50 Years of Gamma-Ray Bursts* * With a biased overemphasis on Neil & stuff I was involved in Josh Bloom UC Berkeley @profjsb IPN Vela Series CGRO (BATSE) Swift HETE-2 Fermi BeppoSAX INTEGRAL High-Energy Era Afterglow Era Multimessenger Era GRB 980425/SN 1998bw GRB 130603B GRB 090423 GRB 030329/SN 2003dh March 5 GRB 970508 GRB 080319b Events GRB 130427A Event Sw J1644+57 GRB 670702 (SGR 0525-66) GRB 970228 GRB 050509b GW/GRB 170817 1970 1980 1990 2000 2010 2020 Burrows+05 Colgate Paczyński Great Debate Frail+01 Berger 14 May 68 86 Sari, Piran, Narayan 98 Gehrels, 50 Years of Eichler+89 Mészáros & Rees 97 Ramirez-Ruiz, & Fox 09 GRBs Klebesadal, Gehrels Aggregate Insights Aggregate Band+93/Kouvelitou+93 Lamb & Reichart 00 Olson & Strong 73 & Memorial Paczyński & Rhoads 93 Meegan+92 Li & Paczyński 98 Theory MacFadyen & Woosley 99 Josh Bloom Discovery & Demographics High-energy Era GRB 670702 Theory: Colgate 68 Discovery & Demographics High-energy Era “short” “long” BATSE •Isotropic SHBs LSBs • Non-Euclidean/ Inhomogeneous 1000 Meegan+92 • Two Populations 100 GRBs XRRs XRFs Bloom10 Kouvelitou+93, Mazets+81 Norris+84 © 1992 Nature Publishing Group © 1992 Nature Publishing Group Discovery & Demographics High-energy Era “No Host Problem” (cf. Larson 97) “Great Debate” here in DC (Apr 95): Galactic or Cosmological? Rees, Paczyński, Lamb https://apod.nasa.gov/debate/debate95.html Discovery & Demographics THE CORRECTED LOG N-LOG High-energy Era FLUENCE DISTRIBUTION OF COSMOLOGICAL v-RAY BURSTS Joshua S. Bloom 1'2, Edward E. Fenimore 2, Jean in 't Zand 2'a 1Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 0P138 “No Host Problem” (cf. Larson 97) 2Los Alamos National Laboratory, Los Alamos, NM 875~ 3 Goddard Space Flight Center, Greenbelt, MD P0771 “Great Debate” here in DC (Apr 95): Recent analysis of relativistically expanding shells of cosmological Galactic or Cosmological? "c-ray bursts has shown that if the bursts are cosmological, then most likely total energy (E0) is standard and not peak luminosity (L0). Assuming a fiat Friedmann cosmology (qo = 1/2, A = 0) and constant rate density (p0) of bursting sources, we fit a standard candle energy to a uniformly selected log N-log S in the BATSE 3B catalog correcting 3rd Huntsville Conference (Oct 95) for fluence efficiency and averaging over 48 observed spectral shapes. We find the data consistent with E0 = 7.3+_°:0r x 1051 ergs and discuss implications of this energy for cosmological models of 7-ray bursts. INTRODUCTION On the basis of strong threshold effects of detectors, Klebesadel, Fenimore, and Laros (7) concluded that GRB fluence tests were largely inconclusive. As a result, nearly all subsequent number-brightness tests have used peak flux (P) rather than fluence (S). However, the standard candle peak lu- minosity assumption that is required by log N-log P studies is unphysical. If, for instance, bursts originateRees, at Paczycosmologicalński, distances Lamb and are produced by colliding neutron stars then one might expect that total energy would be standard and not peak luminosity. Moreover, recent analysis of relativistically expanding shellhttps://apod.nasa.gov/debate/debate95.html models has cast doubt on the standard L0 assumption (9). In this paper, we seek to eliminate the large threshold effects present in log N-log S studies by correcting the observed number of bursts at a given fluence by the trigger efficiency of the detector. PVO CONSISTENCY CHECK The Pioneer Venus Orbiter (PVO) had a peak flux trigger sampled on 0.25, 1.0, and 4.0 sec timescales and was sensitive to bursts down to fluxes of 5 × 10-6 erg cm -2. Despite a substantially lower fluence trigger sensitivity range, PVO saw hundreds more bright bursts than BATSE due the relatively long on-time and large sky-coverage of PVO. As the bright region of the BATSE log N-log (~) 1996 American Institute of Physics 321 at z ~ 0 especially if E0 is large. Therefore, for a given E0, Si, and ¢i(E) we first solve for the redshifts, zi, of the baseline events associated with each spectral shape. The standard// candle energy,¢ooo E0, is(.) given by, Eo = 4~rR~,= N(t,)dts E¢i dE (1) ,#30 where N(ts) is the normalization of the spectrum (ergs keV -1) at time t, at the source. The comoving distance, Ri,z, is defined in eq. [2] of ref. (2). The observed ith baseline burst fluence in the energy range 50-300 keV is, -- abo3°° E¢i [rl+z,.E] l + zi J dE, (2) where N(tob~) is the observed normalization of the spectrum. For a given standard candle energy, E0, we numerically determine the red- shift (1 + zi) of the ith baseline burst using eqs. (1, 2) and letting zr = zi. Note that (1 + zi) f g(ts)dt, = f N(tobs)dtobs. Instead of assuming a spectral shape at the source, we use an average over baseline spectra to compute the number of expected observed bursts, ANexp[Sj to Sj+I] in some fluence range [Sj, Sj+I]: NBAND fR(Sj+I ) P0 AN~xp[Sj to Sj+I]- 4~r ~ j~ e[Si(r)] r2dr. (3) NBAND .