MAMMOTH-Subaru IV. Large Scale Structure and Clustering Analysis of Ly$α$ Emitters and Ly$α$ Blobs at $z=2.2-2.3$
Haibin ZhangZheng CaiMingyu LiYongming LiangNobunari KashikawaKe MaYunjing WuQiong LiSean D. JohnsonSatoshi KikutaMasami OuchiXiaohui Fan
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We report the large scale structure and clustering analysis of Ly$\alpha$ emitters (LAEs) and Ly$\alpha$ blobs (LABs) at $z=2.2-2.3$. Using 3,341 LAEs, 117 LABs, and 58 bright (Ly$\alpha$ luminosity $L_{\rm Ly\alpha}>10^{43.4}$ erg s$^{-1}$) LABs at $z=2.2-2.3$ selected with Subaru/Hyper Suprime-Cam (HSC), we calculate the LAE overdensity to investigate the large scale structure at $z=2$. We show that 74% LABs and 78% bright LABs locate in overdense regions, which is consistent with the trend found by previous studies that LABs generally locate in overdense regions. We find that one of our 8 fields dubbed J1349 contains $39/117\approx33\%$ of our LABs and $22/58\approx38\%$ of our bright LABs. A unique and overdense $24'\times12'$ ($\approx 40\times20$ comoving Mpc$^2$) region in J1349 has 12 LABs (8 bright LABs). By comparing to SSA22 that is one of the most overdense LAB regions found by previous studies, we show that the J1349 overdense region contains $\geq 2$ times more bright LABs than the SSA22 overdense region. We calculate the angular correlation functions (ACFs) of LAEs and LABs in the unique J1349 field and fit the ACFs with a power-law function to measure the slopes. The slopes of LAEs and LABs are similar, while the bright LABs show a $\approx 2$ times larger slope suggesting that bright LABs are more clustered than faint LABs and LAEs. We show that the amplitudes of ACFs of LABs are higher than LAEs, which suggests that LABs have a $\approx 10$ times larger galaxy bias and field-to-field variance than LAEs. The strong field-to-field variance is consistent with the large differences of LAB numbers in our 8 fields.Detection of γ-ray emissions from a class of active galactic nuclei (viz blazars), has been one of the important findings from the Compton Gamma-Ray Observatory (CGRO). However, their γ-ray luminosity function has not been well determined. Few attempts have been made in earlier works, where BL Lacs and Flat Spectrum Radio Quasars (FSRQs) have been considered as a single source class. In this paper, we investigated the evolution and γ-ray luminosity function of FSRQs and BL Lacs separately. Our investigation indicates no evolution for BL Lacs, however FSRQs show significant evolution. Pure luminosity evolution is assumed for FSRQs and exponential and power law evolution models are examined. Due to the small number of sources, the low luminosity end index of the luminosity function for FSRQs is constrained with an upper limit. BL Lac luminosity function shows no signature of break. As a consistency check, the model source distributions derived from these luminosity functions show no significant departure from the observed source distributions.
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We construct and examine the pulsar luminosity function using the new list which includes data for 1328 radio pulsars. In this work, the luminosity function for 1400 MHz is constructed for the rst time. We also present an improved luminosity function for 400 MHz. The luminosity functions at 400 and 1400 MHz are compared. Also, the luminosity functions excluding the binary millisecond pulsars and the pulsars with low magnetic elds are constructed. It is found that the new luminosity function is considerably atter in the low luminosity part for 400 MHz. 1400 HMz luminosity values of radio pulsars together with upper limits of 1400 MHz luminosity for anomalous X-ray pulsars and dim radio quiet neutron stars are presented as a function of both characteristic age and magnetic eld. The implications of the pulsar luminosity function for these new kinds of neutron star are discussed.
