ICRANet Newsletter

ICRANet简报
2016年12月——2017年1月

Armenian - Chinese - English - Italian - Portuguese - Russian

摘要
1. IRAP博士毕业生中产生出第一代年轻巴西教授，Malheiro，鲁菲尼和 Rueda教授强调到：这是CAPES-ICRANet联合项目明确的额外成功
2. 在伊斯法罕的新ICRANet中心和鲁菲尼教授的伊朗之行
3. 首个ICRANet双星驱动极超新星样本目录
4. 巴西数据科学中心的架构
5. Rueda教授访问哥伦比亚
6. 佩斯卡拉伽利略科学高中的两次“校园-工作”项目会议
7. 新的博士论文答辩和学位
8. 最近的出版物

1. IRAP博士毕业生中产生出第一代年轻巴西教授，Malheiro，鲁菲尼和 Rueda教授强调到：这是CAPES-ICRANet联合项目明确的额外成功

一篇题为 “Thermal X-ray emission from massive, fast rotating, highly magnetized white dwarfs”来自ICRANet科学家工作组的新论文刚刚发表 ，它的作者包括: D. L. Cáceres, S. M. de Carvalho, J. G. Coelho, R. C. R. de Lima, Jorge A. Rueda。它发表在著名的天体物理期刊《英国皇家天文学会月刊》上（影响因子为4.952），出版物详情请见: https://doi.org/10.1093/mnras/stw3047.
There are two special types of compact objects: anomalous X‐ray pulsars (AXPs) and soft gamma repeaters (SGRs), which possess very distinct properties among pulsars, namely: lack of evidence of binary companions; narrow distribution of the spin period between 5 and 12 seconds; secular spin-down on timescales of 10³-10⁵ years; variability on very different timescales; absence of radio emission; association with supernova remnants (in some cases) [1]. Historically SGRs were discovered through the detection of repeating short bursts in the hard X-ray/soft gamma-ray range, while persistent emission from AXPs was first detected in the soft X-ray range. Subsequent observations at different wavelengths showed that both types of objects share many characteristics. They are now considered as the same class of objects.
When AXPs and SGRs are viewed as (1) neutron stars (NS) (2) with mass equal to solar mass and (3) radius 10 km, their emitted power appears to exceed by several orders of magnitude the rotational energy loss, requiring different energy source. The most unorthodox proposal in the literature was to use the magnetic energy in the bulk as the energy source powering these objects, e.g. magnetar [2]. The magnetic field estimate, based on observed period and its first derivative, exceeds many times the critical quantum value for vacuum polarization, B_c=4.4x10¹³ Gauss.
A very different model has been proposed by Malheiro, Ruffini and Rueda [5] following the previous works [6,7]. They critically reanalyzed the above three assumptions, understood as not necessary in the explanation of both SGRs and AXPs. The model is based on canonical physics and astrophysics and describes SGRs and AXPs as powered by rotational energy of massive highly magnetized rotating white dwarfs (WDs), in total analogy with pulsars powered by rotating neutron stars. Given its much larger moment of inertia, the WD model naturally explains the energy budget of persistent emission of AXPs and SGRs. Moreover, emission of giant flares and bursts can be explained as consequences of glitches with rotational period fractional change from 10^-7 up to 10^-3. It turns out that within the WD model the energetic of both the steady emission as well as that of the outbursts following the glitch can be simply explained in terms of the loss of rotational energy. This is in sharp contrast with alternative models of magnetars or quark stars, where different components are required for explanation of steady emission and outbursts, respectively. As opposed to the NS case, the magnetic fields involved in the WD model are not extreme and are of the order of the ones observed in most magnetized isolated WDs.


