• ### Broad-line type Ic Supernova SN 2014ad(1801.07046)

Jan. 22, 2018 astro-ph.HE
We present optical and ultraviolet photometry, and low resolution optical spectroscopy of the broad-line type Ic supernova SN 2014ad in the galaxy PGC 37625 (Mrk 1309), covering the evolution of the supernova during $-$5 to +87 d with respect to the date of maximum in $B$-band. A late phase spectrum obtained at +340 d is also presented. With an absolute $V$ band magnitude at peak of $M_{V}$ = $-$18.86 $\pm$ 0.23 mag, SN 2014ad is fainter than Gamma Ray Burst (GRB) associated supernovae, and brighter than most of the normal and broad-line type Ic supernovae without an associated GRB. The spectral evolution indicates the expansion velocity of the ejecta, as measured using the Si\,{\sc ii} line, to be as high as $\sim$ 33500 km\,s$^{-1}$ around maximum, while during the post-maximum phase it settles down at $\sim$ 15000 km\,s$^{-1}$. The expansion velocity of SN 2014ad is higher than all other well observed broad-line type Ic supernovae except the GRB associated SN 2010bh. The explosion parameters, determined by applying the Arnett's analytical light curve model to the observed bolometric light curve, indicate that it was an energetic explosion with a kinetic energy of $\sim$ (1 $\pm$ 0.3)$\times$10$^{52}$ ergs, a total ejected mass of $\sim$ (3.3 $\pm$ 0.8) M$_\odot$, and $\sim$ 0.24 M$_\odot$ of $^{56}$Ni was synthesized in the explosion. The metallicity of the host galaxy near the supernova region is estimated to be $\sim$ 0.5 Z$_\odot$.
• The TMT Detailed Science Case describes the transformational science that the Thirty Meter Telescope will enable. Planned to begin science operations in 2024, TMT will open up opportunities for revolutionary discoveries in essentially every field of astronomy, astrophysics and cosmology, seeing much fainter objects much more clearly than existing telescopes. Per this capability, TMT's science agenda fills all of space and time, from nearby comets and asteroids, to exoplanets, to the most distant galaxies, and all the way back to the very first sources of light in the Universe. More than 150 astronomers from within the TMT partnership and beyond offered input in compiling the new 2015 Detailed Science Case. The contributing astronomers represent the entire TMT partnership, including the California Institute of Technology (Caltech), the Indian Institute of Astrophysics (IIA), the National Astronomical Observatories of the Chinese Academy of Sciences (NAOC), the National Astronomical Observatory of Japan (NAOJ), the University of California, the Association of Canadian Universities for Research in Astronomy (ACURA) and US associate partner, the Association of Universities for Research in Astronomy (AURA).
• ### iPTF13bvn: The First Evidence of a Binary Progenitor for a Type Ib Supernova(1403.7288)

July 30, 2014 astro-ph.SR
The recent detection in archival HST images of an object at the the location of supernova (SN) iPTF13bvn may represent the first direct evidence of the progenitor of a Type Ib SN. The object's photometry was found to be compatible with a Wolf-Rayet pre-SN star mass of ~11 Msun. However, based on hydrodynamical models we show that the progenitor had a pre-SN mass of ~3.5 Msun and that it could not be larger than ~8 Msun. We propose an interacting binary system as the SN progenitor and perform evolutionary calculations that are able to self-consistently explain the light-curve shape, the absence of hydrogen, and the pre-SN photometry. We further discuss the range of allowed binary systems and predict that the remaining companion is a luminous O-type star of significantly lower flux in the optical than the pre-SN object. A future detection of such star may be possible and would provide the first robust identification of a progenitor system for a Type Ib SN.
• ### Properties of Newly Formed Dust Grains in The Luminous Type IIn Supernova 2010jl(1308.0406)

