J. M. Castro Cerón

Bio: J. M. Castro Cerón is an academic researcher from University of Copenhagen. The author has contributed to research in topics: Gamma-ray burst & Galaxy. The author has an hindex of 19, co-authored 29 publications receiving 2178 citations. Previous affiliations of J. M. Castro Cerón include International Trademark Association & Space Telescope Science Institute.

Long γ-ray bursts and core-collapse supernovae have different environments

Abstract: When massive stars exhaust their fuel, they collapse and often produce the extraordinarily bright explosions known as core-collapse supernovae. On occasion, this stellar collapse also powers an even more brilliant relativistic explosion known as a long-duration γ-ray burst. One would then expect that these long γ-ray bursts and core-collapse supernovae should be found in similar galactic environments. Here we show that this expectation is wrong. We find that the γ-ray bursts are far more concentrated in the very brightest regions of their host galaxies than are the core-collapse supernovae. Furthermore, the host galaxies of the long γ-ray bursts are significantly fainter and more irregular than the hosts of the core-collapse supernovae. Together these results suggest that long-duration γ-ray bursts are associated with the most extremely massive stars and may be restricted to galaxies of limited chemical evolution. Our results directly imply that long γ-ray bursts are relatively rare in galaxies such as our own Milky Way.

Probing cosmic chemical evolution with gamma-ray bursts: GRB 060206 at z = 4.048

Abstract: Aims.We present early optical spectroscopy of the afterglow of the gamma-ray burst GRB 060206 with the aim of determining the metallicity of the GRB absorber and the physical conditions in the circumburst medium. We also discuss how GRBs may be important complementary probes of cosmic chemical evolution. Methods.Absorption line study of the GRB afterglow spectrum. Results.We determine the redshift of the GRB to be z=4.04795±0.00020. Based on the measurement of the neutral hydrogen column density from the damped Lyman-alpha line and the metal content from weak, unsaturated S II lines we derive a metallicity of [S/H]=-0.84±0.10. This is one of the highest metallicities measured from absorption lines at z~4. From the very high column densities for the forbidden Si II*, O I*, and O I** lines we infer very high densities and low temperatures in the system. There is evidence for the presence of H2 molecules with log N(H_2)~17.0, translating into a molecular fraction of log{f}≈ -3.5 with f=2N(H2)/(2N(H2) + N(H I)). Even if GRBs are only formed by single massive stars with metallicities below ~0.3 Zo, they could still be fairly unbiased tracers of the bulk of the star formation at z>2. Hence, metallicities as derived for GRB 060206 here for a complete sample of GRB afterglows will directly show the distribution of metallicities for representative star-forming galaxies at these redshifts.

GRB 050509B: Constraints on Short Gamma-Ray Burst Models

Abstract: We have obtained deep optical images with the Very Large Telescope at ESO of the first well-localized short-duration gamma-ray burst, GRB 050509b. We observed in the V and R bands at epochs starting at {approx}2 days after the GRB trigger and lasting up to three weeks. We detect no variable objects inside the small Swift/XRT X-ray error circle down to 5{sigma} limiting magnitudes of V = 26.5 and R = 25.2. The X-ray error circle includes a giant elliptical galaxy at z = 0.225, which has been proposed as the likely host of this GRB. Our limits indicate that if the GRB originated at z = 0.225, any supernova-like event accompanying the GRB would have to be over 100 times fainter than normal Type Ia SNe or Type Ic hypernovae, 5 times fainter than the faintest known Ia or Ic SNe, and fainter than the faintest known Type II SNe. Moreover, we use the optical limits to constrain the energetics of the GRB outflow, and conclude that there was very little radioactive material produced during the GRB explosion. These limits strongly constrain progenitor models for this short GRB.

