Recent observations suggest that some types of GRB are physically connected
with SNe of type Ib/c. However, it has been pointed out by several authors that
some GRBs could be associated also with other types of core-collapse SNe (type
IIdw/IIn). On the basis of a comphrensive statistical study, which has made use
of the BATSE and Asiago catalogues, we have found that: i) the temporal and
spacial distribution of SNe-Ib/c is marginally correlated with that of the
BATSE GRBs; ii) we do not confirm the existence of an association between GRBs
and SNe-IIdw/IIn.Comment: Proceeding of the 4th workshop on Gamma Ray Bursts in the Afterglow
  Era, Rome, 2004; 4 page

Cappellaro, E.

Della Valle, M.

Frontera, F.

Guidorzi, C.

Montanari, E.

Valenti, S.

English

arXiv

Recent observations suggest that some types of GRB are physically connected with SNe of type Ib/c. However, it has been pointed out by several authors that some GRBs could be associated also with other types of core-collapse SNe(t ypeI Idw/IIn). On the basis of a comphrensive statistical study, which has made use of the BA TSE and Asiago catalogues, we have found that: i) the temporal

and spacial distribution of SNe-Ib/c is marginally correlated with that of the BATSE GRBs; ii) we do not confirm the existence of an association between GRBs and SNe-IIdw/IIn