The new publication by D. L. Caceres et al. [8] focuses on the thermal X‐ray emission observed in SGRs and AXPs, in particular 4U 0142+61 and 1E 2259 586, both previously considered in the literature as magnetars [9,10]. Contrary to the magnetar model, where the structure of the magnetic field is unknown, the specific WD rotation assumption, with a well established magnetic field, allows to make the new theoretical developments and further refine the theoretical analysis. Following the Malheiro, Ruffini and Rueda [5] such thermal emission is similar to the one operating in usual pulsars: the magnetic polar cap heating by back flowing electrons and positrons created in the magnetosphere. The authors of publication [8] show that the kinetic energy of particles is effectively transformed into heat in the thin layer on the surface of the WD polar cap, hence this energy is efficiently radiated in the form of thermal soft X-rays. This work by D. L. Caceres et al. confirms previous expectations by Malheiro, Ruffini and Rueda [5] that in AXPs, in addition to the blackbody component observed in the optical wavelengths and interpreted as the surface temperature of the cooling white dwarfs, the blackbody component seen in X-rays can be of magnetospheric origin. This work also adds to the theory of white dwarfs and sheds new light on the properties of magnetosphere, magnetic field structure and pulsed emission properties of rotating magnetized WDs.

Professor S.O. Kepler, the author of the most extended catalogue of white dwarfs

It is appropriate to recall that Brazil through the work of prof. Kepler has today reached a forefront position in the study of WDs. Up to about 600 magnetized WDs have been recently identified in the largest white dwarf catalogue made with the Sloan Digital Sky Survey (SDSS), published by S.O. Kepler [11,12]. This catalogue now contains dozens of thousands of spectroscopically identified white dwarfs. Such unprecedented number of known WDs had enormous impact on the study of these stars. The most recent update of the catalogue has just appeared in 2017 [13].

The work of D. L. Caceres et al. [8] inserts a new fundamental understanding of the role of rotation and magnetic fields in WDs.

参考文献:
[1] S. Mereghetti, Astron Astrophys Rev 15 (2008) 225; S. Mereghetti, Brazilian Journal of Physics 43 (2013) 356.
[2] R. C. Duncan and C. Thompson ApJL 392 (1992) L9; C. Thompson and R. C. Duncan, MNRAS 275 (1995) 255; C. Thompson and R. C. Duncan, ApJ 473 (1996) 322.
[3] H. Tong and R.-X. Xu, IJMPE 20 (2011) 15.
[4] N. Rea, et al., Science 330 (2010) 944.
[5] M. Malheiro, J. A. Rueda and R. Ruffini, PASJ 64 (2012) 56.
[6] B. Paczynski, ApJ 365 (1990) L9.
[7] V. Usov, ApJ 427 (1994) 984.
[8] D. L. Cáceres et al., MNRAS 465 (2017) 4434.
[9] Z. Wang, D. Chakrabarty and D. L. Kaplan, Nature 440 (2006) 772.
[10] R. F. Archibald et al, Nature 497 (2013) 591.
[11] S. O. Kepler, et al., MNRAS 446 (2015) 4078.
[12] E. Garcia-Berro, M. Kilic and S.O. Kepler, IJMPD 25 (2016) 1630005.
[13] S. O. Kepler, arXiv:1702.01134.


关于作者

	Diego Leonardo Caceres Uribe 来自哥伦比亚，他现在在ICRANet佩斯卡拉，是由意大利奖学金支持的IRAP项目博士生。
	Sheyse Martins de Carvalho来自巴西，她曾经是伊拉斯莫-世界IRAP博士生并于2013年获得博士学位。同时她曾经从2014年到2016年2月在Universidade Federal Fluminense 做CAPES-ICRANet博士后。现在她是Universidade Federal do Tocantins (UFT)的教授.
	Jaziel Goulart Coelho 曾经从2014年2月到2015年2月在罗马大学做CAPES-ICRANet博士后，现在他在巴西Instituto Nacional de Pesquisas Espaciais (INPE) 做博士后.
	Rafael de Lima曾经于2014年3月到2016年2月在佩斯卡拉ICRANet总部做CAPES-ICRANet博士后，现在他是巴西Universidade do Estado de Santa Catarina (UDESC)的教授.
	Jorge Rueda是ICRANet教职中的教授，他曾经在2013-2015到巴西作为CAPES-ICRANet做资深访问学者.

