arXiv subjects

Yi-Ping Qin

Publications and source records attributed to Yi-Ping Qin.

At least 19 recordsLinked to original sources

arXiv2021

New Constraint of the Hubble Constant by Proper Motions of Radio Components Observed in AGN Twin-jets

As the advent of precision cosmology, the Hubble constant ($H_0$) inferred from the Lambda Cold Dark Matter fit to the Cosmic Microwave Background data is increasingly in tension with the measurements from the local distance ladder. To approach its real value, we need more independent methods to measure, or to make constraint of, the Hubble constant. In this paper, we apply a plain method, which is merely based on the Friedman-Lemaître-Robertson-Walker cosmology together with geometrical relations, to constrain the Hubble constant by proper motions of radio components observed in AGN twin-jets. Under the assumption that the ultimate ejection strengths in both sides of the twin-jet concerned are intrinsically the same, we obtain a lower limit of the $H_{\rm 0,min}=51.5\pm2.3\,\rm km\,s^{-1}\,Mpc^{-1}$ from the measured maximum proper motions of the radio components observed in the twin-jet of NGC 1052.

astro-ph.GA↗

arXiv2019

Correlation between the ionizing continuum and variable C iv broad absorption line in multi-epoch observations of SDSS J141007.74+541203.3

Correlation between the variations of quasar absorption lines and the ionizing continuum have been recently confirmed in systematic studies. However, no convincing individual case is reported. We present a statistical analysis of the variable C iv broad absorption line (BAL) in the quasar SDSS J141007.74+541203.3, which have been observed with 44 epochs by the Sloan Digital Sky Survey Data Release 14. Grier et al. (2015) has recently concluded that the most likely cause of the variability of the BAL in SDSS J141007.74+541203.3 is a rapid response to changes in the incident ionizing continuum. In this paper, we confirm the anticorrelation between the equivalent width of BALs and the flux of the continuum based on the spectra of this quasar that show significant variations, which serve as another independent evidence for the view of Grier et al. (2015).

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arXiv2017

Correlation between the variation of the ionizing continuum and broad absorption lines

In this Letter, we present an analysis of the relation between the variability of broad absorption lines (BALs) and that of the continuum. Our sample is multi-epoch observations of 483 quasars by the Sloan Digital Sky Survey-I/II/III (SDSS-I/II/III). We derive the fractional flux variations of the continuum and fractional equivalent width (EW) variations for C IV and Si IV BALs, and explore the correlations between the three. Our results reveal moderate anticorrelations with high significance level between the fractional flux variations of the continuum and fractional EW variations for both C IV and Si IV BALs. We also prove a significant positive correlation between the fractional EW variations for C IV and Si IV BALs, which is in agreement with several previous studies. Our discoveries can serve as evidence for the idea: Change of an ionizing continuum is the primary driver of BAL variability.

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arXiv2017

Evidence for photoionization-driven variability in narrow absorption lines

In this Letter, we report the discovery of a strong correlation between the variability of narrow absorption lines (NALs) and the ionizing continuum from a two-epoch spectra sample of 40 quasars containing 52 variable C iv λλ1548; 1551 absorption doublets. According to the concordance index, this sample is classified into two subsamples. Subsample I shows an anti-correlation between the variations of absorption lines and the continuum, while Subsample II exhibits a positive correlation. These results imply that these variable C iv λλ1548; 1551 absorption doublets are intrinsic to the corresponding quasars and that their variations are caused primarily by the fluctuations of the ionizing continuum. Based on our analysis, we propose that there might be two kinds of absorption gas: one that is very sensitive to the continuum variations, the another that is not. In addition, we suggest that in many cases the emergence or disappearance of NALs is caused by fluctuations of the ionizing continuum.

