Welfare, Competition, Specialization and Growth

In this paper we consider a simple model of horizontal differentiation and derive the closed form solutions for the level of the variables in the decentralized economy and in the social planner case. This enables us to analyze consumers' welfare as a function of the parameter representing market power. We surprisingly find that, when the total labor force is greater than a certain level, the welfare function is an inverted-N shape in the decentralized economy and monotonically decreasing in the centralized economy. This suggests that there is another effect which interacts with market power: the degree of returns to specialization.Closed form solutions; Welfare; Competition; Degree of returns to specialization

Welfare, Competition, Specialization and Growth

In this paper we consider a simple model of horizontal differentiation and derive the closed form solutions for the level of the variables in the decentralized economy and in the social planner case. This enables us to analyze consumers’ welfare as a function of the parameter representing market power. We surprisingly find that, when the total labor force is greater than a certain level, the welfare function is an inverted-N shape in the decentralized economy and monotonically decreasing in the centralized economy. This suggests that there is another effect which interacts with market power: the degree of returns to specialization.Closed form solutions; Welfare; Competition; Degree of returns to specialization

Competition and growth: reinterpreting their relationship

In this paper we modify a standard quality ladder model by assuming that R&D is driven by outsider firms and the winners of the race sell licenses over their patents, instead of entering directly the inter- mediate good sector. As a reward they get the aggregate profit of the industry. Moreover, in the intermediate good sector firms compete à la Cournot and it is assumed that there are spillovers represented by strategic complementarities on costs. Our goal is to prove that there exists an interval of values of the spillover parameter such that the relationship between competition and growth is an inverted-U-shape.quality ladder, Cournot oligopoly, strategic complementarities, competition and growth

Competition and Growth: Reinterpreting their Relationship

In this paper we modify a standard quality ladder model by assuming that R&D is driven by outsider firms and the winners of the race sell licenses over their patents, instead of entering directly the intermediate good sector. As a reward they get the aggregate profit of the industry. Moreover, in the intermediate good sector firms compete à la Cournot and it is assumed that there are spillovers represented by strategic complementarities on costs. We prove that there exists an interval of values of the spillover parameter such that the relationship between competition and growth is an inverted-U-shape

Novel calibrations of virial black hole mass estimators in active galaxies based on X-ray luminosity and optical/NIR emission lines

Accurately weigh the masses of SMBH in AGN is currently possible for only a small group of local and bright broad-line AGN through reverberation mapping (RM). Statistical demographic studies can be carried out considering the empirical scaling relation between the size of the BLR and the AGN optical continuum luminosity. However, there are still biases against low-luminosity or reddened AGN, in which the rest-frame optical radiation can be severely absorbed/diluted by the host and the BLR emission lines could be hard to detect. Our purpose is to widen the applicability of virial-based SE relations to reliably measure the BH masses also for low-luminosity or intermediate/type 2 AGN that are missed by current methodology. We achieve this goal by calibrating virial relations based on unbiased quantities: the hard X-ray luminosities, in the 2-10 keV and 14-195 keV bands, that are less sensitive to galaxy contamination, and the FWHM of the most important rest-frame NIR and optical BLR emission lines. We built a sample of RM AGN having both X-ray luminosity and broad optical/NIR FWHM measurements available in order to calibrate new virial BH mass estimators. We found that the FWHM of the H$\alpha$, H$\beta$ and NIR lines (i.e. Pa$\alpha$, Pa$\beta$ and HeI$\lambda$10830) all correlate each other having negligible or small offsets. This result allowed us to derive virial BH mass estimators based on either the 2-10 keV or 14-195 keV luminosity. We took also into account the recent determination of the different virial coefficients $f$ for pseudo and classical bulges. By splitting the sample according to the bulge type and adopting separate $f$ factors we found that our virial relations predict BH masses of AGN hosted in pseudobulges $\sim$0.5 dex smaller than in classical bulges. Assuming the same average $f$ factor for both populations, a difference of $\sim$0.2 dex is still found.Comment: 11 pages, 2 figures, 4 tables, accepted for publication on A&

