118517321
Optical Observations of the Rapidly Expanding Type Ia Supernova 2007gi
We present optical photometry and spectra for the Type Ia supernova (SN Ia) 2007gi in the nearby galaxy NGC 4036. SN 2007gi is characterized by extremely high-velocity (HV) features of the intermediate-mass elements (Si, Ca, and S), with expansion velocities (vexp) approaching ∼15;500 kms � 1 near-maximum brightness (compared to ∼10;600 kms � 1 for SNe Ia with normal vexp). SN 2007gi reached a B-band peak magnitude of 13:25 � 0:04 mag with a decline rate of Δm15ðBÞðtrue Þ¼ 1:33 � 0:09 mag. The B-band light curve of SN 2007gi demonstrated an interesting two-stage evolution during the nebular phase, with a decay rate of 1:16 � 0:05 mag ð100 daysÞ � 1 during t ¼ 60-90 days and 1:61 � 0:04 mag ð100 daysÞ � 1 thereafter. Such behavior was also ob- served in the HV SN Ia 2006X, and might be caused by the interaction between supernova ejecta and circumstellar material (CSM) around HV SNe Ia. Based on a sample of a dozen well-observed R band (or unfiltered) light curves of SNe Ia, we confirm that the HV events may have a faster rise time to maximum than those with normal vexp.
15159726
First results from the lick AGN monitoring project: The mass of the black hole in ARP 151
We have recently completed a 64 night spectroscopic monitoring campaign at the Lick Observatory 3 m Shane telescope with the aim of measuring the masses of the black holes in 13 nearby (z < 0.05) Seyfert 1 galaxies with expected masses in the range ~106-107 M☉. We present here the first results from this project—the mass of the central black hole in Arp 151. Strong variability throughout the campaign led to an exceptionally clean Hβ lag measurement in this object of 4.25−0.66+0.68 days in the observed frame. Coupled with the width of the Hβ emission line in the variable spectrum, we determine a black hole mass of (7.1 ± 1.2) × 106 M☉, assuming the Onken et al. normalization for reverberation-based virial masses. We also find velocity-resolved lag information within the Hβ emission line which clearly shows infalling gas in the Hβ-emitting region. Further detailed analysis may lead to a full model of the geometry and kinematics of broad line region gas around the central black hole in Arp 151.
16104319
The Lick AGN Monitoring Project: Broad-line Region Radii and Black Hole Masses from Reverberation Mapping of Hβ
We have recently completed a 64-night spectroscopic monitoring campaign at the Lick Observatory 3-m Shane telescope with the aim of measuring the masses of the black holes in 12 nearby (z < 0: 05) Seyfert 1 galaxies with expected masses in the range � 10 6 -10 7 Mand also the well-studied nearby active galactic nucleus (AGN) NGC 5548. Nine of the objects in the sample (including NGC 5548) showed optical variability of sufficient strength during the monitoring campaign to all ow for a time lag to be measured between the continuum fluctuations and the response to these fluctuation s in the broad Hemission. We present here the light curves for all the objects in this sample and the subseq uent Htime lags for the nine objects where these measurements were possible. The Hlag time is directly related to the size of the broad-line reg ion in AGNs, and by combining the Hlag time with the measured width of the Hemission line in the variable part of the spectrum, we determine the virial mass of the central sup ermassive black hole in these nine AGNs. The absolute calibration of the black hole masses is based on the normalization derived by Onken et al., which brings the masses determined by reverberation mapping into agreement with the local MBH -�? relationship for quiescent galaxies. We also examine the time lag response as a function of velocity across the Hline profile for six of the AGNs. The analysis of four leads to rather ambiguous results with relatively flat time lags as a function of velocity. However, SBS 1116+583A exhibits a symmetric time lag response around the line center reminiscent of simple models for circularly orbiting broad -line region (BLR) clouds, and Arp 151 shows an asymmetric profile that is most easily explained by a simple g ravitational infall model. Further investigation will be necessary to fully understand the constraints place d on physical models of the BLR by the velocity- resolved response in these objects. Subject headings:galaxies: active - galaxies: nuclei - galaxies: Seyfert