A log NH I = 22.6 Damped Lyα Absorber in a Dark Gamma-Ray Burst: The Environment of GRB 050401*

Abstract: The optical afterglow spectrum of GRB 050401 (at z = 2.8992 ± 0.0004) shows the presence of a damped Lyα absorber (DLA), with log N = 22.6 ± 0.3. This is the highest column density ever observed in a DLA and is about 5 times larger than the strongest DLA detected so far in any QSO spectrum. From the optical spectrum, we also find a very large Zn column density, implying an abundance of [Zn/H] = -1.0 ± 0.4. These large columns are supported by the early X-ray spectrum from Swift XRT, which shows a column density (in excess of Galactic) of log NH = 22.21 assuming solar abundances (at z = 2.9). The comparison of this X-ray column density, which is dominated by absorption due to α-chain elements, and the H I column density derived from the Lyα absorption line allows us to derive a metallicity for the absorbing matter of [α/H] = -0.4 ± 0.3. The optical spectrum is reddened and can be well reproduced with a power law with SMC extinction, where AV = 0.62 ± 0.06. But the total optical extinction can also be constrained independent of the shape of the extinction curve: from the optical to X-ray spectral energy distribution, we find 0.5 AV 4.5. However, even this upper limit, independent of the shape of the extinction curve, is still well below the dust column that is inferred from the X-ray column density, i.e., AV = 9.1. This discrepancy might be explained by a small dust content with high metallicity (low dust-to-metals ratio). Gray extinction cannot explain the discrepancy, since we are comparing the metallicity to a measurement of the total extinction (without reference to the reddening). Little dust with high metallicity may be produced by sublimation of dust grains or may naturally exist in systems younger than a few hundred megayears.

The nature of GRB-selected submillimeter galaxies: hot and young

Abstract: We present detailed fits of the spectral energy distributions (SEDs) of four submillimeter galaxies selected by the presence of a gamma-ray burst (GRB) event (GRBs 980703, 000210, 000418, and 010222). These faint ~3 mJy submillimeter emitters at redshift ~1 are characterized by an unusual combination of long- and short-wavelength properties, namely enhanced submillimeter and/or radio emission combined with optical faintness and blue colors. We exclude an active galactic nucleus as the source of long-wavelength emission. From the SED fits, we conclude that the four galaxies are young (ages 3 × 108 M☉). Their high dust temperatures ( -->Td 45 K) indicate that GRB host galaxies are hotter, younger, and less massive counterparts to the submillimeter-selected galaxies detected so far. Future facilities like Herschel, the James Clerk Maxwell Telescope SCUBA-2, and ALMA will test this hypothesis, enabling measurement of dust temperatures of fainter GRB-selected galaxies.

Multi-messenger observations of a binary neutron star merger

Abstract: On 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of $\sim 1.7\,{\rm{s}}$ with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg2 at a luminosity distance of ${40}_{-8}^{+8}$ Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to 2.26 $\,{M}_{\odot }$. An extensive observing campaign was launched across the electromagnetic spectrum leading to the discovery of a bright optical transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC 4993 (at $\sim 40\,{\rm{Mpc}}$) less than 11 hours after the merger by the One-Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The optical transient was independently detected by multiple teams within an hour. Subsequent observations targeted the object and its environment. Early ultraviolet observations revealed a blue transient that faded within 48 hours. Optical and infrared observations showed a redward evolution over ~10 days. Following early non-detections, X-ray and radio emission were discovered at the transient's position $\sim 9$ and $\sim 16$ days, respectively, after the merger. Both the X-ray and radio emission likely arise from a physical process that is distinct from the one that generates the UV/optical/near-infrared emission. No ultra-high-energy gamma-rays and no neutrino candidates consistent with the source were found in follow-up searches. These observations support the hypothesis that GW170817 was produced by the merger of two neutron stars in NGC 4993 followed by a short gamma-ray burst (GRB 170817A) and a kilonova/macronova powered by the radioactive decay of r-process nuclei synthesized in the ejecta.