RFID: da tecnologia abilitante per l'ottimizzazione dei processi industriali a framework informativo per il raggiungimento dell'operations excellence

2008-11-27Sardegna Ricerche, Edificio 2, Località Piscinamanna 09010 Pula (CA) - ItaliaPrima giornata sulle tecnologie RFID in Sardegn

Black hole masses of tidal disruption event host galaxies

The mass of the central black hole in a galaxy that hosted a tidal disruption event (TDE) is an important parameter in understanding its energetics and dynamics. We present the first homogeneously measured black hole masses of a complete sample of 12 optically/UV selected TDE host galaxies (down to $g_{host}$$\leq$22 mag and $z$=0.37) in the Northern sky. The mass estimates are based on velocity dispersion measurements, performed on late time optical spectroscopic observations. We find black hole masses in the range 3$\times$10$^5$ M$_{\odot}$$\leq$M$_{\rm BH}$$\leq$2$\times$10$^7$ M$_{\odot}$. The TDE host galaxy sample is dominated by low mass black holes ($\sim$10$^6$ M$_{\odot}$), as expected from theoretical predictions. The blackbody peak luminosity of TDEs with M$_{\rm BH}$$\leq$10$^{7.1}$ M$_{\odot}$ is consistent with the Eddington limit of the SMBH, whereas the two TDEs with M$_{\rm BH}$$\geq$10$^{7.1}$ M$_{\odot}$ have peak luminosities below their SMBH Eddington luminosity, in line with the theoretical expectation that the fallback rate for M$_{\rm BH}$$\geq$10$^{7.1}$ M$_{\odot}$ is sub-Eddington. In addition, our observations suggest that TDEs around lower mass black holes evolve faster. These findings corroborate the standard TDE picture in 10$^6$ M$_{\odot}$ black holes. Our results imply an increased tension between observational and theoretical TDE rates. By comparing the blackbody emission radius with theoretical predictions, we conclude that the optical/UV emission is produced in a region consistent with the stream self-intersection radius of shallow encounters, ruling out a compact accretion disk as the direct origin of the blackbody radiation at peak brightness.Comment: 16 pages, 9 figures. Submitted to MNRAS; including minor revisions suggested by the refere

Detection of Faint BLR Components in the Starburst/Seyfert Galaxy NGC 6221 and Measure of the Central BH Mass

In the last decade, using single epoch virial based techniques in the optical band, it has been possible to measure the central black hole mass on large AGN1 samples. However these measurements use the width of the broad line region as a proxy of the virial velocities and are therefore difficult to be carried out on those obscured (type 2) or low luminosity AGN where the nuclear component does not dominate in the optical. Here we present the optical and near infrared spectrum of the starburst/Seyfert galaxy NGC 6221, observed with X-shooter/VLT. Previous observations of NGC 6221 in the X-ray band show an absorbed (N_H=8.5 +/- 0.4 x 10^21 cm^-2) spectrum typical of a type 2 AGN with luminosity log(L_14-195 keV) = 42.05 erg/s, while in the optical band its spectrum is typical of a reddened (A_V=3) starburst. Our deep X-shooter/VLT observations have allowed us to detect faint broad emission in the H_alpha, HeI and Pa_beta lines (FWHM ~1400-2300 km/s) confirming previous studies indicating that NGC 6221 is a reddened starburst galaxy which hosts an AGN. We use the measure of the broad components to provide a first estimate of its central black hole mass (M_BH = 10^(6.6 +/- 0.3) Msol, lambda_Edd=0.01-0.03), obtained using recently calibrated virial relations suitable for moderately obscured (N_H<10^24 cm^-2) AGN.Comment: 13 pages, 3 figures, 1 table. Published in Frontiers in Astronomy and Space Science