Aug. 2, 2013 astro-ph.SR
Supernovae (SNe) have been proposed to be the main production sites of dust grains in the Universe. Our knowledge on their importance to dust production is, however, limited by observationally poor constraints on the nature and amount of dust particles produced by individual SNe. In this paper, we present a spectrum covering optical through near-Infrared (NIR) light of the luminous Type IIn supernova (SN IIn) 2010jl around one and half years after the explosion. This unique data set reveals multiple signatures of newly formed dust particles. The NIR portion of the spectrum provides a rare example where thermal emission from newly formed hot dust grains is clearly detected. We determine the main population of the dust species to be carbon grains at a temperature of ~1,350 - 1,450K at this epoch. The mass of the dust grains is derived to be ~(7.5 - 8.5) x 10^{-4} Msun. Hydrogen emission lines show wavelength-dependent absorption, which provides a good estimate on the typical size of the newly formed dust grains (~0.1 micron, and most likely <~0.01 micron). We attribute the dust grains to have been formed in a dense cooling shell as a result of a strong SN-circumstellar media (CSM) interaction. The dust grains occupy ~10% of the emitting volume, suggesting an inhomogeneous, clumpy structure. The average CSM density is required to be >~3 x 10^{7} cm^{-3}, corresponding to a mass loss rate of >~0.02 Msun yr^{-1} (for a mass loss wind velocity of ~100 km s^{-1}). This strongly supports a scenario that SN 2010jl and probably other luminous SNe IIn are powered by strong interactions within very dense CSM, perhaps created by Luminous Blue Variable (LBV)-like eruptions within the last century before the explosion.
• ### SDSS J123813.73-033933.0, a cataclysmic variable evolved beyond the period minimum(1001.2599)

Jan. 21, 2010 astro-ph.SR
We present infrared JHK photometry of the cataclysmic variable SDSS J123813.73-033933.0 (SDSS1238)and analyze it along with optical spectroscopy, demonstrating that the binary system is most probably comprised of a massive white dwarf with Teff=12000+/-1000 K and a brown dwarf of spectral type L4. The inferred system parameters suggest that this system may have evolved beyond the orbital period minimum and is a bounce-back system. SDSS1238 stands out among CVs by exhibiting the cyclical variability (brightenings). These are not related to specific orbital phases of the binary system and are fainter than dwarf novae outbursts, that usually occur on longer timescales. This phenomenon has not been observed extensively and, thus, is poor understood. The new time-resolved, multi-longitude photometric observations of SDSS1238 allowed us to observe two consecutive brightenings and to determine their recurrence time. The period analysis of all observed brightenings during 2007 suggests a typical timescale that is close to a period of ~9.3 hours. However, the brightenings modulation is not strictly periodic, possibly maintaining coherence only on timescales of several weeks. The characteristic variability with double orbital frequency that clearly shows up during brightenings is also analyzed. The Doppler mapping of the system shows the permanent presence of a spiral arm pattern in the accretion disk. A simple model is presented to demonstrate that spiral arms in the velocity map appear at the location and phase corresponding to the 2:1 resonance radius and constitute themselves as a double-humped light curves. The long-term and short-term variability of this CV is discussed together with the spiral arm structure of an accretion disk in the context of observational effects taking place in bounce-back systems.
• ### The broad line type Ic supernova SN 2007ru: Adding to the diversity of type Ic supernovae(0805.3201)

March 9, 2009 astro-ph
Photometric and spectral evolution of the Type Ic supernova SN 2007ru until around 210 days after maximum are presented. The spectra show broad spectral features due to very high expansion velocity, normally seen in hypernovae. The photospheric velocity is higher than other normal Type Ic supernovae. It is lower than SN 1998bw at $\sim$ 8 days after the explosion, but is comparable at later epochs. The light curve evolution of SN 2007ru indicates a fast rise time of 8$\pm$3 days to $B$ band maximum and post-maximum decline more rapid than other broad-line Type Ic supernovae. With an absolute $V$ magnitude of -19.06, SN 2007ru is comparable in brightness with SN 1998bw and lies at the brighter end of the observed Type Ic supernovae. The ejected mass of \Nifs is estimated to be $\sim0.4\Msun$. The fast rise and decline of the light curve and the high expansion velocity suggest that SN 2007ru is an explosion with a high kinetic energy/ejecta mass ratio ($E_{\rm K}/M_{\rm {ej}}$). This adds to the diversity of Type Ic supernovae. Although the early phase spectra are most similar to those of broad-line SN 2003jd, the [OI] line profile in the nebular spectrum of SN 2007ru shows the singly-peaked profile, in contrast to the doubly-peaked profile in SN 2003jd. The singly-peaked profile, together with the high luminosity and the high expansion velocity, may suggest that SN 2007ru could be an aspherical explosion viewed from the polar direction. Estimated oxygen abundance 12 + log(O/H) of $\sim$8.8 indicates that SN 2007ru occurred in a region with nearly solar metallicity.
• ### Type Ib Supernova 2008D associated with the Luminous X-ray Transient 080109: An Energetic Explosion of a Massive Helium Star(0807.1674)