该工作是由ICRANet和巴西大学合作完成的，详见:
ICRANet-UFF - ICRANet-INPE - ICRANet-UDESC

2. 在伊斯法罕的新ICRANet中心和鲁菲尼教授的伊朗之行

2016年12月10日至11日，ICRANet中心主任雷蒙-鲁菲尼教授和 Narek Sahakyan博士(在Yerevan的ICRANet主任)共同访问了位于Iran的多个中心和机构:The Isfahan University of Technology (IUT), the Institute for Advanced Studies in Basic Sciences (Zanjan) 以及Shahid Beheshti University. 另外，访问期间还在IUT，Isfahan物理系建立了ICRANet中心。


12月10日至11日， 雷蒙-鲁菲尼教授与Isfahan University of Technology 校长和其他领导见面。在参观了物理学院后，与院系全体教职员举行了研讨会，本次行程和Sahakyan教授一同进行，并且Sahakyan教授在物理系做了报告。

Prof. Ruffini visits IASBS - Institute for Advanced Studies in Basic Sciences (Zanjan)

鲁菲尼教授还在此次Iran之行期间访问了 the Institute for Advanced Studies in Basic Sciences (IASBS) in Zanjan，并与学院创始人Yousef Sobouti教授见面。Sobouti Yousef教授是伊朗籍世界著名理论物理学家。他曾是诺贝尔经济学奖得主Subrahmanyan Chandrasekhar的博士生。The Institute for Advanced Studies in Basic Sciences (IASBS)目前被认为是一所以基础科学高等教育为主的大学。详见: http://iasbs.ac.ir/~sobouti/



和伊朗研究机构之间的协议
1. I UT Isfahan University of Technology - Isfahan, Iran (February 21, 2016)
2. Sharif University of Technology - Teheran, Iran (March 12, 2016)
3. IASBS Institute for Advanced Studies in Basic Sciences - Zanjan, Iran (9 April 2016)
4. IPM Institute for Research in Fundamental Sciences - Teheran, Iran (May 3, 2016)
5. Shiraz University - Shiraz, Iran (March 21, 2016)
这些协议的文本可以在此查阅 here.

3. 首个ICRANet双星驱动极超新星样本目录

ICRANet主任雷蒙-鲁菲尼教授公布了首个截至2016年底由175个观测源构成的ICRANet双星驱动极超新星样本目录的发表[1-3]。
在一系列的出版物中，来自ICRANet由雷蒙-鲁菲尼教授所领导的科学家们得到了一个关于伽玛暴的新颖的全面图像，这一切归功于他们发展了一系列新的理论框架。 在这些工作中，诱导引力坍缩图景解释了一类的高能、长时间的伽玛暴，同时伴随着Ib/c 超新星 (SN), 它近来被命名为双星驱动极超新星(见图 1 和 2及文献[4-7]).

Fig. 1: Graphic representation of the IGC scenario. The Ns companion accretes material from the expanding outer layers of the SN which just exploded. If the binary system is tight enough, the accretion process becomes hypercritical, and the NS eventually collapse to a black hole, emitting a GRB.	Fig. 2: This space-time diagram shows all the different physical processes and relative emissions occurring in a BdHN phenomenon.