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arXiv2014

Catalog of narrow C IV absorption lines in BOSS (II): for quasars with zem > 2.4

As the second work in a series of papers aiming to detect absorption systems in the quasar spectra of the Baryon Oscillation Spectroscopic Survey, we continue the analysis of Paper I by expanding the quasar sample to those quasars with zem>2.4. This yields a sample of 21,963 appropriate quasars to search for narrow C IV absorptions with Wr>=0.2A for both lines. There are 9708 quasars with at least one appropriate absorption system imprinted on their spectra. From these spectra, we detect 13,919 narrow Civabsorption systems whose absorption redshifts cover a range of zabs=1.8784 - 4.3704. In this paper and Paper 1, we have selected 37,241 appropriate quasars with median SNR>= 4 and 1.54<= zem <=5.16 to visually analyze narrow C IV absorption doublets one by one. A total of 15,999 quasars are found to have at least one appropriate absorption system imprinted on their spectra. From these 15,999 quasar spectra, we have detected 23,336 appropriate C IV absorption systems with Wr>=0.2A whose absorption redshifts cover a range of zabs=1.4544 - 4.3704. The largest values of Wr are 3.19 A for the \lambda1548 absorption line and 2.93 A for the lambda1551 absorption line, respectively. We find that only a few absorbers show large values of Wr. About 1.1% absorbers of the total absorbers have Wr>=2.0 A.

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arXiv2013

Catalog of narrow $C~IV$ absorption lines in BOSS (I): for quasars with $z_{em} \leq 2.4$

We have assembled absorption systems by visually identifying $C~IVλ\lambda1548,1551$ absorption doublets in the quasar spectra of the Baryon Oscillation Spectroscopic Survey (BOSS) one by one. This paper is the first of the series work. In this paper, we concern quasars with relatively low redshifts and high signal-to-noise ratios for their spectra, and hence we limit our analysis on quasars with $z_{em}\le2.4$ and on the doublets with $W_r\lambda1548\ge0.2$ Å. Out of the more than 87,000 quasars in the Data Release 9, we limit our search to 10,121 quasars that have the appropriate redshifts and spectra with high enough signal-to-noise ratios to identify narrow C IV absorption lines. Among them, 5,442 quasars are detected to have at least one $C~IVλ\lambda1548,1551$ absorption doublet. We obtain a catalog containing 8,368 $C~IVλ\lambda1548,1551$ absorption systems, whose redshifts are within $z_{abs}=1.4544$ - $2.2805$. In this catalog, about $33.7\%$ absorbers have $0.2$ Å$\le W_r\lambda1548<0.5$ Å, about $45.9\%$ absorbers have $0.5$ Å$\le W_r\lambda1548<1.0$ Å, about $19.2\%$ absorbers have $1.0$ Å$\le W_r\lambda1548<2.0$ Å, and about $1.2\%$ absorbers have $W_r\lambda1548\ge2.0$ Å.

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arXiv2013

Roles of the kinetic and dynamic mechanisms in the $L_p - E_p$ relation

The $L_p - E_p$ relation is a well-known relation in gamma-ray bursts. Its implication remains unclear. We propose to investigate the underlying mechanisms of this relation by considering the corresponding kinetic and dynamic mechanisms separately. In this way, one can tell how much the kinetic or dynamic mechanism contributes to the index of the relationship. Our analysis gives rise to several conclusions. (1) The index of the kinetic effect in the $L_p - E_p$ relation can simply be derived from the theory of special relativity, which is generally larger than 2, depending on the situation concerned. (2) The index of the dynamic effect in the relation can be deduced from observation once a model of jets is adopted. According to current GRB data, we find: the dynamic effect alone tends to make an anti-correlation between $L_p$ and $E_p$; in terms of statistics, the dynamic effect is obviously smaller than the kinetic effect; in the situation of jets with moving discrete radio clouds which moves directly towards the observer, the index of the dynamic effect is currently constrained within $(-1.6, -1)$, while in other situations of jets, the constrains are different; both internal and external shocks can account for the current data.

astro-ph.HE↗

arXiv2013

The disappearance of a narrow Mg II absorption system in quasar SDSS J165501.31+260517.4

In this letter, we present for the first time, the discovery of the disappearance of a narrow Mg II $λ\lambda2796,2803$ absorption system from the spectra of quasar SDSS J165501.31+260517.4 ($z_{\rm e}=1.8671$). This absorber is located at $z_{\rm abs} =1.7877$, and has a velocity offset of $8,423\rm ~km~s^{-1}$ with respect to the quasar. According to the velocity offset and the line variability, this narrow Mg II $λ\lambda2796,2803$ absorption system is likely intrinsic to the quasar. Since the corresponding UV continuum emission and the absorption lines of another narrow Mg II $λ\lambda2796,2803$ absorption system at $z_{\rm abs}=1.8656$ are very stable, we think that the disappearance of the absorption system is unlikely to be caused by the change in ionization of absorption gas. Instead, it likely arises from the motion of the absorption gas across the line of sight.

