Abstract
We present extensively dense observations of the super-Chandrasekhar supernova (SC SN) candidate SN 2012dn from −11 to +140 d after the date of its B-band maximum in the optical and ...near-infrared (NIR) wavelengths conducted through the OISTER ToO (Optical and Infrared Synergetic Telescopes for Education and Research Target of Opportunity) program. The NIR light curves and color evolutions up to 35 days after the B-band maximum provided an excellent match with those of another SC SN 2009dc, providing further support to the nature of SN 2012dn as an SC SN. We found that SN 2012dn exhibited strong excesses in the NIR wavelengths from 30 d after the B-band maximum. The H- and K
s-band light curves exhibited much later maximum dates at 40 and 70 d after the B-band maximum, respectively, compared with those of normal SNe Ia. The H- and K
s-band light curves subtracted by those of SN 2009dc displayed plateaued evolutions, indicating an NIR echo from the surrounding dust. The distance to the inner boundary of the dust shell is limited to 4.8–6.4 × 10−2 pc. No emission lines were found in its early phase spectra, suggesting that the ejecta–circumstellar material interaction could not occur. On the other hand, we found no signature that strongly supports the scenario of dust formation. The mass-loss rate of the pre-explosion system is estimated to be 10−6–10−5 M
⊙ yr−1, assuming that the wind velocity of the system is 10–100 km s−1, which suggests that the progenitor of SN 2012dn could be a recurrent nova system. We conclude that the progenitor of this SC SN could be explained by the single-degenerate scenario.
We carried out photometric observations of the SU UMa-type dwarf nova ER UMa during 2011 and 2012, which showed the existence of persistent negative superhumps even during the superoutburst. We ...performed a two-dimensional period analysis of its light curves by using a method called “least absolute shrinkage and selection operator” (Lasso) and the “phase dispersion minimization” (PDM) analysis, and found that the period of negative superhumps systematically changed between a superoutburst and the next superoutburst. The trend of the period change can be interpreted as a reflection of the change of the disk radius. This change is in agreement with the one predicted by the thermal tidal instability model. The normal outburst during a supercycle showed a general trend that the rising rate to its maximum becomes slower as the next superoutburst is approaching. The change can be interpreted as the consequence of the increased gas-stream flow into the inner region of the disk as a result of the tilted disk. Some of superoutbursts were found to be triggered by a precursor normal outburst when the positive superhump appeared to develop. The positive and negative superhumps coexisted during the superoutburst. Positive superhumps were prominent only for four or five days after the supermaximum, while the signal of negative superhumps became stronger after the middle phase of the superoutburst plateau. A simple combination of the positive and negative superhumps was found to be insufficient for reproduction of the complex profile variation. We were able to detect the developing phase of positive superhumps (stage A superhumps) for the first time in ER UMa-type dwarf novae. Using the period of stage A superhumps, we obtained a mass ratio of 0.100(15), which indicates that ER UMa is on the ordinary evolutional track of cataclysmic variable stars.
We report on photometric observations of two WZ Sge-type dwarf novae, MASTER OT J211258.65+242145.4 and MASTER OT J203749.39+552210.3, which underwent outbursts in 2012. Early superhumps were ...recorded in both systems. During the superoutburst plateau, ordinary superhumps with a period of 0.060291(4) d (MASTER J211258) and with 0.061368(11) d (MASTER J203749) on average were observed. MASTERJ211258 and MASTERJ203749 exhibited eight post-superoutburst rebrightenings and more than four, respectively. In the final part of the superoutburst, an increase in superhump period was seen in both systems. We made a survey of WZSge-type dwarf novae with multiple rebrightenings, and confirmed that the superhump periods of WZSge-type dwarf novae with multiple rebrightenings were longer than those of WZSge-type dwarf novae without a rebrightening. Although WZSge-type dwarf novae with multiple rebrightenings have been thought to be likely candidates for period bouncers based on their low mass ratio (q), inferred from the period of fully grown (stage B) superhumps, our new method of using the period of growing superhumps (stage A superhumps), however, implies higher q's than those expected from stage B superhumps. These q values appear to be consistent with the duration of the stage A superoutbursts, which likely reflects the growth time of the 3W1 resonance. We present a working hypothesis that the small fractional superhump excesses for stage B superhumps in these systems may be explained by a gas pressure effect that works more efficiently in these systems than in ordinary SU UMa-type dwarf novae. This result forms a new picture that WZSge-type dwarf novae with multiple rebrightenings and SU UMa-type ones without a rebrightening (they are not period bouncers) are located in the same place on the evolutionary track.