Feb. 18, 2009 astro-ph
We present a theoretical model for supernova (SN) 2008D associated with the luminous X-ray transient 080109. The bolometric light curve and optical spectra of the SN are modelled based on the progenitor models and the explosion models obtained from hydrodynamic/nucleosynthetic calculations. We find that SN 2008D is a more energetic explosion than normal core-collapse supernovae, with an ejecta mass of Mej = 5.3 +- 1.0 Msun and a kinetic energy of E = 6.0 +- 2.5 x 10^{51} erg. The progenitor star of the SN has a 6-8 Msun He core with essentially no H envelope (< 5 x 10^{-4} Msun) prior to the explosion. The main-sequence mass of the progenitor is estimated to be Mms =20-25 Msun, with additional systematic uncertainties due to convection, mass loss, rotation, and binary effects. These properties are intermediate between those of normal SNe and hypernovae associated with gamma-ray bursts. The mass of the central remnant is estimated as 1.6 - 1.8 Msun, which is near the boundary between neutron star and black hole formation.
• ### The evolution of the peculiar Type Ia supernova SN 2005hk over 400 days(0710.3636)

Feb. 25, 2008 astro-ph
$UBVRI$ photometry and medium resolution optical spectroscopy of peculiar Type Ia supernova SN 2005hk are presented and analysed, covering the pre-maximum phase to around 400 days after explosion. The supernova is found to be underluminous compared to "normal" Type Ia supernovae. The photometric and spectroscopic evolution of SN 2005hk is remarkably similar to the peculiar Type Ia event SN 2002cx. The expansion velocity of the supernova ejecta is found to be lower than normal Type Ia events. The spectra obtained $\gsim 200$ days since explosion do not show the presence of forbidden [\ion{Fe}{ii}], [\ion{Fe}{iii}] and [\ion{Co}{iii}] lines, but are dominated by narrow, permitted \ion{Fe}{ii}, NIR \ion{Ca}{ii} and \ion{Na}{i} lines with P-Cygni profiles. Thermonuclear explosion model with Chandrasekhar mass ejecta and a kinetic energy smaller ($\KE = 0.3 \times 10^{51} {\rm ergs}$) than that of canonical Type Ia supernovae is found to well explain the observed bolometric light curve. The mass of \Nifs synthesized in this explosion is $0.18 \Msun$. The early spectra are successfully modeled with this less energetic model with some modifications of the abundance distribution. The late spectrum is explained as a combination of a photospheric component and a nebular component.
• ### The Peculiar Type Ia Supernova 2005hk(astro-ph/0611354)

Nov. 10, 2006 astro-ph
We present a preliminary analysis of an extensive set of optical observations of the Type Ia SN 2005hk. We show that the evolution of SN 2005hk closely follows that of the peculiar SN 2002cx. SN 2005hk is more luminous than SN 2002cx, while still under-luminous compared to normal Type Ia supernovae. The spectrum at 9 days before maximum is dominated by conspicuous Fe III and Ni III lines, and the Si II 6355 line is also clearly visible. All these features have low velocity (~6000 km/s). The near maximum spectra show lines of Si II, S II, Fe II, Fe III, as well as other intermediate mass and iron group elements. Analysis with the code for synthetic spectra SYNOW indicates that all these spectral lines have similar velocities.
• ### GRB 051028: an intrinsically faint GRB at high redshift?(astro-ph/0609654)