BdHNe have a well defined set of observational features which allow to identify them:
- long duration of the GRB explosion, namely larger than 2 s in the rest frame;
- a total energy, released in all directions by the GRB explosion, larger than 10⁵² ergs;
- peak energy released during the GRB explosion larger than 200 keV;
- presence of a flare in the X-ray emission around 100 s in the rest-frame after the GRB explosion, visible if dominant over the underlying X-ray decaying emission [1];
- a plateau phase in the X-ray luminosity emitted between ~100 and ~10⁴ s in the rest-frame after the GRB explosion;
- a universal late time power-law decay in the X-rays luminosity after 10⁴ s, with typical decaying slope of ~1.5 [3, 8].
The first three features regard the prompt GRB emission observed in the gamma-rays by the GBM, BAT, Konus instruments onboard, respectively, Fermi, Swift, Wind satellites. The following three features are observed within the long lasting decaying X-ray emission, well covered by the XRT instrument onboard Swift.


Thanks to this novel theoretical and observational understanding, it was possible for ICRANet scientists to build the 1st BdHNe catalog, composed by the 175 BdHNe identified up to the end of 2016. BdHNe are named as "IBdHN", where the "I" stands for ICRANet, followed by the number identifying the correspondent GRB date of explosion.
Figure 3 shows the first 20 rows of the 1st IBdHNe catalog. The columns show some of the significant observed quantities of the BdHN. The complete list of the quantities contained in the catalog follows:
- z: the observed redshift, z, which gives us information on the distance of the source;
- r-f T90: the duration of the GRB in the rest-frame, namely the observed time during which the GRB has released 90% of its energy corrected by the redshift;
- Eiso: the total energy released by the GRB in any direction, computed between 1-10⁴ keV;
- tstart: the beginning rest-frame time of the late X-ray power-law behaviour;
- tend: the rest-frame time of the last X-ray data observed by Swift/XRT;
- slope: decaying slope of the late X-ray power-law behaviour;
- E_LT: total energy released in all directions in the X-ray band between 10⁴ and 10⁶ s in the rest-frame after the GRB explosion;
- angle: inferred opening angle of the late beamed X-ray emission
- flare: marks the presence of a flare around 100 s in the rest-frame, visible in the X-rays when dominant over the underlying decaying emission;
- satellite: name of the satellite which has the best observed data in the gamma-ray band;
- GCN: number of the GCN circular correspondent to the best gamma-ray data of the source.
This catalogue is currently uploaded in the BSDC.

References:
[1] Ruffini, R., Wang, Y., Muccino, M., et al. in preparation
[2] Ruffini, R., Rueda, J. A., Muccino, M., et al. 2016, ApJ, 832, 136
[3] Pisani, G. B., Ruffini, R., Aimuratov, Y., et al. 2016, ApJ, 833, 159
[4] Fryer, C. L., Rueda, J. A., & Ruffini, R. 2014, ApJ, 793, L36
[5] Rueda, J. A., Ruffini, R., 2012, ApJ, 758, L7
[6] Ruffini, R., Wang, Y., Enderli, M., et al. 2015, ApJ, 798, 10
[7] Ruffini, R., Muccino, M., Bianco, C. L., et al. 2014, A&A, 565, L10
[8] Pisani, G. B., Izzo, L., Ruffini, R., et al. 2013, A&A, 552, L5 https://gcn.gsfc.nasa.gov/gcn3_archive.html

4. 首个巴西ICRANet伽玛暴Blazar样本目录和巴西数据科学中心

在巴西数据科学中心（BSDC），有Paolo Giommi教授和通过ICRANet的IRAP博士项目获得博士学位的巴西博士后Bruno Sversut Arsioli博士合作的以下五个项目。