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arXiv2013

Statistical classification of gamma-ray bursts based on the Amati relation

Gamma-ray bursts (GRBs) are believed to belong to two classes and they are conventionally divided according to their durations. This classification scheme is not satisfied due to the fact that duration distributions of the two classes are heavily overlapped. We collect a new sample (153 sources) of GRBs and investigate the distribution of the logarithmic deviation of the $E_p$ value from the Amati relation. The distribution possesses an obvious bimodality structure and it can be accounted for by the combination of two Gaussian curves. Based on this analysis, we propose to statistically classify GRBs in the well-known $E_{p}$ vs. $E_{iso}$ plane with the logarithmic deviation of the $E_p$ value. This classification scheme divides GRBs into two groups: Amati type bursts and non-Amati type bursts. While Amati type bursts well follow the Amati relation, non-Amati type bursts do not. It shows that most Amati type bursts are long duration bursts and the majority of non-Amati type bursts are short duration bursts. In addition, it reveals that Amati type bursts are generally more energetic than non-Amati type bursts. An advantage of the new classification is that the two kinds of burst are well distinguishable and therefore their members can be identified in certainty.

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arXiv2013

Disappearance of a narrow Mg II absorption system with a measured velocity up to $\rm 166,000 km s^{-1}$

Quasar J152645.61+193006.7 ($z_{\rm e}=2.5771$) was observed by the Sloan Digital Sky Survey (SDSS) on 2006 May 31, and again on 2011 April 9. The time interval of the SDSS two observations is 497.4 days at the quasar rest frame. From the spectra of this quasar, we detect a phenomenon of disappearance of a narrow $\rm Mg II λ\lambda2796,2803$ absorption system with a velocity up to $\rm 166,129 km s^{-1}$ with respect to the quasar. This disappearance event can be caused by changes in the ionization state of absorbing gas or by the bulk motion of the absorbing gas across the quasar sightline. The coverage fraction analysis shows that this absorber partially covers the background emission sources with an effective coverage fraction of $C_{\rm f}=0.40\pm0.06$. The time variation analysis and the coverage fraction analysis imply that this absorber might be intrinsic to the quasar. However, the scenario of a cosmologically separated foreground object located at $z=0.9170$ accounting for the phenomenon cannot be ruled out according to current available data.

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arXiv2008

Relationship between pulse width and energy in GRB 060124: from X-ray to gamma-ray bands

GRB 060124 is the first event that both prompt and afterglow emission were observed simultaneously by the three \emph{Swift} instruments. Its main peak also triggered Konus-Wind and HETE-II. Therefore, investigation on both the temporal and spectral properties of the prompt emission can be extended to X-ray bands. We perform a detailed analysis on the two well identified pulses of this burst, and find that the pulses are narrower at higher energies, and both X-rays and gamma-rays follow the same $w - E$ relation for an individual pulse. However, there is no a universal power-law index of the $w - E$ relation among pulses. We find also that the rise-to-decay ratio $r/d$ seems not to evolve with $E$ and the $r/d$ values are well consistent with that observed in typical GRBs. The broadband spectral energy distribution also suggest that the X-rays are consistent with the spectral behavior of the gamma-rays. These results indicates that the X-ray emission tracks the gamma-ray emission and the emissions in the two energy bands are likely to be originated from the same physical mechanism.