Sept. 24, 2006 astro-ph
We present multiwavelength observations of the gamma-ray burst GRB 051028 detected by HETE-2 in order to derive its afterglow emission parameters and to determine the reason for its optical faintness when compared to other events. Observations were taken in the optical (2.0m Himalayan Chandra Telescope, 1.34m Tautenburg, 4.2m William Herschel Telescope) and in X-rays (Swift/XRT) between 2.7 hours and 10 days after the onset of the event. The data can be interpreted by collimated emission in a jet with a typical value of $p$ = 2.4 which is moving in an homogeneous interstellar medium and with a cooling frequency nu_{c} still above the X-rays at 0.5 days after the burst onset. GRB 051028 can be classified as a gray'' or potentially dark'' GRB. On the basis of the combined optical and Swift/XRT data, we conclude that the reason for the optical dimness is not extra absorption in the host galaxy, but rather the GRB taking place at high-redshift.We also notice the very striking similarity with the optical lightcurve of GRB 050730, a burst with a spectroscopic redshift of 3.967, although GRB 051028 is about 3 mag fainter. We suggest that the bump could be explained by multiple energy injection episodes and that the burst is intrinsically faint when compared to the average afterglows detected since 1997. The non-detection of the host galaxy down to R = 25.1 is also consistent with the burst arising at high redshift, compatible with the published pseudo-z of 3.7 +/- 1.8.
• ### Post-Outburst Phase of McNeil's Nebula (V1647 Orionis)(astro-ph/0602044)

Feb. 2, 2006 astro-ph
We present a detailed study of the post-outburst phase of McNeil's nebula (V1647 Ori) using optical B,V,R,I and NIR J,H,K photometric and low resolution optical spectroscopic observations. The observations were carried out with the HFOSC, NIRCAM, TIRCAM and NICMOS cameras on the 2m HCT and 1.2m PRL telescopes during the period 2004 Feb-2005 Dec. The optical/NIR observations show a general decline in brightness of the exciting source of McNeil's nebula (V1647 Ori). Our recent optical images show that V1647 Ori has faded by more than 3 mags since Feb 2004. The optical/NIR photometric data also show a significant variation in the mags (Delta V = 0.78 mag, Delta R = 0.44 mag, Delta I = 0.21 mag, Delta J = 0.24 mag and Delta H = 0.20 mag) of V1647 Ori within a period of one month, which is possibly undergoing a phase similar to eruptive variables, like EXors or FUors. The optical spectra show a few features such as strong Halpha emission with blue-shifted absorption and the CaII IR triplet (8498A, 8542A and 8662A) in emission. As compared to the period just after outburst, there is a decrease in the depth and extent of the blue-shifted absorption component, indicating a weakening in the powerful stellar wind. The presence of the CaII IR triplet in emission confirms that V1647 Ori is a PMS star. The long-term, post-outburst photometric observations of V1647 Ori suggest an EXor, rather than an FUor event. An optical/IR comparison of the region surrounding McNeil's nebula shows that the optical nebula is more widely and predominantly extended to the north, whereas the IR nebula is relatively confined (dia ~ 60 arcsec), but definitely extended, to the south, too.
• ### The Unique Type Ib Supernova 2005bf: A WN Star Explosion Model for Peculiar Light Curves and Spectra(astro-ph/0509557)

Oct. 28, 2005 astro-ph
Observations and modeling for the light curve (LC) and spectra of supernova (SN) 2005bf are reported. This SN showed unique features: the LC had two maxima, and declined rapidly after the second maximum, while the spectra showed strengthening He lines whose velocity increased with time. The double-peaked LC can be reproduced by a double-peaked $^{56}$Ni distribution, with most $^{56}$Ni at low velocity and a small amount at high velocity. The rapid post-maximum decline requires a large fraction of the $\gamma$-rays to escape from the $^{56}$Ni-dominated region, possibly because of low-density holes''. The presence of Balmer lines in the spectrum suggests that the He layer of the progenitor was substantially intact. Increasing $\gamma$-ray deposition in the He layer due to enhanced $\gamma$-ray escape from the $^{56}$Ni-dominated region may explain both the delayed strengthening and the increasing velocity of the He lines. The SN has massive ejecta ($\sim6-7\Msun$), normal kinetic energy ($\sim 1.0-1.5\times 10^{51}$ ergs), high peak bolometric luminosity ($\sim 5\times 10^{42}$ erg s$^{-1}$) for an epoch as late as $\sim$ 40 days, and a large $^{56}$Ni mass ($\sim0.32\Msun$). These properties, and the presence of a small amount of H suggest that the progenitor was initially massive (M$\sim 25-30 \Msun$) and had lost most of its H envelope, and was possibly a WN star. The double-peaked $^{56}$Ni distribution suggests that the explosion may have formed jets that did not reach the He layer. The properties of SN 2005bf resemble those of the explosion of Cassiopeia A.
• ### Radio, millimeter and optical monitoring of GRB030329 afterglow: Constraining the double jet model(astro-ph/0506169)