The first one, the 1WHSP, is a sample of HSP blazars, with about 1000 objects at |b|>20˚, built based on multifrequency selection criteria including IR colours. At the time, this sample was the largest HSP catalog available, and was key to understand that the CTA sky will be full of new sources to study. This sample is a collection of HE and VHE candidates, to be observed with current and future Cherenkov Telescopes. With this sample, we also study and suggest new association with sources from the 3FGL catalog, which were then considered by the Fermi-LAT team for the 3LAC catalog (listing AGNs with gamma-ray counterparts). In addition, this work also discusses population properties for this particular blazar-family. This work is published in A&A 579, A34 (2015), and is also available online: https://arxiv.org/abs/1504.02801; and a direct link to the SED builder tool is here: http://www.asdc.asi.it/1whsp/ in collaboration with YuLing Chang (also IRAP PhD student, from Taiwan), 1WHSP catalog has been extended. The 2WHSP catalog now goes down to |b|>10˚ and is also based in multifrequency selection criteria, despite we do not use IR color-color selection this time, so we manage to be more complete. We also used updated X-ray catalog, and benefit from more than 160 new Swift XRT observations of WHSP blazars. This allowed us to have a better description of the synchrotron peak parameters, for many know and new HSP sources, so we could revisit some population studies using the 2WHSP sample. The 2WHSP cat has ~1700 objects, and is published in A&A 598, A17 (2017), also available at: https://arxiv.org/abs/1609.05808; and a direct link to the SED builder tool is here: http://www.asdc.asi.it/2whsp/
The third work of this series, is the First Brazilian ICRANet Gamma-ray Blazar catalog. Since we claim the WHSP samples are a collection of god TeV-candidates, they should also be very helpful to unveil new MeV-GeV sources in reach from Fermi-LAT satellite. So, we have used 7.5 yrs of Pass 8 Fermi-LAT data, and study about 400 bright WHSP sources which yet had no gamma-ray counterpart (bright blazar meaning: a sources with bright synchrotron peak nfn). As result, we found 150 new gamma-ray sources. This one we called 1BIGB (First Brazilian ICRANet Gamma-ray Blazar catalog). We describe their spectral parameters in the 0.3-500 GeV band, and showed that they might represent 6-8% of the extragalactic diffuse gamma-ray background around 50 GeV. Also, this work is an important "proof of concept" in the sense that the WHSP samples are really useful to unveil HE sources, and certainly very helpful to select promising TeV-targets.

5. Rueda教授访问哥伦比亚

2016年12月12日至16日，Jorge Rueda教授访问了坐落在哥伦比亚Bucaramanga的Universidad Industrial de Santander (UIS) 并被授予"杰出校友奖" . 在访问期间， Rueda教授在UIS物理系讲授了8小时短期课程"白矮星和中子星的物理与天体物理" ，同时他还在"III Jornadas Científicas Escuela de Física UIS"做了特邀报告及在Bucaramanga的Casa del Libro Total 举办的 "Café Científico" 活动上做了题为"Vida después de la muerte: los cataclismos más potentes del Universo" 的公众报告.

6. 佩斯卡拉伽利略科学高中的两次“学校-工作”项目会议

在与佩斯卡拉伽利略科学高中三年级的两个协议框架下，校园-工作项目从 12月开始启动。参与该项目的总学生为25人，总的理论和实践时间为70小时。由Sigismondi Costantino教授和 Alessandra Di Cecco博士带来的首堂课主题是“ 研究人员科研和工作的价值”。 Sigismondi教授制作了一个关于研究着工作的视频报告，可以再次观看: https://www.youtube.com/watch?v=OOVxOlsEDoU&t=1s 还有两外一个题为 “双子座流星雨和象限仪: 科学观测指南”的视频可以在此链接观看: https://www.youtube.com/watch?v=0xLV0BOrvdg&feature=youtu.be
Alessandra Di Cecco 在此项目中关于天体物理导论的课程可见 http://www.icranet.org/scuola_lavoro/dicecco_sem.pdf


第二个会议的主题是 “天体物理和相对论的历史 ”，负责参与人员 是Gregory Vereshchagin教授, Vladimir Belinski教授 和来自中国的博士生王瑜.

