Recently, an active debate has emerged around greenhouse gas emissions due to indirect land use change (iLUC) of expanding agricultural areas dedicated to biofuel production. In this paper we provide ...a detailed analysis of the iLUC effect, and further address the issues of deforestation, irrigation water use, and crop price increases due to expanding biofuel acreage. We use GLOBIOM – an economic partial equilibrium model of the global forest, agriculture, and biomass sectors with a bottom-up representation of agricultural and forestry management practices. The results indicate that second generation biofuel production fed by wood from sustainably managed existing forests would lead to a negative iLUC factor, meaning that overall emissions are 27% lower compared to the “No biofuel” scenario by 2030. The iLUC factor of first generation biofuels global expansion is generally positive, requiring some 25 years to be paid back by the GHG savings from the substitution of biofuels for conventional fuels. Second generation biofuels perform better also with respect to the other investigated criteria; on the condition that they are not sourced from dedicated plantations directly competing for agricultural land. If so, then efficient first generation systems are preferable. Since no clear technology champion for all situations exists, we would recommend targeting policy instruments directly at the positive and negative effects of biofuel production rather than at the production itself.
Abstract
Recent detection of gravitational waves from a neutron star (NS) merger event GW170817 and identification of an electromagnetic counterpart provide a unique opportunity to study the physical ...processes in NS mergers. To derive properties of ejected material from the NS merger, we perform radiative transfer simulations of kilonova, optical and near-infrared emissions powered by radioactive decays of r-process nuclei synthesized in the merger. We find that the observed near-infrared emission lasting for >10 d is explained by 0.03 M⊙ of ejecta containing lanthanide elements. However, the blue optical component observed at the initial phases requires an ejecta component with a relatively high electron fraction (Ye). We show that both optical and near-infrared emissions are simultaneously reproduced by the ejecta with a medium Ye of ∼0.25. We suggest that a dominant component powering the emission is post-merger ejecta, which exhibits that the mass ejection after the first dynamical ejection is quite efficient. Our results indicate that NS mergers synthesize a wide range of r-process elements and strengthen the hypothesis that NS mergers are the origin of r-process elements in the Universe.
ABSTRACT
Some fraction of narrow absorption lines (NALs) are physically associated to the quasar/host-galaxy materials (i.e. intrinsic NALs) like those of broad absorption lines (BALs) and mini-BALs. ...The relation between these three types of absorption lines has not been understood yet, however one interpretation is that these absorption features correspond to different inclination angles. In this study, we search for intrinsic NALs in 11 BAL/mini-BAL quasar spectra retrieved from VLT/UVES public archive, in order to test a possible relation of intrinsic NALs and BALs/mini-BALs in the geometry models. We use partial coverage analysis to separate intrinsic NALs from ones which are associated to cosmologically intervening materials like foreground galaxies and intergalactic medium (i.e. intervening NALs). We identify one reliable and two possible intrinsic NAL systems out of 36 NAL systems in 9 BAL/mini-BAL quasar spectra after removing two quasars without clear BAL features. In spite of a small sample size, we placed a lower limit on the fraction of BAL/mini-BAL quasars that have at least one intrinsic C iv NAL ($\sim 33^{+33}_{-18}{{\ \rm per\ cent}}$). This can be interpreted that intrinsic NAL absorbers exist everywhere regardless of inclination angle. We found that one of the intrinsic NAL systems detected in SDSS J121549.80−003432.1 is located at a large radial distance of R > 130 kpc, using a method of photoionization model with ground/excited-state lines. Considering the wide range of intrinsic NAL absorber distribution in inclination angles and radial distances, it suggests that origins and geometry of them are more complicated than we expected.