Gravitational Waves and Gamma-Rays from a Binary Neutron Star Merger: GW170817 and GRB 170817A

Abstract: On 2017 August 17, the gravitational-wave event GW170817 was observed by the Advanced LIGO and Virgo detectors, and the gamma-ray burst (GRB) GRB 170817A was observed independently by the Fermi Gamma-ray Burst Monitor, and the Anti-Coincidence Shield for the Spectrometer for the International Gamma-Ray Astrophysics Laboratory. The probability of the near-simultaneous temporal and spatial observation of GRB 170817A and GW170817 occurring by chance is $5.0\times {10}^{-8}$. We therefore confirm binary neutron star mergers as a progenitor of short GRBs. The association of GW170817 and GRB 170817A provides new insight into fundamental physics and the origin of short GRBs. We use the observed time delay of $(+1.74\pm 0.05)\,{\rm{s}}$ between GRB 170817A and GW170817 to: (i) constrain the difference between the speed of gravity and the speed of light to be between $-3\times {10}^{-15}$ and $+7\times {10}^{-16}$ times the speed of light, (ii) place new bounds on the violation of Lorentz invariance, (iii) present a new test of the equivalence principle by constraining the Shapiro delay between gravitational and electromagnetic radiation. We also use the time delay to constrain the size and bulk Lorentz factor of the region emitting the gamma-rays. GRB 170817A is the closest short GRB with a known distance, but is between 2 and 6 orders of magnitude less energetic than other bursts with measured redshift. A new generation of gamma-ray detectors, and subthreshold searches in existing detectors, will be essential to detect similar short bursts at greater distances. Finally, we predict a joint detection rate for the Fermi Gamma-ray Burst Monitor and the Advanced LIGO and Virgo detectors of 0.1–1.4 per year during the 2018–2019 observing run and 0.3–1.7 per year at design sensitivity.

The Supernova Gamma-Ray Burst Connection

Abstract: Observations show that at least some gamma-ray bursts (GRBs) happen simultaneously with core-collapse supernovae (SNe), thus linking by a common thread nature's two grandest explosions. We review here the growing evidence for and theoretical implications of this association, and conclude that most long-duration soft-spectrum GRBs are accompanied by massive stellar explosions (GRB-SNe). The kinetic energy and luminosity of well-studied GRB-SNe appear to be greater than those of ordinary SNe, but evidence exists, even in a limited sample, for considerable diversity. The existing sample also suggests that most of the energy in the explosion is contained in nonrelativistic ejecta (producing the supernova) rather than in the relativistic jets responsible for making the burst and its afterglow. Neither all SNe, nor even all SNe of Type Ibc produce GRBs. The degree of differential rotation in the collapsing iron core of massive stars when they die may be what makes the difference.

Gamma-ray bursts

Abstract: Gamma-ray bursts are the most luminous explosions in the Universe, and their origin and mechanism are the focus of intense research and debate. More than three decades after their discovery, and after pioneering breakthroughs from space and ground experiments, their study is entering a new phase with the recently launched Swift satellite. The interplay between these observations and theoretical models of the prompt gamma-ray burst and its afterglow is reviewed.

Short-Duration Gamma-Ray Bursts

Abstract: Gamma-ray bursts (GRBs) display a bimodal duration distribution with a separation between the short- and long-duration bursts at about 2 s. The progenitors of long GRBs have been identified as massive stars based on their association with Type Ic core-collapse supernovae (SNe), their exclusive location in star-forming galaxies, and their strong correlation with bright UV regions within their host galaxies. Short GRBs have long been suspected on theoretical grounds to arise from compact object binary mergers (neutron star–neutron star or neutron star–black hole). The discovery of short GRB afterglows in 2005 provided the first insight into their energy scale and environments, as well as established a cosmological origin, a mix of host-galaxy types, and an absence of associated SNe. In this review, I summarize nearly a decade of short GRB afterglow and host-galaxy observations and use this information to shed light on the nature and properties of their progenitors, the energy scale and collimation of the relativistic outflow, and the properties of the circumburst environments. The preponderance of the evidence points to compact object binary progenitors, although some open questions remain. On the basis of this association, observations of short GRBs and their afterglows can shed light on the on- and off-axis electromagnetic counterparts of gravitational wave sources from the Advanced LIGO/Virgo experiments.