We present extensively dense observations of the super-Chandrasekhar supernova (SC SN) candidate SN 2012dn from \(-11\) to \(+140\) days after the date of its \(B\)-band maximum in the optical and ...near-infrared (NIR) wavelengths conducted through the OISTER ToO program. The NIR light curves and color evolutions up to 35 days after the \(B\)-band maximum provided an excellent match with those of another SC SN 2009dc, providing a further support to the nature of SN 2012dn as a SC SN. We found that SN 2012dn exhibited strong excesses in the NIR wavelengths from \(30\) days after the \(B\)-band maximum. The \(H\) and \(K_{s}\)-band light curves exhibited much later maximum dates at \(40\) and \(70\) days after the \(B\)-band maximum, respectively, compared with those of normal SNe Ia. The \(H\) and \(K_{s}\)-band light curves subtracted by those of SN 2009dc displayed plateaued evolutions, indicating a NIR echo from the surrounding dust. The distance to the inner boundary of the dust shell is limited to be \(4.8 - 6.4\times10^{-2}\) pc. No emission lines were found in its early phase spectrum, suggesting that the ejecta-CSM interaction could not occur. On the other hand, we found no signature that strongly supports the scenario of dust formation. The mass loss rate of the pre-explosion system is estimated to be \(10^{-6}-10^{-5}\) M\(_{\odot}\) yr\(^{-1}\), assuming that the wind velocity of the system is \(10-100\) km~s\(^{-1}\), which suggests that the progenitor of SN 2012dn could be a recurrent nova system. We conclude that the progenitor of this SC SN could be explained by the single-degenerate scenario.
We report on photometric observations of WZ Sge-type dwarf novae, MASTER OT J211258.65+242145.4 and MASTER OT J203749.39+552210.3 which underwent outbursts in 2012. Early superhumps were recorded in ...both systems. During superoutburst plateau, ordinary superhumps with a period of 0.060291(4) d (MASTER J211258) and of 0.061307(9) d (MASTER J203749) in average were observed. MASTER J211258 and MASTER J203749 exhibited eight and more than four post-superoutburst rebrightenings, respectively. In the final part of the superoutburst, an increase in the superhump periods was seen in both systems. We have made a survey of WZ Sge-type dwarf novae with multiple rebrightenings, and confirmed that the superhump periods of WZ Sge-type dwarf novae with multiple rebrightenings were longer than those of WZ Sge-type dwarf novae without a rebrightening. Although WZ Sge-type dwarf novae with multiple rebrightenings have been thought to be the good candidates for period bouncers based on their low mass ratio (q) from inferred from the period of fully grown (stage B) superhumps, our new method using the period of growing superhumps (stage A superhumps), however, implies higher q than those expected from stage B superhumps. These q values appear to be consistent with the duration of the stage A superoutbursts, which likely reflects the growth time of the 3:1 resonance. We present a working hypothesis that the small fractional superhump excesses for stage B superhumps in these systems may be explained as a result that a higher gas pressure effect works in these systems than in ordinary SU UMa-type dwarf novae. This result leads to a new picture that WZ Sge-type dwarf novae with multiple rebrightenings and SU UMa-type dwarf novae without a rebrightening (they are not period bouncers) are located in the same place on the evolutionary track.
We carried out the photometric observations of the SU UMa-type dwarf nova ER UMa during 2011 and 2012, which showed the existence of persistent negative superhumps even during the superoutburst. We ...performed two-dimensional period analysis of its light curves by using a method called "least absolute shrinkage and selection operator" (Lasso) and "phase dispersion minimization" (PDM) analysis, and we found that the period of negative superhumps systematically changed between a superoutburst and the next superoutburst. The trend of the period change can beinterpreted as reflecting the change of the disk radius. This change of the disk radius is in good agreement with the predicted change of the disk radius by the thermal-tidal instability (TTI) model. The normal outbursts within a supercycle showed a general trend that the rising rate to maximum becomes slower as the next superoutburst approaches. The change can be interpreted as the consequence of the increased gas-stream flow onto the inner region of the disk as the result of the tilted disk. Some of the superoutbursts were found to be triggered by a precursor normal outburst when the positive superhumps appeared to develop. The positive and negative superhumps co-existed during the superoutburst. The positive superhumps were prominent only during four or five days after the supermaximum, while the signal of the negative superhumps became strong after the middle phase of the superoutburst plateau. A simple combination of the positive and negative superhumps was found to be insufficient in reproducing the complex profile variation. We were able to detect the developing phase of positive superhumps (stage A superhumps) for the first time in ER UMa-type dwarf novae. Using the period of stage A superhumps, we obtained a mass ratio of 0.100(15), which indicates that ER UMa is on the ordinary evolutional track of CVs.