June 8, 2005 astro-ph
We present radio, millimeter and optical observations of the afterglow of GRB030329. UBVR_{C}I_{C} photometry is presented for a period of 3 hours to 34 days after the burst. Radio monitoring at 1280 MHz has been carried out using the GMRT for more than a year. Simultaneous millimeter observations at 90 GHz and 230 GHz have been obtained from the Swedish-ESO Submillimeter Telescope (SEST) and the IRAM-PdB interferometer over more than a month following the burst. We use these data to constrain the double jet model proposed by Berger et al. (2003) for this afterglow. We also examine whether instead of the two jets being simultaneously present, the wider jet could result from the initially narrow jet, due to a fresh supply of energy from the central engine after the jet break''.
• ### Type Ia supernova SN 2003du: optical observations(astro-ph/0409494)

Sept. 21, 2004 astro-ph
UBVRI photometry and optical spectra of type Ia supernova SN 2003du obtained at the Indian Astronomical Observatory for nearly a year since discovery are presented. The apparent magnitude at maximum was B=13.53 +/- 0.02 mag, and the colour (B-V) = -0.08 +/- 0.03 mag. The luminosity decline rate, Delta(m_{15}(B)) = 1.04 +/- 0.04 mag indicates an absolute B magnitude at maximum of M_B = -19.34 +/- 0.3 mag and the distance modulus to the parent galaxy as mu=32.89 +/- 0.4.The light curve shapes are similar, though not identical, to those of SNe 1998bu and 1990N, both of which had luminosity decline rates similar to that of SN 2003du and occurred in spiral galaxies. The peak bolometric luminosity indicates that 0.9 Msun mass of 56Ni was ejected by the supernova. The spectral evolution and the evolution of the Si II and Ca II absorption velocities closely follows that of SN 1998bu, and in general, is within the scatter of the velocities observed in normal type Ia supernovae. The spectroscopic and photometric behaviour of SN 2003du is quite typical for SNe Ia in spirals. A high velocity absorption component in the Ca II (H & K) and IR-triplet features, with absorption velocities of ~20,000 km/s and ~22,000 km/s respectively, is detected in the pre-maximum spectra of days -11 and -7.
• ### Early optical and millimeter observations of GRB 030226 afterglow(astro-ph/0312487)

Jan. 13, 2004 astro-ph
The CCD magnitudes in Johnson $UBV$ and Cousins $RI$ photometric passbands for the afterglow of the long duration GRB 030226 are presented. Upper limits of a few mJy to millimeter wave emission at the location of optical are obtained over the first two weeks. The optical data presented here, in combination with other published data on this afterglow, show an early $R$ band flux decay slope of 0.77$\pm$0.04, steepening to 2.05$\pm$0.04 about 0.65$\pm$0.03 day after the burst. Interpreted as the jet break'', this indicates a half opening angle of $\sim 3.2$ degree for the initial ejection, for an assumed ambient density of $\sim 1 {\rm cm}^{-3}$. Broadband spectra show no appreciable evolution during the observations, and indicate the presence of synchrotron cooling frequency $\nu_c$ near the upper edge of the optical band. From the broadband spectra we derive an electron energy distribution index $p = 2.07\pm0.06$ and an intrinsic extinction $E(B - V)\sim0.17$. Millimeter upper limits are consistent with these derived parameters.
• ### Optical observations of the bright long duration peculiar GRB 021004 afterglow(astro-ph/0211108)