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DOI 10.1393/ncc/i2005-10118-1IL NUOVO CIMENTO Vol. 28 C, N. 4-5 Luglio-Ottobre 2005SN/GRB connection: A statistical approach with BATSEand Asiago Catalogues(∗)S. Valenti(1)(2), E. Cappellaro(2), M. Della Valle(3), F. Frontera(1)(4)C. Guidorzi(5) and E. Montanari(1)(1) Physics Department, University of Ferrara, I-44100 Ferrara, Italy(2) INAF - Astronomical Observatory of Capodimonte, Via Moiariello 16, I-80131 Napoli, Italy(3) INAF - Astronomical Observatory of Arcetri, Via Enrico Fermi 5, I-50125 Florence, Italy(4) INFN, IASF, Via Gobetti, 101, 40129 Bologna, Italy(5) Astrophysics Research Institute - Liverpool JM University, Twelve Quays HouseEgerton Wharf, Birkenhead CH41 1LD, UK(ricevuto il 23 Maggio 2005; pubblicato online il 12 Ottobre 2005)Summary. — Recent observations suggest that some types of GRB are physicallyconnected with SNe of type Ib/c. However, it has been pointed out by severalauthors that some GRBs could be associated also with other types of core-collapseSNe (type IIdw/IIn). On the basis of a comphrensive statistical study, which hasmade use of the BATSE and Asiago catalogues, we have found that: i) the temporaland spacial distribution of SNe-Ib/c is marginally correlated with that of the BATSEGRBs; ii) we do not confirm the existence of an association between GRBs and SNe-IIdw/IIn.PACS 98.70.Rz – γ-ray sources, γ-ray bursts.PACS 01.30.Cc – Conference proceedings.1. – Introduction:The association between Supernovae of type Ib/c (SNe-Ib/c) and long duration GRBshas been firmly established only in a few cases (see [2] for a review). However, therehave been claims, based on spatial and temporal SN-GRB coincidencies, that also someother types of core-collapse SNe, the so called SNe-IIdw (see [6] for a review) mightbe associated with GRBs [5, 9, 8]. To test this idea we have correlated the GRBs fromBATSE catalogue (2702 GRBs from April 1991 to May 2000) with SNe of the Asiagocatalogue detected in the same period of BATSE (736 SNe).(∗) Paper presented at the “4th Workshop on Gamma-Ray Burst in the Afterglow Era”, Rome,October 18-22, 2004.c© Societa` Italiana di Fisica 633634 S. VALENTI, E. CAPPELLARO, M. DELLA VALLE, F. FRONTERA ETC.Table I. – a: The number and the frequency for each type of SN, by correlating Asiago andBATSE catalogues (see text) In the sample of SNe we ignored the association (SN1998bw-GRB980425); b: The number and frequency for each type of SN included in the Asiago cataloguein the temporal window of BATSE (1991-2000).SNe Ia II IIb IIn Ibc Tot.N(a) 15 12 0 3 6 36% 41.7 33.3 0 8.3 16.6 100SNe Ia II IIb IIn Ibc Tot.N(b) 448 202 4 38 44 736% 60.9 27.4 0.5 5.2 6.0 1002. – Correlation between Asiago SNe and BATSE GRBs catalogues.We selected all pairs GRB-SN from the BATSE and Asiago catalogues that matchthe following spatial and temporal requirements:– all SNe falling within one sigma error radii of BATSE error-boxes increased withthe sistematic error of the BATSE instrument of 1.85 degrees [1]. This choice ismotivated by the fact that the typical size of the error box associated with GRBs,varies from 0.5 to several degrees, which is much larger than the ‘average’ error box(∼ a few arcsec) associated with SNe of the Asiago archive.– we assumed, on the basis of the SN/GRB associations so far discovered, that SNeand GRBs go off simultaneously. Thus the temporal window is set by the lenght ofthe rising time of the SN from the epoch of the explosion to maximum light. Thisparameter is not well known, however we can assume, on the basis of SN 1998bw,Trise ∼ 15 days. Given the uncertainty affecting the epoch of the SN maximumlight, we assume Trise ± 11 days.3. – Preliminary analysisIn table Ia, we report, for each SN type, the number (N(a)) and the fraction (%) ofGRB-SN pairs, obtained by searching for each GRB error-box, the SNe possibly explodedin that error-box, with maximum light at 15d ± 11d afther GRB occurence.These figures have to be compared with the analogous entries in table Ib, where wereport, for each type of SN, the number (N(b)) and the fraction (%) of SNe includedin the Asiago catalogue. If SNe and GRBs are not physically connected, the temporalconstraints will not introduce any bias in forming SN/GRB pairs. In other words, oneshould expect to find similar or lower frequencies of SNe in table Ia and in table Ib.This is certainly the case for type Ia, normal II, IIb, IIn, whereas for type Ib/c the pairsfrequency is about three times as much as expected, after assuming the pair frequencydue to random coincidences. Simple applications of Poissonian statistic in regime ofsmall numbers ( [4]) suggest a significance of the order of ∼ 93%. Note that we did notinclude in our analysis SN 1998bw.Afterwards we have repeated the cross-correlation by varying the time windows (i.e.Trise ± ∆T/2; with ∆T = 22, 30. . . days) and computed the statistical significance, ofSN/GRB CONNECTION: A STATISTICAL APPROACH WITH BATSE ETC. 635Fig. 1. – Statistical significance of the frequencies of occurence of the pairs SN/GRB, for differentclasses of SNe, as a function of the Temporal Window (= Trise ±∆T/2).the number of pairs obtained after each run, with a Montecarlo simulation. For the resultof this simulation, see the Discussion.4. – The Monte Carlo simulationsWe built up 1000 Simulated Samples of SNe (SS) by keeping the SN positions in thesky (according to the SN catalogue) and changing randomly the SN types. We haverepeated this procedure for 14 temporal windows and we have computed the probabilityto obtain, by chance, the distributions of the SN-GRB pairs actually observed. Theresults are shown in fig. 1.5. – DiscussionWe can summarize our results as follows:1) None of the trends shown in fig. 1 is statistically significant with the possibleexception of SNe-Ib/c for which, in correspondence of a temporal window 26–4 daysbefore maximum (∆T = 22, the first point of the figure), the frequency of Ib/c obtainedwith the Asiago and BATSE archive is significant at the level of 96%, consistently withour preliminary analysis (see sect. 3). Our findings confirm the results of [10] andTable II. – The 6 pairs SN-GRB, with the SN Ib-c, selected with the described method.SN Type Epoch redshift GRB Epoch ErrorBox TypeSN SN SN GRB GRB GRB1993R Ic 1993.41 0.0055 930524 17h44m52s 18.0 short1996bx Ic 1996.88 0.062 961029 06h34m37s 3.3 long1997B Ic 1997.03 0.01 961218 19h35m31s 12.7 long1997dq Hyp 1997.83 0.0032 971013 08h43m23s 8.8 long1999dn Ib-c 1999.62 0.0094 990810 07h24m53s 4.4 short1999ex Ib-c 1999.85 0.0114 991021 01h58m41s 12.3 unknown636 S. VALENTI, E. CAPPELLARO, M. DELLA VALLE, F. FRONTERA ETC.disagree with the conclusions of [7] (both works have used smaller samples of GRBs andSNe).2) The other types of SNe do not show any physical connection with GRBs. Inparticular we do not find any evidence for the existence of a physical association betweenGRBs and SN-IIdw as proposed on the basis of spatial and temporal coincidencies forGRB 970514/SN 1997cy ( [5, 9]) and GRB 980910/SN 1999E ( [8]). Our results suggestthat SNe-IIdw are not the major class of progenitors for GRBs, although one can notexclude that sporadically SNII-dw are able to produce GRBs (see for example [3]).3) Since most SNe listed in the Asiago catalogue have been discovered within z < 0.1our results apply only to SN/GRB associations which occur in the “local” universe.4) A remarkable result of this statistical approach is to obtain a restricted sample ofSN/GRB associations (see table II) worth being further investigated.REFERENCES[1] Briggs M. S., Pendleton G. N., Kippen R. M. et al., ApjS, 518 (1999) 901.[2] Della Valle M. et al., these proceedings (2005).[3] Garnavich P. M., Stanek K. Z., Wyrzykowski L. et al., ApJ, 582 (2003) 924.[4] Gehrles N., ApJ, 303 (1986) 336.[5] Germany L. M., Reiss D. J., Sadler E. M. et al., ApJ, 533 (2000) 320.[6] Hamuy M., in Proceedings of “Core Collapse of Massive Stars”, AAS 200th Meeting, 2003Albuquerque, NM, edited by C. L. Fryer (Kluwer, Dordrecht) 2003.[7] Kippen R. M., Briggs M. S., Kommers J. M. et al., ApJ, 506 (1998) L27.[8] Rigon L., Turatto M., Benetti S. et al., MNRAS, 340 (2003) 191.[9] Turatto M., Suzuki T., Mazzali P. A. et al., APJ, 534 (2000) 57T.[10] Wang L. and Wheeler J. C., ApJ, 504 (1998) L87.

SN/GRB connection: A statistical approach with BATSE

and Asiago Catalogues

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SN/GRB connection: a statistical approach with BATSE and Asiago Catalogues

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