119183491
SN 2008iy: an unusual Type IIn Supernova with an enduring 400-d rise time
We present spectroscopic and photometric observations of the Type IIn supernova (SN) 2008iy. SN 2008iy showed an unprecedentedly long rise time of ~400 d, making it the first known SN to take significantly longer than 100 d to reach peak optical luminosity. The peak absolute magnitude of SN 2008iy was M r ≈ -19.1 mag, and the total radiated energy over the first ~700 d was ~2 x 10 50 erg. Spectroscopically, SN 2008iy is very similar to the Type IIn SN 1988Z at late times and, like SN 1988Z, it is a luminous X-ray source (both SNe had an X-ray luminosity L X > 10 41 erg s -1 ). SN 2008iy has a growing near-infrared excess at late times similar to several other SNe IIn. The Hα emission-line profile of SN 2008iy shows a narrow P Cygni absorption component, implying a pre-SN wind speed of ~100 km s -1 . We argue that the luminosity of SN 2008iy is powered via the interaction of the SN ejecta with a dense, clumpy circumstellar medium. The ~400-d rise time can be understood if the number density of clumps increases with distance over a radius ~1.7 x 10 16 cm from the progenitor. This scenario is possible if the progenitor experienced an episodic phase of enhanced mass loss < 1 century prior to explosion or if the progenitor wind speed increased during the decades before core collapse. We favour the former scenario, which is reminiscent of the eruptive mass-loss episodes observed for luminous blue variable (LBV) stars. The progenitor wind speed and increased mass-loss rates serve as further evidence that at least some, and perhaps all, Type IIn SNe experience LBV-like eruptions shortly before core collapse. We also discuss the host galaxy of SN 2008iy, a subluminous dwarf galaxy, and offer a few reasons why the recent suggestion that unusual, luminous SNe preferentially occur in dwarf galaxies may be the result of observational biases.
118497523
The Transitional Stripped-Envelope SN 2008ax: Spectral Evolution and Evidence for Large Asphericity
Supernova (SN) 2008ax in NGC 4490 was discovered within hours after shock breakout, presenting the rare opportunity to study a core-collapse SN beginning with the initial envelope-cooling phase immediately following shock breakout. We present an extensive sequence of optical and near-infrared spectra, as well as three epochs of optical spectropolarimetry. Our initial spectra, taken two days after shock breakout, are dominated by hydrogen Balmer lines at high velocity. However, by maximum light, He I lines dominated the optical and near-infrared spectra, which closely resembled those of normal Type Ib supernovae (SNe Ib) such as SN 1999ex. This spectroscopic transition defines Type IIb SNe, but the strong similarity of SN 2008ax to normal SNe Ib beginning near maximum light, including an absorption feature near 6270 A due to Hα at high velocities, suggests that many objects classified as SNe Ib in the literature may have ejected similar amounts of hydrogen as SN 2008ax, roughly a few × 0.01 M ☉. Only the unusually early discovery of SN 2008ax allowed us to observe the spectroscopic signatures of the hydrogen-rich outer ejecta. Early-time spectropolarimetry (six and nine days after shock breakout) revealed strong line polarization modulations of 3.4% across Hα, indicating the presence of large asphericities in the outer ejecta and possibly that the spectrum of SN 2008ax could be dependent on the viewing angle. After removal of interstellar polarization, the continuum shares a common polarization angle with the hydrogen, helium, and oxygen lines, while the calcium and iron absorptions are oriented at different angles. This is clear evidence of deviations from axisymmetry even in the outer ejecta. Intrinsic continuum polarization of 0.64% only nine days after shock breakout shows that the outer layers of the ejecta were quite aspherical. A single epoch of late-time spectropolarimetry as well as the shapes of the nebular line profiles demonstrate that asphericities extended from the outermost layers all the way down to the center of this core-collapse SN. SN 2008ax may in some ways be an extragalactic analog of the explosion giving rise to Cassiopeia A, which has recently been determined to be a remnant of an SN IIb.