7. 新的博士论文答辩和学位

Clément Stahl, "On early and late phases of acceleration of the expansion of the universe", defended on 23rd of January, 2017 at the University of Rome "Sapienza"
答辩委员会成员: Jean Audouze (Institut d'Astrophysique de Paris, France), Paolo De Bernardis (University of Rome "Sapienza", Italy), Massimo Della Valle (Osservatorio Astronomico di Capodimonte, Italy) and Nikolaos Mavromatos (King's College London, UK).


This thesis tackles the vast question of generating accelerated periods of expansion of the universe. Models loosely related were developed in the early and late universe. In the early universe, generalizations of the Schwinger effect were developed in curved space (de Sitter) spacetime and some backreaction effects were estimated.
In the late universe, a fractal model was developed and confronted to supernovae data. This relies on the idea of an accelerated expanding universe being nothing but a mirage due to inhomogeneities disposed in a fractal (in this particular model) way. Finally a model of interacting energy based on an Einstein-Cartan gravitational theory was phenomenologically investigated.

发表论文列表:
E. Bavarsad, C Stahl, and S.-S Xue, Scalar current of created pairs by Schwinger mechanism in de Sitter spacetime, Phys. Rev., vol. D 94, 2016.
C. Stahl and E. Strobel, Semiclassical fermion pair creation in de Sitter spacetime, proceeding of the second Cesar Lattes meeting, 2015.
C. Stahl, E. Strobel, and S.-S. Xue, Fermionic current and Schwinger e_ect in de Sitter spacetime, Phys. Rev., vol. D 93, 2016.
C. Stahl, E. Strobel, and S.-S. Xue, Pair creation in the early universe, proceeding of MG14, 2016.
C. Stahl and S.-S. Xue, Schwinger effect and backreaction in de Sitter spacetime, Phys. Lett., vol. B760, 2016.
C. Stahl, Inhomogeneous matter distribution and supernovae, Int. J. Mod. Phys., vol. D25, 2016.
R. Ruffini, C. Stahl, Cosmological fractal matter distribution with an upper cutoff, proceeding of IK14, 2016
D. Bégué, C. Stahl, and S.-S. Xue, A model of interacting dark energy and supernovae, to appear, 2017.

8. 最近的出版物

a. Thermal X-ray emission from massive, fast rotating, highly magnetized white dwarfs", D. L. Cáceres, S. M. de Carvalho, J. G. Coelho, R. C. R. de Lima, Jorge A. Rued, MNRAS (2016) 465 (4): 4434-4440
There is solid observational evidence on the existence of massive, M ∼ 1 M_⊙, highly magnetized white dwarfs (WDs) with surface magnetic fields up to B ∼ 10⁹ G. We show that, if in addition to these features, the star is fast rotating, it can become a rotation-powered pulsar-like WD and emit detectable high-energy radiation. We infer the values of the structure parameters (mass, radius, moment of inertia), magnetic field, rotation period and spin-down rates of a WD pulsar death-line. We show that WDs above the death-line emit blackbody radiation in the soft X-ray band via the magnetic polar cap heating by back flowing pair-created particle bombardment and discuss as an example the X-ray emission of soft gamma-repeaters and anomalous X-ray pulsars within the WD model.
The paper is available here: https://doi.org/10.1093/mnras/stw3047

b. "Polarization of a probe laser beam due to nonlinear QED effects", Soroush Shakeri, Seyed Zafarollah Kalantari, and She-Sheng Xue, Phys. Rev. A 95, 012108
Nonlinear QED interactions induce different polarization properties on a given probe beam. We consider the polarization effects caused by the photon-photon interaction in laser experiments, when a laser beam propagates through a constant magnetic field or collides with another laser beam. We solve the quantum Boltzmann equation within the framework of the Euler-Heisenberg Lagrangian for both time-dependent and constant background field to explore the time evolution of the Stokes parameters Q, U, and V describing polarization. Assuming an initially linearly polarized probe laser beam, we also calculate the induced ellipticity and rotation of the polarization plane.
The paper is available here: http://link.aps.org/doi/10.1103/PhysRevA.95.012108