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arXiv2007

The Neighborhood Function and Its Application to Identifying Large-Scale Structure in the Comoving Universe Frame

In this paper a relative number density parameter, called the neighborhood function, is introduced so that the crowded nature of the neighborhood of individual sources can be described. With this parameter one can determine the probability of forming a cluster by chance. A method is proposed to identify large-scale structure in the cosmological comoving frame. The scale used to sort out clustered sources is determined by the mean local number density, and the sample adopted is required to have regular borders. The method is applied to a sample drawn from the Two Degree Field survey. We find from the analysis that the probability of forming the resulting large-scale structures by chance is very small, and the phenomenon of clustering is dominant in the local universe. Within a 3σconfidence level, a coherent cluster with a scale as large as 357h^{-1}Mpc is identified from the sample. There exist some galaxies which are not affected by the gravitation of clusters, and hence are suspected to be at rest in the comoving frame of the universe. Voids are likely volumes within which very crowded sources are not present, and they are likely formed in embryo by fluctuations in the very early epochs of the universe. In addition, we find that large-scale structures are coral-like and are likely made up of smaller structures; sources with large values of the neighborhood function are mainly distributed within the structure of prominent clusters, and they form the framework of the large-scale structure.

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arXiv2007

Dependence of Temporal Properties on Energy in Long-Lag, Wide-Pulse Gamma-Ray Bursts

We employed a sample compiled by Norris et al. (2005, ApJ, 625, 324) to study the dependence of the pulse temporal properties on energy in long-lag, wide-pulse gamma-ray bursts. Our analysis shows that the pulse peak time, rise time scale and decay time scale are power law functions of energy, which is a preliminary report on the relationships between the three quantities and energy. The power law indexes associated with the pulse width, rise time scale and decay time scale are correlated and the correlation between the indexes associated with the pulse width and the decay time scale is more obvious. In addition, we have found that the pulse peak lag is strongly correlated with the CCF lag, but the centroid lag is less correlated with the peak lag and CCF lag. Based on these results and some previous investigations, we tend to believe that all energy-dependent pulse temporal properties may come from the joint contribution of both the hydrodynamic processes of the outflows and the curvature effect, where the energy-dependent spectral lag may be mainly dominated by the dynamic process and the energy-dependent pulse width may be mainly determined by the curvature effect.

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arXiv2005

Method of determining cosmological parameter ranges with samples of candles with an intrinsic distribution

In this paper, the effect of the intrinsic distribution of cosmological candles is investigated. We find that, in the case of a narrow distribution, the deviation of the observed modulus of sources from the expected central value could be estimated within a ceratin range. We thus introduce a lower and upper limits of $χ^{2}$, $χ_{\min}^{2}$ and $ χ_{\max}^{2}$, to estimate cosmological parameters by applying the conventional minimizing $χ^{2}$ method. We apply this method to a gamma-ray burst (GRB) sample as well as to a combined sample including this GRB sample and an SN Ia sample. Our analysis shows that: a) in the case of assuming an intrinsic distribution of candles of the GRB sample, the effect of the distribution is obvious and should not be neglected; b) taking into account this effect would lead to a poorer constraint of the cosmological parameter ranges. The analysis suggests that in the attempt of constraining the cosmological model with current GRB samples, the results tend to be worse than what previously thought if the mentioned intrinsic distribution does exist.

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arXiv2005

Relationship between the rise width and the full width of gamma-ray burst pulses and its implications in terms of the fireball model

Kocevski et al. (2003) found that there is a linear relation between the rise width and the full width of gamma-ray burst pulses detected by the BATSE instrument based on their empirical functions. Motivated by this, we investigate the relationship based on Qin et al. (2004) model. Theoretical analysis shows that each of the two quantities, the rise width and the full width of observed pulse, is proportional to $Γ^{-2}Δτ_{θ,\rm FWHM}\frac{R_c}{c}$, where $Γ$ is the Lorentz factor for the bulk motion, $Δτ_{θ,\rm FWHM}$ is a local pulse's width, $R_{c}$ is the radius of fireballs and c is the velocity of light. We employ the observed pulses coming from four samples to study the relationship and find that: (1) Merely the curvature effect could produce the relationship with the same slope as those derived from Qin et al. (2004) model in the rise width vs. the full width panel. (2) Gamma-ray burst pulses, long or short ones (selected from the short and long GRBs), follow the same sequence in the rise width vs. the full width panel, with the shorter pulses at the end of this sequence. (3) All GRBs may intrinsically result from local Gaussian pulses. These features place constraints on the physical mechanism(s) for producing long and short GRBs.