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The intriguing observations of Swift/BAT X-ray flash XRF 060218 and the BATSE-BeppoSAX gamma-ray burst GRB 980425, both with much lower luminosity and redshift compared to other observed bursts, naturally lead to the question of how these low-luminosity (LL) bursts are related to high-luminosity (HL) bursts. Incorporating the constraints from both the flux-limited samples observed with CGRO/BATSE and Swift/BAT and the redshift-known GRB sample, we investigate the luminosity function for both LL- and HL-GRBs through simulations. Our multiple criteria, including the log N - log P distributions from the flux-limited GRB sample, the redshift and luminosity distributions of the redshift-known sample, and the detection ratio of HL- and LL- GRBs with Swift/BAT, provide a set of stringent constraints to the luminosity function. Assuming that the GRB rate follows the star formation rate, our simulations show that a simple power law or a broken power law model of luminosity function fail to reproduce the observations, and a new component is required. This component can be modeled with a broken power, which is characterized by a sharp increase of the burst number at around L < 10^47 erg s^-1}. The lack of detection of moderate-luminosity GRBs at redshift ~0.3 indicates that this feature is not due to observational biases. The inferred local rate, rho_0, of LL-GRBs from our model is ~ 200 Gpc^-3 yr^-1 at ~ 10^47 erg s^-1, much larger than that of HL-GRBs. These results imply that LL-GRBs could be a separate GRB population from HL-GRBs. The recent discovery of a local X-ray transient 080109/SN 2008D would strengthen our conclusion, if the observed non-thermal emission has a similar origin as the prompt emission of most GRBs and XRFs.
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We have analysed the optical luminosity-redshift distribution properties of bright QSOs, using a new large sample from the Hamburg/ESO survey. The sample provides insight into the hitherto poorly sampled bright tail of the luminosity function, allowing to monitor its evolution with redshift up to $z\approx 3$. The slope increases significantly towards higher $z$, inconsistent with the predictions of pure luminosity evolution, but also with other recently proposed parameterisations. This phenomenon is opposite to what would be expected from gravitational lensing, showing that magnification bias does not significantly distort the QSO luminosity function within the redshift range covered. The space density of high-luminosity QSOs continues to increase up to the high-redshift limit of the survey, without indication of reduced evolution above $z\simeq 2$. The sample also permits an improved estimate of the local ($z\approx 0$) luminosity function of QSOs and bright Seyfert~1 nuclei, over the luminosity range $-27\la M_{B_J}\la -20$. No evidence for a break or change of slope is found down to absolute magnitudes $M_{B_J}\simeq-20$.
QSOS
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An analysis of the color indices and absolute magnitudes of the "classical" supersoft X-ray binary sources (SSXBs), the V Sge-type stars (VSs), the symbiotic SSXBs, and the classical novae in the soft X-ray phase is presented. This approach can help comparing the properties and configuration of the reprocessing medium in the individual systems. The range of of the individual objects is very large, from to , most systems having . The objects with the orbital period days tend to possess brighter with the increasing Porb. The same trend is apparent also for . There is no systematic difference between the classical SSXBs and the VSs, as regards their and . The soft X-ray phase of the novae V 1974 Cyg and V 382 Vel occurred at significantly brighter than those of most other SSXBs while of the recurrent nova U Sco was comparable to the SSXBs of the comparable Porb. We showed that the luminosity of the reprocessing medium in the symbiotic SSXBs does not increase much with Porb, when compared with the luminosity of the classical SSXBs and VSs; this speaks against large disks in these symbiotics. The classical SSXBs and the VSs have colors very similar each to other and form closed groups in the color-color diagrams. A Balmer jump occurs frequently in emission as inferred from the colors. The correlation between the bolometric luminosity, determined from the X-ray spectra and or of all kinds of the SSXBs is rather weak, but resolvable, and is more prominent for . The implications for the reprocessing medium are discussed.
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Constraints are found on the Galactic gamma‐ray burst luminosity function (assumed to be a truncated power law), assuming gamma‐ray bursts to be Galactic. Although most observed bursts span a narrow luminosity range, the intrinsic luminosity range can be very large. Angular isotropy additionally constrains the intrinsic luminosity range to be less than a factor of 5 for power‐law indices between −1 and 5, and requires either the maximum luminosity, the minimum luminosity, or both to be between 7.6×1041 and 1.5×1042 erg sec−1.