We present the discovery of Balmer-line absorption from H
$\alpha$
to H9 in an iron low-ionizaton broad absorption line (FeLoBAL) quasar, SDSS J172341.10
$+$
555340.5, by near-infrared spectroscopy ...with the Cooled Infrared Spectrograph and Camera for OHS (CISCO) attached to the Subaru Telescope. The redshift of the Balmer-line absorption troughs is 2.0530
$\ \pm\ $
0.0003, and it is blueshifted by 5370 km s
$^{-1}$
from the Balmer emission lines. It is more than 4000 km s
$^{-1}$
blueshifted from the previously known UV absorption lines. We detected relatively strong (EW
$_{\rm rest} =$
20
Å
) O III emission lines that are similar to those found in other broad absorption line quasars with Balmer-line absorption. We also derived the column density of neutral hydrogen of 5.2
$\times$
10
$^{17}\ $
cm
$^{-2}$
by using the curve of growth and taking account of Ly
$\alpha$
trapping. We searched for UV absorption lines that had the same redshift with Balmer-line absorption, and found Al III and Fe III absorption lines at
$z =$
2.053 that correspond to previously unidentified absorption lines, and the presence of other blended troughs that were difficult to identify.
A 70-year-old man was diagnosed with multiple lung metastases from hepatocellular carcinoma, and lenvatinib was initiated. Three months later, the response was progressive disease. Sorafenib therapy ...as a second-line drug was started. Three months later, the lung metastases had shrunk. After the sorafenib failure, the patient received regorafenib treatment for six months until failure. After the regorafenib failure, sorafenib rechallenge therapy as a fourth-line treatment was initiated. The sorafenib rechallenge, which continued for two months, induced a partial response. Sorafenib after lenvatinib failure and sorafenib rechallenge may be a good option, but further prospective studies are needed.
Abstract
We have performed intensive follow-up observations of a Type IIn/Ia-CSM supernova (SN IIn/Ia-CSM), 2020uem, with photometry, spectroscopy, and polarimetry. In this paper, we report on the ...results of our observations focusing on optical/near-infrared (NIR) photometry and spectroscopy. The maximum
V
-band magnitude of SN 2020uem is less than −19.5 mag. The light curves decline slowly with a rate of ∼0.75 mag/100 days. In the late phase (≳300 days), the light curves show accelerated decay (∼1.2 mag/100 days). The optical spectra show prominent hydrogen emission lines and broad features possibly associated with Fe-peak elements. In addition, the H
α
profile exhibits a narrow P-Cygni profile with an absorption minimum of ∼100 km s
−1
. SN 2020uem shows a higher H
α
/H
β
ratio (∼7) than those of SNe IIn, which suggests a denser circumstellar medium (CSM). The NIR spectrum shows the Paschen and Brackett series with a continuum excess in the
H
and
Ks
bands. We conclude that the NIR excess emission originates from newly formed carbon dust. The dust mass (
M
d
) and temperature (
T
d
) are derived to be (
M
d
,
T
d
) ∼ (4−7 × 10
−5
M
⊙
, 1500–1600 K). We discuss the differences and similarities between the observational properties of SNe IIn/Ia-CSM and those of other SNe Ia and interacting SNe. In particular, spectral features around ∼4650 Å and ∼5900 Å of SNe IIn/Ia-CSM are more suppressed than those of SNe Ia; these lines are possibly contributed, at least partly, by Mg
i
and Na
i
, and may be suppressed by high ionization behind the reverse shock caused by the massive CSM.
A 79-year-old man was admitted to our hospital because of increased hepatobiliary enzyme levels. Dynamic computed tomography and magnetic resonance imaging showed a liver tumor measuring 60mm ...containing fat foci at the cranial aspect of the tumor. We diagnosed the patient with hypovascular hepatocellular carcinoma (HCC) and fat deposition, and performed a caudate lobe resection. Pathology examination revealed two intermingled components: moderately differentiated HCC with fat deposition and neuroendocrine carcinoma (NEC). Primary combined NEC and HCC is extremely rare. To our knowledge, this is the first report of combined NEC and HCC including a fat component. HCC is the most common primary hepatic malignancy with fat. HCC might include fat, even if HCC coexists with another type of cancer. The imaging characteristics of and HCC with another type of cancer vary depending on the amount of each component. We should not simply diagnose such tumors as HCC, but think about the possibilities of HCC with another type of cancer, because there is a fat component.