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arXiv2005

Characteristics of the curvature effect of uniform jets or spherical fireballs

Qin et al. (2004) have derived a formula of count rates based on a model of highly symmetric expanding fireballs, where the Doppler effect is the key factor to be concerned. In this paper, we employ the formula to both the Qin model and the uniform jet model to study how the rising timescale, $Δτ_{θ,r}$, and the decay timescale, $Δτ_{θ,d}$, of a local pulse affect the light curve of GRBs. Our analysis shows that they do make contributions to both rising and decay portions of the light curve of GRBs. Associated with a local pulse with both rising and decay portions, the light curve of GRBs in the rising portion is expected to undergo a concave phase and then a convex one, which we call a "concave-to-convex" character, whereas that in the decay portion is expected to evolve an opposite process which is called a "convex-to-concave" character, regardless of being in Qin model or in the uniform jet model. These characteristics are independent of local pulse shapes and their rest frame radiation forms. The diversity of light curves are caused by different forms of local pulses and different ratios of $Δτ_{θ,r}$ to $Δτ_{θ,d}$. We study a sample of 86 GRB pulses detected by the BATSE instrument on board the Compton Gamma Ray Observatory and find that the "concave-to-convex" (expected in the rising portion of the light curve) and "convex-to-concave" (expected in the decay portion) characters, which result from the curvature effect of spherical surface (or the Doppler effect), do exist in the light curve of some GRBs.

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arXiv2005

Relation between the hardness ratio and time in the first 2 seconds for compatible samples of short and long gamma-ray bursts

In this paper, we randomly selected a sample (sample 1) of long gamma-ray bursts, with its size being the same as that of the short burst group (sample 2) (N=500), from the Current BATSE Bursts Catalog. We randomly selected a short burst and assigned its T90 to each of these long bursts. We thus constructed a long burst sample with both the sample size and the distribution of T90 being the same as those of the short burst sample obtained from the Current BATSE Bursts Catalog. Then we calculated the hardness ratio ($hr_{T}$) over the assigned T90 for the long bursts and over their own T90 for the shout bursts, and studied the relation between the hardness ratio and the corresponding T90 for these two samples. We also calculated the hardness ratio ($hr_{t}$) over the randomly selected 64 ms time intervals within the T90, and investigated the relation between this hardness ratio and the selected 64 ms time interval. In addition, the $hr_{t}$ within and beyond the first 2 seconds for all the long bursts (sample 3; N=1541) were also investigated. We found that the KS probabilities of the distributions of the $hr_{T}$ (7.15337E-15) and $hr_{t}$ (9.54833E-10) for samples 1 and 2 are very small, and the average value of $hr_{T}$ and $hr_{t}$ of short bursts are obviously larger than that of the long bursts. The correlations between log$hr_{T}$ and logT90, and between log$hr_{t}$ and log t, for samples 1 and 2 are different. These show that short and long bursts in the first 2 seconds have different characters and they probably originate from different progenitors. For sample 3, for the two time intervals, the KS probability is 5.35828E-5, which suggests that the hardness ratios in different time intervals for long bursts are also different.

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arXiv2005

Distributions of the Hardness Ratio of short and Long Gamma-Ray Bursts in Different Time Intervals within the First 2 Seconds

In the present paper, we investigated the distribution of hardness ratio (HR) for short and long gamma-ray bursts (GRBs) in different time scales for the first two seconds. After including and subtracting the background count, we performed a Kolmogorov--Smirnov (K-S) test to the HR distributions of the two classes of GRBs in each time interval. Our analysis shows that the probabilities of the KS test to the distributions are very small, suggesting that the two classes of bursts are unlikely to arise from the same HR distributions, and indicating that they probably originate from the different physical processes and central engine. In addition, we found that the hardness ratio of short bursts within the time interval of 0$-$0.96 seconds changes hard-to-soft, on the other hand long bursts do not. The two kinds of bursts have different characteristics in the first 2 seconds which might be associated with different physical mechanisms.

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