Abstract
We present the spectroscopic discovery of 69 quasars at 5.8 <
z
< 7.0, drawn from the Hyper Suprime-Cam (HSC) Subaru Strategic Program (SSP) imaging survey data. This is the 16th publication ...from the Subaru High-
z
Exploration of Low-Luminosity Quasars (SHELLQs) project, and it completes identification of all but the faintest candidates (i.e.,
i
-band dropouts with
z
AB
< 24 and
y
-band detections, and
z
-band dropouts with
y
AB
< 24) with Bayesian quasar probability
P
Q
B
>
0.1
in the HSC-SSP third public data release (PDR3). The sample reported here also includes three quasars with
P
Q
B
<
0.1
at
z
∼ 6.6, which we selected in an effort to completely cover the reddest point sources with simple color cuts. The number of high-
z
quasars discovered in SHELLQs has now grown to 162, including 23 type II quasar candidates. This paper also presents identification of seven galaxies at 5.6 <
z
< 6.7, an O
iii
emitter at
z
= 0.954, and 31 Galactic cool stars and brown dwarfs. High-
z
quasars and galaxies compose 75% and 16%, respectively, of all the spectroscopic SHELLQs objects that pass our latest selection algorithm with the PDR3 photometry. That is, a total of 91% of the objects lie at
z
> 5.6. This demonstrates that the algorithm has very high efficiency, even though we are probing an unprecedentedly low luminosity population down to
M
1450
∼ −21 mag.
Deposits of β-amyloid (Aβ) and α-synuclein (α-syn) are the hallmark of Alzheimer’s disease (AD) and Parkinson’s disease (PD), respectively. The detection of these protein aggregates with fluorescent ...probes is particularly of interest for preclinical studies using fluorescence microscopy on human brain tissue. In this study, we newly designed and synthesized three push–pull benzothiazole (PP-BTA) derivatives as fluorescent probes for detection of Aβ and α-syn aggregates. Fluorescence intensity of all PP-BTA derivatives significantly increased upon binding to Aβ(1–42) and α-syn aggregates in solution. In in vitro saturation binding assays, PP-BTA derivatives demonstrated affinity for both Aβ(1–42) (K d = 40–148 nM) and α-syn (K d = 48–353 nM) aggregates. In particular, PP-BTA-4 clearly stained senile plaques composed of Aβ aggregates in the AD brain section. Moreover, it also labeled Lewy bodies composed of α-syn aggregates in the PD brain section. These results suggest that PP-BTA-4 may serve as a promising fluorescent probe for the detection of Aβ and α-syn aggregates.
Quasar Luminosity Function at z = 7 Matsuoka, Yoshiki; Onoue, Masafusa; Iwasawa, Kazushi ...
Astrophysical journal. Letters,
06/2023, Letnik:
949, Številka:
2
Journal Article
Recenzirano
Odprti dostop
Abstract
We present the quasar luminosity function (LF) at
z
= 7, measured with 35 spectroscopically confirmed quasars at 6.55 <
z
< 7.15. The sample of 22 quasars from the Subaru High-
z
Exploration ...of Low-Luminosity Quasars (SHELLQs) project, combined with 13 brighter quasars in the literature, covers an unprecedentedly wide range of rest-frame ultraviolet magnitudes over −28 <
M
1450
< −23. We found that the binned LF flattens significantly toward the faint end populated by the SHELLQs quasars. A maximum likelihood fit to a double power-law model has a break magnitude
M
1450
*
=
−
25.60
−
0.30
+
0.40
, a characteristic density
Φ
*
=
1.35
−
0.30
+
0.47
Gpc
−3
mag
−1
, and a bright-end slope
β
=
−
3.34
−
0.57
+
0.49
, when the faint-end slope is fixed to
α
= −1.2 as observed at
z
≤ 6. The overall LF shape remains remarkably similar from
z
= 4 to 7, while the amplitude decreases substantially toward higher redshifts, with a clear indication of an accelerating decline at
z
≥ 6. The estimated ionizing photon density, 10
48.2±0.1
s
−1
Mpc
−3
, is less than 1% of the critical rate to keep the intergalactic medium ionized at
z
= 7, and thus indicates that quasars are not a major contributor to cosmic reionization.
Indian hedgehog (Ihh) regulates endochondral ossification in both a parathyroid hormone-related protein (PTHrP)-dependent and -independent manner by activating transcriptional mediator Gli2. However, ...the molecular mechanisms underlying these processes remain elusive. Here by using in vivo microarray analysis, we identify forkhead box C1 (Foxc1) as a transcriptional partner of Gli2. Foxc1 stimulates expression of Ihh target genes, including PTHrP and Col10a1, through its physical and functional interaction with Gli2. Conversely, a dominant negative Foxc1 inhibits the Ihh target gene expression. In a spontaneous loss of Foxc1 function mouse (Foxc1(ch/ch)), endochondral ossification is delayed and the expression of Ihh target genes inhibited. Moreover, the pathological Foxc1 missense mutation observed in the Axenfeld-Rieger syndrome impairs Gli2-Foxc1 association as well as Ihh function. Our findings suggest that Foxc1 is an important transcriptional partner of Ihh-Gli2 signalling during endochondral ossification, and that disruption of the Foxc1-Gli2 interaction causes skeletal abnormalities observed in the Axenfeld-Rieger syndrome.
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