Abstract
Type IIn/Ia-CSM supernovae (SNe IIn/Ia-CSM) are classified by their characteristic spectra, which exhibit narrow hydrogen emission lines originating from strong interaction with a ...circumstellar medium (CSM) together with broad lines of intermediate-mass elements. We performed intensive follow-up observations of SN IIn/Ia-CSM 2020uem, including photometry, spectroscopy, and polarimetry. In this paper, we focus on the results of polarimetry. We performed imaging polarimetry at 66 days and spectropolarimetry at 103 days after discovery. SN 2020uem shows a high continuum polarization of 1.0%–1.5% without wavelength dependence. Besides, the polarization degree and position angle keep roughly constant. These results suggest that SN 2020uem is powered by strong interaction with a confined and aspherical CSM. We performed simple polarization modeling, based on which we suggest that SN 2020uem has an equatorial-disk/torus CSM. Besides, we performed semi-analytic light-curve modeling and estimated the CSM mass. We revealed that the mass-loss rate in the final few hundred years immediately before the explosion of SN 2020uem is in the range of 0.01–0.05
M
⊙
yr
−1
, and that the total CSM mass is 0.5–4
M
⊙
. The CSM mass can be accommodated by not only a red supergiant (RSG), but also by a red giant (RG) or an asymptotic giant branch (AGB) star. As a possible progenitor scenario of SN 2020uem, we propose a white dwarf binary system including an RG, RSG, or AGB star, especially a merger scenario via common envelope evolution, i.e., the core-degenerate scenario or a variant.
The unprecedentedly bright optical afterglow of GRB 130606A located by Swift at a redshift close to the reionization era (z = 5.913) provides a new opportunity to probe the ionization status of the ...intergalactic medium (IGM). Here we present an analysis of the red Lyα damping wing of the afterglow spectrum taken by Subaru/FOCAS during 10.4–13.2 hr after the burst. We find that the minimal model including only the baseline power-law and H i absorption in the host galaxy does not give a good fit, leaving residuals showing concave curvature in 8400–8900 Å with an amplitude of about 0.6% of the flux. Such a curvature in the short wavelength range cannot be explained either by extinction at the host with standard extinction curves, intrinsic curvature of afterglow spectra, or by the known systematic uncertainties in the observed spectrum. The red damping wing by intervening H i gas outside the host can reduce the residual by about 3 σ statistical significance. We find that a damped Lyα system is not favored as the origin of this intervening H i absorption, from the observed Lyβ and metal absorption features. Therefore absorption by diffuse IGM remains as a plausible explanation. A fit by a simple uniform IGM model requires an H i neutral fraction of f
H i
∼ 0.1–0.5 depending on the distance to the GRB host, implying high f
H i
IGM associated with the observed dark Gunn–Peterson (GP) troughs. This gives new evidence that the reionization is not yet complete at z = 6.
Discovery of Merging Twin Quasars at z = 6.05 Matsuoka, Yoshiki; Izumi, Takuma; Onoue, Masafusa ...
Astrophysical journal. Letters,
04/2024, Letnik:
965, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Abstract We report the discovery of two quasars at a redshift of z = 6.05 in the process of merging. They were serendipitously discovered from the deep multiband imaging data collected by the Hyper ...Suprime-Cam (HSC) Subaru Strategic Program survey. The quasars, HSC J121503.42−014858.7 (C1) and HSC J121503.55−014859.3 (C2), both have luminous (>10 43 erg s −1 ) Ly α emission with a clear broad component (full width at half maximum >1000 km s −1 ). The rest-frame ultraviolet (UV) absolute magnitudes are M 1450 = − 23.106 ± 0.017 (C1) and −22.662 ± 0.024 (C2). Our crude estimates of the black hole masses provide log ( M BH / M ⊙ ) = 8.1 ± 0.3 in both sources. The two quasars are separated by 12 kpc in projected proper distance, bridged by a structure in the rest-UV light suggesting that they are undergoing a merger. This pair is one of the most distant merging quasars reported to date, providing crucial insight into galaxy and black hole build-up in the hierarchical structure formation scenario. A companion paper will present the gas and dust properties captured by Atacama Large Millimeter/submillimeter Array observations, which provide additional evidence for and detailed measurements of the merger, and also demonstrate that the two sources are not gravitationally lensed images of a single quasar.
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