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The high redhsift blazars powered by supermassive black holes with masses exceeding $10^9\:M_\odot$ have the highest jet power and luminosity and are important probes to test the physics of relativistic jets at the early epochs of the Universe. We present a multi-frequency spectral and temporal study of high redshift blazar PKS 0537-286 by analyzing data from Fermi-LAT, NuSTAR Swift XRT and UVOT. Although the time averaged $\gamma$-ray spectrum of the source is relatively soft (indicating the high-energy emission peak is below the GeV range), several prominent flares were observed when the spectrum hardened and the luminosity increased above $10^{49}\:{\rm erg\:s^{-1}}$. The X-ray emission of the source varies in different observations and is characterised by a hard spectrum $\leq1.38$ with a luminosity of $>10^{47}\:{\rm erg\:s^{-1}}$. The broadband spectral energy distribution in the quiescent and flaring periods was modeled within a one-zone leptonic scenario assuming different locations of the emission region and considering both internal (synchrotron radiation) and external (from the disk, broad-line region and dusty torus) photon fields for the inverse Compton scattering. The modeling shows that the most optimistic scenario, from the energy requirement point of view, is when the jet energy dissipation occurs within the broad-line region. The comparison of the model parameters obtained for the quiescent and flaring periods suggests that the flaring activities are most likely caused by the hardening of the emitting electron spectral index and shifting of the cut-off energy to higher values.
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We present the QSO luminosity function of the completed 2dF-SDSS LRG and QSO (2SLAQ) survey, based on QSOs photometrically selected from Sloan Digital Sky Survey imaging data and then observed spectroscopically using the 2dF instrument on the Anglo-Australian Telescope. We analyse 10637 QSOs in the redshift range 0.420.0, as found previously by Richards et al. (2005). The luminosity function is consistent with other previous, much smaller, samples produced to the depth of 2SLAQ. By combining the 2SLAQ and SDSS QSO samples we produce a QSO luminosity function with an unprecedented combination of precision and dynamic range. With this we are able to accurately constrain both the bright and faint ends of the QSO LF. While the overall trends seen in the evolution of the QSO LF appear similar to pure luminosity evolution, the data show very significant departures from such a model. Most notably we see clear evidence that the number density of faint QSOs peaks at lower redshift than bright QSOs: QSOs with Mg>-23 have space densities which peak at z<1, while QSOs at Mg<-26 peak at z>2. By fitting simple luminosity function models in narrow Mg intervals we find that this downsizing is significant at the 99.98 per cent level (abridged).
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BL Lac object
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We report on the XMM-Newton observation of the HMXRB X Persei, the prototype of the persistent and low-luminosity Be/neutron star pulsars, which was performed in February 2003. The source was detected at a luminosity level of ~1.41035 erg s-1, which is the highest level of the latest three decades. The pulsation period has increased to 839.3 s, thus confirming the overall spin-down of the neutron star detected in the previous observations. The folded light-curve has a complex structure, with features not observed at lower luminosities, and shows a significant energy dependence. The spectral analysis reveals the presence of a significant excess, at low energies, over the main power-law spectral component, which can be described by a black-body spectrum of high temperature ( 1.5 keV) and small emitting region ( 360 m); its properties are consistent with a polar-cap origin. Phase-resolved spectroscopy shows that the emission spectrum varies along the pulse period, but it is not possible to prove whether the thermal component is pulsed or not.
Black hole (networking)
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We derive, adopting a direct method, the luminosity function and the formation rate of long Gamma Ray Bursts through a complete, flux-limited, sample of Swift bursts which has a high level of completeness in redshift z (~82%). We parametrise the redshift evolution of the GRB luminosity as L = L0(1 + z)k and we derive k = 2.5, consistently with recent estimates. The de-evolved luminosity function φ(L0) of GRBs can be represented by a broken power law with slopes a = −1.32 ± 0.21 and b = −1.84 ± 0.24 below and above, respectively, a break luminosity L0,b = 1051.45±0.15 erg/s. Under the hypothesis of luminosity evolution we find that the GRB formation rate increases with redshift up to z ~ 2, where it peaks, and then decreases in agreement with the shape of the cosmic star formation rate. We test the direct method through numerical simulations and we show that if it is applied to incomplete (both in redshift and/or flux) GRB samples it can misleadingly result in an excess of the GRB formation rate at low redshifts.
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