropriate initial tool for the evaluation of focal breast complaints. Mammography could be performed on indication only.
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