15737210
CORONAL LINES AND DUST FORMATION IN SN 2005ip: NOT THE BRIGHTEST, BUT THE HOTTEST TYPE IIn SUPERNOVA
We present optical photometry and spectroscopy of SN 2005ip for the first 3 yr after discovery, showing an underlying Type II-L supernova (SN) interacting with a steady wind to yield an unusual Type IIn spectrum. For the first ~160 days, it had a fast linear decline from a modest peak absolute magnitude of about –17.4 (unfiltered), followed by a plateau at roughly –14.8 for more than 2 yr. Initially having a normal broad-lined spectrum superposed with sparse narrow lines from the photoionized circumstellar medium (CSM), it quickly developed signs of strong CSM interaction with a spectrum similar to that of SN 1988Z. As the underlying SN II-L faded, SN 2005ip exhibited a rich high-ionization spectrum with a dense forest of narrow coronal lines, unprecedented among SNe but reminiscent of some active galactic nuclei. The line-profile evolution of SN 2005ip confirms that dust formation caused its recently reported infrared excess, but these lines reveal that it is the first SN to show clear evidence for dust in both the fast SN ejecta and the slower postshock gas. SN 2005ip's complex spectrum confirms the origin of the strange blue continuum in SN 2006jc, which also had postshock dust formation. We suggest that SN 2005ip's late-time plateau and coronal spectrum result from rejuvenated CSM interaction between a sustained fast shock and a clumpy stellar wind, where X-rays escape through the optically thin interclump regions to heat the preshock CSM to coronal temperatures.
121291778
Infrared aspects of the one-loop, scalar glueball operator-product expansion
Abstract The one-loop gluon condensate contribution to the 0 ++ glueball correlation function will be calculated using a non-zero momentum insertion of the condensates. It is demonstrated that the operator-product expansion coefficient is free of infrared divergences, supporting the concept that the condensates contain the long-distance effects in the operator-product expansion. It is anticipated that these results will be important for improved sum-rule estimates of the glueball mass and width.
120140404
Mass, width, and decay constant of the first pion-excitation: a QCD sum rule approach
A Laplace QCD sum rule treatment of the first pion excitation (Π) as a subcontinuum resonance in the pseudoscalar channel is presented. Parameters characterizing this resonance are obtained via a global sum rule fit to the hadronic (π+Π+continuum) content of the appropriate sum rule, incorporating 1) Breit-Wigner departures from the narrow resonance approximation, 2) explicit direct single-instanton contributions, and 3) purely perturbative field-theoretical contributions to two- and three-loop order. The results of this analysis [MΠ=1.15±0.28 GeV, ΓΠ<0.48 GeV, r≡FΠ2MΠ4/fπ2mπ4=4.7±2.8; uncertainties are 90% confidence levels] are consistent with the present empirical range of the Π(1300) mass, and predict a rather large decay constant for this resonance. A by-product of this analysis is the prediction (mu+md)/2=7.7±2.2 MeV for the light quark masses evaluated at an energy scale of 1 GeV.
1549334
Holder inequalities and bounds on the masses of light quarks
Abstract QCD Laplace sum-rules must satisfy a fundamental (Holder) inequality if they are to consistently represent an integrated hadronic cross-section. After subtraction of the pion-pole, the Laplace sum-rule of pion currents is shown to violate this fundamental inequality unless the u and d quark masses (respectively denoted by m u and m d ) are sufficiently large, placing a lower bound on the 1 eV MS running masses.
121012513
Broad sub-continuum resonances and the case for finite-energy sum-rules
Abstract. There is a need to go beyond the narrow resonance approximation for QCD sum-rule channels which are likely to exhibit sensitivity to broad resonance structures. We discuss how the first two Laplace sum rules are altered when one goes beyond the narrow resonance approximation to include possible subcontinuum resonances with nonzero widths. We show that the corresponding first two finite energy sum rules are insensitive to the widths of such resonances, provided their peaks are symmetric and entirely below the continuum threshold. We also discuss the reduced sensitivity of the first two finite energy sum rules to higher dimensional condensates, and show these sum rules to be insensitive to dimension 
$> 6$ condensates containing at least one 
$\bar{q}q$ pair. We extract the direct single-instanton contribution to the 
$F_1$ sum rule for the longitudinal component of the axial-vector correlation function from the known single-instanton contribution to the lowest Laplace sum rule for the pseudoscalar channel. Finally, we demonstrate how inclusion of this instanton contribution to the finite-energy sum rule leads to both a lighter quark mass and to more phenomenologically reasonable higher-mass-resonance contributions within the pseudoscalar channel.

120488620
Mass of the scalar glueball. Higher-loop effects in the QCD sum rules
Abstract One-loop gluon condensate (〈 α s G 2 〉) corrections to the 0 ++ glueball correlation function will be used to obtain the leading 〈 α s G 2 〉 behaviour in the unsubtracted QCD sum rules (SR). The influence of these and other higher-loop effects on the scalar glueball will be investigated. Predictions of the 0 ++ mass and coupling are given based on stability criteria of the SR analysis.