Oct. 17, 2003 astro-ph
The CCD magnitudes in Johnson $B,V$ and Cousins $R$ and $I$ photometric passbands are determined for the bright long duration GRB 021004 afterglow from 2002 October 4 to 16 starting $\sim$ 3 hours after the $\gamma-$ray burst. Light curves of the afterglow emission in $B$,$V$,$R$ and $I$ passbands are obtained by combining these measurements with other published data. The earliest optical emission appears to originate in a revese shock. Flux decay of the afterglow shows a very uncommon variation relative to other well-observed GRBs. Rapid light variations, especially during early times ($\Delta t < 2$ days) is superposed on an underlying broken power law decay typical of a jetted afterglow. The flux decay constants at early and late times derived from least square fits to the light curve are $0.99\pm0.05$ and $2.0\pm0.2$ respectively, with a jet break at around 7 day. Comparison with a standard fireball model indicates a total extinction of $E(B-V)=0.20$ mag in the direction of the burst. Our low-resolution spectra corrected for this extinction provide a spectral slope $\beta = 0.6\pm0.02$. This value and the flux decay constants agree well with the electron energy index $p\sim 2.27$ used in the model. The derived jet opening angle of about $7^{\circ}$ implies a total emitted gamma-ray energy $E_{\gamma} = 3.5\times10^{50}$ erg at a cosmological distance of about 20 Gpc. Multiwavelength observations indicate association of this GRB with a star forming region, supporting the case for collapsar origin of long duration GRBs.
• ### Optical afterglow of the not so dark GRB 021211(astro-ph/0304481)

Oct. 5, 2003 astro-ph
We determine Johnson $B,V$ and Cousins $R,I$ photometric CCD magnitudes for the afterglow of GRB 021211 during the first night after the GRB trigger. The afterglow was very faint and would have been probably missed if no prompt observation had been conducted. A fraction of the so-called dark'' GRBs may thus be just optically dim'' and require very deep imaging to be detected. The early-time optical light curve reported by other observers shows prompt emission with properties similar to that of GRB 990123. Following this, the afterglow emission from $\sim 11$ min to $\sim 33$ days after the burst is characterized by an overall power-law decay with a slope $1.1\pm0.02$ in the $R$ passband. We derive the value of spectral index in the optical to near-IR region to be 0.6$\pm$0.2 during 0.13 to 0.8 day after the burst. The flux decay constant and the spectral slope indicate that optical observations within a day after the burst lies between cooling frequency and synchrotron maximum frequency.
• ### SN 2002ap, the hypernova of class Ic(astro-ph/0304482)

April 27, 2003 astro-ph
The supernova SN 2002ap was discovered in the outer regions of the nearby spiral M74 on January 29.4 UT. Early photometric and spectroscopic observations indicate the supernova belongs to the class of Ic hypernova. Late time (After JD 2452500) light curve decay slopes are similar to that of the hypernovae SN 1997ef and SN 1998bw. We present here the $BVRI$ photometric light curves and colour evolutions of SN 2002ap to investigate the late time nature of the light curve.
• ### Optical Photometry of the GRB 010222 Afterglow(astro-ph/0104363)

July 24, 2001 astro-ph
The optical afterglow of GRB 010222 was observed using the recently installed 2-m telescope at the Indian Astronomical Observatory, Hanle, and the telescopes at the Vainu Bappu Observatory, Kavalur, beginning ~ 0.6 day after the detection of the event. The results based on these photometric observations combined with others reported in the literature are presented in this paper. The R band light curve shows an initial decline of intensities proportional to t^{-0.542} which steepens, after 10.3 hours, to t^{-1.263}. Following the model of collimated outflow, the early break in the light curve implies a very narrow beam angle (~ 2-3 deg). The two decay rates are consistent with the standard jet model in a uniform density ambient medium, but require a hard spectrum of electron power density with p ~ 1.5. The R band light between 14 and 17 hours since outburst departs from the power law fit by 0.1 mag and shows some evidence for fluctuations over timescales of an hour in the observer's frame. Such deviations are expected due to density inhomogeneities if the ambient medium is similar to the local interstellar medium. GRB 010222 is thus an example of a highly collimated outflow with a hard spectrum of electron energy distribution in normal interstellar environment.
• ### Short term optical variability in broad absorption line QSOs(astro-ph/9712294)

Dec. 22, 1997 astro-ph
We present the first results from a pilot programme to monitor the short term optical variability in Broad Absorption Line system QSOs. Intra-night optical variations of ~5% were detected on time scales of ~ one hour in QSOs 0846+156 and 0856+172. Further, the mean magnitude level decreased in the two objects by ~0.05 and ~0.15 magnitude respectively during the period of our observations. The observed light curves are quite similar to those previously seem in the flat spectrum radio-loud sources, especially the BL Lacertae objects, and can provide important constraints for the origin of microvariability, and also a possible evolutionary link between the radio-loud and the radio-quiet QSOs.