= R(Si) 1 + Zr where NBAND ---- 48 is the number of baseline spectra used and po is the rate density of bursts per comoving volume. The quantity Si(r) is the predicted fluence (using eqs. [1, 2]) of the it__h baseline burst if it was at a distance r. This distance corresponds to a redshift 1 + zr. Discovery & Demographics We constructTABLE 11 fluence1. Best binsFit Distribution(in BATSE of channels E0 = 7.0 2+3× 1051 corresponding ergs to approximatelyTHE CORRECTED50-300Fluence keV) Ranges~(50-300 of roughly keV)equalLOG number AN[SjN-LOG of tobursts. S3+i ] We select High-energy Era burstsBin Number(j) with Cmin/Cmax Sj > 1 on eitherSj+I the 256 Observedor 1024 bms Predictedtimescale, 1then + zj find aFLUENCE minimized X2 between DISTRIBUTION the number of predicted burstsOF and observed 1 2.16e-07 3.82e-07 51 38.4 3.88 by varying E0. For 9 degrees of freedom we find an acceptable X2 = 14.7 COSMOLOGICAL2 3.82e-07 5.85e-07 v-RAY BURSTS42 50.5 3.24 corresponding to a standard candle E0 .....7 2 +0.7 a.0 × 1051 ergs. Table (I) gives 3 5.85e-07 7.55e-07 42 36.3 2.84 the bin ranges, number of observed bursts per bin, number of predicted bursts Joshua4 S. Bloom7.55e-07 1'2, Edward 1.13e-06E. Fenimore 2, Jean46 in 't Zand63.0 2'a 2.64 for the 5best fit energy,1.13e-06 and their 1.43e-06implied redshifts. 37 36.8 2.36 1Harvard-Smithsonian6 1.43e-06 Center for2.00e-06 Astrophysics, Cambridge,48 MA 0P13849.7 2.22 “No Host Problem” (cf. Larson 97) 2Los Alamos National Laboratory, Los Alamos, NM 875~ 7 2.00e-06 CONCLUSIONS2.80e-06 39 44.3 2.04 8 3 Goddard2.80e-06 Space Flight Center,4.05e-06 Greenbelt, MD 44P0771 41.1 1.89 9 4.05e-06 6.20e-06 37 37.2 1.74 Our fit of E0= 7 •0 +0.7-1.0x 1051 [30-2000 keV] ergs seems a plausible number “Great Debate” here in DC (Apr 95): 10 6.20e-06 1.36e-05 40 44.7 1.60 on the Recentbasis thatanalysis GRBs of relativistically last on the expandingaverage 10shells sec ofand cosmological L0 = 4.6 x 105° erg Galactic or Cosmological? 11 1.36e-05 6.60e-05 41 32.3 1.41 s -1 from"c-ray logbursts N-log has shown P studies that if (2).the burstsHowever, are cosmological, this E0 implies then most a rather large efficiencyIn ergslikely cmoftotal -2energy energy conversion (E0) is standard to 7-rays and (~not 10%)peak luminosityif the bursting (L0). mechanism bis BurstscollidingAssuming with neutron aCmin/Cmax fiat Friedmann stars >(Mtotal 1cosmology on the~ 2.8Mo).256 (qo or= 1/2,1024 Nevertheless, A =ms 0) timescale and constant this in resultBATSE would 3B. rate density (p0) of bursting sources, we fit a standard candle energy to seem a touniformly help resolve selected the log N-log"no-host" S in theproblem BATSE (cf. 3B catalogref (3)). correcting Interestingly, that 3rd Huntsville Conference (Oct 95) the dimmestfor fluence bursts efficiency (S -and 5 xaveraging 10 -s erg over cm 48 -2) observed are required spectral to shapes. be at a redshift of 1 + z We~_ 6.4find given the data this consistent E0, would with seem E0 = to7.3+_°:0 ruler xout 1051 several ergs and cosmological discuss models that implicationsrequire GRB of thisprogenitors energy for cosmologicalto be 324within models galaxies of 7-ray (although bursts. see reference (8)). This surprisingly high redshift is due to the correct blueshifting of the baseline spectra back to the source in eq. (1). If we neglect this factor, we obtain a smaller, more tenableINTRODUCTION redshift of the dimmest bursts (1 + z = 5.2). Whatever the conclusion about the models, we note two important results. First,On the the basis bend of instrong the thresholdlog N-log effects S curve of detectors,in BATSE Klebesadel, is real, not Fenimore, an artifact of andstrong Laros threshold (7) concluded effects. that This GRB implies fluence that tests we were are largelyseeing eitherinconclusive. a truncated Asspatial a result, distribution nearly all of subsequent GRBs (as number-brightnessin Galactic models) tests or have an effectused peakdue to the fluxexpansion (P) rather of the than universe. fluence The(S). bendHowever, might thealso standard be caused candle by a combinationpeak lu- of minosityrate density assumption or number that density is required evolution, by log andN-log a study P studies of their is unphysical.possible effects is If, for instance, bursts originate at cosmological distances and are produced certainly warranted.